Strategies to Reduce Bond-line Read-out in Adhesive Joined SMC Automotive Body Panels

Parameter sensitivity analysis on a 2D finite element model of adhesive-joined SMC hat/plate structure was performed to evaluate the relative impact of design, application, and material parameters on the bond-line read-out (BLRO) defect. Based on the sensitivity analysis and the ease of implementation, a list of strategies in the order of their effectiveness in reducing the BLRO defect is proposed. Choosing a low modulus, low cure temperature, and low shrinkage adhesive, raising the stiffness of the exterior SMC panel, and lowering the stiffness of the interior SMC panel in the regions around the bond-line were found to reduce the BLRO defect.