Threshold Properties of Woven GFRP Laminates under Acid Environment

研究了玻璃纤维增强塑料（GFRP）的应力腐蚀开裂机理.首先，研究了玻璃纤维/乙烯基酯机织层合板的组分对断裂的影响以及裂纹扩展的门槛值特性。在盐酸溶液中，在水中和在空气中的传播行为进行了评价。结果表明，在da/dt-K_I图上绘制了该行为。裂纹扩展速率da/dt分布在水中比在空气中有很大的提高，而在HCl溶液中的提高程度与在空气中的接近。因此，单向FRP的裂纹扩展性能进行了研究，以确定纤维方向的作用。在da/dt-K_I曲线上观察到90 °单向纤维增强复合材料的临界性能，通过有限元分析证实了临界性能的产生是由于纤维桥联所致。降解描述见B ...更多信息 y界面脱粘能。通过测量纤维断裂点附近的界面脱粘长度，计算了界面脱粘能量。同时还测量了基体的塑性区，因此在能量平衡模型中考虑了基体的塑性，从而确定了界面脱粘能。采用双劈裂钻孔压缩（DCDC）试验对纤维和界面的断裂行为进行了评价。并将一束纤维束埋入试件中，以估计断裂机制。裂纹绕纤维束偏转，纤维/基体界面发生脱粘。结果表明，脱粘长度取决于界面降解程度。界面脱粘长度和界面脱粘能决定了裂纹表面的桥接应力。纤维断裂使裂纹表面的牵引力减小，但桥连应力决定了裂纹表面的牵引力。最后讨论了与牵引力有关的增韧效果。少

The stress corrosion cracking mechanism of glass fiber reinforced plastics (GFRP) were investigated in this work. First of all, an effect of the constituents on the fracture and the threshold properties on the crack propagation of woven C-glass/vinyl ester laminates. The propagation behavior was evaluated in HCl solution, in water and in air. As a result, the behavior was plotted on the da/dt-K_I diagrams. The crack-propagation rate da/dt distribution in water was largely enhanced in comparison with that in the air, and it was nearly as promoted as that in the HCl solution. Therefore the crack-propagation properties of unidirectional FRP were investigated to confirm the role fiber direction. The threshold properties the 90° unidirectional FRP were appeared on the da/dt-K_I diagrams and the it is confirmed that the cause is the fiber bridging by the FEM analysis.Single fiber model composites were applied to evaluate the interfacial degradation mechanisms. The degradation was described b … More y interfacial debonding energies in this study. And the interfacial debond length near the fiber failure point was measured to calculate the energies. The matrix plastic zone was also measured, therefore the plasticity was considered in the energy balance model to decide the interfacial debonding energies. Furthermore it was suggested that the interfacial debonding energy kept the constant value.In order to estimate the fracture behaviors of the fiber and interface, the double cleavage drilled compression (DCDC) test was applied. And one fiber bundle was embedded in the specimen in order to estimate the fracture mechanisms. The crack was deflected around the fiber bundle and the fiber/matrix interface was debonded. As a result, it was found that the debond length depended on the interfacial degradation. The debonding length and interfacial debonding energy decided the bridging stress on the crack surface. And the bridging stress determined the traction on crack surface, although the traction decreased due to the fiber failure. Finally the toughening effect that depended on the traction was discussed. Less