Stress intensity factors in finite orthotropic plates with a crack under mixed mode deformation

This paper presents an analysis of mixed mode fracture mechanics problems arising in anisotropic composite laminates. The boundary element method (BEM) and the Jk integral are presented as accurate techniques to compute the stress intensity factors K~ and Kn of two dimensional anisotropic bodies. Using function of a complex variable a decoupling procedure is derived to obtain the stress intensity factors. The procedure is based on the computation of the Jl-integral and of the ratio of relative displacements at the crack faces, near the crack tip. Applications are presented for unidirectional and symmetric laminates of glass, boron and graphite-epoxy materials. Numerical examples of problems of pure mode I and mixed mode deformations are given, in order to demonstrate the accuracy of the method.

Section: Introductionmentioning

confidence: 99%

Fracture mechanics analysis of anisotropic plates by the boundary element method

Sollero

Aliabadi

1993

“…According to (8) and (10) In the same way, z~r on the crack surfaces can also be verified to be zero. Therefore, the stress-free conditions on the crack surfaces have been satisfied by the proposed functions.…”

Section: Appendix Stress-free Condition On the Crack Surfacesmentioning

confidence: 68%

“…Later, Bowie and Freese [-6] analyzed the problem of a central crack in a rectangular sheet of orthotropic material using the modified mapping-collocation technique. Gandhi [7], Yum and Hong [8] extended this method further for the mixed problem of an inclined crack. Chan and Cruse [9] applied the boundary integral equation technique for computing SIF for anisotropic compact-tension specimens with inclined cracks.…”

Section: Introductionmentioning

confidence: 99%

Analysis of an internal crack in a finite anisotropic plate

Woo

Wang

1993

In this paper the boundary collocation method is presented for computing the stress intensity factors for an internal crack in a finite anisotropic plate. The stress functions are assumed such that they can represent the stress singularity at the crack tips, satisfying not only the governing equations of the anisotropic plate theory in the domain, but also the stress-free conditions on the crack surfaces. Therefore, only the boundary conditions of the plate need to be considered, and they can be satisfied approximately by the Boundary Collocation Method. Numerical examples demonstrated that the proposed method gives satisfactory results compared with the existing solutions.

“…Chu and Hong [4] applied the Jl and J2 integrals to find the stress intensity factors for anisotropic materials. Yum and Hong [5] utilized the modified mapping collocation method with both uniform stress and uniform displacement boundary conditions to evaluate stress intensity factors for composites. The finite element iterative method was used by Heyliger [6] to determine the stress intensity factors for anisotropic materials.…”

Section: Introductionmentioning

confidence: 99%

Simulating stress intensity factors for anisotropic materials by the least-squares method

1996

The main purpose of this paper is to investigate the accuracy of the least-squares method incorporating the finite element method for finding the stress intensity factors of composite materials. Numerical simulations in this paper indicate that the least-squares method can be used to calculate stress intensity factors accurately, if seven or eight displacements terms are included. The calculated stress intensity factors by using the least-squares method can be as accurate as the calculated J-integrals by using the J-integral formulation. If seven or eight displacement terms are included, the calculated stress intensity factors of this method are independent of the maximum radius of the area from which data is included; furthermore, a very fine mesh is also not necessary.