Transcript for:
Webinar on Metal Fatigue Analysis Using ANSYS

and welcome to the webinar on metal fatigue analysis using ancest and core design lives just to give a brief introduction about the critique the fitting is the term which is borrowed from the human reaction of the tiredness due to repetitive works because if somebody has been asked to do the same kind of work repeatedly so you'll be getting bored up at doing the same thing so the same is being expressed as fatigue whereas the scene terminology when it is been adopted to materials so materials which are subjected to repeated fluctuating alternating cyclic load tends to develop A peculiar characteristic Behavior which differs fundamentally in certain respect from their usual Behavior understand static loading this unusual behavior due to these cyclic loading in the material is called as the fatigue so here we have a specified that the loads are being repeated fluctuating alternating cycle so when I say repeated it may be the same Lord which is been repeating let us take an example that a tensile load which has been acting from 0 to 50 Newton and again coming back to zero and again going back to 50. that will call it as a repeated loading whereas when you describe it as a punctuating load that type of load which we are going to consider is going to be initially it starts from 0 reaches t a specific value of tensile loading let us take about 20 newtons and again it is going to be subjected to a compressive loading of 10 Newton that means the sense of loading is going to be changed after a certain duration of time and if this is going to be repeating you call such a loads as fluctuating load whereas we also Define it as an alternating cycle that means here the magnitude of the sense of loading are going to be having the same value that means initially starts from 0 goes back to tensile load of 20 Newton turns and again comes back to a compressive load of 20 meter and back to zero so this cyclic loading which is having the same magnitude but reverse sign you call this to be as alternating cyclic block and for all calculation purpose and the empirical relations which are being derived is going to be based on this alternating cyclic load that means it is going to be subjected to a same magnitude but of different sense in one cycle So based on this how exactly the material is going to be behaving and the corresponding mathematical relations are being derived so the critic is a weakening of a material that caused by the repeated applied law and it is a progressive and localized structural damage that occurs in the material is subjected to cycling loading so as we decided that the material which is going to be behaving in a particular manner when static loading severeign as per the Esme standard wedding is a general term used to describe the behavior of the material and the repeated cycle of stress or strain which causes the deterioration of the material that results in the Progressive fracture so when we say fracture fracture which is resulting from fatigue or among the most difficult to foresee because of the condition producing the fatigue are frequently not clearly recognizable but inside the material there may be the initiation of the crack due to the fatigue and ends it is not going to be easy for identifying where exactly the deterioration takes place in the material then we Define the hepatic strength it is the stress required to cause the failure by fatigue in a given number of cycle so at what level of stress when you induce the member the member is going to fail for how many number of Cycles so this facility is going to be induced for that particular number of cycle is what called as the Pedic strength of the material and it is a quantitative relation between the stress range and the number of Cycles to the predict failure then we have the fatigue limit or the endurance limit which is going to be one of the property of the material the stress below which the material never fails no matter how large the number of Cycles then it will never fail at all such a type of material which in which it is induced to a stress level where for any number of Cycles the material does not fail and the value of that particular value of the stress is called as the fatigue limit or the endurance limit materials you call it as the material which is going to be resisting to fitting for infinite life and that is going to be one of the property of the material for all calculation purposes which are available in the standard data handbook or any calculations which we try to perform for the critic life so fatigue life is defined as the number of cycle of a specified stress loading characters it may be repeated fluctuating or alternating but the standard datas which are available for different material the fatigue life is based on the alternating cyclic floor that the material can sustain before failure occurs at a specified nature by most cases the fatigue life is calculated as the number of cycles that a member or a part or a material can sustain a specified specific for the failure occurs that he is going to be the number of Cycles permitted at a specified stress before the material paints by fatigue that means you have a specific value of the stress then calculate for how many number of Cycles it is going to considered before it fails and that you call it as the number of Cycles which it can sustain for a specified value of the stress is what called as the fatigue-like factor member some of the notations and symbols or abbreviations which are being used in the pity life or the fitting analysis we know that usually in the conventional method of design or in any mechanical systems the stresses have been abbreviated in terms of Sigma for the normal stress and toe for the shear stress now to make it a difference from the fatigue analysis parameters in fatigue we try to represent the stress in terms of yes here we try to Define what you call it as the mean stress or myth is the superpost of awesomely dreams this is ASM which is going to be representing Sigma mean which is nothing but the average of the sum of the maximum and the minimums Plus then the stress amplitude is the amplitude of the superposed oscillating stress has been defined as SCA which is nothing but the difference between the maximum and the mean value or it is going to be equal to the average difference between the maximum and the minimum spec induced in the component then the stress range abbreviated as Sr it is the difference between the maximum and the minimum that is going to be equal to the price that's the same amplitude then we also use the terminology in most of the empirical relations which one defined as first ratio and the specificity is nothing but the ratio of the minimum stress to cut off the maximum space and when we had amplitude ratio which is nothing but the ratio of the stress amplitude to the means this now with these notations as I discussed in the beginning when we say fatigue loading we have different types of clothing that is repeated load fluctuating load and often being cyclic lower so in the repeated load you can observe here that it is going to be causing a test hello hello oh yeah sir are you speaking sir or just hold yourself so can I ask you a question please quick question yeah yeah in your first slide you said that you know A peculiar behavior of the material is observed what exactly that peculiar why you are saying it's a peculiar characteristics we'll be discussing later okay okay peculiar behavior in the sense it is going to be at the atomic level how exactly it is going to be behaving okay okay yeah yeah so again when we are trying to represent the repeated load it is going to be either subjected to only tensile loading or the compression loading but there is a variation in the magnitude such a type of floating you call it as a repeated load in which we will be observing that the stress ratio is going to be varying between 0 to Plus 1. whereas in the case of fluctuating load we have the sense of loading changing from one case to the other case as for sometime it is going to be subjected to tensile and for some other period it is going to be subjected to compression so in which it is going to be having the stress ratio which is leading between -1 and 0. whereas in the case of alternating cyclic floor we have that the express ratio is always going to be equal to 1 because the magnitude of the loading or the stresses that are induced in the material is going to be having the same magnitude but different cells and here you one can observe that the mean stress for the repeated load is going to be non-zero it may be either positive or negative depending upon the sense of load which is been acting on the member again in the case of fluctuating load the mean stress is always going to be non-zero again it depends upon the magnitude of the tensile and the compressor is first but it can be either positive or negative whereas in the case of alternating cyclic load it is always going to be zero that is the mean stress and then here you can see that the alternating cyclic floor is going to be the simplified load which can be taken mathematically equivalent to the sinusoidal wave behavior of the loading so therefore most of the key is in the Dynamics are we try to consider the loading to be harmonic and that will specifically simple hormone then in such case the loading behavior is going to be sinusoidally varying and that's the reason so even in the fatigue calculations we take this alternating cyclic load as the standard clothes for all calculation purpose and the standard values which are being determined and available in the data handbooks are being based on alternating cyclic law whether it may be for defining the endurance limit or for defining the number of Cycles or defining the variation of the stress and the number of Cycles to failure which required as acid curve or the same number of Cycles curve there is e and curve all these things are mean based on alternating cycling glow uh here the mechanism of padding is being classified under three mainly one is in the middle and allies we see that there is a localized changes in the atomic structures which begins within the very first few cycle at a scattered point in the material this is what the peculiar Behavior whereas in the static loading it is not going to be changing the localized atomic structures in the static loading it is going to be distributed among the attempts and then all the atoms try to resist the loading whereas in the case of fatigue loading the way the stress distribution across the thickness are going to be different and thereby the weakest atom is going to be behaving in a different way when compared to the strongest atom and this weakness atom is prone for the initiation of the crack now then these uh so develops into a Microsoft microscopic cracks which grows as the cycle loading continues and finally when the crack grows to some critical size at which the remaining of the material cross section area cannot resist the given loading condition the member breaks so these piece pages of the fatigue is referred as the nucleation or the track initiation and then the crack growth and then the fracture so here to describe this initially we have the figure first figure again in which we see that there is a atomic or the green which is very close to the boundary which is the weakest one because the inner grains may be having the adjacent atoms and it may be strong but the greens or the atoms which are nearer to the surface are prone for the weakest atom so at this particular atom as the loading is going to be cyclically loaded so the bond between thus due to the frictional resistance there may be some slippage occurring between the bond and this slippage has been causing the orientations of the green structures and other things in a different fashion as the loading increases these clip planes keeps on increasing and we can see