Parameter optimization of L-joint of composite sandwich structure based on BP-GA algorithm

Composite superstructure could provide excellent performances during surface combat. L-joint in the superstructure plays a significant role in the long-term service and would bear a complicated external load. In this paper, an all-composite L-joint was proposed and subjected to a bending test. A progressive damaged finite element analysis was performed to reveal its failure mode. An optimization based on the BP-GA algorithm was conducted to obtain the optimal geometries. The results showed that the primary failure mode of the L-joint was the crack of the stiffener outer skin. It was dominated by the fiber compressive failure. The average ultimate loadbearing capacity of the L-joint was 2.321 kN. And the simulated result was 10.09% lower than the experiment. The maximum relative error between the BP-GA prediction and actual values was less than 8%. The optimal structure obtained showed an enhancement of the load-bearing capacity about 1.41 times and stiffness about 1.65 times.