ME728A
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FRACTURE AND FATIGUE
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Fracture: Energy release rate, Linear elastic fracture mechanics: crack tip stress and deformation fields, Stress intensity factor (SIF) for plane and penny shaped crack, First order estimate of plastic zone using Irwin’s and Dugdale approach; Elasto-plastic fracture: HRR fields, J-integral and CTOD, Mixed mode fracture; Evaluation of SIF from experimental measurements, numerical simulations. Determination of fracture toughness under small scale yielding and elasto-plastic situations. Fatigue fracture: Crack nucleation and growth, Fatigue life prediction, Advanced topics.
Lecture wise Breakup
I. Introduction (4):
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Background; Griffith theory of fracture, energy release rate (ERR), conditions for stable and unstable crack growth, crack arrest
II. Linear elastic fracture mechanics (14):
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Williams analysis of stress field at the tip of a crack
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Solution of stress and displacement field for plane cracks using complex methods in plane elasticity (Westergaards or Kolosov-Muskhelishvili approach)
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Stress intensity factor (SIF) for plane and penny shaped cracks
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Equivalence of SIF and ERR, fracture toughness
III. Elasto-plastic fracture mechanics (10):
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First order estimate of crack tip plastic zone using Irwin’s and Dugdle’s approach
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Plastic zone for plane stress and plane strain situation and effect on fracture toughness
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Review of small strain plasticity
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Crack tip fields in an elasto-plastic material (Discussion on HRR fields)
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J-integral as a fracture parameter and crack tip opening displacement
IV. Mixed mode fracture (3):
V. Experimental measurement of SIF and fracture toughness (3):
VI. Fatigue crack growth (4):
VII. Advanced topics (one from the following) (4):
References:
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Fracture Mechanics, C.T. Sun and Z.H. Jin
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Fracture Mechanics, T.L. Anderson
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Fracture Mechanics, An Introduction, E.E. Gdoutos
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