Publication: The behaviour of three-dimensional elastoplastic crack tip (j-integral) affected by changes of elastic modulus to yield strength and strain hardening.
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Date
2024-07-12
Authors
Luqman Hakim bin Abdul Aziz
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Abstract
Current J-integral estimation for a straight through thickness-crack consistently show a decrease pattern towards the crack front with its maximum and minimum values being at the midplane and free-surface, respectively for elasto-perfectly plastic material. The aim of this project is to examine the polynomial expansion proposed by Yusoff and Yusof (2019) [23] for other material responses, and to propose a flexible mathematical expression equation that can be used to estimate the variation of Jintegral of through-thickness of crack model for all conditions (nonhardening, hardening response with effect of Young’s modulus to yield strength and strain hardened material). In this project, the profile of local J at the crack-tip and J far at the outer boundary were examined numerically using finite element analysis based on a three-dimensional crack model using boundary layer formulation method. The crack model was constructed by referring the linear elastic crack tip singularity field following Williams (1957) [29] series expansion in obtaining in-place displacement to generate a dominant elastic stress field surrounding the crack-tip plasticity and Ramberg Osgood’s stress-strain curve for hardening rate of the material. The results of J-integral obtained from simulation analysis were fitted based on an exponential curve estimation. Finally, it is envisaged that the proposed analytical expression could help to estimate the local J of crack-tip deformation for cracked specimens without the need to conduct full-fledge crack tip finite element analysis.