纤维长径比对环氧复合材料动态力学性能的影响

本文研究不同纤维长径比对碳纤和玻纤环氧复合材料动态力学性能的影响.结果表明,随长径比的增大,材料的力学内耗下降而模量增加;在低长径比,碳纤复合材料的内耗值比玻纤复合材料的高.达到一定长径比后,内耗值和模量值趋于连续纤维复合材料的值.温度越高,基体模量下降,达到相同纤维刚度的使用效率所需要的长径比就越大.用材料在外载荷或热缩应力作用下,纤维及其界面上沿纤维方向上的应力大小和分布随长径比的变化规律解释上述现象.

EFFECTS OF FIBER ASPECT RATIO ON THE DYNAMIC MECHANICAL PROPERTIES OF EPOXY COMPOSITES

The effects of fiber aspect ratio on the dynamic mechanical properties for both the glass/epoxy and carbon/epoxy composites have been investigated. The results show that the mechanical internal friction of materials reduces and the modulus enhances with fiber aspect ratio. After a certain aspect ratio both the internal friction and modulus begin to level off and to approach the values of continuous fiber composites. Therefore, the fiber utilization effici-ency is fully played. The internal friction of carbon fiber composite is higher than that of glass one. The higher the test temperature and the lower the matrix modulus, the fiber efficiency will be lower. Hence, the aspect ratio for the same fiber efficiency will be higher. The phenomenon mentioned above could be aceounted by that the stresses in the fibers and at the fiber/resin interface along the length of the fibers would change with aspect ratio under the external loading or the thermal shrinkage stresses are applied.