Determination of the Crush Stiffness Coefficients of a Typical Aftermarket Frontal Protective Guard Used in Light Trucks and Vans with Comparisons between Guard Stiffness and Frontal Vehicle Crush Coefficients

Abstract

Crush stiffness coefficients were determined for a typical I-beam constructed frontal grill guard used in the aftermarket on vehicles classified as light trucks or vans. These crush coefficients were determined by virtual impacts of a typical guard construction into a rigid barrier using finite element analysis (FEA) methods and collision stiffness computations. It was found that the addition of a frontal protection guard is capable of significantly changing the frontal stiffness of the vehicle to which it is attached. The federal motor vehicle safety standards (FMVSSs) require vehicles to give a certain crash response in order to protect occupants. Engineers have designed features such as frontal and rear crash zones to dissipate crash energies to meet the FMVSS requirements. Changing the stiffness of the vehicle by the addition of a frontal guard may alter the crash response and airbag deployment of the vehicle to which it is attached, along with the crash response of the guard-struck vehicle. The determination of the crush stiffness coefficients for a frontal guard will allow a comparison with the engineered frontal stiffness of vehicles in order to start the examination of the effect of frontal guard stiffness on crashworthiness of the collision partners. In addition, the determination of these coefficients will allow accident reconstructionists to assess the change in velocity of vehicles involved in collisions with frontal guards from guard crush damage.