平纹编织C/SiC复合材料的剪切性能

采用IOSIPESCU纯剪切试件,改进反对称四点弯曲装置进行循环加卸载,试验研究了CVI工艺二维平纹编织C/SiC复合材料的面内剪切特性。分析了不同应力水平下卸载模量、残余应变的变化。基于试验研究结果,将剪切应变分解为弹性应变与非弹性应变,分别分析弹性应变和非弹性应变的变化规律,给出了剪切应力应变关系表达式。试件断裂时,最窄截面位置形成平断面,断面扫描电镜分析发现,基体和界面裂纹是主要损伤机理,0°纤维束最后断裂。

In-Plane Shear Fracture Characteristics of Plain-Woven C/SiC Composite

Plain-woven ceramic matrix composites (CMCs) are promising high temperature materials for applications in aerospace field. It is important to understand the in-plane shear properties for efficient design of CMC structures. In this paper, the in-plane shear properties of 2D woven C/SiC composite were investigated experimentally with IOSIPESCU specimens and improved asymmetric four-point bending set-up. In order to characterize the nonlinear stress-strain behavior, the total strain was divided into elastic strain and inelastic strain, the relationships between unloading modulus and stress, inelastic strain and stress were studied by cycling loading and unloading. An equation was provided to describe the shear stress-strain relationship. The specimens were sheared to failure in the narrow section plane. SEM observation shows that matrix cracking and interphase debonding are the major damage mechanisms. The 0- degree bundles broken at last.