Nonlinear thermo-mechanical coupling behaviours and damage mechanisms of 3D braided composites subjected to longitudinal and transverse tensile at room and elevated temperatures

This paper examines thermo-mechanical coupling behaviours and damage mechanisms of 3D4D (three-dimensional four-directional) braided composites subjected to longitudinal and transverse tensile at room and elevated temperatures. New nonlinear constitution model of 3D braided composites is derived in consideration of thermo-mechanical coupling effect, non-linear shear constitutive relationship of fibre yarn and elastoplastic deformation characteristics of matrix, and novel mixed criterion is then presented based on von-Mises rule, 3D Hashin criterion, B-K energy and quads damage model. After this, an improved progressive damage algorithm is devised for modelling progressive thermo-mechanical coupling damage process of 3D braided composites. Quasi-static longitudinal and transverse tensile tests are respectively performed on 3D4D braided composites at RT (room temperature) and 85 ∘C, and nonlinear thermo-mechanical coupling behaviours are analyzed and discussed from experiment results. In order to verify the model and algorithm mentioned previously, a high-fidelity full-scale mesoscale finite element (HFFSMFE) model is generated and integrated with improved algorithm for modelling progressive damage process of 3D4D braided composites subjected to longitudinal and transverse tensile at both temperatures, and numerical predictions agree well with experimental findings, demonstrating the apt and effective usage of new model proposed in the paper.