Failure prediction analysis‐based mechanostructural design of ply overlap joint for conformal load‐bearing antenna structure

Abstract Ply overlap joint designs were investigated in the mechanostructural point of view to secure the mechanical performance of an electromagnetic (EM) window of conformal load‐bearing antenna structures (CLAS). The EM window was constructed with a combination of dissimilar materials of carbon‐fiber (CF) fabrics and glass‐fiber (GF) fabrics. Three types of ply overlap joints laminated in [0/45/−45/0] stacking sequence for each CF and GF fabric were considered: staggered overlap, flush overlap, and hybrid overlap. Evaluation and analysis of each ply overlap joint design was performed through tensile testing and finite element analysis. The tensile tests revealed that the staggered overlap, the hybrid overlap, and the flush overlap have the higher joint strength in order, and that the increase in the overlap length accompanied the increase in the joint strength for the staggered joint and the hybrid one. Finite element analysis with a cohesive zone model that mimics interlaminar behavior and a progressive damage model that imitates a failure behavior was able to accurately predict the fracture behavior observed in the experiment. This study can provide a deeper understanding of the structural behavior of ply overlap joints for CLAS. Highlights CLAS offers load‐bearing and antenna functions, replacing protruding antennas. Ply overlap joint can be an effective design for the structural performance of CLAS. Staggered overlap showed the highest structural performance in tensile loading mode. FE analysis using the cohesive zone model was in good agreement with the experiment.