TY - JOUR

T1 - A Fundamental Study on the Evaluation and Applicability as a Mixed-mode Fracture Criterion of Crack Energy Density in an Arbitrary Direction

AU - Utsunomiya, Takao

AU - Watanabe, Katsuhiko

PY - 1989

Y1 - 1989

N2 - It has previously been shown that crack energy density can be defined in any direction at a crack tip without any restrictions on constitutive equations. The crack energy density, εφ, in an arbitrary direction can be divided into the contributions of each mode (εφ= εI φ+εII φ+εIII φ;εI φ,εII φand εIII φ are the contributions of modes I, II and III, respectively), which can be evaluated by path-independent integrals corresponding to each. These are defined for a completely sharp crack as the limits where the notch root radius ρ approaches zero in a notch model. Therefore, it is necessary to use a notch model with a sufficiently small value of ρ in evaluations of the quantities through FEM. In this paper, εφ and εI φ are evaluated by path-independent integrals through elastic-plastic finite element analyses varying the value of ρ, and we discuss which of ρ should be adopted in evaluations of them. Moreover, by applying these results to an experimental result of ductile fracture under a mixed mode, we show that εI φ is a potential parameter for expressing elastic-plastic fracture criterion under a mixed mode.

AB - It has previously been shown that crack energy density can be defined in any direction at a crack tip without any restrictions on constitutive equations. The crack energy density, εφ, in an arbitrary direction can be divided into the contributions of each mode (εφ= εI φ+εII φ+εIII φ;εI φ,εII φand εIII φ are the contributions of modes I, II and III, respectively), which can be evaluated by path-independent integrals corresponding to each. These are defined for a completely sharp crack as the limits where the notch root radius ρ approaches zero in a notch model. Therefore, it is necessary to use a notch model with a sufficiently small value of ρ in evaluations of the quantities through FEM. In this paper, εφ and εI φ are evaluated by path-independent integrals through elastic-plastic finite element analyses varying the value of ρ, and we discuss which of ρ should be adopted in evaluations of them. Moreover, by applying these results to an experimental result of ductile fracture under a mixed mode, we show that εI φ is a potential parameter for expressing elastic-plastic fracture criterion under a mixed mode.

KW - Crack Energy Density

KW - Finite Element Method

KW - Fracture Criterion

KW - Fracture Mechanics

KW - Mixed-mode Crack

KW - Path-independent Integral

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U2 - 10.1299/kikaia.55.1832

DO - 10.1299/kikaia.55.1832

M3 - Article

AN - SCOPUS:0024715416

SN - 0387-5008

VL - 55

SP - 1832

EP - 1840

JO - Nihon Kikai Gakkai Ronbunshu, A Hen/Transactions of the Japan Society of Mechanical Engineers, Part A

JF - Nihon Kikai Gakkai Ronbunshu, A Hen/Transactions of the Japan Society of Mechanical Engineers, Part A

IS - 516

ER -