Optimization of the mechanical structure of a dishwasher and its packaging module using finite element method

In this study, drop test simulation of the mechanical structure of a redesigned dishwasher is accomplished using a detailed finite element (FE) model. The nonlinear explicit finite element code LS-DYNA® is used for the drop impact simulations. The finite element model is validated by conducting real tests for two drop scenarios (vertical and inclined to the side). Validation of the packaging module material model (EPS foam) is conducted. An optimization study is performed in order to find the values of design variables for optimum crash performance. The effects of geometrical parameters and material properties on the weights of certain components (dogleg plate and bottom foam) are investigated. Surrogate-based optimization approach is followed to find optimum values of the dogleg plate thickness, the bottom foam density and increment in the bottom foam height to minimize the weights of both components. Two different surrogate models, namely polynomial response surfaces and radial basis functions, are used to predict optimization problem constraints that have crucial role on the crash performance of the dishwasher mechanical structure and the packaging module. It is observed that the dogleg plate mass can be slightly reduced and the bottom foam mass can be significantly reduced. The weight of the dogleg plate and the bottom foam can be lowered as much as 5.95% and 24.8% respectively. Finally, multi-objective optimization is performed by minimizing a composite objective function that provides a compromise between the weights of both components. For multi-objective optimization the weight reduction of 5.0% and 22.9% can be obtained for the dogleg plate and the bottom foam respectively.