复合材料加筋壁板长桁终止端混合连接设计分析

Combined joint design and analysis at stringer run-outs in stiffened composite panels

对缩短胶接面长度以提高起裂载荷的复合材料加筋壁板长桁终止端新型混合连接设计进行了研究。采用经试验验证的有限元方法,对长桁终止端混合连接的传载与失效机制进行分析,并研究了胶接面长度对结构起裂载荷的影响规律。研究结果表明:新型混合连接设计中紧固件提供的法向约束以及剪切载荷传递路径可显著提升终止端结构的起裂载荷,并增强终止端处界面的抑制损伤扩展能力;结构的起裂载荷随着胶接面的缩短而提高;当胶接面前缘退至连接区末排紧固件之后,可避免结构在最终破坏前发生界面失效,结构强度由蒙皮的机械连接强度决定。

A novel combined joint design principle at stringer run-outs in stiffened composite panels was studied with reducing bond-line configurations to improve the structural debond load. FEM verified by experiment results was used to analyze load transferred and failure mechanisms of combined joint at stringer run-outs, and research the influence of bond-line length to stringer terminations debond load. The results illustrate that normal constraint and shear load path provided by fasteners in the novel combined joint concept can improve structural debond load significantly, and enhance the capacity of arresting damage propagation at the bond-line tip. Moreover, the debond load increases with bond-line configurations reducing, interface failure can be avoided while the bond-line tip is beyond fasteners in the last row, and the failure load is determined by the strength of skin mechanically joints.