Fracture damage of integrated composite joint for fuselage structure under tensile loading

拉伸载荷下机身整体复合材料接头的断裂损伤研究

¹ School of Aeronautics, Northwestern Polytechnical University, Xi’an 710072, China
² Chengdu Aircraft Design and Research Institute, Chengdu 610041, China

Received: 20 December 2020

Abstract

In order to solve the complex load transfer and structural design of the joint structures including skin, longeron and frame in the composite fuselage, the adhesively bonded integrated composite joint was designed. Static tensile test was performed and the strain-load curves and damage modes were obtained. Then the numerical simulation model of integrated composite joint was built. The damage initiation, propagation and failure process of integrated composite joint under tensile load were simulated and analyzed. Results show that: the first load drop and the ultimate failure load of the joint are 120.82 kN and 168.11 kN respectively; the initial damage occurs at the corner bend region of the lower-left corner-shaped preform, and extends across the radius bend region among short flange, long flange and web, and leads to the interface debonding of the upper and lower corner-shaped preform and the delamination of corner-shaped preform and L-shaped preform. Compared with the experimental results, the errors of the first load drop and the ultimate failure load from numerical calculated results are 6.68% and 2.61% respectively, which agree with each other very well.

摘要

为了解决机身蒙皮、纵梁和框连接区域的复杂传力及结构设计问题，设计了复杂胶结整体复合材料接头，完成了该整体复合材料接头的拉伸试验，得到了其应变-载荷曲线和损伤模式。建立了整体复合材料接头数值分析模型，研究了其在拉伸载荷下的损伤起始、扩展及失效过程。结果表明：接头首次降载和极限破坏载荷分别为120.82和168.11 kN；初始损伤发生在左下侧角盒的角弯曲处，然后沿着短翼缘，长翼缘以及腹板间的圆弧过渡区扩展，导致上下角盒的胶结界面脱黏，角盒和L型层合板的胶结界面分层失效。数值计算得到的首次降载和极限破坏载荷与试验结果相比误差分别为6.68%和2.61%，两者符合较好。