Mesomechanical simulation of rate-dependent mechanical behavior for triaxially braided composites

Triaxially braided composite is a state-of-Art material used for engine fan case structure. The mechanical failure behavior of triaxially braided composite is very complicated due to its complex structure in the mesoscale. Extensive studies have been conducted experimentally and numerically to investigate its progressive failure behavior and size-dependent properties under quasi-static loading rates. In this paper, a mesomechanical model is presented to study the rate-dependent failure behavior of T700s/PR520 triaxially braided composite. Strain-rate dependent mechanical properties of the matrix are implemented into a micromechanical model to determine the mechanical properties of fiber tows at various strain rates (1×10-5, 1, and 500 /s), which are then imported into the mesomechanical model to investigate the rate dependency of effective properties and failure behavior for the braided composite. Comparison studies on the strain and stress field, damage contours of triaxially braided composite under axial tension, and transverse tension of different strain rates are conducted using the presented model. The numerical results elaborate the effect of strain rate on the damage progression behavior and identify the main factors that affecting the failure strength. The results of this work can be useful for developing more accurate constitutive and damage model for impact modeling of engine fan case made from triaxially braided composite.