here some of the slip planes which are precluding outside and some of the slip planes are including inside that means these slip planes which are precluding out are called as extruders and these planes which are inside the materials are called as Intruders and these Intruders planes makes the cross-section area of the member to be minimum and that is going to be the again the weakest plane which it can resist the loading and this is the clean at which the initiation of the crack is going to be starting which is being shown in this figure where you have at many different planes there is the slipping whereas the weakest plane at which the slip is going to be more that is where the initiation of the cracks starts and then in the second state the crack tends to grow and in the third stage when it cannot resist it is going to be paining now here you can see that the initial initiation of the crack is going to be taking some time and the growing of the crack is going to be taking some time which are going to be slow and as the behavior of the material in the first and the second state that he is at the nucleation and the crack growing stage the beer appearing to be ductile behavior and you can see in the sketches and also some of the calm components that are being experimentally carried out and shown as the photographs these are having the very fine grain structure in which the behavior up till it reaches a critical crack is going to be ductile failure and as soon as reaches a critical length of the crack then it is going to cause the critical failure and this is being shown together the trails are the initiation of the track and the crack propagations will be slow and it's going to be done in behaving as so it is a Time material but once it has reaches a critical crackling then sudden rupture occurs it is going to be breaking in nature that knowing this to study the behavior of the material one should know how exactly the stresses it is going to be induced in the member is going to be wearing as the number of Cycles are really increased and from this one will be getting that when the members have been loaded at different stress levels how many number of Cycles he can sustain that is what is going to be the number of Cycles which the material can sustain for a specified value of stress is what important so for every material when it is being subjected to a specific value or stress you will be getting a specific value of number of Cycles like that when the member is being subjected to different stress conditions we get the different life of the member and the plot which is going to be plotted for the level of the stress which is induced in a member so that that's the number of Cycles which it can sustain is called as the endurance curve or the endurance graph or indolence curves or the graph showing the applied stress amplitude as a function of the number of River Cycles to train your to credit these girls are also been known as the inventor of this curve pullers and these are also being defined as the ruler store the most common procedure for generating the stressful number of Cycles data is the rotating bending test now these stress uses the four point bending test which is going to be considered to be as a simple member he is going to be subjected to uniform pending to others the specimen is being assumed whatever which has been considered for the testing is something to be depicted at this phase and the stresses which is going to be induced in the member is going to be calculated based on the elastic beam Theory given by the beam equation where the stress in use is going to be equal to the movement which it causes sorry gives us the stress into the distance of the October most fiber from the neutral axis divided by the initial the DC area movement of inertia right are plotted with the Cycles to pay near or the horizontal axis and the stress amplitude on the vertical axis uh since the number of Cycles which you are going to consider is going to be sometimes going Beyond millions of number of sectors in the conventional graph when we try to plot that it is going to be a two conversion process instead of that we try to plot in terms of logarithmic scale so that large amount of data can be shown on the graph using the logarithmic scale and thus the ascent curve represents the mean stress that us that is the stress to the number of cycle test datas are usually presented on a logarithmic scale and this slight relationship which is going to be approximated as his pipeline or a large range of endurance yes even though the curve which you are going to obtain in the actual case it may be of a different variation but when it is converted into logarithm scale can be converted to be as a linear variation thus the ascent curve is obtained by conducting several rotating bending fatigue tests now the specimen is voted to create a certain level of stress and rotated until it fractures so that you'll be getting one particular data like that number of tests has to be conducted now when the specimen fractures the level of stress applied yes and the number of Cycles two factors are noted and this will give you one point on the Curve here you can see that the standard specimen which is being used to see or circular specimen of a specific diameter which is been mounted on two varying house and this is being put on to the Loading fixture which is being loaded in such a way that it is going to cause a pure bending within the gauge length of the member and this has been connected with a flexible coupling which in turn is connected to the high speed motor which can be used for conducting the experiment and along with that you have the counter which is been giving us the number of rotations the motor is going to be running but the setup is being done in such a way that the circuit is being linked to the counter and as soon as the specimen breaks the motor stops and thereby the number of Cycles with it as taker is also going to be counted off now the results of the tests are represented by a point on this curve that's a different stress level from Ultimate strength down the a very low stress value with the corresponding cycle to fracture pH multiples of test points for constructing the SN curve now the expressway the curve becomes asymptotic or horizontal line is determined as an endurance strength of the material so here you can observe that most of the metals it is going to be subjected to the fatigue loading is going to be behaving in this particular fashion in which we see that initially when it is being subjected to an ultimate tensile strength and up to the yield stress most of the time or sometimes at Point times T ultimate strength of the material the material is going to be behaving in a systematic manner in which it has a specific slope so after reaching a specific value of the stress level and that is going to be behaving with a different slope and then after reaching to a specific value where the material is subjected to a stress level Which is less than this is going to be observing that the number of Cycles are going to be the same that means it is going to be having infinite life the value at which you have the asymptotic line that is the curve which is going to be parallel to the horizontal axis and that is the location at which the stress is considered to be as the endurance limit or the endurance strength of the material now here we have two slopes in the very first stage then when it is being subjected to a high stress value where it started from there an Ultimate strength to a point eight times ultimates and are usually and sometimes you will also treating that up till the yield stress the mental behavior is going to be different having a different slope and that particular region you call that to be as low cycle petting or in a standardized sense we observe that any material which is going to be failing before thousand number of Cycles before thousand number of Cycles we call such a type of behavior as a low Psychopathic Behavior so any material which is going to be sustaining more than 1000 number of Cycles but within 10 raised to the power of six number of cycles that is nearly about 10 million cycle so if it is going to be within the train then we Define the behavior of the material to be as a high cycle fitting so anything which is going to be more than 10 raised to the power of six number of Cycles is being called as material which has infinite life so up till 10 number of six number of Cycles or ten number 10 to the power of seven number of Cycles nowadays everybody expects a little bit more that is obtaining 10 days for a seventh cycle temperature for seven Cycles to be as the limit at which the endurance band is considered after that you hold up to be as a finite life anything which is going to be sustaining more than that is going to be in finite life now in the finite life where the number of Cycles is going to be less than 10 raised to the power of 6 can be bifurcated into two times one is the low cycle Pedic which has a number of Cycles less than thousand number of Cycles the other one is between 1000 to 10 raised to the power of six number of Cycles we call that as high cycle Pedic anything which is going to be sustaining more than 10 raised over six Cycles we call it as in finite life thus here the fitting is considered as a High cycle when the peak stress in the material are held within elastic limit while the low cycle fatigue occurs when the stresses are above elastic limit so again here the low cycle fitting will be treated in a different Manner and the high cycle trading will be treated in different manner which will be discussing the later on Steam now the mathematical representation of the essential as you have classified as a low cycle and high Psychopathic region which has been bifurcating by which is going to be varying from material to material depending upon the tensile properties of the material so the main interest in the engineering design is for a high cycle region that is essential which is being treated in the high cycle region where the member is being subjected to the stress level within elastic limit however the low cycle predict can be advantages only when a short Lifeline is required refers to the ultimate tensile strength that is the stress value which is equal to the ultimate tensile strength while the endurance strength AC is taken to be as 0.5 times ultimate strength of the material which is going to be usually sustaining a number of Cycles it is equal to 10 rational plus six cycle now the stress amplitude is about 0.8 times the ultimate strength by which the high cycle fatigue starts that is when the stressors are going to be within elastic limit then the high cycle fatigue is going to be stuck thereby the correlation between the stress from the number of Cycles in the high cycle fitting a region where the number of Cycles is greater than 10 raised to the power of 3 and less than temperature for rough six can be obtained which are being derived of by the mathematical equations which gives you the equation of a strike line Y is equal to m x plus c and the same thing replacing y by this first and X Y the number of Cycles one can write this to be as s equal to M into n plus c by considering the logarithm this can be expressed as log of s equal to M into log n plus C or S is equal to 10 degrees C into n base to the power of M or the number of Cycles which the material can sustain can be obtained as 10 raised to the power of minus C by m into s to the power of 1 by m where m is the slope of the curve in the high cycle fatigue region given by minus of 1 by 3 into log of 0.8 of ultimate tensile strength to the internal Sun and C is The Intercept of the high cycle pedicure with the vertical axis and that is being found to be of log of Point D of ultimate tensile Center Square divided by the entire strength of the material now there are four major factors that affect the Pedic life of the component