Investigating the Effect of Aperture Flange Curvature on Tailgate Seal Bulb Height: A CAE-Based Approach

Water leakage is a common issue in vehicles, especially during water testing. It often occurs due to a gap between the seal bulb and the closure panel. This gap can result from variations in flange angle, flange curvature, closure surface, or seal bulb height. This study focused on how flange curvature affects seal bulb height and sealing performance. A Computer-Aided Engineering (CAE) method was used, supported by tests on physical samples. Multiple simulations were done using different flange curvatures. Results showed that with a constant flange angle of 150°, increasing the flange radius reduced seal bulb deformation. The optimal radius was 250 mm, where the bulb compression was 1.1 mm. Sharp or tight flanges caused the bulb to deform more, reducing contact and sealing force. To reduce this deformation, a hollow tube was inserted inside the seal bulb. The hollow tube used had an internal diameter of 10 mm and an external diameter of 12 mm. With the hollow tube, the optimum flange radius dropped to 100 mm. At this point, the seal bulb collapse height improved by 40%, and Compression Load Deflection (CLD) increased by 300%, which may increase the door closing efforts. Further improvement was made by changing the hollow tube material from sponge EPDM (specific gravity 0.6) to a super soft solid sponge EPDM (specific gravity 0.25), optimizing the CLD increase to 220%. CAE results showed 90% correlation with physical tests for seal bulb deformation, and 85% for CLD, for both with and without the hollow tube. This research can help in optimizing seal bulb height, sealing gaps, sealing force, and especially flange curvature and angle during the early design stage of vehicle apertures. This method enables automotive engineers and researchers to minimize costly late-stage design changes and achieve a right-first-time seal and Body-in-White (BIW) structure.