Linzhi Wu

The interface crack problem under a concentrated load for a functionally graded coating–substrate composite system

Abstract The plane crack problem for a functionally graded coating–substrate system under a concentrated load is studied in this paper. The medium consists of a functionally graded coating bonded to a homogeneous substrate of finite thickness, containing an interface crack of finite length. With use of the integration transform and differential factor methods, the displacement form can be obtained. By introducing auxiliary functions, the present problem can be turned into solving a group of singular integral equations. The mixed-mode stress intensity factors (SIFs) and strain energy release rates (SERRs) are obtained. The influences of the parameters such as the load location, nonhomogeneity constants and the geometry parameters on the SIFs and SERRs are studied.

A damage model for 3D braided composites with transverse cracking

Abstract A simplified model of three-dimensional (3D) braided composites with the transverse cracking is presented. By using the principle of minimum complementary energy, the stress components are obtained in closed-form expressions in terms of a perturbation function, which is governed by two fourth-order inhomogeneous ordinary differential equations. All possible expressions of this perturbation function are obtained in closed forms. The effective Young’s modulus and Poisson ratio of 3D damaged braided composites are calculated using the determined minimum complementary energy. To demonstrate the solution, some examples are analyzed.

Post-buckling analysis of stiffened braided cylindrical shells under combined external pressure and axial compression

A post-buckling analysis is presented for a stiffened braided thin shell subjected to combined loading of external pressure and axial compression. The effects of the nonlinear large deflection and the initial geometrical imperfection are considered in the formulations. The analysis uses perturbation method to determine the interactive buckling loads and the post-buckling equilibrium paths and a three-cell model are used to obtain the elastic constants of braided shell. Some effects such as imperfection parameter, stiffened and Braiding parameters on the post-buckling path are discussed in the article.

Interaction of two circular cylindrical inhomogeneities under anti-plane shear

A simple and effective method is used to derive the elastic field of the infinite homogeneous isotropic medium with two circular cylindrical inhomogeneities under the anti-plane shear. The analytical solution is obtained by using the conformal mapping and the theorem of analytic continuation. When two circular cylindrical inhomogeneities are tangent to each other and/or they are holes and/or rigid inhomogeneities, the corresponding specific cases are also considered in this paper. Finally, numerical results are illustrated to apply the present results to composite materials.