莫来石纤维增强SiO_2气凝胶复合材料的力学性能试验

为了探究莫来石纤维增强SiO_2气凝胶复合材料的拉伸和层间剪切性能,开展了相关试验。首先,进行了复合材料在室温下的面内拉伸试验,获得了复合材料的室温面内拉伸模量;然后,采用引伸计方法和数字图像相关法分别对拉伸变形进行测量,并对2种方法进行了对比分析;最后,开展了不同温度下的层间剪切试验,研究了复合材料在不同温度下的层间剪切性能,并对其微观结构进行了分析。结果表明:复合材料的拉伸模量约为285.17 MPa;由引伸计方法测得的拉伸变形计算出的拉伸模量比数字图像相关法获得的拉伸模量高2.4%;在室温和高温下,试样呈现明显的层间剪切破坏;对复合材料的微观分析发现,SiO_2气凝胶基体主要分布在层间区域,增强纤维主要分布在铺层内。所得结论表明莫来石纤维增强SiO_2气凝胶复合材料拉伸和层间性能较差,当承受层间载荷时,SiO_2气凝胶基体起主要作用,且温度对复合材料的性能影响较大。

Mechanical property tests of mullite fiber-reinforced SiO2 aerogel composites

In order to investigate the tensile and interlaminar shear properties of mullite fiber reinforced SiO2 aero-gel composites,related tests were conducted.The in-plane tension tests of the composites were carried out at room temperature firstly,and the in-plane tensile modulus of the composite at room temperature was obtained.Then,the extensometer method and digital image correlation method were adopted respectively to measure the tensile deforma-tions,and the two methods were compared and analyzed.Finally,the interlaminar shear tests at different tempera-tures were conducted,the interlaminar shear properties of the composites at different temperatures were investiga-ted,and the microstructures were analyzed.The results show that the tension modulus of the composites is about 285.17 MPa.The tensile modulus calculated by the tensile deformation obtained by the extensometer method is 2.4% higher than the tensile modulus obtained by the digital image correlation method.The specimens present obvi-ous interlaminar shear damage at room temperature and high temperature.The microscopic analyses on composites find that SiO2 aerogel matrix mainly distributes in interlaminar areas and reinforced fibers mainly distributes in plies. The conclusions obtained show that the tensile and interlaminar properties of mullite fiber reinforced SiO2 aerogel composites are relatively poor,SiO2 aerogel matrix plays a main role under interlaminar shear load,and temperature has a great influence on the properties of the composites.