Systematical mechanical analyses of 3D printed short carbon fiber reinforced polyetheretherketone composites

Though the micro-structure of 3D printed short carbon fiber reinforced thermoplastic (SCFRTP) composites is well reckoned to have a great influence on their mechanical performances, the existing models are deficient in considering microscopic factors and thus large errors existed in their predictions. In this work, the effects of micro-structure on the mechanical properties of 3D printed SCFRTP composites are systematically analyzed. The microscopic representative volume elements (micro-RVEs) of 3D printed SCFRTP composites with fibers of probability density distributed length and void defects are established using the modified random sequential adsorption (RSA) algorithm based on experimental results. The present model (m-RVE_{fv_d}) can evaluate the mechanical performances of 3D printed SCFRTP composites more accurately and effectively compared with the existing models that did not consider the effects of void defects and fiber probability density distributions. In addition, it is observed that as the fiber content increases, the average length of short fibers decreases while the content of void defects increases. When fiber content is less than 5 wt%, the composite mechanical properties are dominated by fiber content; as the fiber content exceeds 5 wt%, the composite mechanical properties are mainly affected by microscopic defects. Finally, a strategy is proposed for achieving high mechanical performance SCFRTP composites based on the systematical mechanical analyses conducted in this work.