A Math-Based CAE High-Speed Punch Methodology for Polymer Airbag Cover Design

Owing to the complex processing effects of injection molding and the influence of the wide-range of in-service conditions (e.g., from -40°C to 90°C) on the performance of polymer airbag covers, the current development of airbag performance criteria is largely conducted on a trial-and-error basis. This paper represents a recently developed virtual engineering tool which uses the LS-DYNA FEA (finite element analysis) solver for predicting the performance of polymer airbag cover designs under high-speed punch tests. The key element of this math-based technology is the method for determination and application of the rate-of-deformation and the temperature dependent material database; namely, Young's modulus, yield point, and ultimate strain. Experimental and virtual high-speed impact punch tests on Tekron 4300D-88A TPE (thermoplastic elastomer) were conducted at -40°C, 13°C, and 90°C with an impact speed of 6.7m/s (15 miles per hour). The comparisons between the experimental data and the CAE simulation results clearly show that the analysis accurately predicts the impact load (force)-time characteristic curves, tear kinematics, and failure mechanisms of the tear seam for an airbag cover during the high-speed impact tests. The findings from this methodology provide useful information for the development of advanced airbag system components, such as air-bag cover materials, pressure sensors, ignition system control, etc., at various temperatures and service conditions. The method has been employed in several driver and passenger airbag cover designs.