Ceramic matrix composites (CMCs) are the preferred materials for solving advanced aerospace high-temperature structural components;it has the comprehensive advantages of higher temperature (~1500˚C) and low density. I...Ceramic matrix composites (CMCs) are the preferred materials for solving advanced aerospace high-temperature structural components;it has the comprehensive advantages of higher temperature (~1500˚C) and low density. In service environments, CMCs exhibit complex damage mechanisms and failure modes, which are affected by constituent materials, meso-architecture and inhere defects. In this paper, the in-plane tensile mechanical behavior of a plain-woven SiCf/SiC composite at room and elevated temperatures was investigated, and the factors affecting the tensile strength of the material were discussed in depth. The results show that the tensile modulus and strength of SiCf/SiC composites at high temperature are lower, but the fracture strain increases and the toughness of the composites is enhanced;the stitching holes significantly weaken the tensile strength of the material, resulting in the material is easy to break at the cross-section with stitching holes.展开更多
A theoretical model with extensible yarns for plain-woven fabrics is developed to determine the calculation of Poisson ratios.The stress ratio( warp: weft),as one of parameters corresponding to Poisson ratio variation...A theoretical model with extensible yarns for plain-woven fabrics is developed to determine the calculation of Poisson ratios.The stress ratio( warp: weft),as one of parameters corresponding to Poisson ratio variations, is introduced to complement the theoretical model. To evaluate the reliability of the theoretical analysis,a series of biaxial tensile tests of a plain-woven fabric with nine stress ratios are conducted carefully,and the theoretical results are compared with the experimentally measured values. The effects of other influencing factors, including geometric and mechanical parameters of yarns,on Poisson ratios are analyzed thoroughly.This solution method could be applied without difficulty to estimations of Poisson ratios and realistic designs for plain-woven fabrics.展开更多
为探究平纹织物复合材料的组分细观强度,笔者基于细观力学失效(micro-mechanics of failure, MMF)理论提出了一种确定平纹织物复合材料细观强度的跨尺度分析方法。建立了单向带复合材料和平纹织物复合材料纤维束的细观尺度代表体积单元...为探究平纹织物复合材料的组分细观强度,笔者基于细观力学失效(micro-mechanics of failure, MMF)理论提出了一种确定平纹织物复合材料细观强度的跨尺度分析方法。建立了单向带复合材料和平纹织物复合材料纤维束的细观尺度代表体积单元有限元模型,并介绍了基于代表体积单元模型的宏-细观应力转换方法;根据单向带复合材料的宏观强度测试结果确定了单向带复合材料的组分细观强度;以单向带复合材料组分细观强度为基础,根据组分强度不变的假设反推了平纹织物复合材料的纤维束强度,并以平纹织物复合材料层板宏观强度试验结果对反推所得的纤维束强度进行了校验与修正;以纤维束强度为基础,结合细观尺度代表体积单元模型,确定了平纹织物复合材料的纤维、基体组分强度。针对T300/环氧复合材料,应用上述方法并结合宏观强度测试,确定了平纹织物复合材料的组分细观强度。研究结果表明所提出的分析方法和计算结果与实验结果较为符合,可应用于实际工程复合材料。展开更多
文摘Ceramic matrix composites (CMCs) are the preferred materials for solving advanced aerospace high-temperature structural components;it has the comprehensive advantages of higher temperature (~1500˚C) and low density. In service environments, CMCs exhibit complex damage mechanisms and failure modes, which are affected by constituent materials, meso-architecture and inhere defects. In this paper, the in-plane tensile mechanical behavior of a plain-woven SiCf/SiC composite at room and elevated temperatures was investigated, and the factors affecting the tensile strength of the material were discussed in depth. The results show that the tensile modulus and strength of SiCf/SiC composites at high temperature are lower, but the fracture strain increases and the toughness of the composites is enhanced;the stitching holes significantly weaken the tensile strength of the material, resulting in the material is easy to break at the cross-section with stitching holes.
基金National Natural Science Foundations of China(Nos.51278299)Natural Science Foundation of the Jiangsu Province,China(No.BK 20150775)
文摘A theoretical model with extensible yarns for plain-woven fabrics is developed to determine the calculation of Poisson ratios.The stress ratio( warp: weft),as one of parameters corresponding to Poisson ratio variations, is introduced to complement the theoretical model. To evaluate the reliability of the theoretical analysis,a series of biaxial tensile tests of a plain-woven fabric with nine stress ratios are conducted carefully,and the theoretical results are compared with the experimentally measured values. The effects of other influencing factors, including geometric and mechanical parameters of yarns,on Poisson ratios are analyzed thoroughly.This solution method could be applied without difficulty to estimations of Poisson ratios and realistic designs for plain-woven fabrics.
文摘为探究平纹织物复合材料的组分细观强度,笔者基于细观力学失效(micro-mechanics of failure, MMF)理论提出了一种确定平纹织物复合材料细观强度的跨尺度分析方法。建立了单向带复合材料和平纹织物复合材料纤维束的细观尺度代表体积单元有限元模型,并介绍了基于代表体积单元模型的宏-细观应力转换方法;根据单向带复合材料的宏观强度测试结果确定了单向带复合材料的组分细观强度;以单向带复合材料组分细观强度为基础,根据组分强度不变的假设反推了平纹织物复合材料的纤维束强度,并以平纹织物复合材料层板宏观强度试验结果对反推所得的纤维束强度进行了校验与修正;以纤维束强度为基础,结合细观尺度代表体积单元模型,确定了平纹织物复合材料的纤维、基体组分强度。针对T300/环氧复合材料,应用上述方法并结合宏观强度测试,确定了平纹织物复合材料的组分细观强度。研究结果表明所提出的分析方法和计算结果与实验结果较为符合,可应用于实际工程复合材料。
