Steel-Polypropylene-Steel Laminate – A New Weight Reduction Material

Abstract

The dent resistance, flexural stiffness, fatigue strength, and formability are characterized for a steel-polypropylene-steel (S-P-S) laminate for automotive applications. Many of these physical properties are comparable to those of steel. The S-P-S laminate takes advantage of the I-beam principle in bending. The highest stress is in the surface, with the lowest stress at the neutral axis. The material has a high stiffness-to-weight ratio, with the potential to reduce component weight by 50% with no loss in flexural stiffness. Applications where bending stiffness is the major design criterion include: seat backs, load floors, covers, narrow body panels, truck trailer sides, and interior trim. One disadvantage of S-P-S is loss of bolt torque due to creep by the polypropylene core. This loss is a function of the applied stress level, core thickness and temperature.