are a part those are the loading and the loading cycle or the cyclic specific and the second is the surface condition and the third one is the design concentration and then the natural environment which causes the fatigue life to deteriorate now depending on the upon the complexity of the geometry and the loading one or more properties of the stress State need to be considered such as the stress amplitude or the mean stress or the range of stress the stress ratio or the way in which the stresses are acting as a uniaxial or a biaxial or multi-action cpts multi-action whether it is Hill Pace or outer face or whether it is going to cause some shear stress and the way in which the loadings are being acting the sequence of loading all these things are going to be affecting the padding light of the component now here we did the load Factor affecting the petting lines are one is the maximum tensile stress of sufficiently high value and there is there is a large amount of variation or fluctuation in the applied stresses or a sufficiently large number of cycles of the applied sources so here we see these effects when we are trying to plot Restless amplitude to the number of Cycles where the mean stress is going to be the playing the key role because we see that whenever the loading is going to be alternating lower the mean stress is zero whereas other two cases where it is going to be fluctuating load or alternating lower then in such cases it is going to be having a a non-zero means plus so on the mean stress when we take that if M three is going to be greater than M2 and M2 is going to be greater than M1 that means M1 is going to be minimum M2 intermediate nm3 is higher balance and when you have the mean stress when it is plotted versus the stress amplitude to the number of cycles and you can observe that here for the same value of the stress amplitude let us assume that if the stress amplitude is of 150 Mega Pascal and we can see that when the mean stress says of M3 Sigma m 3 the life which you are going to get is going to be 1 to the power of 10 6 or 7. whereas for the same stress if the mean stress e is equal to Sigma m 2 the life phase increase for the same stress level the life is going to be different band so this is how then predict alive which is going to have the effect which is mainly depending on the value of the mean space and again the type of loading one can see that if the mean stress is of tension in nature the stress amplitude to the number of Cycles is going to be very less if the mean stress is going to be zero whereas in the mean stress is compressive it has an advantage now you can see that at a specific value of the stress amplitude you have three different failure values in which by the means this is tension that gives you a less number of Cycles when the mean stress is zero it is intermediate and the mean stress is compressive it is going to be giving a high cycle 12 billion so that's the reason one of the advantage of having the in our inducing a residual compressive stress in the member as an advantage for the fitting life of the component and we see nowadays many lot of research which is going on for inducing the compressive residual stress in the component so as we enhance the pity life of the component say from this figure one can see that how many days the mean stress is going to be compression the petite life is being increased then based on the surface condition how the effective life is going to have an effect the first is the surface condition hardness hardness of the surface are enhanced by the heat treatment process but should avoid stress concentration due to the heat treatment then the roughness so how graph this or how smooth the surface is because we have seen that almost most of the components when it is being subjected to the petty glow it is at the outermost surface the weakest of grains are the weakest atoms are being prone for the initiation of the crack and thereby the roughness is going to be playing the key role in the spreading life of the company so pretty life of a structure is highly dependent on the surface quality and there is a quantitative relation between the Surface roughness Sunday fatigue like and then all these suppose the residual stresses which can be beneficial or determinant depending upon whether the stress is compressive or tensile if it is compressive it is beneficial if it is competenciled it is going to be determinant that means a potential residual stresses induced in the component then the life of the component can be expected to be very low or it is going to be less if it is subjected to residual compressors plus one can enhance the uh static life of the component then the material when we consider the design concentration as we all know that in the design the first and the foremost thing which you look at the selection of the material so I under the selection of the material again we try to see that how the grain structures and the distributions and is there any defects in that all those things are to be looked upon and then in the design aspect when we look at how exactly the geometry of the member has to be designed such that as far as possible one has to avoid sharp Darkness or notches try to provide certain fillets and instead of sharp partners and thereby by providing the geometrical descriptions appropriately without any sharp Partners or nurtures and by providing the fillet one can enhance the fatigue life of the component and also in the design consideration one has to look about the environmental condition which causes the corrosion erosion or enbridgement of which is having an effect on the fatigue life then again the temperature of the working environment because extreme high or low temperature can decrease the fatigue expense as you all know that the thermal fatigue occurs in the material is subjected to higher low temperature variation there is a fluctuation in the temperature which usually called as thermal loading and that is going to be called as a thermal pity and this thermal fatigue conditions uh enhances or as the effect on the fatigue life of the component so for taking into consideration of these things one has to see how the endurance occur or the particular limit or the endurance element can be modified because the ascent curve whatever which we have drawn is going to be for an ideal condition which is available in the standards but if all these factors which affects the fatigue life is also taken into account then in such case we have to see how the different habit is going to be different from that of the the standard Isn Club so most commonly used specimen for fatigue analysis test in the laboratory or the rotating beam specimen which are prepared very carefully and testified very closely controlled condition now it is unrealistic to expect the same endurance limit of an actual mechanical or a structural member to match the result determined in the laboratory so here we see that we cannot say that always it is going to be our presented specimens the components are going to have a different shape different materials all those things so the some of the things which are to be considered is material whether the composition is going to be similar to that of the standard test specimen which is going to be the basics for the failure and the variability involved in the material how the material is going to be behaving all those things and the way in which the product is manufactured the method which is been adopted for manufacturing the heat treatment which is being given and operating corrosion surface conditions and stress concentrations which is been causing during the manufacturing has to be taken into account to make some modifications in the fatigue life of the company not only that even the environments which has an impact of the corrosion which is going to we are causing due to the chemical effect or if there is a variation in the temperature the behavior of the material is going to be totally different and the way in which the stress States conditions and the relaxation time for the special actuation and other things as in the case of creep where a constant stress which is been acting for a long duration of time may also pass the period of the component so these things should also be taken into account when it comes to the design aspects or the size the shape Reliance sustain the stress concentration and the speed that is the rate at which the loading has been occurred and if there is any friction between the parts of those things have to be taken into account and these factors ought to be incorporated into the behavior of the material so for all this conditions Marine identified the factors that quantify the effect of surface conditions size loading temperature and other miscellaneous items so the most prominence given to the fatigue testing was to gain an empirical understanding of the effect of various factors on the Baseline standard Essence curves which are available in the data handbooks for most of these standards material so if for any other materials other than the standards then one has to look into this aspect so Marine equation is therefore written for the fatigue limit of emission Parts as the endurance strength AC is going to be ke k b k c k d k e k f ntse Dash are going to be the modification factors due to various reach condition and you see that she is nothing but the endurance strength of that particular material under the standard the specimen for the rotating bending bedding limit so Ka is the surface condition modification Factor KB is a size modification Factor KC is the load modification but KD is the temperature modification Factor K is a relative Factor km is the miscellaneous modification Factor now when they enter in space of the parts are not available then the estimation of the place of the component can be made by using different factors to predict the endurance limit of the component so that is taken by one that the effect of surface finish Factor ke now the surface modification Factor Ka depends on the quality of the finish of the actual part and on the tensile strength of the part material now put to quantify the expression of a common finish a machine part or a grounded machine or a cold run or a hot rod or a force part the coordinates of the data points were recaptured from a plot of endurance limit versus the ultimate tensile strength and the data are being represented by k e equal to a into s u to B where s u 2 is the minimum tensile strength and a and b are the constants to be determined which depends on the type of surface finish usually given in the standard data handbook thus the size Factor has been evaluated using 133 setup data fine and the results for the bending and torsions may be expressed as KB is equal to 1.24 into D to the power of minus 0 1 0 7 for the members which is having the diameter of the specimen to be varying from point to 0.79 and less than 51 mm KB is going to be 1.51 into D to the power of minus of 0.157 for the diameter of the member which lies between 51 and 254 mm and for the axial loading more size effect is there so KV is second degree as one so what do we do when the round bar is bending is not rotating or when the bar is considered to be non-circular cross sections are being used so the approach to consider the effective Dimensions D is obtained by equating the volume of the material which is being stress at 10 above 95 percent of the maximum stress of the same volume in the rotating beam specimen now in these two volumes are equated they are length cancels and so that we consider only the area having outer diameter D and an inside diameter of point of nine Pi diameter so designating the 95 percent of the stress area as e equal to 0.9 Pi Sigma then we have the 95 percent area which is going to be equal to Pi into d square minus 0.95 d square by 4 and that is going to be equal to 0.0766 d square now this equation also valid for a rotating Hollow circular