Unit 2103: Mechanical Properties of Materials

1. Introduction to Mechanical Properties of Materials

• Definition of mechanical properties
• Fundamental concepts:
  • Stress and strain: definitions, units, and types (normal, shear)
  • Elasticity and Hooke’s Law
  • Plasticity and yield point
  • Toughness and resilience
• Importance in engineering design and material selection

2. Tensile Testing

• Purpose and significance
• Tensile test procedure:
  • Specimen preparation
  • Test setup and execution
• Stress-strain curve:
  • Elastic region
  • Yield point and yield strength
  • Ultimate tensile strength
  • Fracture point
  • Modulus of elasticity
• Interpretation and calculation of mechanical properties from the curve

3. Hardness Testing

• Concept of hardness and its engineering relevance
• Overview of hardness testing methods:
  • Rockwell hardness test: principle, scales, and application
  • Brinell hardness test: procedure and typical materials
  • Vickers hardness test: technique and advantages
• Comparison of methods and selection criteria
• Application examples

4. Impact Testing

• Purpose: evaluating material toughness under sudden loads
• Common impact tests:
  • Charpy impact test: apparatus, specimen, and procedure
  • Izod impact test: differences and similarities with Charpy
• Energy absorption and notch sensitivity
• Interpretation of results and relevance to material performance

5. Fatigue and Creep Behavior

• Fatigue behavior:
  • Definition and importance
  • Cyclic loading and stress-life (S-N) curves
  • Factors influencing fatigue life (surface finish, size, environment)
• Creep behavior:
  • Definition and mechanisms
  • Stages of creep
  • Influence of temperature and stress
• Engineering implications and examples

6. Fracture Mechanics

• Introduction to fracture mechanics concepts
• Fracture toughness and critical stress intensity factor
• Crack initiation and propagation
• Failure modes: brittle vs ductile fracture
• Failure analysis approaches
• Predicting life expectancy using fracture mechanics

7. Material Selection for Engineering Applications

• Criteria for material selection:
  • Mechanical properties (strength, ductility, hardness, toughness)
  • Environmental considerations (corrosion, temperature)
  • Cost and availability
• Case studies of material selection in various industries
• Tools and charts for material selection

8. Influence of Microstructure on Mechanical Properties

• Microstructural features:
  • Grain size and boundaries
  • Phase distribution and types
  • Inclusions and defects
• Relationship between microstructure and properties:
  • Strengthening mechanisms (grain boundary strengthening, precipitation hardening)
  • Effect on hardness and ductility
• Techniques for microstructural analysis

9. Thermal and Mechanical Processing Effects

• Heat treatment processes:
  • Annealing, quenching, tempering
  • Effects on microstructure and properties
• Mechanical processing:
  • Forging, rolling, extrusion
  • Work hardening and grain refinement
• Combined effects on final mechanical properties

10. Case Studies in Material Failure

• Real-world examples:
  • Structural failures due to fatigue
  • Failures caused by improper material selection
  • Impact of microstructural defects
• Lessons learned and importance of mechanical property knowledge
• Preventative measures and design considerations