JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD

Prerequisite

Strength of Materials, Theory of Elasticity desirable.

Course Objectives:

• Acquire fundamental understanding of the fracture of solid materials.
• Develop detailed understanding of fracture mechanics, creep, and fatigue.
• Obtain fundamental knowledge of corrosion and environmentally-assisted cracking.
• Acquire basic understanding of the techniques used to perform failure analysis.

Course Outcomes

At the end of the course the students will be able to

• Predict material failure for any combination of applied stresses.
• Estimate failure conditions of a structure
• Determine the stress intensity factor for simple components of simple geometry
• Predict the likelihood of failure of a structure containing a defect

UNIT - I

Introduction to fracture Mechanics: The Crack Tip Plastic Zone, Methods for Measuring Fracture Toughness.

UNIT - II

Strength of cracked bodies- potential energy and surface energy – Griffith’s theory – Irwin – Orwin extension of Griffith’s theory to ductile materials – Stress analysis of cracked bodies – Effect of thickness on fracture toughness – Stress intensity factors for typical geometries.

UNIT - III

PHYSICAL ASPECTS OF FATIGUE: Phase in fatigue life - Crack initiation – Crack growth - Final fracture - Dislocation – Fatigue fracture surfaces. Safe Life and Fail safe design philosophies Importance of Fracture Mechanics in Aerospace structure – Applications to composite materials and structures.

UNIT - IV

STATICAL ASPECTS OF FATIGUE BEHAVIOUR: Low cycle and high cycle fatigue - Coffin- Manson’s Relation –Transition Life – Cyclic strain hardening and softening – Analysis of load histories – Cycle counting techniques – Cumulative damage – Miner’s theory, other theories.

UNIT - V

Dynamic Fracture, Stress Corrosion Cracking, Corrosion Fatigue, Fatigue - Crack Propagation under Variable - Amplitude Load Fluctuation, Fatigue - Crack Initiation, Fatigue - Crack Propagation under Constant - Amplitude Load Fluctuation.

TEXT BOOKS:

• 1. Introduction to Fracture Mechanics by Hellan K, McGraw Hill
• 2. Fracture Vol II by Liebowitz, H.Editor, Academic Press
• 3. The Practical Use of Fracture Mechanics by Broek.D, Kluwer Academic Publisher.
• 4. Elementary Engineering Fracture Mechanics IV th Edition– Broek.D, Martinus Nijhoff. R19 M.Tech. Machine Design

REFERENCE BOOKS:

• 1. Fatigue of Aircraft Structures by Barrpos. W., and Ripley, E.L., Pergamon Press, Oxford, 1983.
• 2. Mechanics of Fracture by Sih, C.G., Vol. 1 Sijthoff and Noordhoff International Publishing Co., Netherlands, 1989.
• 3. Fundamentals of Fracture Mechanics by Knott, J.F., Butterworth & Co., (Publishers) Ltd., London. 1983 R19 M.Tech. Machine Design M. TECH. I Year I Sem. (MACHINE DESIGN)