This paper presents an investigation on the effects of hydrothermal aging on Sheet Molding Compound (SMC) composite. Two different techniques were carried out to study the inner structure of aged SMC composite. Firstly, X-ray micro computed tomography (XµCT) was used to evaluate the changes using 3D images. The results showed cracks in all the composite structure with different shapes and volume in response to the hydrothermal conditions. The cracks results from the build up of an osmotic pressure in microcavities, which is proportional to water concentration. However, it was not possible to quantify separately the hydrothermal induced damage in the studied SMC composite material. Therefore, the XµCT analyzes were supplemented by a microscopic study. This step has been studied in terms of crack density evolution and crack propagation rate. The results obtained by XµCT technique and SEM observations show that the damage increases continuously with time and temperature during aging. The damage was found to be located in the voids contained in the matrix at early stage of aging. Then it is mostly developed into the fiber interface in the form of fiber/matrix interfacial debonding.

本文对水热老化对片状模塑料（SMC）复合材料的影响进行了研究。进行了两种不同的技术来研究老化的SMC复合材料的内部结构。首先，使用X射线微计算机断层扫描（XµCT）来评估使用3D图像的变化。结果表明，响应水热条件，不同形状和体积的复合材料结构均出现裂纹。裂纹的产生是由于微腔内的渗透压升高，该渗透压与水浓度成正比。但是，不可能单独量化研究的SMC复合材料中水热引起的损伤。因此，XµCT分析得到了微观研究的补充。已经根据裂纹密度的演变和裂纹扩展速率研究了这一步骤。通过XµCT技术和SEM观察得出的结果表明，在老化过程中，损伤随时间和温度的增加而不断增加。发现该损伤位于老化早期的基质中所包含的空隙中。然后，它主要以纤维/基质界面剥离的形式发展成纤维界面。