Modelling Carpet for Use in Occupant Crash Simulations

Prediction of occupant injury using crash simulations can require numerical representation of materials that are not normally included within the structural model. Intuitively, it makes sense that the carpet would be required to predict the tibia index during frontal crash events; however, there appears to be little published on the topic. The tibia index is an injury criteria that needs to be predicted during IIHS frontal offset occupant simulations, but is also be looked at during unbelted FMVSS 208 simulations. Since carpet behaves quite differently during compressive and tensile loading, a numerical representation that can stably capture both regimes during occupant modelling is needed. This paper outlines a method to model the carpet using a specific meshing method and two material models. Shell elements in combination with the *PIECEWISE_LINEAR_PLASTICITY material model are used to model the tensile load carrying capacity of the carpet, while brick elements with the *MAT_FU_CHANG_FOAM material model are used to represent the compressibility of the carpet. Validation of using this modelling method with test data is presented, as well as the application of the carpet model in larger occupant models.