Heavy Vehicle Crash Safety - Improved Thoracic Injury Prediction in Frontal Crash Testing

Sammanfattning: Frontal crashes are regarded as some of the most injurious accidents for Heavy Goods Vehicle (HGV) drivers. One of the leading HGV manufacturers regularly conducts frontal crash testing for occupant safety. The Hybrid III crash test dummy was developed for frontal testing in passenger cars and has become the standard in crash laboratories. This project was initiated to investigate the suitability of the Hybrid III in HGV frontal crash testing. The cab geometries and occupant posture in an HGV differ from passenger cars. The driver chest will thus experience a different loading in a frontal crash. The objective of this thesis was to establish if and how the Hybrid III could be used in frontal HGV crash tests, in particular how to best assess chest injury risk in HGV crash tests with the Hybrid III. Database analyses of real-world HGV crashes were carried out to establish which injuries to prioritise in the most common and serious crash types. The results confirmed that chest injuries in frontal crashes are a top priority. The chest was the body region with the highest frequency of severe injuries. The occupant load case was studied in frontal sled crash tests, with a Hybrid III seated in an HGV cab. The chest of the Hybrid III was found to contact the steering wheel rim in all tested configurations. The study concluded that the Hybrid III was able to accurately register chest deflections with the aid of additional instrumentation. Furthermore, the steering wheel rim-to-chest contact was found to be a previously unexplored load case in injury biomechanics, and the need for further biomechanical knowledge regarding this load case became apparent. A representative HGV frontal crash chest load case was identified. Post Mortem Human Subject (PMHS) testing provided data to confirm the suitability of the Finite Element (FE) Human Body Model (HMB) Total HUman Body Model for Safety (THUMS) as a human surrogate. An FE model of the Hybrid III was validated from physical tests in the representative load case. A simulation test matrix including the THUMS and the FE Hybrid III, was applied to develop a transfer function from the chest response of the Hybrid III to existing injury criteria. The application of the added chest deflection instrumentation and this transfer function enables much improved chest injury assessment with the Hybrid III in frontal HGV crash tests. These results have the potential to facilitate the development of improved HGV occupant safety systems, to reduce the severity of HGV driver injuries, or all-together prevent injuries from occurring. Additional research, including more PMHS testing, is recommended to establish these chest tolerance limits.