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为了研究应变率对准三维针刺碳纤维增韧的碳化硅复合材料(Cf/SiC)层向压缩力学性能的影响,本文利用分离式Hopkinson压杆装置对三维针刺Cf/SiC复合材料进行了应变率为10-4至6.5×103s-1的单轴压缩力学性能测试。实验结果表明,由于材料缺陷,其动态压缩强度分布遵循Weibull分布。破坏时,材料并未表现出典型的脆性破坏,而是在应力达到压缩强度后经历了较大的伪塑性变形才最终破坏。这表明三维针刺Cf/SiC复合材料沿厚度方向针刺的碳纤维有助于提高材料的韧性。同时,材料的压缩强度随应变率的升高显著增大,并与对数应变率近似成线性关系。借助光学显微镜和扫描电镜对压缩断口的观察表明:材料的失效模式随着应变率变化而发生改变。在准静态下,材料主要表现为剪切和分层破坏,而在高应变率下,则主要表现为劈裂。
In order to study the effect of strain rate on the compressive mechanical properties of three-dimensional acupuncture-carbonized carbon fiber reinforced composites (Cf / SiC), a three-dimensional acupuncture-Cf / SiC composite was subjected to strain Uniaxial compressive mechanical properties of 10-4 to 6.5 × 103s-1 were tested. Experimental results show that the dynamic compressive strength distribution follows the Weibull distribution due to material defects. When destroyed, the material did not show the typical brittle failure, but eventually undergone greater pseudoplastic deformation after the compressive strength of the stress was reached. This shows that the three-dimensional needle-punched Cf / SiC composites along the thickness of the needle-punched carbon fiber helps to improve the toughness of the material. At the same time, the compressive strength of the material increases with the increase of strain rate, and it is approximately linear with the logarithmic strain rate. The observation of the compression fracture with optical microscope and scanning electron microscope showed that the failure mode of the material changed with the change of strain rate. Under quasi-static conditions, the material is mainly shear and delamination failure, while at high strain rates, the material is mainly split.