Influence of infill density on the dynamic behavior of 3D-printed CF-PEKK composites using split Hopkinson’s pressure bars
Résumé
The dynamic mechanical behavior of 3D-printed CF-PEKK composites has been studied using the split Hopkinson pressure bar (SHPB). Three sets of samples with different infill densities (20, 50, and 100%) were impacted at different impact pressures (1.4, 1.7, 2.0, 2.4 bar) to characterize their dynamic behavior in terms of strain rate, stress, and strain performance. Moreover, the samples’ dynamic response and failure behavior are cross-referenced with each infill density sample's microstructural behavior and physical parameters, which can give an excellent dynamic response under different strain rate ranges. The results showed that dynamic stress and strain behavior are proportional to the infill density with a maximum dynamic stress of approximately 90 MPa with 100% infill density. In addition, the behavior of the transmitted wave during the dynamic impact showed that a sample with less infill density could attenuate/absorb dynamic impact. These results obtained under this impact pressure indicate the high precision and repeatability of the SHPB approach for the tested 3D composites under dynamic loading and prove that the striker bar velocity significantly impacts the amplitudes of different recorded waves to understand the behavior in detail. In addition, high-speed camera images also showed that the 3D-printed composite sample showed that using a higher infill density enhanced both the damage performance and the impact resistance of the three-dimensionally printed composites at each impact pressure because of the minimized intensity and the amount of final macro damage. This study is useful and helpful for design engineers to study the influence of the process parameter of infill on the dynamic behavior of printed composite materials and confirms the growing interest in 3D printing of composite materials to be employed in different engineering applications which are not limited to static or quasi-static loading circumstances but mainly include dynamic loading conditions.