Informatics Publishing Limited

Gaurav Nilakantan ¹, Ala Tabiei ²

Affiliations
1 Center for Composite Materials, University of Delaware, US
2 University of Cincinnati, US

Abstract

Anti tank (AT) mines and improvised explosive devices (IED) pose a serious threat to the occupants of infantry vehicles. The detonating explosives create shock waves, which induce large acceleration impulses and deformations in the vehicular structure. These impulse loads are transmitted to the occupant through vehicle-occupant contact interfaces such as the floor and seat. If the resulting loads and accelerations transmitted to the occupant are not sufficiently attenuated to values below thresholds set by occupant injury criteria, they can lead to severe injury and fatality. The occupant’s feet are usually in direct contact with the floor and therefore lower extremity injuries are very common during AT and IED explosions. This study focuses on the assessment of acceleration-induced injuries of lower extremities during a mine blast underneath an armoured vehicle, where the occupant's torso is shielded from the direct effects of the mine blast. Numerical models of the mine blast experimental test set-up are created using the dynamic finite element code LS-DYNA®. A numerical HYBRID III dummy is used to simulate the occupant’s response. Simulations results are compared with experimental data to validate the use of the HYBRID III dummy for injury assessment in such an application. The occupant lower extremity response to varying magnitudes of vehicle floor impact velocities caused by mine blasts is parametrically studied to lend insight into the maximum sustainable and survivable loading conditions as well as the design of protective structures that can be incorporated into the vehicle structure to attenuate these loads. Characteristic trends in the occupant response are used for predicting the response for new loading conditions. The effect of initial position of the occupant's lower extremities on the impact response and associated injury levels is also studied.

Keywords

Lower leg; Injury assessment; Mine blasts; Occupant protection; Survivability; Foot impact; HYBRID III dummy

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Ala Tabiei ¹, Gaurav Nilakantan ¹

Affiliations
1 Dept. of Aerospace Engineering and Engineering Mechanics, University of Cincinnati, OH 45221, US

Abstract

A material model has been developed to realistically simulate the behavior of loose woven fabrics with elastic crimped fibers subject to varying loading conditions such as in-plane and transverse loading. It is based upon a multi-scale micromechanical approach that includes the architecture of the fabric and the phenomenon of fiber reorientation, with fiber simplified as one dimensional elastic members with a single failure criterion. The material model is implemented as a user-defined subroutine in the explicit, non-linear dynamic finite element code LSDYNA. Results of fabric test simulations run in LSDYNA using this material model agree well with experimental results, demonstrating the material model s capability to accurately simulate ballistic impact of woven fabrics.

Keywords

Computational Micro-Mechanical Material Model, Flexible Woven Fabric, Ballistic Impact Simulations, Nonlinear Explicit Finite Element Analysis, LSDYNA; Protective Structures.

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