Crash Padding Mechanical Properties and Impact Response Analysis

Highly deformable materials are used to pad automobile interior surfaces for occupant crash protection. Thick energy-absorbent pads usually provide better protection than thin pads nonabsorbent pads. Material selection tends to be the primary design variable because interior space is limited. Padding design requires analysis of the effects of typical crashes on the force-time history that an occupant will experience when he strikes an interior surface. To be practical the analysis must be physically realistic but must avoid excess numerical detail that might obscure basic trends. A practical method based on simplified occupant and vehicle models and empirical description of material properties is presented. The models focus on essential geometry and inertia parameters. A constitutive equation for an actual foam rubber is derived from the results of laboratory tests.