Rib and Thoracic Response in Frontal Car Crashes: A Study Using a Finite Element Human Body Model

Licentiate thesis, 2012

Traditionally, restraint systems have been evaluated with Anthropomorphic Test Devices (ATDs) and the thoracic injury criteria have been based on parameters assessed using ATDs, such as chest compression. ATDs have limitations since they are only a gross representation of the human body. ATDs and injury criteria have shown insensitivity to modern restraint systems, such as seat belts and air bags. The evaluation of current and development of new restraint systems require improved tools and injury criteria. Using Finite Element (FE) Human Body Models (HBMs) may be a possible complement. FE HBMs offer a more detailed description of the human anatomy compared to ATDs and potentially they may also allow the study of injuries at tissue level. In this thesis, the FE HBM Total HUman Model for Safety version 3.0 (THUMS v3.0) was improved and the biofidelity of the resultant model, THUMS v3-M, was assessed in table top, pendulum and sled tests. THUMS v3-M was used to study the rib response and thoracic stiffness and coupling responses under loads representative of modern restraint systems in frontal impacts. The knowledge on rib response was applied to identify characteristics of future rib and thoracic injury criteria candidates. The knowledge on thoracic deformation was applied to make recommendations for the improvement of THOR. THUMS v3-M performed better than THUMS v3.0 in the biofidelity assessment tests used in this thesis. It was found that injury criteria candidates should be sensitive to bending, shear and torsion loads in the rib. The recommendations to improve THOR were to decrease the rib stiffness and include the stiffness of the thoracic organs as spring-damper mechanisms, and to represent the intercostal muscles by means of a mechanical structure.