层间颗粒增韧复合材料层压板的Ⅱ型层间断裂韧性

Mode Ⅱ Fracture Toughness of Thermoplastic-Particle Interlayered Composite Laminates

采用热塑性颗粒对HT7/5228、HT3/NY9200G、HT3/5224和HT3/3234四种热固性树脂基体复合材料进行层间增韧,测试了未层间增韧对比件和层间增韧改性件的型层间断裂韧性G c。试验结果表明,增韧颗粒和基体树脂形成的Interlayer层有效的吸收了断裂能量并抑止了裂纹的失稳扩展,G c显著提高。层间增韧的几何效应、裂纹传播路径控制、裂尖屏蔽和颗粒桥联是主要的增韧机理。有限元分析结果表明Interlayer层降低了裂纹尖端J积分值和裂尖应力集中,进一步解释和支持了增韧机理。

Interleaving laminates with thermoplastic particles is an effective method to improve fracture toughness and impact resistance. In order to achieve high toughness improvement, four types of carbon-fibre epoxy composites, HT7/5228, HT3/NY9200G, HT3/5224 and HT3/3234, were interlayer toughened and Mode Ⅱ fracture toughness tests were conducted by using end notch flexure (ENF) specimens. The experimental results indicate that the interlayer zones formed by particles and epoxy can significantly absorb fracture energy and suppress unstable crack propagation, G_(Ⅱc) was significantly increased. Geometrical effect, crack path kinking and deflection, particle bridging and crack shielding are the main toughening mechanisms. A Finite Element Analysis (FEA) was finally conducted to further explain the toughening mechanisms. FEA results show that interlayer zones can effectively lower J-integral and 2D maximal shear stress around the crack tip, and the high stress distribution in the region close to the interface is the driving force for interfacial failure.