AE2030 FATIGUE AND FRACTURE
OBJECTIVETo study the concepts of estimation of the endurance and failure mechanism of
components
UNIT I FATIGUE OF STRUCTURES 8
S.N. curves - Endurance limits - Effect of mean stress, Goodman, Gerber and Soderberg
relations and diagrams - Notches and stress concentrations - Neuber's stress
concentration factors - Plastic stress concentration factors - Notched S.N. curves.
UNIT II STATISTICAL ASPECTS OF FATIGUE BEHAVIOUR 9
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 III PHYSICAL ASPECTS OF FATIGUE AND FRACTURE 12
Phase in fatigue life - Crack initiation - Crack growth - Final Fracture - Dislocations -
fatigue fracture surfaces - Strength and stress analysis of cracked bodies - Potential
energy and surface energy - Griffith's theory - Irwin - Orwin extension of Griffith's theory
to ductile materials - Effect of thickness on fracture toughness - stress intensity factors for typical geometries.
UNIT IV FATIGUE DESIGN ANDTESTINIG 8
Safe life and Fail-safe design philosophies - Importance of Fracture Mechanics in
aerospace structures - Application to composite materials and structures.
UNIT V FUNDAMENTALS OF FAILURE ANALYSIS 8
Common causes of failure. Principles of failure analysis. Fracture mechanics approach to
failure problems. Techniques of failure analysis. Service failure mechanisms - ductile and
brittle fracture, fatigue fracture, wear failures, fretting failures, environment induced
failures, high temp. failure. Faulty heat treatment and design failures, processing failures
(forging, casting, machining etc.),
TOTAL: 45 PERIODS
TEXT BOOKS
1. Prasanth Kumar - "Elements of fracture mechanics" - Wheeter publication, 1999.
2. Barrois W, Ripely, E.L., "Fatigue of aircraft structure", Pe/gamon press. Oxford, 1983.
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