cross section not only bending and this is for the standard specimen now they say you are going to take it and equate it to the equivalent area for another kind of specimen which is not of circular shape or which is not rotating or which is not depending so for a non-rotating solid or a circular cross section the 95 percent stress area is twice the area outside of the two panel cars having this facing of 0.95 diameter where D is the diameter Now using the exact computation this gives you the 95 percent area stress induced area as point zero one zero four sensor d square uh where the D in equation 1 and setting this equation 2 equal to each other and solving for D we get the equivalent diameter equal to 0.37 times the diameter of the axial specimen which you are going to use and this is what here it is being shown if it is not solid if it is a hollow so when I say look about the 95 percent area what is the specific skin use we calculate this and if it is going to be other than circular let us say rectangular cross section for which the cross section area is a p into T and the 95 percent of the maximum stress which is induced is going to be this Now using this new compare with the standard diameters we get e is equal to 0.808 root of 15. so these Dimensions can be taken for evaluating the factors affecting the size then the load Factor so when The Vedic tests are carried out with axial pull and push or rotating bending and torsion bloating the endurance limit differs because in the case of Standards specimen it has been subjected to rotating when bending both now the ratio of the endurance limit ranges from 0.7 to 0.9 thus AC that is axial is going to be varying from 0.7 to 0.9 times the ultimate that is endurance limit of the standard testing special one and thus KC becomes 0.85 usually it has been taken as average for axial loading now the ratio of the endurance limit for using and rotating bending test range from 0.5 to 0.6 that is when you take it only for thousand and it is going to be usually considered to be varying between 0.5 to 0.6 times the entrance limit which is a stand for based on the standard testing so the average value KC is taken to be 0.59 the average load factor for bending usually considered to be equal to one that is because of it is similar to that of the testing condition then the temperature Factor KDE is going to be so whenever the operating temperatures are below room temperatures we find that the pretty fracture is the strong possibility and that should be investigated to us but when the operating temperatures are higher than the room temperature yielding should be investigated first because the yielding strength drops rapidly with the temperature so any thermal stress will also induce peep in the material when the operating temperature at the High characters so that these factors have to be taken into account now defining the load Factor KD as the ratio of the strength of the operating temperature to the center of the root temperature thus KD is equal to Sut divided by s u r t the temperature is going to be KD into the endurance limit at the room temperature now the relative factor a which is going to be based on a reference rate as soft from the standard specimen and the estimation of the real Beauty factor is completely based on the assumptions that the scatters are scattered or approximated by the normal or the statistical probabilities or density distribution so taking the miscellaneous effect other than what all the things that you have not considered all those things is taken as effective miscellaneous factor which is KM is intended to account for the reduction in the entrance limit due to all other effects it is really intended that these must be accounted for Because the actual value of KF are not always available as in the case of stress concentration or non-sensitivity or residual stress or when it is a metal to grow spring due to that chemical effects or corrosion or due to cyclic frequencies or electroplating whatever it may be the case then this effect is going to be taken into account so when we try to take all these factors and try to modify the essential so the modified SN curve which is being plotted for the space amplitude versus the number of Cycles to failure is being taken into account and you can see here the endurance fantasy is going to be a c Dash k e a k b k c k d k e d and this is the endurance strength after taking into all the factors into account and this is going to always be a little bit lesser than the actual endurance band of the material let us see how the fatigue life query is going to be predicted now the fitting failure were developed to characterize the importance of Pedic recyclic loading which is being cast up in the right way Lord which has been observed by ruler's past so he carried out an experimental for a rotating bending test on various Alloys and an empirical relations were being developed and that is what which we call it as endurance curve or also called as Hulu's flow now the prediction of the fitting life has an outstanding importance and must be considered during the first step of the design of any component or a part the engineers have used many methods to determine the fitting life of the material among them the four methods are vital used in today's industry one is the slip method or a top line or which we call it as SN approach then the sign life method are called as track initiation or en approach then the third one is the crack growth method which is also called as fatigue life prediction by infection mechanics approach and the fourth is the probabilistic method which can be used on either light path or the current growth or the combination of all these things and the probabilistic way of for predicting the fatigue life is the probabilistic method so the first slave method or the top life or SN approach another endurance curve which relates the stress amplitude to the endurance or generalized to make more widely applicable so there are three main areas which has been generalized those are to allow the constant stress amplitude endurance curve to be used to analyze complex stress history and then to allow the endurance curve drawn from a smooth surface the specimen to be used with a different shape of the component or to allow the endurance were established by testing one material to be used to the calculate the fatigue life of another material and if possible to estimate the life properties of a material without performing the fatigue test so in these three ways one can just consider the standard essential and try to implement for the analysis or carrying out or predicting the effective life of the component so in the stress life approach shot the rules curves which are being considered and based on that task and proposed a mathematical equation to represent the part of the ascent talk specifically in the high cycle critic region where the number of sectors is more than thousand cycle and less than 10 raised to the power of six cycle and that has been related as s r equal to a into n to the power B where Sr is alternating reversing reversing size stress which will give the fatigue life of n cycles for greater than thousand number of cycles and less than 10 days across six seconds and a and b are the material constants without to be determined so taking the logarithms of these three equations we get the log of s r equal to log a plus b log n now for a small number of specifications let us say that when it is having the intermediate between the low cycle Pedic and the recycle fatigue where the number of second is taken to be as thousand number of cycle where we consider that to be equal to the stress level which is going to be induced in the component as 0.8 or 0.9 times the ultimate strength of the material thus at n equal to thousand number of Cycles s r is either 0.8 or 0.9 here I have taken both the cases and substituted that value and we will be getting 4.9 times the automation this equation or when it is 0.8 this is the equation for the uh stress I induced and the number of Cycles relating the constants A and B now we know that that the when the number of Cycles is 10 raises for six cycle that is where the limit of the stress or the stress it is induced is colored as the endurance Plus and substituting the endurance stress at that value we get the expression as log of AC equal to log a plus of B into 10 raised to the Power log of 10 raised to the power of 6 or it is log AC into log a plus 6B now while calculating these two and taking the previous equation and subtracting one can get the constants A and B so B is going to be given by this expression and E is between P by a defining this expression now knowing A and B and using the equation for the by the brassman s r equal to a into n power B one can clearly plot the S and curve and also determine the number of Cycles to failure occurs for the specified stress range knowing A and B this is a usually mathematically we calculate so here we have taken the calculations for three different cases for bending action and torsion and we can see that the torsion is going to be having giving us less taking into effect all these factors so the standard values which are being considered for the indirect stress serving specified now similarly for other materials say if you are specified to consider the endurance length of the material which is going to be now another thing which is going to be key in the stress life approach is the stress concentration as we all know that the quantitative evidence for the stress concentration excuse me yeah yeah can you just go back to the previous slide these are all available in the standards okay I just want to ask you that you know uh what is the for steels for steel what do you take uh the endurance strength uh correction that body based on the modification factors um so by what factor do you reduce the uh uh you know this Factor no 0.52 Su is there no so there how much is the factor you can consider by considering all those surface finish factors and all those factors which we discussed so what is the value that you recommend here for steel no that has to be looked upon which is the factor which you are going to consider and we discuss what is the value factors which you are going to consider take up yeah those things are to be incorporated here this is going to be reducing yeah so what what is the recommendation value because 0.35 and all is still very conservative which will generally not uh yeah these are not the standards and these are to be considered as the standards and the factors it's affecting the fatigue lives are to be incorporated here and then based on that which factors are going to be prone and which is the most important those are the factors which are to be taken into account this is going to be varying from 10 to 20 variations are will be there taking all the factors into account on either side 10 to 20 percent hmm okay I have one question one more question for you okay um so we derive the endurance stress by all those things uh but you know we have some value for the endurance stress let us assume that we take is a 0.4 percent of the ultimate strength and we get some Factor there and is it possible that you know a material will still have a finite life uh if the number of loadings whatever you have number of load is very high we are having a repeated loadings are very high but the stresses below the endurance strength whatever we have derived is it possible that the material can still have a finite life yeah definitely because it also depends on the magnitude of the stress induced in that and the way the sequence in which it is going to be and the speed at which it is going to be acting you know uh what I mean to say is our stress is not very high or it is below the endurance and whatever we have derived the engine strength based on that it is the slide below that second thing is uh if the loading number of you know blocks that you