Papers by Author: P.H. Wen

Abstract: The Finite Block Method (FBM) for computing the Stress Intensity Factors (SIFs) and the T-stress under transient dynamic load is presented. In order to capture the stress intensity factor and the T-stress, the Williams' series of stress function is introduced in the circular core for statics generally. In the Laplace domain, the Deng's series of stress and displacement is too complicated to be used easily like Williams' series. However, the numerical solutions show that Williams' solution of series is still valid with smaller core size. Comparisons have been made with the solutions given by the finite element method (ABAQUS).

Abstract: The analysis of sphere nonlocal elasticity is carried out by using the improved point collocation method. The approach is based on the Eringen’s model and two and three dimension problems are transformed to one dimension problems considering the polar symmetry. One dimension second order differential equation in terms of radial displacement is derived with domain integral. Due to the excellent accuracy of the point collocation method to one dimension differential equation using the radial basis function interpolation, the numerical solutions can be used as benchmarks. This approach can be easily extended to dynamic nonlocal elasticity and plasticity for sphere.

Abstract: This paper presents a new fatigue crack growth prediction by using the dimensional reduction methods including the dual boundary element method (DBEM) and element-free Galerkin method (EFGM) for two dimensional elastostatic problems. One crack extension segment, i.e. a segment of arc, is introduced to model crack growth path. Based on the maximum principle stress criterion, this new prediction procedure ensures that the crack growth is smooth everywhere except the initial growth and the stress intensity factor of mode II is zero for each crack extension. It is found that the analyses of crack paths using coarse/large size of crack extension are in excellent agreement with analyses of the crack paths by the tangential method with very small increments of crack extension.

Abstract: . In this paper a variational technique is developed to calculate stress intensity factors with high accuracy using the element free Glerkin method. The stiffness and mass matrices are evaluated by regular domain integrals and the shape functions to determine displacements in the domain are calculated with radial basis function interpolation. Stress intensity factors were obtained by a boundary integral with a variation of crack length along the crack front. Based on a static reference solution, the transformed stress intensity factors in the Laplace space are obtained and Durbin inversion method is utilised in order to determine the physical values in time domain. The applications of proposed technique to two and three dimensional fracture mechanics are presented. Comparisons are made with benchmark solutions and indirect boundary element method.

Abstract: A variational technique has been developed to evaluate the static stress intensity factors of mixed mode problems with mesh free method in this paper. The stiffness is evaluated by regular domain integrals and shape functions are determined by both radial basis function (RBF) interpolation and moving least-square (MLS) method. The stress intensity factors are obtained by two boundary integrals with variation of crack length. The applications of proposed technique to two-dimensional fracture mechanics have been presented with several examples. Comparisons are made with benchmark solutions.

Abstract: An element-free Galerkin method is developed using radial basis interpolation functions to evaluate static and dynamic mixed-mode stress intensity factors. For dynamic problems, the Laplace transform technique is used to transform the time domain problem to frequency domain. The so-called enriched radial basis functions are introduced to accurately capture the singularity of stress at crack tip. The accuracy and convergence of mesh free Galerkin method with enriched radial basis functions for the two-dimensional static and dynamic fracture mechanics are demonstrated through several benchmark examples. Comparisons have been made with benchmarks and solutions obtained by the boundary element method.

Abstract: A computational method for the micro-mechanical material model of woven fabric composite material was developed in this paper based on a repeated unit cell approach and two smooth fibre modes were presented. The stiffness matrix was evaluated with a domain integral by the use of radial basis function interpolations without element mesh. The applications of mesh free method to evaluate woven fabric composite elastic moduli have been presented and good accuracy has been achieved compared with the results by other approaches.