二步法和四步法三维编织复合材料轴向力学性能的比较研究

Research on the axial direction mechanical properties of the two-step and four-step three-dimensional braided composites

对具有不同细观结构参数的二步法方型三维编织复合材料试件进行轴向拉伸及轴向压缩的力学性能测试,以其结果与纤维体积含量基本相等的四步法方型三维编织复合材料的基本力学性能数据进行对比.结果表明,前者的轴向力学性能较为优越.文中同时还从宏观角度分析了编织纱的种类、编织纱与轴纱的线密度之比以及编织节距长度对其材料力学性能的影响,确认二步法三维编织复合材料的轴纱对轴向拉伸和压缩性能起主导作用,节距长度增大、编织纱线密度增加,轴向拉伸强度、拉伸模量以及轴向压缩强度和模量均有增大的趋势.

This paper presents the results of an experimental study of the mechanical properties of the twostep rectangle 3D braided composites. The tests include tensile and compression in the axis. The comparison is made between the twostep and fourstep rectangular braided composites which have the same fibre volume fraction. It shows that the axial direction mechanical properties of the former are superior than that of the latter. On the basis of the character of the twostep braided preform microstructure, this paper relates the influence of microstructural variables such as the kinds and sizes of braided yarns, the linear density ratio of axial to braided yarns and the pitch length on the mechanical properties of these composites from macroscopical view. It shows that the axial yarns dominant the tension and compression properties in the axial direction. The strength and modular of tension and compression in the axial direction increase with the pitch length and size of braided increasing.