For each phase of this study historical post-mortem human surrogate (PMHS) test cases are first selected from the Medical College of Wisconsin (MCW) database for match paired testing. Selection of these cases are made based on their similarity to spaceflight loading dynamics and Astronaut demographics. Once these data are selected, the Hybrid III 50th percentile male and THOR Anthropomorphic Test Device (ATD) are tested in identical conditions. A survival analysis is then used to relate the resulting ATD responses to identified PMHS injuries and develop injury risk correlation. This correlation will be used to improve upon the injury metrics previously developed in other research tasks. The resulting metrics will be used to update NASA standards and provided to the Orion and Commercial Crew Program to allow additional insight into verification, validation and risk analysis. Currently phase 1 – lower neck injury under rearward impact has been completed. A supplemental phase of this project, cervical spine injury under vertical contact loading, has also been completed. For this supplemental phase injury risk functions were developed from PMHS test only. It was determined that compressive contact loading, used in PMHS testing, had minimal value in matched paired ATD testing due to the inflexibility of the ATD head/neck structure in this loading configuration. The remaining lateral injury metrics for the neck, thorax, and pelvis are in various stages of completion and are on track to be finished by September 2020. The lateral lower neck metric development has completed the necessary ATD matched-pair testing, but due to a low number of those tests being applicable to spaceflight loading dynamics, additional cases are currently being run using finite element models to supplement the current data. In addition, tests using the GHBMC whole body finite element model are also being run in lateral neck loading conditions.
ATD testing in the lateral acetabular loading cases showed that the ATDs are too stiff to match the input conditions of the cadaveric data. Therefore, an injury assessment reference value (IARV) is being created based on the cadaveric data, instead of the ATDs.
The IARV for lateral chest compression is rib fracture. Correlation between cadaveric and ATD chest compression is difficult due to the mechanism to calculate fracture. The method for calculating fracture for the cadaveric and different ATDs are all different and do not necessarily correlated to the same points on the thorax and can not necessarily be used together. Current research includes finding the best way to create the IARV for rib fracture.
Other current research includes finding the injury metrics for pelvis and examining the effect of sex differences in lower neck, lateral thorax, lateral pelvis injuries, as well as sex differences in lordosis.