Dynamic constitutive modeling and compressive mechanical behavior of needle-punched C/C composites

Needle-punched C/C composites exhibit pronounced strain rate sensitivity during service. However, due to their highly complex internal structure, significant anisotropy is observed. The dynamic mechanical behavior of this material currently lacks adequate explanation and analysis. This study investigates the dynamic mechanical response under various conditions by conducting compression impact tests on needle-punched C/C composites at different strain rates and along different orientations. The results indicate that under high kinetic energy, crack nucleation and propagation occur within the material. Compression along different orientations alters crack propagation paths, leading to distinct failure modes: along the needling direction, failure primarily manifests as fiber shear fracture and interfacial debonding; perpendicular to it, failure is dominated by interfacial delamination and matrix cracking. Simultaneously, a certain level of kinetic energy exhibits an inhibitory effect on interfacial debonding, enhancing the load-bearing capacity to some extent. Finally, a dynamic constitutive model incorporating the strain rate effects on elastic modulus and peak strength is established. Validation through numerical simulations confirms that the model effectively describes the dynamic mechanical behavior of needle-punched C/C composites.