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| 循环载荷对单向CMCs应变分布均匀性的影响 |
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杨丛橙1,2,高希光1,2,于国强1,2,宋迎东1,2,3
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(1. 南京航空航天大学 能源与动力学院，航空发动机热环境与热结构工业和信息化部重点实验室，江苏 南京 210016;2. 南京航空航天大学 能源与动力学院，江苏省航空动力系统重点实验室，江苏 南京 210016;3. 南京航空航天大学 机械结构力学及控制国家重点实验室，江苏 南京 210016)
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| 摘要: |
| 采用数字图像相关方法(Digital Image Correlation，DIC)获得单向C/SiC复合材料在加载过程中的应变分布，并研究应变分布的特点以及循环载荷对应变分布均匀性的影响以更好地理解CMCs的力学特性。结果表明，单向C/SiC复合材料在加载初期，由于材料内部存在初始缺陷，应变呈现点状分布，对应应力-应变曲线中最初的线性阶段；在加载中期，应力-应变曲线进入非线性，此时基体裂纹开始增加，应变分布散乱；加载后期，应变呈现带状分布，且应变带位置与裂纹位置相对应，近似于等间距分布，此时应力-应变曲线恢复线性变化。循环加载会对材料受单向拉伸时的拉伸应变分布产生较大影响，使其分布散乱；但随着单向拉伸应变增大，试件上的拉伸应变分布趋于均匀。 |
| 关键词: 陶瓷基复合材料 循环载荷 应变分布 数字图像相关方法 |
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| 基金项目:国家重点研发计划(2017YFB0703200)；国家自然科学基金(51575261；51675266)；江苏高校优势学科建设工程 |
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| Effects of Cyclic Loading on Strain Distribution Uniformity of Unidirectional CMCs |
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YANG Cong-cheng1,2,GAO Xi-guang1,2,YU Guo-qiang1,2,SONG Ying-dong1,2,3
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(1. Key Laboratory of Aero-Engine Thermal Environment and Structure，Ministry of Industry and Information Technology，College of Energy and Power Engineering，Nanjing University of Aeronautics and Astronautics，Nanjing 210016，China;2. Jiangsu Province Key Laboratory of Aerospace Power System， College of Energy and Power Engineering，Nanjing University of Aeronautics and Astronautics，Nanjing 210016，China;3. State Key Laboratory of Mechanics and Control Mechanical Structures，Nanjing University of Aeronautics and Astronautics，Nanjing 210016，China)
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| Abstract: |
| The digital image correlation (DIC) technique was applied to the tensile test of unidirectional C/SiC composites to investigate the strain field distribution. The characteristic of strain field and the effects of cyclic loading on strain field uniformity were discussed. The results show that the non-linear macroscopic tensile stress-strain curve can be divided into three stages. During the first linear stage， the strain field shows dot-type distribution which centered on the initial imperfections of the material. After that the stress-strain curve turns into non-linear stage with the increase of the load due to the evolution of matrix cracking， and the strain distribution shows inhomogeneity. Finally， the strain field shows equispaced band-type distribution which corresponds to matrix cracks. In this stage， the stress-strain curve turns into linear again. The cyclic loading makes strain distributions scattered at the beginning of uniaxial tension test. However， the strain field becomes more uniform with the increase of the average strain. |
| Key words: Ceramic matrix composite Cyclic loading Strain distribution Digital image correlation |
