Failure analysis of laminated composites with shear nonlinearity and strain-rate response

Abstract Prediction of the mechanical response and failure behavior of laminated composites is vital for an efficient design in engineering applications. Vast quantity of failure models for composites were developed and compared in accuracy and applicability. In practice, many concerns usually appear at the material and damage model selection stage, since some models are not sensitive to important mechanical effects, while others are too complicated and require a large amount of experimental data. Presented work proposes a flexible approach for a failure modelling and initially requires only minimum of commonly available experimental data, but with possibility of extension to capture different forms of physical nonlinearity, including nonlinear shear and strain-rate effect. Proposed failure model is based on introduction of two damage parameters. Nonlinear shear response is formulated by introduction of an arbitrary polynomial shear stiffness dependency on shear strain component. Strain rate effects are considered using damage rate parameter, which has some advantages in constitutive equation formulation and practical usage. Special analytical relations for damage rate influence are presented with successful test correlation. Proposed model was implemented in commercial finite element analysis software via special user subroutines for practical computations. Numerical simulations for example problems of composites under biaxial loading and open-hole compression plate test were performed and a good correlation between theoretical and experimental results were achieved.