层间短纤维的桥联和增韧分析

Analysis of interlaminar short-fiber bridging and toughening

根据短纤维在层间杂乱分布和接近裂纹表面的特点,考虑基体剥落和纤维拉出耦合,本文建立了一个层间短纤维桥联模型,分析短纤维的层间增韧机理和主要影响因素。计算结果表明,纤维增强树脂层板在层间加入少量的Kevlar短纤维时,裂纹张开位移导致短纤维从基体中剥离和拉出,在纤维相互干扰下,拉出过程中产生大的能量耗散,从而明显地提高层间断裂韧性。纤维界面性质对ΔGIC有重要影响,纤维杂乱分布引起的相互干扰及纤维初始弯曲,使层间断裂韧性显著增加。比较表明,ΔGIC的理论预测与实验结果相符合。

Based on the characteristics that chopped short fibers are distributed in interlayers randomly and near crack surfaces, a model on chopped short fiber bridging and toughening was presented, in which the coupling of matrix spalling (failure of matrix along surfaces of cracks) and fiber pull-out was considered. The model was used in the analysis of the mechanism of toughening and the influence of some main factors, as well as in the prediction of the interlaminar toughness increment GIC. The numerical results show that if a small amount of chopped short Kevlar fibers are embedded in the interlayers of continuous fiber reinforced plastics laminates, the interlaminar crack opening displacement and the tension of fibers in bridging cause the matrix spalling and fiber pull-out. Under the interaction among chopped short fibers, the pull-out process leads to large dissipation of energy and obvious increase of interlaminar toughness. The interface properties affect GIC significantly. The moderate interface fraction is more beneficial to toughening. The interaction among fibers and initial curvature of fibers caused by random distribution may greatly increase the interlaminar toughness. The theoretical prediction of interlaminar toughness increment GIC agrees well with the experiment results. It shows the effectiveness of the proposed model.