JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD

Overview

Course objectives:

• To obtain knowledge of stress response of materials, load bearing ability, elastic and plastic deformation.
• To obtain insight about different mechanical properties of materials under engineering applications. Course outcomes: After completing this course, students will be able:
• To explain how elastic and plastic deformations as events taking place at atomic and crystal levels
• To understand the concept of plastic deformation and the role of dislocations in plastic deformation of materials
• To explain the mechanisms of fatigue and creep failures in materials
• To discuss strengthening mechanisms in metals as well as failure analysis methods
• To understand the load bearing ability of different materials and their response to stress under engineering applications.

UNIT - I

Plastic Deformation in Metals and Alloys: Critical resolved shear stress. Defects in crystalline materials Point defects and line defects. The concept of dislocation - Edge dislocation and screw dislocation. Interaction between dislocations, sessile dislocation, glissile dislocation, dislocation climb, Jogs, Forces on dislocations Energy of a dislocation. Frank Reed source, slip and twinning.

UNIT - II

Fracture: Elementary theories of fracture, Griffith’s theory of brittle fracture, Ductile Fracture, Notch sensitivity. Hardness Test: Methods of hardness testing Brinells, Vickers, Rockwell, Rockwell superficial, Shore and Poldi methods, Microhardness test, relationship between hardness and other mechanical properties.

UNIT - III

Tension Test: Engineering stress and Engineering strain, True stress-strain curve. Tension Test and tensile properties, conditions for necking, effect of temperature and strain rate on tensile properties. Compression Test, Impact Test: Notched bar impact test and its significance, Charpy and Izod Tests, significance of transition temperature curve, Metallurgical factors affecting the transition temperature, temper embrittlement. DBTT curve and its importance. Fracture toughness testing - COD and CTOD tests.

UNIT - IV

Fatigue Test: Introduction, Stress cycles, S-N Curve, Effect of mean stress, Mechanism of fatigue failure, effect of stress concentration, size, surface condition and environments on fatigue. Effect of metallurgical variables on fatigue. Low cycle fatigue - High cycle fatigue.

UNIT - V

Creep and Stress Rupture: Introduction, The creep curve, Stress-rupture test, Structural changes during creep, Mechanism of creep deformation, theories of creep. Fracture at elevated temperature, Effect of Metallurgical variables on creep.

R18 B.TECH MME

TEXT BOOKS:

• 1. Mechanical Metallurgy by George E Dieter, McGraw-Hill Education; 3 edition June 1986
• 2. Mechanical Behaviour of Materials, Thomas H Courtney, McGraw-Hill Education;2 revised edition

REFERENCE BOOKS:

• 1. Mechanical Behaviour of Materials, Marc Andre Meyers and Krishnan Kumar Chawla, Cambridge University Press, 2 edition
• 2. Mechanical Metallurgy - White & Le May R18 B.TECH MME