Preliminary Methods for Modeling Stress-Strain Curves of Human Ribs from Structural Dynamic

It is important to understand and quantify rib behavior in dynamic impacts because thorax injuries are common in motor vehicle crashes and have a high incidence of morbidity and mortality. The goal of this research was to develop a preliminary method to calculate stress and stress-strain curves for which a quantitative model could be used to identify material properties from structural rib tests. Dynamic bending experiments were successfully conducted on 30 whole, mid-level, excised ribs affixed with uniaxial strain gages. A custom MATLAB code was created to calculate stress based on precise cross-sectional geometry at the fracture location. In combination with the strain data, stress-strain curves were created, and a continuous piecewise model was successfully developed to characterize each curve. This model was based on multiple parameters that were used to describe the linear elastic and plastic portion of the stress-strain curve. The model revealed an excellent fit for the stress-strain curves with R 2 values ranging from 0.985 - 0.999. Because of the high degree of fit, material properties were extracted directly from the model. Elastic modulus values were overestimated by the model and future work is needed to obtain more accurate results. This model seeks to provide a new method of extracting specific material parameters that could be applied to a large, existing experimental rib fracture data set.