【作者】 刘芳；

【导师】 顾伯洪；

【作者基本信息】 东华大学 ， 纺织材料与纺织品设计， 2005， 硕士

【摘要】 三维编织复合材料由于结构的整体性特点,从根本上克服了层压复合材料断裂韧性及层间剪切强度低的缺点,从而在耐冲击领域得到应用。然而目前还没有文献涉及测试四步法三维编织复合材料在冲击拉伸条件下的基本力学参数。 用无碱玻璃纤维束在四步法1×1三维编织机上编织8×2型预型件,选用热固性环氧树脂作为基体,采用树脂传递模塑成型（RTM）技术制成四步法玻纤/环氧三维编织复合材料试件。分别在 New MTS 810 材料试验机和分离式 Hopkinson 拉杆 （Split Hopkingson Tension Bar 即SHTB）上对编织复合材料进行不同应变率的拉伸试验,获得在应变率为0.001 s^-1、1600 s^-1、2100 s^-1、2400 s^-1、3200 s^-1时的面内拉伸应力-应变曲线、得到相应应变率时三维编织复合材料的拉伸刚度、失效应力和应变等力学参数。试验结果表明编织复合材料的拉伸刚度和失效应力随应变率的增大而增大,而失效应变随应变率的增大而减小,即玻纤/环氧三维编织复合材料为应变率敏感材料;观测试件断口形态,发现试件在高应变率拉伸时具有脆性破坏特点,且随着应变率的增加,断口界面渐趋整齐。更多还原

【Abstract】 Compared with laminated composites, 3-D braided composites has higher fracture toughness and inter-layer shear strength because of its structural integrity. This leads applications of 3-D braided composites to impact resistance regime. However, there are not references concerned with mechanical parameters testing of the 3-D braided composites under impulsive loading, i.e., tensile test under high strain rates.The E-glass filament tows were employed to weave 8 ×2 braided preform with 4-step l ×1 braided technique. The epoxy resin, as a matrix, was used to form 3-D braided composites with RTM (Resin Transfer Molding) technique. The tensile properties of 3-D braided composites under different strain rates were tested on MTS 810 and the split Hopkinson tension bar (SHTB). The stress-stain, stress-time curves of the composites under strain rates of 0.001s~-1, 1600s~-1, 2100s~-1, 2400s~-1, and 3200s~-1 were obtained. The Young’s modulus, failure stress and strain were also gotten. It was found that the Young’s modulus, failure stress increase with the increase of the strain rate while failure strain decreases. From the stress-strain curves of the composites at various strain rates, it is shown that the E-glass/epoxy 3-D braided composites is strain rate sensitive material. The fractograph of the composites depicts that the 3-D braided composites fails in more brittle mode at high strain rate. As the increasing of strain rate, the fractograph becomes more smooth compared with that in lower strain rates.更多还原