Exploration of Vehicle Body Countermeasures Subjected to High Energy Loading 2023-01-0003

Enhanced protection against high speed crashes requires more aggressive passive safety countermeasures as compared to what are provided in vehicle structures today. Apart from such collision-related scenarios, high energy explosions, accidentally caused or otherwise, require superior energy-absorbing capability of vehicle body subsystems. A case in point is a passenger vehicle subjected to an underbody blast emanating shock wave energy of military standards. In the current study, assessment of the behavior of a “hollow” countermeasure in the form of a depressed steel false floor panel attached with spot-welds along flanges to a typical predominantly flat floor panel of a car is initially carried out with an explicit LS-DYNA solver. This is followed up with the evaluation of PU (polyurethane) foam-filled and liquid-filled false floor countermeasures. In all cases, a charge is detonated under the false floor subjecting it to a high-energy shock pressure loading. For the case of the liquid-filled countermeasure, a novel ALE (Arbitrary Lagrangian-Eulerian) formulation for fluid-structure interaction has been adopted with a Hybrid III dummy seating above the flat floor with a modified MIL-LX legform for injury prediction. In order to establish confidence on the ALE model, a drop-weight impact test on a liquid-filled square aluminum tube has been carried out and its behavior predicted, prior to the analysis of the countermeasures mentioned. It appears that the fluid-filled countermeasure is a promising solution in countering the effects of a shock pressure loading by greatly reducing the load transferred to the lower limb of an occupant sitting right above a detonated charge placed under the floor of a car.