【作者】 王浩伟；

【导师】 张大旭；

【作者基本信息】 上海交通大学 ， 建筑与土木工程， 2016， 硕士

【摘要】 过去三十多年,研究者们已经对陶瓷基复合材料的力学性能和损伤机理进行了大量的研究,目前主要关注整体性能较好的纺织结构陶瓷基复合材料。由于纺织结构陶瓷基复合材料本身细观结构复杂且不规则、内部缺陷较多,目前仍然无法准确地预测和分析其力学行为,仍需要研究来揭示其力学行为,故有必要对其力学性能和损伤破坏机理进行研究探索。本文综合应用数值模拟和解析方法,结合试验数据,对平纹陶瓷基复合材料及其开孔试件的拉伸性能及损伤开展了纤维束、平纹结构的单胞,和层合板三个尺度上的研究。在单胞尺度上,本文采用域分解方法建立了平纹机织结构的单胞模型,通过二次开发子程序,考虑了拉伸过程中纤维束损伤引起的材料非线性,通过施加拉伸荷载,得到了单胞模型的拉伸应力应变响应,与试验数据对比结果基本一致,并对平纹结构对材料拉伸性能的影响进行了分析。在纤维束尺度上,本文采用解析方法依次得到了单向纤维束、0°/90°层合板的拉伸应力应变响应,然后在有限元模型的计算结果和试验数据的基础上,将解析方法扩展到平纹结构的拉伸应力应变响应上,与试验数据对比,结果基本吻合。在层合板尺度上,本文对开孔平纹机织陶瓷基复合材料建立了有限元模型,通过二次开发子程序引入了蔡-吴破坏准则,分析了开孔对平纹机织结构的力学性能的影响。通过与试验数据的对比,验证了模型的正确性。更多还原

【Abstract】 In the past 30 years,great efforts have been made to study the mechanical behavior and damage of ceramic matrix composites(CMCs).Nowadays the majority of studies focus on textile structure CMCs,which has excellent integral performance.Due to the complicated topology of mesostructured and large amount of internal defects of textile CMCs,it is still a challenge to accurately analyse and predict their mechanical behavior.Further investigations are certainly needed to reveal the mechanical behavior of CMCs,and therefore the dissertation carried out a study on tensile property and damageBased on experimental data,the current work employed numerical and closed-form methods to study the tensile and damage behavior of CMCs materials and an open-hole specimen at the scales of fibre tows,unit cells,and laminates.Firstly,at the unit cell scale,a finite element model has been created by using the domain decomposition method,in which,the nonlinear material properties of fiber tows caused by strain-induced damage are taken into account by coding a user defined subroutine.The stress-strain response of a unit cell model under uniaxial tension has been predicted.The simulation results have a good correlation with the experimental data.The effects of plain weave mesostructured on the material’s tensile behavior are addressed.Secondly,at the fibre tow scale,a closed-form approach is used to predict the tensile stress-strain response of a unidirectional tow and a 0°/90° laminate.On the basis of the finite element results and test data,the closed-form method is extended to analyse the tensile behavior of a plain weave CMC,and the close-form results agree well with the test data.Finally,at the laminate scale,the finite element model of an open-hole specimen is developed,in which,the Tsai-Wu failure criterion and nonlinear material properties are considered by using a user defined subroutine.The fidelity of the model is verified by comparing the finite element result with the experimental data.更多还原