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

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.