Evaluation of Human and Dummy Finite Element Models under Spaceflight Loading Conditions

In an effort to develop occupant protection standards for future crewed spacecraft, the National Aeronautics and Space Administration (NASA) has been investigating the test device for human occupant restraint (THOR) dummy in relevant impact test scenarios. In this study, the biofidelity of THOR and total human model for safety (THUMS) finite element (FE) models were evaluated against a series of human-volunteer tests previously performed by the United States Air Force (USAF). The pre-test human position and sled acceleration pulses measured during testing were used to setup the FE simulations. Predicted responses by both human and dummy models were compared to human test data recorded under the same impact conditions. In addition, dummy injury criteria and human stress/strain data were calculated to evaluate the risk of injury predicted by the dummy and human model, respectively. While some differences were observed in thorax load distribution and neck stiffness, the results show reasonable biofidelity of the dummy/human FE models in terms of kinematic response. In addition predicted dummy injury criteria and human model stress/strain values are shown to positively relate. As a compliment to dummy testing, numerical simulation provide efficient means to assess vehicle safety throughout the design process and further improve the design of physical dummies. The assessment of the THOR and THUMS FE models in spaceflight testing condition is an essential first step to implementing these models in the computational evaluation of space transport vehicle occupant safety. Promising results suggest future use of these models in this field.