Now we will talk about glass fractures. So how does a glass fracture happen? Each force causes a deformation of many, leave a visible mark on the fracture of glass. If any pressure or force is applied on the glass, then I have told you that the nature of glass is brittle nature.
So their fracture also creates a fracture in the characteristic feature and you see a visible mark. This can be used to determine the direction and amount of force. So, by looking at the fracture of this glass, you can find out the direction. If a bullet has come, then from which area has it come, where has it exited. Or the area of application of force, force has been applied from outside or from inside to break the window.
So, you can find out the direction and amount of force by looking at the condition of that glass. That how much amount of force is there. Glass act initially as an elastic surface and then bends away. So glass tries to not break by showing its elastic nature but after that it bends.
So if a little force is applied then glass will not break due to its elastic feature, due to its elastic surface but if more force is applied then it bends and breaks. Its tensile strength. So when there is more pressure than the tensile strength, then that thing will break.
It works on the glass and it also affects your bone. That means the same theory works on the bone too. That your body and your bones also have a tensile strength.
That it can bend to an extent, it can bear pressure to an extent. But when there is more pressure than the tensile strength, then your bones will also break. And glass is glass.
It is a brittle substance. So our brittle surface, our brittle glass, In substance, if the energy or force is more than the tensile strength, then it breaks and the glass cracks or should be said glass fracture happens. So, glass fracture basically happens in two ways. One is radial cracks and radial fractures.
The other is co-centric cracks or co-centric fractures. So, this is radial fracture and co-centric fracture. Radial fracture or concentric fracture. So radial fracture what happens is it forms first It forms first and are propagated in a short segment on the opposite side of force So these radial fractures These are radial fracture. These are radial fracture And what is the characteristic of radial fracture?
It forms first Pressure applied, glass broken, first to appear. First, these radial fractures are created. And where are they created? Side opposite to the force.
If you have applied force from here, then your radial fracture will be here. If you have applied force from here, then your radial fracture will be here. So, it means that the side from which force is applied, radial fractures are formed on its opposite side.
This you have to remember. Co-centric fractures, what are they? They come later.
These are formed after radial fracture and when pressure continues, they form on the same side They form on the same side of the force applied So as we said radial fracture is formed on the opposite side So co-centric fracture is formed on the same side and they are formed later First radial fracture will be formed on the opposite side They will propagate, when pressure is still applied, then co-centric fracture is formed Co-centric fracture comes on the second number and they are formed on the same side What we do is, they are formed on the same side. If you have applied force on this side, then your co-centric fractures will also be formed here. If you have applied force on this side, then co-centric fractures will also be formed here.
Okay? So, it is clear? Radial fracture and co-centric fracture.
So, radial fracture is formed opposite to pressure. Co-centric fractures are formed on the side of your pressure. Radial fractures are created first. Co-centric fractures are created later. and the theory of the same side opposite side is clear I think so see here force is applied from this side on the opposite side, radial fractures will be formed and when the pressure increases, this pressure moves and this small small small small this rib cage is formed due to pressure due to pressure in the glass in these small small segments Convert to jata.
Do you just like just one thing? You just like just one day these all are concentric fractures you just like just one day these all are radial fractures You're ready to fractures and can buy the major joke crack hotel. I gave you a course and the factures Okay, edges of broken piece of glass will show rib or stress mark They look like rib or show stress mark. What are these?
What is this? This is stress mark. This is stress mark.
This is stress mark. This is because of pressure, the stress that is created in the glass, these marks are formed. This is the way of rib.
Because of this, it looks like rib. That's why we call it rib marks or rib. rib cage ki jaise dikhte hai ye jo glasses hai ye rib marks show karte hai ya stress marks show karte hai in a radial crack the rib marks are perpendicular radial cracks me kya hota hai radial fracture me ye jo rib marks hota hai ye perpendicular hota hai to unhold the side and parallel to a loaded side to unhold the side jo jis side pe apke pressure hai uske parallel ye bante hai the arrow shows the side of received the impact This arrow shows the pressure it has received And the marks that are formed here Where did the pressure come?
Upwards direction to downward direction So this shows you the side and direction of the pressure And it also has a 3R rule There is a 3R rule on radial cracks So what is applied on radial cracks? Radial cracks are the gives a rib marks that make right angle on the reverse side Radial cracks give rib marks to right angle in the reverse side This is 3R rule, first R, second R and third R So radial cracks make rib marks at right angle Means they tell you the angles and directions and where they are made They are made on the reverse side, opposite side where pressure is applied. There are some types of glasses like tempered glass.
How tempered glass fracture? Fracture in the form of dice. Tempered glass does not make ridge marks.
This ridge characteristic, rib sorry, does not give rib and stress marks. These break in the form of dice, tempered glass or we should say safety glass. These break in the form of small dice, so they don't show any stress marks.
Very small windows held tightly in the frame. Can't bend to block appreciately. So the small windows that are tightly closed, they don't break easily.
and the windows that break due to heat, they tell you the point of impact they tell you the no point of impact they don't show any particular point of impact if the glass is broken due to heat or explosion then you don't know any initial point from where the pressure was applied and how the window broke they are curved, their edges are smooth and the breaking point is smoother and there is no set initiating or point of impact you don't know if bullets projectile or bullets means if bullets of your gun cracks a glass or it passes through then what characteristics we get to see load side in the entrance side unloaded side is the exit side so where load is there where load is more that will be the entrance side unloaded side will be the exit side you can also find out the entry of bullet and exit of bullet the low speed projectiles means low speed bullets projectiles is nothing but bullets the projectiles or bullets in low speed rib marks may indicate where breaking force was applied so this makes rib marks radial force you will get to see radial fracture and it will tell you where pressure was applied as the width the bullet velocity increases the center of hole becomes smaller. If the velocity of the bullet is more, then the entrance of the bullet will be smaller and cracking pattern becomes simpler. And the crack pattern of the bullet will be a simple pattern. You must have seen that The spiders that make webs like this You will also get to see glass fractures like this When the bullet enters, if its velocity is high, then a small entry hole will be created And this breaking pattern is not complex, it is simple The exit hole becomes wider and the exit is bigger than the entrance hole bullet enter from here is small in high velocity and exit is bigger in exit exit unloaded side is wider than the entry and loaded side so i said that exit point is more wide or bigger in surface as we compare the entry side entry side is small and exit is Big stress lines on the glass edges are of radial cracks from right angle on the reverse side of the force This is 3R rule which works on the radial cracks stress line on the glass edge of co-centric cracks form a right angle on the same side of the force So the stress lines which are formed in the co-centric fracture they form right angle at the same side of the force This is the