An investigation is presented on increasing the fracture toughness of epoxy/short carbon fibre (SCF) composites by alignment of SCFs using an externally applied alternating current (AC) electric field. Firstly, the effects of SCF length, SCF content and AC electric field strength on the rotation of the SCFs suspended in liquid (i.e. uncured) epoxy resin are investigated. Secondly, it is shown the mode I fracture toughness of the cured epoxy composites increases with the weight fraction of SCFs up to a limiting value (5 wt.%). Thirdly, the toughening effect is greater when the SCFs are aligned in the composite normal to the direction of crack growth. The SCFs increases the fracture toughness by inducing multiple intrinsic and extrinsic toughening mechanisms, which are identified. Based on the identified toughening mechanisms, an analytical model is proposed to predict the enhancement to the fracture toughness due to AC electric field alignment of the SCFs.

提出了通过使用外部施加的交流（AC）电场通过对齐SCF来提高环氧/短碳纤维（SCF）复合材料的断裂韧性的研究。首先，研究了SCF长度，SCF含量和交流电场强度对悬浮在液态（即未固化）环氧树脂中的SCF旋转的影响。其次，表明固化的环氧复合材料的模式I断裂韧性随着SCF的重量分数达到极限值（5重量％）而增加。第三，当SCF在复合材料中垂直于裂纹扩展方向排列时，增韧效果更大。SCF通过诱导多种内在的和外在的增韧机制来提高断裂韧性，这些机制已被确定。根据已确定的增韧机制，