Papers by Author: Li Cheng Guo

Abstract: A thermal shock problem of a functionally graded material plane (FGMP) containing a crack is considered. All the material properties of the FGMP are assumed to be dependent on the coordinates.The transient temperature fields are solved by combining the finite difference method (FDM) and the finite element method (FEM). Then the transient thermal stress intensity factors (TSIFs) are obtained using the interaction energy integral method. The transient characteristics of the TSIFs are investigated.

Abstract: An interface crack problem in two nonhomogeneous plates under thermal loading is investigated. The interaction energy integral method (IEIM) is developed for obtaining the mixed-mode thermal stress intensity factors (TSIFs) of interface crack. The domain-independence of the present IEIM is verified. Numerical examples are presented and the results show good agreement with the analytic ones. Numerical results show that the method is very effective for the thermal interface crack of nonhomogeneous plate.

Abstract: Functionally graded materials (FGMs) with continuous varying properties have absorbed great attention for the purpose of eliminating the mismatch of material properties which may result in cracking. In this paper, three-dimensional finite element method (3D FEM) based on nonhomogeneous elements is used to study the fracture behaviors of a 3D FGM plate. Since real material properties at Gaussian integration points are adopted during forming the element stiffness matrix, the nonhomogeneous material properties can be applied in each element. Moreover, 20-node singular elements are used around the crack front to deal with the singularity of stress fields at the crack front. By this way, the stress intensity factors (SIFs) can be calculated with high efficiency and accuracy. Therefore, compared with the general FEM using homogeneouos elements, the calculating efficiency and accuracy can be increased. Finally, parameter analysis is conducted. It is found that the material nonhomogeneity constant and the crack parameter have significant influences on the SIFs.

Abstract: The crack problem for a functionally graded orthotropic coating-substrate structure under an in-plane load is studied. The orthotropic coating is assumed to contain a crack perpendicular to the interface. Integral transform method is used to obtain singular integral equation. Stress intensity factors (SIFs) are evaluated. The influences of orthotropic material constants and the geometry parameters on SIFs are analyzed.