Dynamic Similitude of Human Head Surrogates

Due to the highly transient nature of head injury events that lead to traumatic brain injury (TBI) and the complexity of the human head, a structural-dynamics-informed design process is needed to augment research efforts that utilize human head surrogate models. Such models are capable of accurately mimicking the response of biological systems and allow for models that explore biological differences between individuals. This study explores the relevant mechanisms and parameters that contribute to the dynamic response of biological and additive manufactured surrogate head models and proposes an iterative design process to compare the two systems. Using experimental and finite element method (FEM) modal analysis, a balance between geometric complexity, computational resources, and manufacturability are considered when building a head model for obtaining pressures, strains, or other relevant injury indicators similar to that of a biological system. This study used a simplified ellipsoid head model to meaningfully change the response of the additive manufactured model similar to a model simulated with biological material properties. Additionally, a single layer of a digital material was used to mimic the dynamic response of the simulated head surrogate with two layers of biological materials; the scalp, and the skull. This study successfully outlined and exhibited the most basic application of a structural-dynamics-informed design process to create improved head surrogate models and to effectively compare the results from current head surrogate models to real biological systems.