A Comparative Study of Composite and Steel Front Rails for Vehicle Front Impact Safety

Weight reduction is a primary concern in the design of today's automobiles. Fiber reinforced composites (FRC) comprise a category of materials that may offer advantages in terms of weight and cost when compared to both steel and aluminum. The viability of low cost FRCs such as a glass fiber reinforced plastic (GFRP) as a structural material for automotive applications can, however, be diminished by functional requirements such as energy absorption and crush under impact loading. In this context, the crash safety performance of front rails of a compact passenger car is evaluated by assuming these to be made of GFRPs with constant strand mat (CSM) plies. The safety assessment of rails is carried out with the aid of the explicit nonlinear finite element analysis code LS-DYNA with utmost attention being paid to the proper constitutive modeling of the composites considered. All analyses are carried out with an available damage-based material model in LS-DYNA which is suitable for representing laminated composites. The current study shows that further work is needed to make affordable composite-based structural components in production passenger cars a reality in terms of lower weight and impact safety.