Increase in Vehicle Front, Rear and Side Stiffness Coefficients in the Past Twenty Years Necessitates New Representative Database

Abstract

When vehicle-specific stiffness coefficients cannot be acquired, stiffness coefficient values that are representative of the desired vehicle type, class, wheelbase or weight are routinely used for accident reconstructions. Since the original compilation of representative vehicle stiffness data almost 20 years ago, changes in crash testing standards and other safety and technological improvements in vehicular design have affected vehicle stiffness. While generic frontal stiffness data have been recently updated to reflect these vehicular changes, rear and side stiffness data have not. Structural, geometric and inertial data for over 300 passenger cars and light trucks were collected. Among the vehicles targeted were the top-selling cars, SUVs, vans and pickups for model years 1990 to 2012. Results indicated that all vehicle types demonstrated increases in mean stiffness over the time period considered. SUVs were, on average, the stiffest vehicle type in the front, rear and side. There was a correlation between vehicle wheelbase and stiffness, with longer vehicles having greater stiffness than shorter vehicles. Vehicle class also affected stiffness. In the front and rear, mid-size passenger cars had the greatest mean “A” and “B” stiffness coefficients of all passenger cars. By contrast to the front and rear, mean side stiffness of all passenger cars classes was similar. In conclusion, the updated structural stiffness and geometric data presented here for the front, rear and side, provide an accurate representation of today's market for use in crash reconstructions.