Development and validation of a mechanical thorax surrogate for the evaluation of the blunt trauma due to ballistic impacts

Development and validation of a mechanical thorax surrogate for the evaluation of the blunt trauma due to ballistic impacts

Although fruits of few decades worth of research carried out worldwide by scientists, engineers and researchers, have been available to everybody with a mouse click, engineering problems have not always been easy to accomplish. The complexities of the real life problems are due to lack of resources, lack of applicability of the available data and also due to the increasingly innovative and competitive marketplace. Therefore, engineers always face challenges and strive to accomplish the tasks to obtain desired outcome with continuous research and innovative approach. Two of such challenges, one related to the validation of a closed cell foam material for fabrication of non-lethal munitions and the other related to the development of compliant vehicle front protection systems (VFPS) for modern passenger cars, necessitated extensive research study and led to the development of the finite element (FE) model of thorax surrogate (Mechanical THOrax for Trauma Assessment – MTHOTA) and development a computer aided engineering (CAE) based method for the development of airbag compatible and ADR 69/00 (Australian Design Rule for vehicle occupant safety) compliant multi-variant vehicle front protection systems for a vehicle with multi-variants, with a minimum number of crash tests. These two challenging problems, pertinent research, development, and the outcome, have been presented in this thesis.

Initially, four anthropomorphic test devices (ATDs) were reviewed for their suitability for the evaluation of the blunt trauma. As they were found unsuitable for the intended application, novel concepts for the thorax surrogate were developed and studied for their feasibility. One of the novel ideas was pursued further and developed into a fully correlated (validated) FE model of a thorax surrogate (MTHOTA). Robustness and efficacy of the MTHOTA surrogate was verified for many cases studies from the published literature. Biomechanical responses obtained for the MTHOTA surrogate have shown a correlation with the respective cases. Due to its simplicity, accuracy,easy setup, fast solving and non-ambiguity, the MTHOTA surrogate was successfully
used for the evaluation of:
1. the blunt thoracic trauma due to ballistic impacts and the risk of commotiocordis due to solid sports ball impacts
2. the effect of material, spin and impact speed of the solid sports ball on the thoracic trauma
3. projectile – thorax energy interactions and their relation with the viscous criterion
4. the performance of new non-lethal weapons and foam materials
5. the effect of the energy-absorbing mechanisms on the blunt thoracic trauma caused by Kinetic Energy Non-Lethal Weapons (KENLW)

Concerning the second challenge mentioned above, a systematic procedure based on the non-linear finite element analysis simulations was devised for the development of compliant front protection systems for vehicles with and without airbags. The devised method has successfully been implemented and made commercially non-viable and extremely cumbersome FPS development projects into reality.

By exploiting the non-linear FE simulations expertise and foam material data, effect of foam embellishments on the pedestrian safety characteristics of the FPS was examined highlighting the benefits of garnishing FPS with such semi-rigid foam parts and presented in the thesis. Effect of FPS on the crash compatibility between vehicles was also studied and made recommendations for reaping the benefits of the VFPS.