Presented at the American Helicopter Society 69 th Annual Forum, Phoenix, AZ, May 21-23, 2013. Copyright © 2013 by the American Helicopter Society International, Inc. All rights reserved. This is a work of the U.S. Government and is not subject to copyright protection in the U.S. Validation and Sensitivity Analysis of a Finite Element Model of THOR-NT ATD for Injury Prediction under Vertical Impact Loading Jacob B. Putnam jacobp@vt.edu Graduate Research Assistant Virginia Tech Blacksburg, VA, U.S. Costin D. Untaroiu costin@vt.edu Research Associate Professor Virginia Tech Blacksburg, VA, U.S. Justin Littell Justin.D.Littell@nasa.gov Research Aerospace Engineer NASA Langley Research Center Hampton, VA, U.S. Martin Annett Martin.S.Annett@nasa.gov Aerospace Engineer NASA Langley Research Center Hampton, VA, U.S. ABSTRACT Anthropometric test devices (ATDs) are effective tools to use when conducting aerospace safety evaluations. In this study, the latest FE model of Test Device for Human Occupant Restraint (THOR) ATD was simulated under vertical impact conditions based on data recorded in a series of drop tests conducted at NASA Langley Research Center (LaRC). The purpose of this study was threefold. The first was to improve and then validate the FE model for a vertical loading environment through kinematic and load response comparisons. The second was to evaluate dummy injury criteria under variable impact conditions. The last was to determine the response sensitivity of the FE model with respect to its pre-impact postural position. Results show that the updated FE model performs well under vertical loading and predicts injury criteria values close to those recorded in testing. In the posture study, the head center of gravity (CG) resultant acceleration and lumbar force showed to be sensitive to the pre-impact head angle and thorax angle, respectively. The promising results shown by the dummy model recommend it for use in impact simulations with deceleration pulses close to those used in this study. In addition, it is believed that assigning accurate viscoelastic material properties to deformable parts of the model may further increase the model fidelity for a larger range of impacts. INTRODUCTION The safety of aerospace transport for both fixed and rotary wing aircraft is evaluated primarily through testing of anthropometric test devices (ATDs), commonly known as crash test dummies. These evaluations are essential to the development of improved rotorcraft technology in both the military and civilian sectors, as safety remains the priority in all vehicular transport. Historically, the Hybrid II, Aerospace Hybrid III, and FAA Hybrid III dummies have been the most commonly used ATDs in rotorcraft crashworthiness testing. Recently, the National Aeronautics and Space Administration (NASA) has been investigating developing aerospace occupant protection standards specific to the Test Device for Human Occupant Restraint (THOR) ATD. The THOR ATD, developed and continuously improved by National Highway Traffic Safety Administration (NHTSA), exhibits improved biofidelity over the industry standard, Hybrid III (ATD) [Ref. 1]. Certification tests under automotive horizontal impact conditions have been conducted on the latest build of the ATD, known as the THOR-NT [Ref. 2]. However, to be recommended for use within the aerospace industry, the performance of this ATD in vertical impact conditions must be evaluated. As a path finding effort, the THOR-NT was tested at the NASA Langley Research Center (LaRC) under a series of controlled vertical impact loading conditions [Ref. 3]. The response of the THOR-NT dummy was evaluated in comparison to other ATDs tested under similar conditions [Ref. 4]. The ATD testing provides an effective method for vehicular safety evaluation. However, the high cost and limited availability of ATDs makes performing large numbers of impact tests in the multitude of aerospace configurations difficult. Numerical simulations of impact may provide an important compliment to ATD