Parametric design and static stiffness prediction of steel-reinforced automotive rubber isolators

Rubber isolators are critical for automotive noise, vibration, and harshness (NVH) performance. However, optimizing their complex anisotropic stiffness under strict spatial constraints remains challenging. This study systematically investigates the mechanical behavior and stiffness prediction of steel-reinforced rubber isolators used in cooling modules. A parametric framework of 84 validated finite element models quantitatively isolates the structural influences of the steel insert, lateral support thickness and diagonal support height. The results demonstrate that the steel insert fundamentally amplifies structural anisotropy. It increases axial and radial stiffness by 124.48 %–142.42 % and 21.70 %–50.03 %, respectively. The insert also enhances axial strain energy density by 104.03%–111.56% and reduces frictional dissipation energy by 20.55 %–48.12 %. Furthermore, parametric decoupling reveals that lateral support thickness primarily governs axial stiffness while diagonal support height determines radial response. Based on these findings, we develop a semi-analytical static stiffness prediction method. The proposed theoretical model is highly accurate and computationally efficient, with maximum relative errors of 1.37 % in the axial direction and -5.58 % in the radial direction. This approach provides an efficient tool for designing advanced automotive isolators.