title: Development of head injury assessment reference values based on NASA injury modeling.
abstract: NASA is developing a new crewed vehicle and desires a lower risk of injury compared to automotive or  commercial aviation. Through an agreement with the National Association of Stock Car Auto Racing, Inc. (NASCAR®), an  analysis of NASCAR impacts was performed to develop new injury assessment reference values (IARV) that may be more  relevant to NASA's context of vehicle landing operations. Head IARVs associated with race car impacts were investigated by  analyzing all NASCAR recorded impact data for the 2002-2008 race seasons. From the 4015 impact files, 274 impacts were  selected for numerical simulation using a custom NASCAR restraint system and Hybrid III 50th percentile male Finite Element  Model (FEM) in LS-DYNA. Head injury occurred in 27 of the 274 selected impacts, and all of the head injuries were mild  concussions with or without brief loss of consciousness. The 247 noninjury impacts selected were representative of the range of  crash dynamics present in the total set of impacts. The probability of head injury was estimated for each metric using an ordered  probit regression analysis. Four metrics had good correlation with the head injury data: head resultant acceleration, head change  in velocity, HIC 15, and HIC 36. For a 5% risk of AIS≥1/AIS≥2 head injuries, the following IARVs were found: 121.3/133.2 G  (head resultant acceleration), 20.3/22.0 m/s (head change in velocity), 1,156/1,347 (HIC 15), and 1,152/1,342 (HIC 36)  respectively. Based on the results of this study, further analysis of additional datasets is recommended before applying these  results to future NASA vehicles.
authors.affiliation: Wyle Integrated Science and Engineering Group, Houston, TX 77058, USA. jeff.somers@nasa.gov
authors.forename: Jeffrey T
authors.initials: JT
authors.lastname: Somers
authors.forename: Bradley
authors.initials: B
authors.lastname: Granderson
authors.forename: John W
authors.initials: JW
authors.lastname: Melvin
authors.forename: Ala
authors.initials: A
authors.lastname: Tabiei
authors.forename: Charles
authors.initials: C
authors.lastname: Lawrence
authors.forename: Alan
authors.initials: A
authors.lastname: Feiveson
authors.forename: Michael
authors.initials: M
authors.lastname: Gernhardt
authors.forename: Robert
authors.initials: R
authors.lastname: Ploutz-Snyder
authors.forename: John
authors.initials: J
authors.lastname: Patalak
mesh_terms: D015998:Abbreviated Injury Scale; D000054:Acceleration; D000063:Accidents, Traffic; D001334:Automobile Driving; D001924:Brain Concussion / Q000517:prevention & control; D003198:Computer Simulation; D006259:Craniocerebral Trauma / Q000517:prevention & control*; D020342:Finite Element Analysis; D006260:Head Protective Devices; D006801:Humans; D008959:Models, Neurological; D012016:Reference Values; D012044:Regression Analysis; D013177:Sports; D014481:United States; D018557:United States National Aeronautics and Space Administration