分层界面角度对CFRP层板Ⅱ型分层的影响

Effect of delamination interface angle on Mode Ⅱ delamination behavior of CFRP laminates

Ⅱ型层间断裂韧度是复合材料结构损伤容限设计的关键力学参数。针对5种具有不同预置分层界面的国产T300复合材料端部缺口弯曲(ENF)实验件,开展Ⅱ型分层测试,获得预嵌薄膜末端开裂的Ⅱ型层间断裂韧度 G Ⅱc,NPC 和预开裂裂纹处扩展的Ⅱ型层间断裂韧度 G Ⅱc,PC 。结果表明:5种分层界面下 G Ⅱc,NPC 均比 G Ⅱc,PC 高,并且对于 G Ⅱc,NPC 值,0°/0°分层界面的最高,0°/90°分层界面的最低;而对于 G Ⅱc,PC 值,0°/45°分层界面的最高,0°/90°分层界面的最低。同时,采用虚拟裂纹闭合技术(VCCT)模拟不同分层界面处的Ⅱ型分层扩展,获得了分层扩展过程中分层前缘应变能释放率分布,结合实验结果分析了分层界面角度对Ⅱ型断裂韧度测量值的影响。

Mode Ⅱ interlaminar fracture toughness is an indispensable mechanical performance parameter for damage tolerance design of composite structure. The domestic T300 composite end notched flexure (ENF) specimens with five different delamination interfaces were tested for mode Ⅱ delamination form, mode Ⅱ interlaminar fracture toughness G Ⅱc,NPC corresponding to the delamination initiated at the film insert and the mode Ⅱ interlaminar fracture toughness G Ⅱc,PC of the delamination growing from the pre-cracking were obtained. For five delamination interfaces, the values of G Ⅱc,NPC are higher than that of G Ⅱc,PC . For G Ⅱc,NPC values, G Ⅱc,NPC of the 0°/0° interface is the highest, G Ⅱc,NPC of the 0°/90° interface are the lowest. For G Ⅱc,PC values, G Ⅱc,PC of the 0°/45° interface is the highest, G Ⅱc,PC of the 0°/90° interface is the lowest. In addition, VCCT was used to simulate the mode Ⅱ delamination process, from which the strain release energy distribution at the delamination front during propagation along different interfaces was obtained. The effect of the delamination interface on the mode Ⅱ fracture toughness was investigated combined with the experimental results.