Sūkshma
Laboratory for Micro and Nano mechanics of Materials

Mechanical Behavior of Materials

Syllabus:Theory of Elasticity - Theory of Plasticity. Review of elementary dislocation theory - deformation of single and polycrystals temperature and strain rate effects in plastic flow - strain hardening - grain size strengthening, solid solution strengthening - order hardening, precipitation hardening, dispersion strengthening - strengthening by martensitic transformation, creep, fatigue and fracture.

1. Kelly, A and Nicholson R.B. (Eds.) Strengthening methods in crystals.
2. G.E. Dieter, Mechanical Metallurgy, McGraw-Hill, London (1988).

Course Outline

Stress, Strain &Elasticity - Stiffness, Strength, and Toughness, Types of mechanical behavior, Relevance, Measurement, data, Macroscopic, continuum behavior, Physical mechanisms controlling behavior. Introduction, Stress, strain, compliance and stiffness tensors, Physical origin of elastic moduli, Generalized Hooke’s law and its application to crystals, Designing for modulus and Composites.

(Stress,strain&elasticity.pdf)

Continuum Plasticity - True stress-true strain, Necking and Considère’s Criterion, Yield Criteria and yield locus, Normality, Isotropic and kinematic hardening, Plastic stress-strain relations.

(Continuum plasticity.pdf)

Microstructural Aspects of Plasticity - Theoretical shear strength, Dislocations and Burger’s vector, Elastic properties and energy of dislocations, Forces between dislocations, Partial dislocation and stacking faults, Dislocation-dislocation interactions, The Peierls-Nabarro Stress, Origin and multiplication of dislocations, Crystallography of Slip and Independent Slip systems, Slip plane rotation, Twinning and twin geometry, Twinning in HCP crystals.

(Microstructural aspect of plasticity.pdf)

Strengthening Mechanisms - Work hardening, Taylor’s and Kuhlmann-Wilsdorf Theories, Grain boundary strengthening, Hall-Petch and Cottrell theories, Solid solution strengthening, Point defect –dislocation interaction energy, Yield point phenomenon, Precipitation hardening, Dislocation-precipitate interactions.

(Strengthening mechanism.pdf)

Fracture - Importance of Fracture Mechanics, Griffith Fracture Theory, Crack Driving Force & Energy Release Rate, Modes of fracture, Stress intensity factors, Similitude, Role of Crack-tip Plasticity-Plastic Zone Size & Shape, K-dominance, Fracture Toughness-Microstructural Issues.

(Fracture.pdf)

Fatigue - Total life approaches, Fatigue design approaches, HCF and LCF, Fatigue crack inhibition, Fatigue crack growth, Paris law and models, Threshold, Damage tolerant approach, Striations, Different stages of fatigue crack growth, Examples.

(Fatigue.pdf)