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目前在土木工程,建筑,汽车等领域里使用的复合材料中,玻璃纤维是用量最大的增强材料。由于保护地球环境的呼声日趋高涨,天然纤维被期待着代替源于石油而且再利用困难的玻璃纤维,成为绿色复合材料的必要材料之一。本文通过注射成型工艺制作了玻璃短纤维,大麻短纤维以及混杂型纤维增强复合材料,并在拉伸实验中应用两种不同频率的声发射技术检测了拉伸断裂特性。实验发现,随着大麻纤维的加入和混杂复合材料绿色度的增加,复合材料的拉伸弹性模量随之线性增大,而拉伸强度基本保持不变。当大麻纤维的含量超过20wt%的时候,拉伸强度开始降低。在不同频率的声发射实验中,混杂型复合材料的声发射事件的产生都比单一纤维增强型复合材料要来的晚,也就是说,纤维的混杂有助于推迟微裂纹的产生。
Currently in composite materials used in civil engineering, construction, automotive and other fields, glass fiber is the largest amount of reinforcing material. Due to the rising demands for protecting the Earth’s environment, natural fibers are expected to replace glass fiber, which is derived from petroleum and difficult to be reused, and becomes one of the necessary materials for green composite materials. In this paper, glass staple fibers, hemp short fibers and hybrid fiber-reinforced composites were fabricated by injection molding. Tensile properties were measured by two different frequencies of acoustic emission in the tensile test. The experimental results show that with the addition of hemp fiber and the green degree of hybrid composites, the tensile modulus of composites increases linearly, while the tensile strength remains unchanged. When the content of hemp fiber exceeds 20% by weight, the tensile strength begins to decrease. Acoustic emission experiments at different frequencies show that the acoustic emission events of hybrid composites are later than that of single fiber reinforced composites. That is, the hybridization of fibers helps to delay the occurrence of microcracks.