A Displacement-Approach for Liftgate Chucking Investigation 2012-01-0217

A displacement-based CAE analysis is applied to liftgate chucking noise problems. A CAE simulation model of a small-size sport utility vehicle (SUV) is simulated with a set of realistic road loads as a time transient simulation. The model contains a trimmed vehicle, a liftgate and structural body-liftgate interface components such as the latch-striker wire, contact wedges and slam bumpers. Simulation design of experiments (DOE) is carried out with the model. As performance measures, the relative displacements at the contact points of the interface components are selected, since they are considered the direct cause of liftgate chucking. As design variables, body structure stiffness, liftgate stiffness, liftgate opening stiffness, stiffness characteristics of the interface components and additional liftgate mass are selected. Results of the simulation DOE is post-processed, and response surface models (RSM) are fit for the performance measures. Then, a sensitivity study is carried out by analysis of variance methods (ANOVA) based on the RSMs. The sensitivity results show that liftgate opening stiffness and contact wedge stiffness characteristics are the two most significant parameters influencing the relative displacements at the interface components. This paper describes the CAE methodology employed including DOE model generation, RSM fitting and functional ANOVA sensitivity analysis. Physical tests performed to verify CAE results are also presented.