某3D SiC/SiC陶瓷基复合材料拉伸和弯曲损伤机制

《复合材料学报》优先在线发表论文。

摘  要：为了研究某三维编织SiC/SiC陶瓷基复合材料损伤机理，开展了室温条件下的单调拉伸和三点弯曲试验。实验前，利用扫描CT（Computed Tomography, CT）手段，明确了CMCs（Ceramic Matrix Composites, CMCs）试样的编织组织形态。对拉伸和三点弯曲试样的微观分析表明：（1）原生孔洞和微裂纹导致了材料在单调拉伸过程中形成局部应力集中，随着拉伸载荷的增加，基体的横向开裂和纤维束间纵向层间裂纹逐渐演化形成纤维内部裂纹，导致材料最终的脆性断裂失效；（2）在三点弯载荷作用下，表现为剪切、拉压共生的多耦合破坏模式，拉应力一侧首先发生失效，随后在中性面处发生剪切破坏，紧接着失效迅速向上下两侧扩展，直至截面在整个厚度方向发生失效；断口与纤维束的走向相关性很大，裂纹基本上沿着纤维束之间的界面进行扩展，造成最终失效未发生在理论失效位置处。

关键词：三维编织；复合材料；单调拉伸；三点弯曲；损伤机理

Abstract: In order to study the failure mechanism of a three-dimensional braided SiC/SiC ceramic matrix composite, the uniaxial tension and three-point bending tests at room temperature has been carried out. Before the experiment, the morphology of the braided structure of the CMCs(Ceramic Matrix Composites, CMCs) specimen was clarified by means of scanning CT (Computed Tomography, CT). Microscopic analysis of tensile and three-point bending specimens show: (I) During the tensile process, local stress concentration was developed in the material as a result of the primary pores and microcracks. As the tensile load increased, the cracking in the transverse direction of the matrix as well as the longitudinal interlaminar cracks between the fiber bundles gradually developed and internal fiber cracks were formed, ultimately resulting in a brittle fracture of the material. (II) Under the three point bending load, a combination of shear and tension failure mode was found. The failure firstly happened in the bottom side of the specimen with tensile stress. Then, shearing occurred at the neutral surface. After that, the cracking developed to both of the top and bottom sides, and finally the specimen failed totally. The fracture surface was strong correlative to the direction of the fiber bundle. The crack propagated substantially along the interface between the fiber bundles, which made the real failure location different from the theoretical prediction position.

Keywords: Three-dimensional woven; Composite material; Uniaxial tensile; Three-point bending; Failure mechanism

作者：胡晓安等，南昌航空大学 飞行器工程学院，南昌

通讯作者：阳海棠，中南大学 航空航天学院，长沙

全文详见中国知网学术期刊优先数字出版。