1. (a)(b)(c)Explain the difference between Griffith and Irwin's approachto determine the critical stress in cracks for fast fracture inengineering materials.Why are dislocations necessary for explaining the plasticitytypically seen for crystalline materials?A thin sheet of aluminium alloy of width 200mm and 200mm long with an internal crack of 80mm is subjected to anapplied stress of 130MPa perpendicular to the crack plane.Apply Irwin's Approach for plasticity correction to find theplastic zone size of the crack tip, and hence find the stressintensity factor at the crack tip (for 2 iterations).The yield strength of aluminium alloy is 380MPa.The stress intensity factor K₁ is given byK₁=Y σ (na)¹/²where a is the crack length and is the applied stress.Note that the geometric correction factor graph and therelevant equations are provided in the Appendix.

Solution:- 1). Griffith's hypothesis of fragile crack can be re-deciphered as a basic instance of…

Answered: 1. (a) (b) Explain the difference…

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1. (a) (b) Explain the difference between Griffith and Irwin's approach to determine the critical stress in cracks for fast fracture in engineering materials. Why are dislocations necessary for explaining the plasticity typically seen for crystalline materials?