CET 135 - Chapter 4: Properties of Materials Overview

Introduction

• Focus on Chapter 4 of the building instruction textbook.
• Minor typos noted in the textbook, e.g., table numbering errors.
• Report any issues for clarification.

Classification of Materials

• Physical Properties: Materials are classified by physical properties as they perform physical jobs.
• Common Materials: Concrete, steel, carbon nanofibers, plastics, etc.

Basic Physics Concepts

• Elasticity and Plasticity: Related to stretching or compressing materials.
• Compressive Force: Pressure applied to compress an object.
• Tensile Force: Force applied to elongate an object.

Equilibrium in Structures

• Static Equilibrium: All forces balanced, preventing movement.
• Applications: Buildings, bridges, etc.
• Simulations: Interactive physics and bridge-building games demonstrate concepts.

Stress and Strain

• Stress Formula: Stress = Force / Area.
• Units: Use of psi, Kpsi, and differences with metric units.
• Elongation: Materials stretch under tension and may permanently deform.
• Strain: Change in length/original length, noted as a ratio or percentage.

Material Failure

• Tensile Strength: Maximum stress a material can withstand.
• Stress-Strain Diagrams: Graphical representation of material behavior under stress.
• Hooke's Law: Related concepts to elastic properties.

Ductility and Brittleness

• Ductility: Ability to deform under tensile stress.
• Brittle Materials: Tend to fracture without significant deformation.

Structural Concepts

• Deflection: Bending of materials under weight or load.
• Neutral Axis: Area experiencing the least deformation.
• Innovations: Use of I-beams for reduced weight and increased efficiency.
• Reinforcements: Importance of rebar and other reinforcing methods in construction.

Safety and Testing

• Safety Margin: Difference between actual strength and required strength.
• Factor of Safety: Ratio of failure stress to allowable stress.
• Thermal Expansion: Expansion or contraction of materials due to temperature changes.
• Heat Transfer: Conductivity and its application in building sciences.

Practical Applications

• R-value: Measure of thermal resistance; higher R-value indicates better insulation.
• U-value: Measure of thermal transmittance, inverse of R-value.
• Material Examples: Wood, glass, steel, and their thermal properties.

Conclusion

• Encourage understanding by asking if concepts make sense in real-world applications.
• Reach out with questions or clarifications needed regarding textbook content or lecture material.