A 3D Simulation Methodology for Predicting the Effects of Blasts on a Vehicle Body 2019-01-1033

Triggered explosions are increasingly becoming common in the world today leading to the loss of precious lives under the most unexpected circumstances. In most scenarios, ordinary citizens are the targets of such attacks, making it essential to design countermeasures in open areas as well as in mobility systems to minimize the destructive effects of such explosive-induced blasts. It would be rather difficult and to an extent risky to carry out physical experiments mimicking blasts in real world scenarios. In terms of mechanics, the problem is essentially one of fluid-structure interaction in which pressure waves in the surrounding air are generated by detonating an explosive charge which then have the potential to cause severe damage to any obstacle on the path of these high-energy waves. An alternative to physical testing would be to use an advanced simulation technique such as an ALE (Arbitrary Lagrangian-Eulerian)-based explicit nonlinear finite element formulation implemented in a well-known solver such as LS-DYNA. It has been observed by the present authors that the previously reported explorations in this area are primarily laboratory testing of structural components supplemented with an axisymmetric or a 2D finite element analysis. In the present study, keeping in mind the need for evaluating the effect of an arbitrarily located blast on a complex system such as a passenger car, a 3D finite element modelling approach has been deployed for capturing the effect of a blast not only on the vehicle underbody but also on an occupant in the form of a Hybrid III dummy with a modified lower limb corresponding to a MIL-LX leg. Initially, the consistency of the present 3D ALE-based modeling approach is verified by obtaining good correlation of computed pressure-time curve at a point in space at a given distance from a 1.5 kg explosive charge, with a published test result. The study is then extended to the simulation of effect of blast on a passenger car represented by a previously-validated finite element model for front impact safety assessment.