Abstract:

The tensile strength of the glass fiber composites using vacuum-assisted scarf repairs was first tested, and the final failure mode of repair structure was obtained. A three-dimensional finite element model of motherboard and patch in the repaired structure were established respectively, the material failure of unidirectional composites was simulated with continuum damage mechanics model, motherboard and patch contact with each other was assumed through the viscous force, and the contact analysis was defined for the secondary curing interface which was formulated by vacuum-assisted wet scarf repairs, the exponential softening cohesive model was used to simulate the properties of the interface contact. Test results and numerical simulation results agree well, so the model can be used to predict the tensile properties of the entire repaired structure. The damage and failure of the entire repaired structure were analyzed for the whole stretching process, the weak layer premature injury phenomenon is found, which caused by the stress concentration on the motherboard due to the additional patches. The influence of scarf angles on the strength of repaired structure in different sizes were discussed, the conclusion can guide technical staffs to make reasonable repair scheme.

Key words: vacuum-assisted scarf repaired, continuum damage mechanics model, cohesive theory, contact analysis

摘要：

对真空辅助玻璃纤维增强复合材料斜接型挖补修理后结构进行了拉伸强度试验研究,获得了修理后结构最终破坏模式。分别建立了挖补修理结构中母板与补片三维有限元模型，采用了各向异性连续损伤力学模型模拟了母板与补片复合材料单向带失效模式，假定母板与补片通过黏性力接触，在真空辅助湿法挖补修理形成的无厚度二次固化界面处定义了接触面,
采用指数型软化cohesive模型模拟了界面接触属性。试验结果与数值模拟结果吻合较好,表明所采用的模型能很好地预测整个修理结构的拉伸性能。分析了整个拉伸过程中层合板斜接挖补修理结构的损伤破坏过程，发现了附加补片引起的应力集中是造成母板中薄弱层过早损伤的原因。讨论了不同斜接挖补角度对修理后结构强度的影响，结论可以引导工艺人员制订合理的修补方案。

关键词: 真空辅助斜接型挖补, 连续损伤力学模型, cohesive理论, 接触分析