复合材料层合板机械连接修理拉伸性能

带损伤孔的复合材料层合板拉伸强度会降低约55%,需要对其进行修理以恢复力学性能、满足使用要求。针对带圆形损伤孔的复合材料层合板设计了机械连接修理方案,通过轴向拉伸试验评估其修理效果。根据试验条件建立了有限元模型,分析不同的修理方案对破坏模式、破坏载荷、应力分布、钉载分配等产生的影响。试验及有限元分析(FEA)均表明,修理后的复合材料层合板,其强度恢复率达到55%~60%左右,应力集中部位主要在修理区域最外侧的钉孔旁,最终破坏模式为母板沿修理区域最外侧一排钉孔断裂。使用双面修理、增加螺栓排数、采用金属补片、适当增加补片厚度,可减缓应力集中,改善钉载分配,提高结构强度恢复率。

Tensile performances of mechanically fastened repairs of composite laminates

Composite laminates with a damage hole, whose strength will reduce by about 55% under tensile loads, need to be repaired in order to recover their mechanical properties and meet the usage requirements. Mechanically fastened repair projects of composite laminates with a circular hole were designed and the repair effects were evaluated by tensile tests. Finite element models were established according to test condition, from which the effects of different repair projects on the failure loads, failure modes, stress distributions, and bolt load distributions were analyzed. The results of tests and finite element analysis (FEA) show that the recovery rate of failure strength of bolted repaired laminates will reach about 55%-60%. The areas beside the outermost bolt holes in the repair area of the laminates mainly produce stress concentration. The final failure mode of the laminates is breaking along the outermost bolt holes in the repair area. Methods such as double patch repair, adding fastened bolts, using a metal patch and increasing the thickness of patch properly can reduce stress concentration, improve bolt load distributions and enhance the recovery rate of structural failure strength.