have for the loading is very high is it possible that this stress will uh you know you you get a damage which is you know which will have finite number of life that is what is my question because the endurance strength whatever which is being given according to the standards is been based on the alternating stress cycle and on the standard specimen but in the actual situation the specimen is not is what which you are testing the actual component has a different geometry different material different loading conditions all those things so when you even for a simple example the loading the loadings will never be always having the same amplitude for some number of Cycles the loading is going to be having a specific range and after a certain duration of time the range may be changing when the rain changes shifter the behavior of the material is also going to be affecting the fitting line okay okay because because when we see that the third approach that is the crack growth approach in which we adopt the fracture mechanics approach so in the fracture mechanics the crack growth is depending on the previous load history so previous cycle how the Lord was so whenever there is a change in the load history then the variation in the stresses are going to be too critical okay it is going to be a function of load stream that is one example which I am giving and again you cannot say that it is going to be always having the same amplitude you know each and every cycle so if the variations of the loading is random in nature then we have to adopt these statistical methods to make it a band a narrow band of uh datas which are to be calculated for treating that number of cycles and the variable frequency amplitude cost you have a separate this thing we have to adopt that and then make it as a equivalent constant amplitude bands and then calculate the values so all these things without the effect even though it is stress Beyond below the yield that is strength of the material okay okay so that is what because recently we came across one situation maybe I'll discuss with you separately online okay yeah thank you so the notch effects is going to be very critical so as we know that the stress concentration is what which is been considered in the Statics design whereas when it comes when the loads are going to be cyclic then we have to look into the stressa concentration Factor due to fatigue so how we Define the stress concentration in the static analysis which is given the ratio of the maximum stress to nominal stress similarly the fatigue loading Factor KF is defined as the peak stress to the nominal stress so with this we have the not sensitive effect Q defined by K of minus 1 divided by KT minus 1. where the Mass Effect is being taken into account here and one can see that the notch factors are KF is going to be the specific is going to be induced for the yield with a smooth specimen to that of the non-spacing based on that one can determine what is going to be the value of the stress static Factor empirical relations which are being derived so this relationship was being considered and when one can get the what is going to be the particular concentration Factor KF then we have the screen life for method and this has been widely used for the low circle fatigue so where the highest stresses have been induced in that and coffin and Mason were the first people who arrived at the effect of high stresses task due to the thermal petting and they developed the plastic stress pain relation and they noted that the logarithm of the plastic strain amplitude which has been plotted against the number of floating reversing cycle relating the increment in the plastic spine relating to the number of Cycles now here you can see that the how the variations are of the stress distribution and the there will be some amount of stress or the string which is in the plastic Zone and in the elastic Zone so the total amount of strain in use in that is going to be partially elastic and partially plastic and these are being related and then arrive at the the first two number of Cycles curve where we have the resultant Accenture which has been plotted by considering independently the elastic Behavior and the plastic Behavior so the elastic behavior of the material is heated here which is going to have the slope which is going to be equal to B whereas the plastic behavior of the curve is being plotted here which is going to be having the slope C now the resultant of this is going to be the actual behavior of the material in the highly special component treated under the Spain increment as the Spain approach so I hope you can observe that in the region which is having the number of Cycles less than enough that is at which the interaction between the intersection of the elastic nature Behavior and the plastic nature behavior is going to be within this it is going to be the plastic status frame is going to be causing mainly for the Pedic period whereas anything which is going to be having the number of Cycles greater than NF Beyond this it is going to be the elastic portion of the spine which is going to cause the Pedic failure and the number of Cycles for failure is related with the specific and eggs modulus with the constant which are the slopes of this curve then in the fracture mechanics approach it is going to be for the crank growth because Paris is the first person will reduce the fracture mechanics and proud to be as an useful tool for the fatigue crack growth and since then this structural mechanics approach has been used to analyze the fatigue life of the comp Prime the method and the procedure for the analysis of the constant amplitude fatigue and the small scale leading condition that the connectives are fairly well established but although the number of uncertainty remains this is what year it is the variable amplitude loading large scale plasticity shortcrack interjection added complexity and not fully understood even today so I hear similitude that means comparison between the two who are actual case and the predicted one and the correct tips are going to be taken into account so these things are being taken and then analyzes and see how exactly the presence of a constant amplitude stress cycle and the plastic sum which is going to be developed at the tip of the cycle is taken into account in which you have the maximum Mass space intensity factor and the minimum stress intensity factor and the rate at which the current growth is given by D A by DN and here it is going to be found that it is a function of the range of stress intensity factor and the ratio of the stress intensity factor now here when it is this is for a constant amplitude if it is a variable amplitude then the load history of the previous cycle is also going to be one of the function now if you assume that it has a constant amplitude for a constant amplitude cycle then the number of cycles per failure has been taken by integrating this and that can be determined to be as n is equal to the integral of d a by FN of Delta K into R within the limit from a naught to a f where a naught is the initial crackling which has been developed and AF is the final curriculum so with this one can determine how exactly the crack is going to be growing and when the failure is going to be occurring now this is what you should call it as assembly to curve a typical fatty crack growth Behavior in which it has three region first regions second and third the first and the third region are of not of most important in the high cycle trading it is the second region is more important and based on this we see that there is a linear variation Cyclone is there and this is being used for the prediction of the fatigue life most of the empirical relations are based on this so here I have listed some of them since time is getting shot and just uh go to this stuff the different class and the different empirical relations for calculating the rate at which the current growth with the number of Cycles are being specified and among these equations any one of those can be used depending upon the type of application and other things so here all the equations are strictly valid only for constant amplitude loading now each of the equation one to seven can be integrated to estimate the critic life of the component and the most generally is the petty crack growth model containing the material constant CM K critical and trade threshold so the threshold stress intensity factor range is again going to be another important in the predicting the fatigue life of the component by using the fracture mechanics approach and also it depends on the ratio of the stress intensity factor that is K minimum to K minus any questions any questions yeah I think we can proceed further thanks uh to Dr Jagdish uh there is a course on metal fatigue uh at virtual engineering you can browse it through and then you can take up the post we will send you the details uh post this uh interaction so uh moving forward there are three uh different uh topics we'll be covering one is just to uh introducing the Deo research and then we have metal fatigue analysis using ansys mechanical as a standalone tool and using encode as an design Life as a special code for metal fatigue analysis okay so myself Santosh I'll just uh brief about uh the jio research thing in five minutes time uh then we will get into my colleague arvind will demonstrate the how to calculate or the capabilities within ansys mechanical workbench with a fatigue tool the water the facilities available and how to calculate the metal fatigue life within K cell and then I will demonstrate a small workflow for encode design Life For Life fatigue analysis part encode design life has lot of features and lot of applications things we will be having coming out with subsequent webinars or the workshops in the future test to cover all of them today we will cover most of the workflow pattern for it so in continuation uh we would like to introduce our company which is deo research and Engineering private limited it's a 12 year old company predominantly on analysis segments so we work on structural mechanics computational fluid dynamics the manufacturing aspect thermal hydraulic material modeling and simulation then the piping pressure vessels and so on so about 40 people team 11 Consultants working in Bangalore we have office in rajajinagar Bangalore so major activity uh here is on the structural mechanics if you look at we work on all the complete range of the non-linear fvm part whether it is static to Dynamic to linear to non-linear to Thermal explicit implicit so that's our starting point for all the activity and then we work on fatigue durability and Fracture mechanics and that's uh our Force strength uh not just the metal fatigue even we work on polymorph fatigue like assessing the life of elastomers polymers or it can be tired or rubber Bush or any of the elastomeric material and inside the load measurement because your standard equipment standard operations you will get the load from the standard standard handbook or the measured part but when it comes to off-road kind of vehicles or nothing the load is becomes a very critical so or developing a duty cycle which is required for the metal fatigue or the fatigue evaluation or followed by a fracture mechanics part so we have been evaluated for various uh structural Integrity assessment with rla studies and so on and we also go simulate manufacturing process simulation and computational fluid dynamics at a system level component level mesh free method and discrete element similarly we characterize the material for different aspects from the atomic level to macro level of applications part and for all the kind of mechanical and other equipments uh we do a Consulting r d sell some of the softwares which are very Niche area applications based things and then we also do a training activity where you can reach out to our virtual engineering there are a lot of physics based