Collaboration Between Chalmers and Autoliv

Chest Injury Prediction using the Finite Element Models
THUMS, THOR and Hybrid III

Collaboration between Chalmers and Autoliv

The vehicle industry has developed occupant restraint systems that offer significant protection of vehicle occupants in crashes. The main restraint systems in the vehicles today are seatbelts and airbags. These restraint systems have significantly reduced the number of occupants killed and injured in automobile crashes. However, occupants are still injured in vehicle crashes. One body region that is vulnerable is the chest which frequently is injured. The most frequent chest injury is rib fractures that can result in serious complications for those that are elderly, e.g. pneumonia, and also lead to soft tissue injuries, e.g. hemothorax and pneumothorax.

To design and evaluate occupant restraint systems, a detailed knowledge about the behavior of a human body when loaded in crashes is needed.

-  One of the tools used to predict the behavior of an occupant in a crash are crash test dummies. The crash test dummy is considered to be a crude representation of a human. However, the experience using these dummies, especially the Hybrid III dummy, is vast. While final evaluation of a restraint system is carried out with a physical dummy, most of the restraint and vehicle developments are now carried out with FE-models of the crash test dummies. The finite element version of the Hybrid III dummy (FE-Hybrid III) is one of the most commonly used such model.

-  Tools developed more recently are mathematical models of humans (HBM). With these models detailed analysis of the behavior of various structures of the body can be evaluated. One of the most used complete models of the human is the Total Human Model for Safety (THUMS).

Output data from a mathematical crash test dummy is commonly similar to those obtained in the physical counterpart; kinematics and global criteria levels. The THUMS allow for an analysis of kinematics and criteria on global, organ and tissue level. However, it is not clear how all this additional data will be used and the experience using the THUMS is limited.

The aim with this thesis is to compare the injury predictability offered by the THUMS and FE-Hybrid III in car collisions and give recommendations for future studies.

To meet these aims several frontal and oblique real-world car collisions will be simulated using the FE-Hybrid III, the THUMS and models of the vehicles involved in the crashes. The simulation results will be compared to the real-world cases.

The study will include a literature study on thorax injury prediction. Several frontal and oblique car collisions will be simulated in LS-Dyna using the FE-Hybrid III, the THUMS and vehicle models. The output from these simulations will be compared to the real-world crashes. Limited accident reconstructions will be carried out. A sensitivity study will be carried out. Based on the results from comparison and sensitivity study recommendations for the use of the FE-Hybrid III and THUMS will be proposed.

The project is suitable for two students studying mechanical engineering. Finite element knowledge and experience is a pre-requisite. The work will be carried out at Vehicle Safety, Applied Mechanics at SAFER, Lindholmen.

Examiner and supervisor: Johan Davidsson, Applied Mechanics

Supervisor: Bengt Pipkorn, Autoliv.

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Phone: +46730346436