Accurate equivalent models of sandwich laminates with honeycomb core and composite face sheets via optimization involving modal behavior

An approach is introduced for determining accurate two-dimensional equivalent laminated models of sandwich laminates with honeycomb core and composite facesheets by optimization involving modal behavior. The approach relies on minimizing the objective function which is defined as the sum of the square of the differences between the natural frequencies of the honeycomb sandwich laminate estimated by the finite element analysis of the 3D detailed model with the actual honeycomb core geometry and by the 2D equivalent laminated model with the honeycomb core replaced by the equivalent 2D orthotropic material model. Equivalent elastic constants of the 2D orthotropic model of the honeycomb core are defined as the design variables of the optimization problem, and a finite element solver and genetic algorithm-based optimizer are coupled to perform the optimization task. Results show that with the optimization-based approach, very accurate 2D equivalent models of honeycomb sandwich laminates are obtained compared to equivalent models obtained by replacing the honeycomb core with elastic constants of the 2D orthotropic material model obtained utilizing analytical models available in the literature.