as well as code based uh software Based training programs are happening so this is our total solutions for the fatigue or structural Integrity studies uh the everything starts with an ansys space claim where you start modeling the cad model or from the measured data from different segments like for example scan data or uh the lasers different the measured data once the cad is prepared then we move on to the like FM preparation we work with answers uh then also for other ports for the fem evaluation then it comes to the fatigue when the fatigue there are three aspects which is majorly looked at one is the material data we where we can test it and to the material data the other one is a load curve we work on true load true load isn't software developed by Worldstar Technologies in us which works very integrated way with tobaccus lens ansys and other ports and it can have a correlation between the physical measure data and simulated to develop and duty cycle uh for the fatigue and you know the loads curve for the fem part in the metal fatigue we work on encode and encode is uh for the detailed metal fatigue evaluations a different kind of fatigues it can evaluation it can handle especially on the like weld fatigue vibration fatty Thermo mechanical creep fitting interactions uh the other segments where the physics Orthopedic is getting changed so that is capable of handling with the encode design like we will look into the basic introduction today and then subsequently on different physics then comes is the elastomer or rubber fatigue where we work with endurika and dendorica is a very specialized code for handling the uh the like polymeric material fatigue which is little different from the metal fatigue applications part and then we move on to the next stage where the fatigue will definitely all of us know that it will handle up to the crack initiation number of Cycles for crack inciation once the crack is initiated introducing the crack and further doing the fracture mechanic simulation we work with Frank 3D Frank 3D is a 3D crack growth simulation works on M integral based approach as well as the displacement correlation method or the J integral based approach we also have a probabilistic approach because Frank thread is a more deterministic approach where you get in one uh if the crack introduced and the crack propagation part where the animal is coming from the manufacturing and other aspects are not uh specifically handled which will go with and Darwin the organism swi type developed software which is Southwest research used to develop software all of this works with an ansys ecosystem and to handle the from the conceptual design to up to the fracture or the failure applications there's a partial list of customers we serve from defense to public sectors to oems different oems and around 800 plus customers we served in last 12 years and also worked very closely with all the iits and Associated academic institutions on different physics solving and other aspects uh this is our technical presence and Publications where we have published paper with damage tolerance studies for remaining life of an turbine generator of hydro shaft in the with cpri as well as with IG car and ISC and the other organizations uh I think some couple of you may be familiar with our conferences which is coming in I mean which typically happens every year but due to covet to after 2019 it is not the 2024 it will be in the March April time uh the International Conference where you see 500 to 600 people attend and there will be an expert uh joining and Springer is being our publishing partners and we also have very dedicated training programs keep on conducting and you can just please be part of the things we'll share the detail to studies for the different this is the overnight trained structure of a reclaimer and similarly we have executed around 300 projects uh more than 300 projects because our area of application is very Niche and we are only into the analysis segment this is just to introduce our company into the things we have been working in fatigue and Fracture for quite some time now and uh with this I'll just ask my colleague because of time shot we're just rushing through uh my Kali Garvin to demonstrate the fatigue case how to do it in ansys and then we'll get into the encode part of it uh arvind's over to you oh yes sir thank you hello everyone myself arvind I am working as application engineer at Geo research and Engineering uh today we can have a simple demonstration on universal joint and how to give the loadings and Boundary condition for that and including and also we can see how can we estimate the fatigue life for due to that load and also damage and safety factors let's move into the simulation yeah I think my screen is visible yes yeah this is the uh this is actually the GUI of the work bench where you can see on the left of the screen you can see the various types of analysis for each of this we can perform the fatigue life for analysis let's say in static analysis we can perform the fatigue life in some cases due to the varying load with respect to time like transient analysis uh in transgender analysis also we can perform the fatigue life and in in some cases like vibrations and dynamic cases like random vibration Spectrum loading and those things in those things also we can perform the fatigue life and in some cases due to the friction uh there is a generation of heat due to the friction between the components in that case we are going to use this coupled field transient analysis there we are merging between the transient structural part and and with the thermal part there we can perform the fatigue life the first and the foremost thing we need to have the material details to estimate uh the fatigue life let's say we need to for the first thing we need to drag and drop this structural part or whatever the analysis you are performing and then the step wise procedure like we need to include the material data and we need to include uh import the geometry and then comes the boundary condition and loading then the post processing things let's move into engineering data for the default uh we have the structure still in ansys let's take the structural steel for this case and then and then we need uh the basic uh inputs like density and the isentropic elastic eggs modulation the poisons ratio are based on this inks modulus and poisons ratio the software will calculate uh the bulk modulus and the shear modulus and then we need the ascent curve uh the SN code can be inputted in uh to three ways like uh depending on the inputs like what we have log uh like log log scale you can see on the right of the screen you have the graph which is showing the number of Cycles to the alternative Cycles which is in terms of log scales if you have any semi log scale you can change this into semi-lock scale when you change it into semi-log skill is going to change one of the uh like let's say Cycles are in a log scales and this is in the 10 power 9 Cycles uh depending on that we can Define them and also a linear scale with in both are in a numerical uh unit wise and then let's keep it in log log scale and then if you uh this is an experimental data which we need to get it from the experiment uh data like we need to in we need to give the number of Cycles versus alternating stress uh it can be of like pascals or MPA you can change it over here uh you can change the parameters sorry the assign units and then you can introduce the values uh into the engineering data and then after this you can see the graph of the SN code and you need to introduce like input the yield strength and the ultimate strength and let's say this is uh this is the essential is used in only when we are performing uh distress uh which is developed in a body Which is less than the yield strength in that case we can perform the ascent where when the yields when the material is subjected to a load which in produces or create this stress which is more than the yield stance in that case we need to perform this train life parameter this in this strain line parameter we need to give this coefficient values like custom coefficient and exponential and ductility exponential and cycle strength and hardening exponential these are the experimental datas we need to give from the experiment and depending on that as the degree sir has explained you you can see this this is a plastic strain life and this is elastic strain life or due to this combination of these two we get this plastic total strain life cow and then we need to import the geometry here so this is a simple case this is geometry which I am going to use now this is universal joint and then after that we can move into amazing parts and boundary conditions let's say in Geometry we need these are the parts we which we have included and we need to assign the material here you can see the material which I am assigning as structural steel and this is a step-by-step procedure we need to carry out uh with in this the green thick marks and indicate that this geometry is sufficient for the next step in the same way the each step to be indicated with a green tick mark or else it will show a question mark which means we need to give some input data are missing so in material details so you can check whether the given inputs material values are being correct or not and then we can move into like Connections in the context we can Define between the two parts like connecting uh using contacts or joints like revolute joints I have defined between these two parts I have defined the revolute joint after that uh we need to do some machine I have kept as a default machine we can have some refinement uh over the part which we have the more interest of estimating the life and then like uh when you come to the boundary conditions and loading uh when you click on insert we can have this boundary conditions at the bottom and the tops are the loadings and here I have introduced the moment for one of the one of the end of The Joint uh with the moment of point to 10 power uh Pi moment a Newton per mm and then one of the end is fixed support the same moment will be transferred over this uh to this shaft due to this loading we can get when you solve this uh problem uh we will get the total deformation and insert the total deformation and stress and strain values and we can see the fatigue life uh tool here when you insert this fatigue tool we can estimate the life damage and uh equivalent alternative stress and also the fatigue sensitivity and this moment reaction is introduced by using the probe value in this post processing we can see the total deformation and the equivalent stress is maximum over here when you switch to maximum it's showing somewhere somewhere here uh between the joints between the two joints like here about a 141.56 Which is less than the yield strength of the material uh so we can get some number of Cycles uh it can so uh it can serve like uh this is a direction of deformation in X Y and z and in the same way we can get the principal stresses maximum principle stress and the minimum principal stress and when we come into the fatigue Tool uh we can see like as as related to theoretical part we have hopefully reverse zero based and ratio and this history data is like a Time dependent varying load we can input uh using history data and zero based when you click on zero based it takes only the positive uh value of the stress like only the tensile uh property and and other end with zero stress and in the same way when you move when you click on fully reversed you can see the both the compressive and the tensile loading are being applied with a factor of one we can change the factors so like if you want to increase the load with the uh let's say having introduce the load with 5 into 10 power 5 Newton per mm if you need to increase that loading we can increase this safety scale factor over here and then when you come into ratio we can Define the