Session: 05-15-03: General Topics in Biomedical and Biotechnology - III

Paper Number: 94897

94897 - Numerical Investigation of Finite Element Lower Extremity Model Response in Blast Loading 

Landmine and Improvised explosive device (IED) explosions cause injury, maims, or even kill persons when activated by the victim's presence, proximity, or contact. They are of growing concern as they are not only used by defense forces worldwide but often used by terrorists and anti-government armed wings.

The number of uncleared landmines worldwide was estimated at 80-110 million in 64 countries by the US department of state in 1994. International Committee of Red Cross (ICRC) estimated that landmines claim approximately 26000 lives annually. The lower extremity, being proximal to the origin of the blast, is the most commonly injured part of the body, with foot and ankle being major anatomical locations of injuries. Lower extremity injuries also raise concern because they can affect the victim's weight bearing capacity and ability to walk.

Both experimental investigation and computational analysis play a significant role in the research to investigate blast injuries and their mechanism. However, the conduct of experiments is expensive, time-consuming, and ethically challenging. Therefore, the numerical analysis serves as a valuable tool in analysing these situations. In the current study, THUMS (Total HUman Model for Safety) lower extremity finite element model was evaluated as a tool to study lower extremity response in the blast. Biofidelity of the lower extremity model in under-body blast was assessed by numerically recreating the response of PMHS (Post Mortem Human Surrogate) experiments of Barbir and McKay. Their experimental setup included a cadaveric leg connected to a Hybrid-III ATD (Anthropomorphic Test Device) at mid-thigh using bone cement. In the simulation, THUMS lower extremity FE model was used for the cadaveric part, and the hybrid-III dummy FE model was used for the ATD used in the experiment. Three levels of accelerative loading severity corresponding to floorplate velocities of approximately 7 m/s, 9.3 m/s, and 12 m/s were chosen from these experiments. Mid-tibial sectional force was tracked in the simulation, consistent with the load cell location in the experiment, and compared with experimental data. Numerical predictions were in agreement with the experimental response concerning the peak force as well as duration. CORA (Correlation and Analysis) rating of 0.96 was obtained for the non-injurious domain corresponding to floorplate velocity of 7m/s and 0.87 for the floorplate velocity of 9.3 m/s, suggesting a good match between THUMS response and the available experimental data. Due to wide scatter in the experimental data, no comparison was possible for the floorplate velocity of 12 m/s. However, injuries observed in the simulation such as calcaneus fracture, talar fracture, and erosion at distal condyle of the tibia were consistent with those reported in the experiments.

This validated model was then used to predict the lower extremity response and injuries inflicted upon the leg in anti-personnel mine blast. Multi-material Arbitrary Lagrangian Eulerial formulation was used to model explosive, air, and soil. The interaction between the lower extremity model and detonation products was provided using the fluid structure interaction algorithm in LS-DYNA. The amount of explosive used was 40 gm TNT, consistent with the small mine M-14, placed below the heel of the leg. The sensitivity of the lower extremity model was evaluated by varying the amount of explosive from 40 gm to 100 gm. Sectional force in tibia and calcaneus was tracked and the spread of injuries were correlated with experimental data from the literature.

Presenting Author: Sudipto Mukherjee Indian Institute of Technology Delhi

Presenting Author Biography: N/A

Authors:

Aman Vikram Indian Institute of Technology Delhi
Anoop Chawla Indian Institute of Technology Delhi
Sudipto Mukherjee Indian Institute of Technology Delhi