The development, validation, and comparison of a finite element human thorax model for automotive impact injury studies

Computational simulations are becoming more important in automotive safety engineering. To simulate the occupants during the crash environment, dummies are currently used to represent the occupants. However, current dummies and dummy models lack the detailed information to predict the occupant injuries during a crash. And for the human thorax models, simplified geometry and non strain-rate material properties were used for the rib cage with no ability to simulate the rib fractures often seen in an automotive crash. Therefore, a detailed finite element human thorax model with proper material properties and the capability to simulate the rib fractures is needed to better understand the thoracic injuries under frontal and side impacts.; In the current thorax model, digital surface images were used to construct the three-dimensional finite element representation of the spine, rib cage, arms, surface muscles, heart, lungs, and major blood vessels. Strain-rate-dependent properties were utilized for the rib cage. Mechanical properties of the biological tissues were obtained from the test data. The constitutive equations, proposed in the literature for the heart and lungs, were implemented in Dyna3D.; The thorax model was validated against cadaver responses for both the frontal and side impacts. Good agreements with the cadaver tests were achieved on the force and deformation time histories. Design of Experiment studies were used to improve the model responses. Comparisons to the rigid body model showed that finite element models are better tools in injury predictions. This is the first model with realistic anatomic structure to successfully demonstrate its capability to simulate both the frontal and side impacts in good agreement with test data with the predictions of rib fractures. It was found that the model with rib fractures was more compliant than the one without. Changes in predictions of fracture patterns with the change in the ultimate stresses of the ribs revealed the importance of bone quality in predicting the fracture patterns in response to impact loading. Better correlation with the test data was achieved with the comparisons to the other models. This model has provided a good foundation for the development of a bio-fidelity human model.