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高传力效率的斜面式胶接在飞机复合材料传力接头和修补中被广泛使用,但该结构的低速冲击损伤阻抗和损伤容限未在飞机结构设计中考虑。本文研究了低速冲击下的较厚的复合材料斜胶接板的力学性能及损伤失效。在胶接区域布置不同冲击点,寻找最敏感位置,在该位置进行冲击能量变化研究,通过冲击响应(冲击载荷、挠度、能量等)及冲击损伤两个方面获取其规律和失效机制。小能量和大能量冲击结果表明,胶接区域五个典型冲击位置中,中心位置冲击损伤最大,冲击敏感性最高,因此中心点为冲击损伤阻抗最小位置。中心点不同能量冲击时,冲击响应研究揭示了冲击过程中冲击载荷具有典型的4阶段行为。冲击载荷还具有双峰值力的现象。冲击后沿试样中心线切开的显微损伤图揭示了该结构有两种损伤模式,包括复合材料损伤及胶层损伤。复合材料的损伤包含90°和45°层基体的开裂和0°与90°层之间的层间损伤。胶层损伤出现在试样冲击点正下方背部的复合材料斜接尖端部位。进一步通过考虑复合材料层内、层间损伤以及胶层损伤的渐进损伤模型对试验进行仿真研究,找出导致第Ⅱ阶段冲击载荷突降的主要原因为复合材料层间损伤,第Ⅳ阶段冲击载荷再一次突降时由于胶层出现了损伤。
High power transmission efficiency of the ramp adhesive bonding aircraft in the composite material and repair joints are widely used, but the structure of low-speed impact damage resistance and damage tolerance is not considered in the structural design of the aircraft. In this paper, the mechanical properties and damage failure of thick slab composite slabs under low velocity impact are studied. The impact point (impact load, deflection, energy and so on) and the impact damage are obtained by two different impact points in the bonding area to find the most sensitive position. The impact energy change is studied at this position. The results of small energy and large energy impact show that among the five typical impact locations in the bonded area, the center location has the highest impact damage and the highest impact sensitivity, so the center point is the minimum impact damage impedance location. Shock response studies at different energy shocks at the center reveal the typical 4-stage behavior of impact loads during impact. Impact load also has a bimodal force phenomenon. Microscopic damage patterns cut along the centerline of the specimen after impact revealed two modes of damage for the structure, including composite damage and adhesive damage. Damage to the composite material includes cracking of the 90 ° and 45 ° base layers and interlaminar damage between 0 ° and 90 ° layers. Layer damage occurs at the back of the composite miter tip immediately below the impact point of the specimen. Furthermore, through the simulation study of the progressive damage model considering the interlaminar layer, interlaminar damage and plastic layer damage, the main causes of the sudden drop of the second stage impact load are the interlaminar layer damage, the fourth stage impact load Once again due to the sudden drop in the plastic layer damage.