Structural-acoustic optimization of composite sandwich structures

Structural-acoustic concerns are present in aerospace, marine and other transportation industries where the composite sandwich structures are widely utilized. These concerns are the consequence of the fact that composite sandwich structures have been optimized for only the strength to weight performances during the design stage. However, novel composite sandwich structures must meet not only stiffness to weight ratio demands, but also have improved acoustic structural-acoustic performances. The design parameters of the composite sandwich structures, such as anisotropic material properties, core geometry and boundary conditions can be tailored to optimize the structural-acoustic performances in addition to the stiffness to weight demands. Furthermore, optimization with these passive design parameters has become practically feasible due to the advances in composite manufacturing technologies and in numerical methods. This study addresses the structural-acoustic optimization of composite sandwich structures with respect to the design parameters including anisotropic material properties, cellular core geometry and boundary conditions.; Optimization of composite sandwich structures for structural-acoustic performance is computationally intense. In order to improve the computational efficiency of the optimization, we focus on the composite sandwich modeling and analytical sensitivity analysis. The structural modeling of the composite sandwich with a balanced consideration of accuracy and computational efficiency is essential to accomplish the structural-acoustic optimization. Also, analytical expressions for sensitivity functions of the structural-acoustic performances with respect to design parameters can improve the accuracy and computational efficiency of the optimization based upon the gradient-dependent search algorithms. This study has investigated these issues in detail.; We have considered optimization problems of minimizing sound radiation of beams and plates as well as sound transmission into the interior of a cylindrical shell. The features of composite sandwiches including anisotropic material properties, core geometry and boundary conditions serve as design parameters. Both tonal and broadband optimizations demonstrate that optimized composite sandwiches can indeed provide much improved structural-acoustic performance.