The present paper is dealing with the implementation of the explicit FE Code LS-DYNA to the simulation of the crash behavior and energy absorption characteristics of 3D braided composite tubes subjected to axial impact loading. The effects of geometrical and braid parameters on the energy absorption characteristics are investigated in this paper. The obtained numerical results are compared with actual experimental data, showing very good agreement.

A simplified model of 3D braided composites with transverse and longitudinal cracks is presented. By using the principle ofminimum 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. The effective Young's modulus and Poissonratio of 3D braided composites with transverse and longitudinal cracks are calculated using the homogenization theorem. Todemonstrate the solution, some examples are analyzed.

The analysis of three-dimensional braided composites is more difficult due to its complex microstructure. A new type of finite element method is used to predict the nonlinear response and damage evolution of three-dimensional braided composites. Good correlation is observed between the predicted and the experimental results presented in the published literature.

The analysis of 3D braided composites is more difficult due to its complex microstructure. A new type of finite element method isdeveloped to predict the effective moduli and the local stress within 3D braided composites under the 3D mechanical loading. Toverify the present method, the material properties of undamaged 3D braided composites predicted in this paper are compared withthe previous work. To demonstrate this method, some examples are analyzed.

The analysis of three-dimensional (3D) braided composites is more difficult due to its complex microstructure. A new type of finite element method (FEM) is developed to predict the local stress and strength within 3D braided composites under the three-dimensional mechanical loading. To verify the present method, the material properties predicted in this paper are compared with the previous work. By using the model, the stress components within a unit cell are obtained and used to analyze the strength of 3D braided composites.

The present paper develops a numerical technique named FSMS for simulating the crack growth of multilayered composites. Numerical simulations for the crack growth of multilayered ceramic/metal composites are carried out. The effects of some factors such as thickness ratio, initial crack length, material properties and dimensions of the structure on the crack growth are investigated. Numerical results show good agreement with experiments. FSMS is also a simple numerical method to solve crack problems of complex composite structures.

Apost-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.

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

A theoretical treatment of mode I crack problem is put forward for a functionally graded orthotropic strip. The internal crack and edge crack perpendicular to the boundaries are investigated, respectively. The elastic property of the material is assumed to vary continuously along the thickness direction. The principal directions of orthotropy are parallel and perpendicular to the boundaries of the strip. The singular integral equation for solving the problem and the corresponding asymptotic expression of the singular kernel are obtained. Three different loading conditions, namely crack surface pressure, fixed-grip loading and bending, are considered during the analysis. The influences of parameters such as the material constants and the geometry parameters on the stress intensity factors (SIFs) are studied.

The dynamic fracture behavior of a functionally graded coating–substrate system with an internal crackperpendicular to theinterface is studied under an in-plane impact load. The structure consists of a functionally graded coating and a semi-infinite homogeneoussubstrate. The crackis located in the functionally graded coating. The mixed boundary value problem is formulatedanalytically by use of integral transform techniques and singular integral equation. The influences of material constants and thegeometry parameters on the dynamic stress intensity factors (SIFs) are studied.