In this study, an improved eight-node quadrilateral finite element based on a twice-interpolation strategy (TIS) is given for correctly modeling the singular stress field near 2D crack tip of structures. In present approach, the approximation functions for interpolation strategy are established by using the TIS which included nodal values as well as averaged nodal gradients respectively. The stress intensity factors (SIFs) are therefore calculated following the proposed method. The accuracy of the proposed element and its numerical solutions are described by several examples.

Modeling of a crack propagating through a finite element mesh under mixed mode conditions is of prime importance in fracture mechanics. This paper presents an application of the finite element method to the analysis of crack growth problems in linear elastic fracture mechanics and the correlation of results with experimental data. In the present study, the crack growth simulation has been numerically simulated by using the finite element source code program using Visual FORTRAN language. This code includes the mesh generator based on the advancing front method as well as all the pre and post process for the crack growth simulation under linear elastic fracture mechanics theory. The maximum circumferential stress criterion has been used for prediction of the crack growth in isotropic materials under mixed-mode loading. Furthermore, the equivalent domain integral method has been used for calculating the stress intensity factors values during crack growth. The crack grows when the stress intensity factor exceeds the fracture toughness of the material in the case of static loading. Verification of the predicted crack path is validated with relevant experimental data and numerical results obtained by other researchers with a good agreement.

The linear elastic analysis of homogeneous, isotropic cracked bodies started in the 1900s. The existence of three dimensional corner point effects in the vicinity of a corner point where a crack front intersects a free surface was investigated in the late 1970s. An approximate solution by Bažant and Estenssoro explained some features of corner point effects but there were various paradoxes and inconsistencies. Results derived from finite element models showed that the analysis is incomplete. The stress field in the vicinity of a corner point appears to be the sum of two different singularities (i.e. stress intensity factors and corner point singularities). In this paper some recent results for the corner point singularities under in and out of plane loadings is reviewed and discussed.

In this paper, the stress intensity factors (SIFs) for an interfacial notch in a bi-material joint have been calculated using the experimental method of photoelasticity. A bi-material Brazilian disc specimen with a central interface notch was employed to determine the SIFs for different mode mixities. In this approach, SIFs were calculated experimentally for an Al/Polycarbonate bi-material Brazilian disc specimen and two different loading angles (i.e. modes I and II dominated loading conditions). The results of experimental approach were then compared with the numerical values of finite element method. Experimental results were in good consistency with the numerical values.