莫来石纤维增强SiO_(2)气凝胶复合材料压缩回弹性能实验与建模研究

Experimental and modeling investigation on compression springback property of mullite fiber reinforced silica aerogel composites

对莫来石纤维增强SiO_(2)气凝胶复合材料开展面外方向单轴压缩实验,研究不同极限应变、热暴露温度对压缩回弹行为与变形恢复能力的影响,基于微观结构形貌变化阐释内在机制,对加载和卸载阶段的变形行为建立唯像力学模型。结果表明:莫来石纤维增强SiO_(2)气凝胶复合材料的压缩回弹行为呈现非线性特征,极限应变越大,变形恢复能力越差;高温热暴露预处理会对压缩回弹性能产生影响,热暴露温度越高,变形恢复能力越差,基体颗粒-团簇结构的聚集、大尺寸孔洞的形成和塌陷是主要原因;所建立的唯像力学模型可以用来描述材料在压缩加载-卸载时的应力-应变曲线,拟合结果与实验数据吻合较好。

Uniaxial compression tests were carried out on mullite fiber reinforced silica aerogel composites in the out-of-plane direction.Influences of different ultimate strains and thermal exposure temperatures on the compression springback behavior and deformation recovery capability were investigated.Internal mechanisms based on the microstructure morphology changes were explained.Phenomenological mechanical models were established respectively for the deformation behavior in the loading and unloading stages.The results show that the compression springback behavior of mullite fiber reinforced silica aerogel composites exhibits nonlinear characteristics.The greater the ultimate strain,the worse the deformation recovery capability.High temperature thermal exposure pre-treatment has an effect on the compression springback property,the higher the thermal exposure temperature,the worse the deformation recovery capability.The aggregation of matrix particle-cluster structure and the formation and collapse of the large size holes are main causes.The phenomenological mechanical model can be used to describe the stress-strain curve of the composites during loading and unloading.The fitting results are in good agreement with the experimental data.