碳／环氧编织复合材料热膨胀特性分析

Thermal expansion coefficients of carbon/epoxy braided composites

采用理论与试验相结合的方法,研究了碳/环氧三维编织复合材料的热膨胀特性。通过试验方法获得了不同规格的三维编织复合材料在编织方向的热膨胀系数,并基于均匀化理论建立了编织材料热弹性性能的分析方法,对数值结果与试验值进行了比较。研究表明,三维编织复合材料在编织方向上具有典型的负膨胀特性;与三维四向编织结构复合材料相比,三维五向编织结构复合材料具有较小的负膨胀系数;三维编织复合材料编织方向的负膨胀系数随着纤维体积含量的增大而减小,随着编织角的增大而增大;基于均匀化理论的热弹性数值分析方法可有效地预报三维编织复合材料的等效热膨胀系数,数值计算值与试验结果吻合较好。

The thermal elastic properties of 3D carbon/epoxy braided composites were investigated by means of the experimen- tal method and the theoretical approach. The coefficient of thermal expansion （CTE） of 3D braided composites was tested by using a differential dilatometer. Then a theoretical approach was developed for predicting the effective thermo-elastic properties of 3D brai- ded composites based on the homogenization theory, and the numerical results were compared with the experimental data. The re- suhs show that 3D braided composites have the typical negative CTE in the braiding direction. The negative CTE of 3D five-direc- tional braided composites is smaller than that of 3D four-directional braided composites. Meanwhile the negative CTE in the braiding direction decreases as the fiber volume fraction increases, and it increases as the braiding angle increases. Finally, the effective CT- Es of 3D braided composites were simulated by means of the homogenization method. The numerical results are in good agreement with the experimental data.