Assessment of fiber reinforcement strategies for additively manufactured thermoplastic composites using mechanical testing and finite element analysis

Additively manufacturing (AM) for fiber-reinforced plastic (FRP) composites is gaining increasing opportunities in small batch parts designed for aviation applications for their high specific strength, freedom of tailorable properties, creep resistance, and accessibility. The fused filament fabrication (FFF) production suites of 3D-printed FRP composites are commercially available, easily operable, and mechanically simple to provide close-proximity manufacturing of parts-in-need. Experimental verification of properties can be made selective and cost-effective when accompanied by validated predictive capabilities. This becomes even more relevant when considering 3D-printed parts on demand for in-space manufacturing and space exploration. The results reported here were supported by a NASA program to develop that comprehensive approach. The research aims are two-fold—to deliver performance-centric strategies for AM design made by continuous and discontinuous FRP and the validation technique for such strategies by finite element analysis (FEA) simulation. The numerical modeling based on FEA was developed in conjunction with materials properties made available from experiments and literature. A rate-dependent plasticity model for additively manufactured short fiber reinforced composites and an orthotropic material model for continuous fiber-reinforced composites were implemented. Reinforcing strategies were developed to test the effectiveness of each fiber pattern and layout. Tensile specimens were configured, fabricated, and tested to generate experimental data to evaluate the strategies. The feasibility of the modeling approach predicting mechanical performances was examined by comparison of the simulated and empirical results. The procedure would help validate in-field 3D-printed components where mechanical tests might be limited or inaccessible, as in the case of space exploration.