An equivalent mechanical analysis approach for variable-thickness composite material structures considering the lay-up process

Mechanical performance of the composite structures is dependent on the local fiber orientation. The manufacturing-induced fiber orientation variations should be considered to precisely predict the performances. However, limited simulation studies have addressed the impact of manufacturing-induced fiber orientation variations on composite structure. This paper proposes an equivalent mechanical modeling approach for the variable-thickness composite structures that considers the manufacturing process. Initially, the spatial distribution of fiber orientation variation is determined through draping simulation. Subsequently, the local equivalent mechanical properties of the structure are evaluated using a shell-solid mesh mapping technique combined with a multi-layer equivalent mechanical method. To assess the effectiveness of the proposed method, composite tapered beams are examined, showing close agreement with reference results and a maximum natural-frequency error below 7%. The approach is further applied to the DTMB4119 composite propeller, a representative variable-thickness structure exhibiting fiber shear deformation during lay-up. The predicted mode shapes match the reference solution well, with errors in low-order modal frequencies and displacements under 7% and 2%. Owing to its straightforward implementation and suitability for automated modeling, the method can significantly accelerate the design process while maintaining high accuracy, making it well aligned with engineering applications.