Access Type

Open Access Thesis

Date of Award

9-22-2005

Degree Type

Thesis

Degree Name

M.S.

Department

Biomedical Engineering

First Advisor

Cynthia Bir

Abstract

The aim of this study is to assess the ability of lower limb surrogates to predict injury due to floor impact in military vehicles during anti-vehicular (AV) landmine explosions. Most such surrogates have originally been constructed for use in automotive crash applications, where footwell intrusion is the main source of lower limb injury. Land mine explosions, however, create different loading conditions on the lower leg. Comparatively, the peak loads are higher but the durations are shorter and the loading occurs axially through the tibia, instead of the axial loading combined with foot rotation that is often observed in automotive applications.

The specific aims of this study are 1) reproduction of the vehicle floor movement and tibia force during an anti-vehicular mine blast using a linear impactor; 2) determination of human response corridors as a result of such impact conditions; and 3) assessment of the existing mechanical surrogates' ability to match these corridors.

The vehicle floor movement and tibia force experienced by a Hybrid III dummy during an AV mine explosion test was reproduced using a linear impactor for three different conditions representing three different explosive masses. Next, the same impact conditions were applied on instrumented PMHS legs and the resulting tibia forces were measured as well as injuries in two legs impacted under the most severe condition noted. Human response corridors were developed based on normalized and averaged data. The existing human surrogates: Hybrid III with a ankle/toe assembly and the THOR lower leg were assessed on their ability to match these corridors. The THOR lower leg was found to be a closer match to these corridors, especially under less severe conditions, while under higher conditions a compliant element which can handle higher forces is necessary. Using the ankle/toe complex, ankle forces were found to be the largest forces in the leg under axial impact. The boot was found to have a smaller influence on the THOR tibia than on the Hybrid III tibia, causing it to lower the measured lower tibia forces by 17% for the THOR and 50% for the Hybrid III with a ankle/toe assembly. Lower tibia forces were generally found to be slightly higher than upper tibia forces in the THOR lower leg. In the ankle/toe assembly, the boot was found to influence the difference between the ankle and tibia forces, causing it to be smaller in the cases with the boot.

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