Numerical study on off-axis tensile behavior of 3D braided composites at elevated temperature

3D braided composites consolidated by heat-resistant resin are expected to become essential structural material of new generation aerospace vehicles. In this work, the thermo-mechanical behavior of 3D braided composites subjected to general off-axis tensile loadings at room and elevated temperatures is evaluated based on the meso-scale finite element (FE) model. A user-material subroutine UMAT is adopted to implement the thermal stress analysis, temperature-dependent failure initiation criteria and material properties degradation scheme of both fiber yarns and matrix. The meso-scale damage evolutions under thermal-mechanical coupling loads are simulated based on ABAQUS/Standard and the corresponding detailed failure mechanisms are revealed. The off-axial elastic moduli and strengths of 3D braided composites under elevated temperatures are also predicted. The numerical results indicate that high temperature affects the material properties mainly by weakening the matrix properties while off-axis loading affects the damage mechanisms by changing the load distribution of fiber yarn in each direction. The present work provides routine support for the numerical study of structural properties and damage behavior of other textile composites in service temperature environment.