A finite element stratification method for a polyurethane jounce bumper

The primary problem in the finite element analysis of polyurethane jounce bumpers, bumper stops, or similar structures is the identification of a mathematical model for the constitutive material. The densities of the exterior polyurethane area and the interior polyurethane area usually differ owing to the manufacturing process. This difference results in inaccuracy when predicting the mechanical behavior of the jounce bumper and bumper stop if a homogeneous material model is used. Thus, this work proposes a stratification method for finite element analysis of a polyurethane jounce bumper. The polyurethane structure was divided into three regions (the ‘skin layer’, the ‘transition layer’, and the ‘core area’) with different material properties. A foam model was utilized as the constitutive relationship. The foam model coefficients of the core area were obtained by a curve-fitting process using uniaxial compression test results. Subsequently, the material properties of the skin layer and the transition layer were also obtained. The finite element analysis results show that the proposed stratification strategy improves the prediction of the deformed shapes of the polyurethane jounce bumper. Furthermore, the calculated load–displacement curve is reliable for small to medium strains (0–0.4). Therefore, the proposed stratification method can be applied to enhance the reliability of jounce bumper simulations and to simplify the design process.