Three-dimensional printing is becoming increasingly popular because of its extensive applicability. However, printing materials remain limited. To determine the mechanical properties of polylactic acid (PLA) and copper powder-filled polylactic acid (PLA-Cu) materials subjected to static and dynamic loading, stress–strain curves were obtained under the conditions of different strain rates using a universal material testing machine and a separated Hopkinson pressure bar experimental device. Scanning electron microscopy (SEM) was used to analyze the micro-morphology of the quasi-static compression fracture and dynamic impact sections. The results revealed that the yield stress and elastic modulus of the two materials increased with increasing strain rate. When the strain rate reached a critical point of 0.033 s⁻¹, the rate of crack propagation in the PLA samples increased, resulting in the material undergoing a change from ductile to brittle. The strength of the material subjected to dynamic loading was significantly higher than that subjected to quasi-static loading. The SEM image of the PLA-Cu material revealed that copper powder was evenly distributed throughout the 3D-printed sample and that stress initially began to concentrate at the defect site corresponding to the interface between the copper powder and PLA matrix; this resulted in comparatively lower toughness. This finding was consistent with the photographs captured via high-speed photography, which confirmed that the destruction of the specimen was accompanied by an explosive crushing process. Additionally, a Zhu–Wang–Tang constitutive model was used to fit the experimental results and establish a viscoelastic constitutive model of the material. By comparing the dynamic stress–strain curve to the theoretically predicted curve, we found that the established constitutive model could predict the mechanical properties of the PLA-Cu material with reasonable accuracy when the strain was below 7%.

The jet formed by the traditional metal liner has a slender shape. The diameter of the jet head is consistent with that of the tail, and the ductility is good. When it is used to penetrate the target, it has a good damage effect. The low-density jet formed by the PTFE/Cu liner, according to the different preparation processes and densities, has different degrees of radial expansion. This phenomenon may lead to the expansion of the jet head during the penetration process, resulting in a damage effect, which is different from the previous jet on the target. In this paper, the numerical simulation of PTFE/Cu liners with different preparation processes penetrating steel targets is carried out, and the effects of different preparation processes and liner density on the penetration characteristics of jets penetrating steel targets are compared and analyzed. The PTFE/Cu shaped charge liner was processed according to different preparation processes, and the jet penetration steel target experiment was carried out, so as to verify and analyze the numerical simulation results.

In order to study the microstructure evolution of polytetrafluoroethylene–copper (PTFE-Cu) composites under compression load and reveal the molecular dynamics mechanism of deformation failure, three PTFE-Cu composites with different densities (3.0 g/cm³, 3.5 g/cm³, 4.0 g/cm³) were prepared in this study. The crystallinity of PTFE in each sample was determined via differential scanning calorimetry (DSC). The quasi-static compression mechanical properties test was carried out to analyze the effect of PTFE crystallinity on the macroscopic mechanical response of the composites. It is found that the crystallinity of the three PTFE-Cu composites was 43.05%, 39.49% and 40.13%, respectively, showing a non-monotonic trend of decreasing first and then increasing with an increase in copper powder content. The elastic modulus and yield strength of the material are negatively correlated with the crystallinity. The failure mode is the axial splitting failure and the composite morphology of axial splitting failure and shear tearing. Finally, the molecular dynamics simulation method is used to reveal the microstructure evolution and deformation failure mechanism of PTFE-Cu composites under compression load from the atomic scale, which provides a theoretical basis and experimental support for understanding the mechanical properties of PTFE-Cu composites.

In this paper, the effect of manufacturing methods on the compressive properties of Cu‐PTFE (polytetrafluoroethylene) composites was investigated. Two types of specimens were prepared through different manufacturing methods (extrusion forming and hot‐press sintering). The specimens were tested using an electrohydraulic press and split‐Hopkinson pressure bars for quasi‐static loading and dynamic impact, respectively. The specific fracture processes were recorded by using a high‐speed camera, and the failure microstructures of the specimens were analysed by SEM. According to the results, hot‐press sintered specimens have consistently higher strength and toughness under dynamic compression than the extruded specimens, while the mechanical properties of hot‐press sintered specimens are inferior to those of extruded specimens under quasi‐static compression. The failure of extruded specimens is primarily caused by the elastic mismatch between the PTFE matrix and Cu particles, as well as the polymerisation of plastic pores, which leads to particle pullout. However, the cracks in the hot‐press sintered specimens were caused by the shear deformation and interface sliding of the PTFE matrix, which led to matrix tearing.