【作者】 李旺；

【导师】 邱夷平；

【作者基本信息】 东华大学 ， 纺织材料与纺织品设计， 2006， 硕士

【摘要】 李旺 三维正交机织复合材料的制造和高应变率压缩行为的研究（论文在邱夷平教授指导下完成） 三维正交机织复合材料已经被广泛地运用航天航空领域,并且采用此类材料制造的构件经常受到高应变行为的作用,所以本文重点论述了三维机织复合材料的制造过程,还利用了HOPKINSON杆技术研究了此类材料的高应变率效应。 三维正交织物是经纱,纬纱和Z纱线相互垂直交织而成,本研究中采用三维混编织物,经纱和Z纱线采用芳纶纤维,纬纱采用玻璃纤维。三维正交织物是采用东华大学纺织学院自主开发的正交三维织机织造而成,然后将三维织物和环氧树脂采用真空辅助加压技术加工成三维正交机织复合材料。由于Z方向纱线增强的原因,此材料具有良好的抗冲击性能,并能够有效的抑制了材料的分层现象。再把材料制成9mm×9mm的试样在面内经向和纬向及面外三个方向进行准静态压缩实验和动态HOPKINSON杆压缩实验。准静态实验是在上海交通大学MTS实验机上测试,实验获得应变率为0.0001s^-1;动态压缩实验实在东华大学纺织材料实验室进行测试,应变率分布为900s^-1到3200 s^-1。材料的破坏模式采用光学显微镜进行分析。 试验结果显示三维正交机织复合材料在三个测试方向上都表现出对应变率敏感的特性,随着应变率的增大,材料的失效应力也会增大,材料的模量也增大,但是材料的失效应变会减小。由于采用了三维混编结构,在面内经向和纬向这两个方向上材料就表现出强度和模量和应变率的很大的各向异性,材料在纬向比经向具有较大的压缩强度和模量,这是由于纤维本身的强度和应变不更多还原

【Abstract】 The vast differences in strength, ultimate strain and modulus during high strain rate deformation of materials have been a very long-standing subject of engineering interest. This thesis deals with characterization of mechanical properties of 3D orthogonal woven hybrid composites. The focus of this study is to compare the mechanical properties of these composite materials at high strain rates and quasi-static conditions and to find out the effects of failure modes on high strain rate mechanical properties of these materials.The 3D woven hybrid perform construction was evaluated: warp and Z yarns used Twaron fibers, fill yarns used glass fibers. The preforms were fabricated on the computer-controlled, fully automated, 3D weaving machine developed at The College of Textiles, Donghua University. The preforms were consolidated in epoxy matrix with the VARTM method. The static compression tests were tested using MTS servo-hydraulic machine which obtained the strain rates of about 0.001s~-1. Split Hopkinson Pressure Bar (SHPB) apparatus is used for the HSR testing of materials at varying strain rates, varying from 900s~-1 to 3200 s~-1. The specimens were tested in three directions such as warp, fill and through-the-thickness direction. Failed specimens are consequently observed under optical microscope in order to understand the fracture modes of these materials.The results of the tests on materials demonstrate considerable increase in peak strength and the elastic modulus under high strain rate in any direction. It is also observed that the failure strain values vary considerably with increasing strain rate in three directions. Because the material use different fibers in fill and warp direction, in the fill direction, the specimens showed higher strength and stiffness. In the through-the-thickness direction, there existed higher failure strain. At the same time, in the warp direction, the Twaron fiber show lower sensitivity to strain rate than the E-glass fibers in the fill direction. The damage modes of fill and warp direction are kink band deformation, matrix crack, fiber broken and declamation. In the through-the-thickness direction, the damage modes are shear deformation, matrix crack and fiber breakage. These results are essential for conducting realistic numerical simulations for safe design of structures.更多还原