Orthotropic Constitutive Modeling and Tsai–Wu Failure Criterion for Carbon Fiber-Reinforced PEEK Composites

This paper performs orthotropic constitutive modeling for short carbon fiber-reinforced polyetheretherketone (CF-PEEK) composites fabricated using material extrusion 3D printing technology. A variety of specimens for tensile, compressive, and shear tests are 3D printed under different deposition path patterns. The related experimental results disclose the strong directional mechanical properties, including tensile/compressive modulus and strength. The Tsai-Wu failure criterion is also developed based on the experimental data. The tensile-compressive behavior models of different orthotropic materials were constructed by importing the experimental data into COMSOL, followed by a compression simulation of the S-shaped specimen. The experimental results of the S-shaped compression test were compared with the COMSOL-based simulation analysis, which validated the effectiveness of the Tsai-Wu failure prediction. The predicted failure timings, locations and load-displacement curves all show a good agreement with experimental observations. Furthermore, the Tsai-Wu failure index is incorporated as a stress constraint in structural topology optimization, showing the effect of significantly reduced stress concentration. These findings and data will be supportive for the design and optimization of 3D printed CF-PEEK composites.