ratio between the tensile and compressive loads uh here it has taken as minus one and one we can change the values here so that you can see the tensile properties whatever the stress 141.85 will be included half of it will be included for the compressive load that is the factor we are going to use here let's keep it as a minus one that is equal so that we can go for a fully reversed life type and then we can estimate at uh at a different time intervals and we can go for for a ductile material we prefer for Ramin stress Theory with uh Soder bug and we can estimate the units the life in terms of Cycles hours or seconds or days or month and these are the outcomes we can get it from the simulation and then I will go by fully reversed with a factor of 1 and with a solder bug equation if you evaluate these things life you can see this blue indicates with the maximum life of a 10 power 6 Cycles whereas uh the minimum life is over here it's about uh 91 000 Cycles we can perform with this loading and you can see the damage is also maximum over here uh let's say I will clear this data let's say you can give the design life whatever you are expecting from this model like I have given like 10.6 Cycles to be the service life of this component so that what is the damage you can estimate this is a damage value from this uh loading and in the same way for the fretic sensitivity we can get excuse me uh what is the damage you got it should be lesser than one right yeah you are getting 10.91 you are getting so then how your life is uh 10 000 Cycles no sir uh like for the damage for this life cycle if you for this uh let's say I will decrease this life cycle if I decrease less than I don't know what stress combination method you have used uh you have taken maximum principle right uh you should usually for a ductile meter you should you're supposed to use one myself yeah you should use one my sisters right stress component here equivalent stress okay okay then why did you use sodomberg usually Gerber method is uh preferred your sodomberg is very conservative yeah for all this uh for this example you can use any of them the option is available there yes you can use the different uh stress theories for this cell I have considered like a ductile material so I used this soda bug is yeah it depends on your problem statement and also the material dependence so yeah you can use the facility uh the what he's demonstrating is you can use those equations and uh okay now go to damage what is the damage you are getting um I'm not um [Music] it's not updated I think you update that yeah yeah so uh as you ask because uh the life for the limiting uh this can serve up to 91 000. damage you please show me them and damage life uh if I give uh less than the life like uh 90 000 Cycles it can it will show less than one if we increase the number of Cycles here it's going to give the higher value of the damage if you are adding below that definitely the damage will be controlled below that only so if you are adding uh if you're expecting for let's say 10 to or six then the damage levels also goes High yeah no no thing is no the inverse of the damage would be the life that it gives right yeah like damage is we have a formula for the damage like uh whatever the life we are expecting design Life by uh total uh life the damage whatever your my damage what you are getting here getting here that should be the inverse of your life whatever your but it is not matching that is what I'm saying the 0.988 is it's getting how much lipid you can expect with 0.98 uh if you calculate like damage is equal to the number of design life you are expecting like I am expecting 90 000 Cycles divided by whatever the life you are getting 91 uh thousand in ninety thousand sixty eight if you divide this uh design Life by this total life you will get the damage value this uh 0.98 if I show let's say one second the damage is coming high that is what is my damage damages with uh if it is within the cycle failure cycle then the damage is within one number right if the cycle you are giving High then the damage also need to be high right I mean yes sir that's what uh because what we are what we are seeing here is with the below the uh 90 000 cycle if you are giving 10 or 6 then it will be damage will also be high so you can see the damage value here This Is The Life what we are expecting ninety thousand and then this is a live what we are getting from the simulation if you divide the these two things we are getting the damage of 0.98 the same value we are we are getting like 0.9882 I think uh it's clarified I will discuss it separately two ways of looking at a cycle yeah okay okay I'll just brief you there are two ways of looking at one is uh you subject component for number of repeats and understand like how much life it can withstand okay the second one is you expect the component what will be the damage level within the my targeted uh Cycles so uh what design life option gives in answers here is you can give a Target uh cycle and see that whether it there is a damage or whether the like the damage levels within that cycle else you can if it is not if the like life cycle is uh not Crossing then the damage level also will be less than one yes sir that's right thank you sir and then if you come to fatigue sensitivity uh here we can have a graph like uh this is a whatever the load we are applied it's showing the number of alternating Cycles with respect to this as we decrease the uh loading uh it's going to increase the number of Cycles uh this is what it's showing and if we increase the number of uh sorry the factor of loading it's going to decrease uh the Cycles this is the sensitivity and this is how we can calculate the fatigue life using ansys and then we can move into like encode uh this will be demonstrated from with by Santosh sir I will hand over to Santos sir yeah just to add here and answers Standalone Tool uh can predict the fatigue up to certain extent and then specialized tool is a encode part thank you sir okay so when we so ansys has two options for you uh to perform uh the fatigue life assessment part of it one is ansys ansyspatic tool within the ansys workbench and in the Enterprise editions you will get the fatigue evaluation also Premium Edition you get and the further detailed analysis of fatigue can be done with the ansys encode design life encode design life is a specialized product for the fatigue evaluation where you want to account a different uh loading patterns different uh of the like material models and also the specialized data for the fatigue so uh we all know like typically the what encode can give you is uh how do like what are the parameters which will uh make an issue with or we will be contributing in terms of fitting life calculations so you can standardize your fatigue evaluation curves so uh this is basically to help the designer in evaluating the fatigue life well in advance and accounting the realistic load into consider load and material data into considerations so I'll just skip all these things so coming to here so typically we will have a design and then we prepare the afvm model where you you can take the material data and then based on the material data as well as the loading conditions the loading conditions either you can do a cycle assigned in the fvm here and the repeat in the fatigue or you can assign a unit load and then make it in the fatigue you can repeat by mapping the things so that's where the duty cycle development and the combinations will come so one is the load combination the second one is the fem results and then material property from the fatigue side and then combining all the things we will get the fatigue The Contours and also it will help you to redesign the uh by changing the geometry you can rerun it so when you are running a fatigue analysis independently and when you are running fatigue analysis along with the ansys workbench whether it is ansys fatigue or ansys encode fatigue the advantage is it will help you in the redesign quickly because your geometry can be quickly optimized or you can use the optimization package within the ansys encode where you can change the geometry and take it to the fatigue and update the results in the fatigue you will be able to see that what is the influence of your change in Geometry is contributing to the fatigue life whereas in other cases what happens is if you are looking at a fem done separately and then import it there's a continuously you have to do this activity it cannot be automated whereas uh in in the encode using within ansys workbench that is the advantage of automating from the cad to Fem to fatigue and also including the uh the like including the optimizations part so we can do a cad to FM continuous seamless integration and comprehensive fatigue analysis is possible and we can also do a design optimization that is by changing the parameter you can see that what is the life variations you can set the target life required typically that I think this is a familiar process where we build the model and we set a parameter okay this parameters are something like for example if you are having a a sharp let's say you have a shaft kind of thing you have a radius a length and the material and other things we can set that as a parameter in the option and this parameter will work within the design modeler to change the model continuously and that can be taken into a static stack structural analysis to perform the single cycle of the stress levels uh then you can take it to the ansys encode design life in the encode design life we will look into that and there are two multiple options are available to handle constant loading conditions then then there is a en based uh constant en based time series SL based constant SN based time series vibrations and so on and all the parameter can be set again back to the optimization cycle where you can have the design Explorations where it gives a better life and or the what kind parameters are contributing to the life of the component that can be done with the sensitivity analysis and so on so the advantage here is you will be able to simulate from start to end the automation of complete fatigue including the optimizations part uh there are two sets of databases we will be seeing in the uh like seeing in Nancy's workbench with a standard material database these are standard material database typically you get from ansys engineering database there is another set of the database can come from granta granta is an material database and for the uh when you are installed encode part encode also gives you a material database with a very detailed uh fatigue the properties for the given material uh then once we bring the model uh I think we will uh just get into the uh the model once we bring it inside there are multiple options you can see on the right hand side where you can see the input functions the basic signal processing design life calculation based on different aspects this is the difference which makes from inbuilt uh inbuilt fatty code within the ansys and also the additional options which you can see here and then the loads the time histories you can apply and then perform the the fatigue evaluation where we will be first mapping the material and then we will map the load conditions and then we will map the let's say uh advanced settings where we will select like what should be the mean mean stress correction equations what should be the stress values it should consider for calculating the fatigue Life part so this is the GUI of uh encode and coming to further so three inputs which will go to the input design life one is basically the experimental material data the second one is the load histories the third one is the Fe results so this will be uh taken from ansys to workbench automatically here and then to the adding the time history and material selections will follow from here to here so this the material we select can be a both are same and you can have changes as well so the based on these three input encode will compute compute the uh the damage as well as the life required life of the component and also you can this is a kind of a process automated where you can have if you are evaluating a design or the fatigue evaluation criteria based on certain step you can use the uh box the available box and build your own evaluation criteria within the encode environment once this is done you can use it for SN cup based approach or en curve based approach just approach a strain approach and also damage calculations based on the safety factors we can handle the thermo mechanical there is a short fiber composite fatigue is also available within the encode and there are many components are being used from starting from a simple uh the consumer good to the biomedical to Aerospace to other applications over the year so uh with this we can also have a cyclic symmetric component where you want to account the cyclic symmetry into account you can consider that as well let's look into the model part so uh I will just duplicate this to uh show you the quick analysis things so when you open this ansys workbench you will also have encode installed on the same machine where additional options of analysis will be get added on the left hand side you can see the encode en constant design life encode en time series design life input ensn constant and time series then vibration SN vibration with PSD then weld shell Sim then there are other options of the uh things are there so these are associated with the stress based life and strain based applications I'm just yeah so here uh when I take it on engineering the first thing is engineering data when you click on engineering data you may not have uh the encode that here you can go to the data sources the answer is working prestigious Remains the Same so here you can browse it and typically the when you go to the C drive you will have a encode uh installed in the encode you can open the encode DW and then go to the max in the mats you can find the material data grade I run and nothing and there are number of material data you can import this open the data it's already opened here you can see that when you double click on it you will be able to see the material properties for different material the database of encode provides the detailed uh stressful strain life parameter stress life parameters and so on and also you can integrate the granta database and the grant that granted database also has a lot of material properties in the ansys world and it can be integrated with ansys workbench you can see that here there are different material properties are available but it's not a limitation you can add your own material property by changing adding a new material and changing the things as like we do for standard ansys workbench and here the database is therefore um for that like around 250 to 226 material but around 4000 is available with the uh granta database so you can just select the material and add to the your application model similarly I'll just take mild steel here you can just say that plus button you can add it so now come back to projects and then just refresh the project you will be it is added to the engineering database here and then you can open the geometry and see the geometry model it is opening geometry model as simple geometry is created here and I will open the analysis model and show the things you can apply uh different loads here the same load is applied you can make it as uh if you don't if in the analysis system if you don't select it as a number of uh steps if I added three then in the encode you can identify all the three as you all the three loads individual individually if I keep it one as a value then it will be all the three will be combined load will be applied onto in steps will be considered if I take it one and this is a downwards then upwards then the other load is taken into account just uh solve the case or update the results yeah that's all we do in the workbench you can take any model uh like applying the load case once we have done this then we need to uh let let me first select the uh encode constant thing drag and drop onto the solution when you drag and drop onto the solutions it will automatically connect with the previous model and then you just go here because once it is connected you need to update the model such that it takes all the data which is required for the further process with the encode and then you can open the solution that is by clicking an encode design life will open and this is the GUI of the import design life and where you can have a design life there is a studio where you can change the parameter material manager is there where you can add the material database from the different material part browse and add it it will be automatically added onto the database part of it then there is a separate vibrational model manager is that on the left hand right hand side if you look at there are multiple options you can introduce one is the input if you are using ASCII input or different kind of input you can use this option the other option is to go is insert here input to the glyp or function displays output whatever depending on the things you can make it and also you can make it a interactive run mode similarly we have the functions which are like you want to manipulate the histogram or Channel controls all these parameters time series multi column the test splitter or test combination you want to add it so these are the additional features which will add more realistic calculations or realistic handling of the of the fatigue loads then we have a standard solvers which will handle creep the dang One models en based thing SN based safety Factor vibration strain gauging all the options are available as a standard then you can see the composite solver available then vibration profile designer like if you have extreme response Spectrum shock response or other things when you add insert from the input glass like for example if I use a histogram you can see that it get added to the canvas and then you can design from here I'll just remove this and this is the standard workflow which is typically get added when you drag and drop from the workbench part of it you can also build the your own application including the script map and the Matlab and then there will be a super life options there are display options are available chart display and depending on what kind of output you want to make it it's about most pre-processing of the fatigue evaluations as well as the post processing option for the fatigue part Let's uh click on this display you can observe here the model is already taken I just hold a control button and you will be able to uh see the model I have considered uh here and now it the model is added to here in in this case you can right click on the here and if there is a edit material option material mapping and you can see the carbon steel or mild steel whatever you want to use it the earlier one we have used with the carbon steel option unless I uh in the workbench uh I need to change that material to the respective material data so I'll be using here with the my carbon steel only going for a default so the material is updated you can also see the uh view the assigned one you this is the properties of the material type UTS e and then all the property and also like you can ratio Circle you can do it if you have a tested data you can bring the tested data directly so this helps us in mapping the material once you map the material edit the mapping then goes with the load mapping uh here we are not using a Time series if you are using a Time series then it makes more sense and where you can map it for the things but you can see that uh the all the three load cases you will get single load cases in the workbench if you make it as one step if you are making it different steps you can it will automatically display here with the different load cases and also you it is a constant loot load cases you can have a Time series added to that or you can have it time step based options where the scaling Factor can also be added for each of the load cases and then you can a concept amplitude is what I'm looking at now then you can add also at a duty cycle you can add a vibration loads you can add a hybrid of them you can add a rain flow counting based on that so these are multiple options which you can use it for uh handling your load conditions just say okay and then you click on the advanced edit option where you can see that advanced edit options gives you various methods for example SN method we are using now so the under that also there are different things you can refer all this the heck diagrams or other channels in the encode Theory manual which will give you a description of a different SN methods are being added combination methods you can use a maximum absolute maximum principle or one myself or maximum principle Shear critical plane there are different approaches are available here with it same way you can use the mean stress Corrections options where you can go with the Goodman Gerber or fkm depending on what kind of model you're going so we can just take a good one here and also you can have a multi-axle a simple bioxide by axility or standard or Auto so I will leave most of these parameters as an default and also like I'm just showing all these options it is when you go depending on your problem statement and nothing it will be a uh this window will change and also you can change the parameter in the analysis group as well so this is the whole detail of load mapping uh sorry Advanced edit part so uh because it's just uh and one more thing I missed to show um here you can see the surface nodes only you can activate is false if you want to go for all fatigue is a Surface phenomena you can take it as true uh if you are only it will be quicker so I am using true as an option for the same after this I think the the initial setup for a basic analysis is done then click on this button it will run the analysis part you can see the zero completed entities and other cases so just maximize this hold a control button where you can rotate and see there are different post processing options are available uh because of time constraint I am just rushing through with this here you can see the damage levels the static values and also you can you can put a band double click on this you will be able to see the results for different load Cycles depending on what load cycle you want to see or load cases the damage levels you want to evaluate or you can use it for all or go to the result which will add options for different uh options of the total average and you also have a damage here the live calculations the and you can also add your own calculation method the buy axility then plane angle maximum stress minimum stress observed all this let's take a life only damage you have seen we will take the life options there you can set the ranges and also you can make a custom range if you are looking at a component how it is getting damaged within the desired cycle or within the desired cycle if it is passing then what is the level of damage observed or life observed you can click it so you when you click on it you will be able to see the uh the static failure plus the life ad and repeats so this is the critical area where you get an different stress values so this shows the workflow part of it there are multiple options are available within design like encode so as I shown uh using these histograms or the processing the basic function as the integration as well as your PST data calculation The Strain positive models train flow counting models the graph frequency spectrum handling the force Warrior filters you're adding so we the options are more this today's is just to introduce what options are available why a simple workflow and the next webinar we will be covering uh each one of these Topics in detail