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External Biofidelity Evaluation of Pedestrian Leg-Form Impactors

SAE International Journal of Transportation Safety

Hyundai Kia R&D-Haeyoung Jeon
University of Virginia-Daniel Perez-Rapela, Jason Forman, Jeff Crandall
  • Journal Article
  • 2017-01-1450
Published 2017-03-28 by SAE International in United States
Current state-of-the-art vehicles implement pedestrian protection features that rely on pedestrian detection sensors and algorithms to trigger when impacting a pedestrian. During the development phase, the vehicle must “learn” to discriminate pedestrians from the rest of potential impacting objects. Part of the training data used in this process is often obtained in physical tests utilizing legform impactors whose external biofidelity is still to be evaluated. This study uses THUMS as a reference to assess the external biofidelity of the most commonly used impactors (Flex-PLI, PDI-1 and PDI-2). This biofidelity assessment was performed by finite element simulation measuring the bumper beam forces exerted by each surrogate on a sedan and a SUV. The bumper beam was divided in 50 mm sections to capture the force distribution in both vehicles. This study, unlike most of the pedestrian-related literature, examines different impact locations and velocities. The results show how the Flex-PLI and the PDI-1 exert greater forces on the bumper beam than the THUMS, while the PDI-2 produced bumper beam forces similar to the THUMS. The PDI-2 is…
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Influence of Driver Input on the Touchdown Conditions and Risk of Rollover in Case of Steering Induced Soil-Trip Rollover Crashes

Toyota Technical Center USA, Inc.-Mark Clauser
University of Virginia-Varun Bollapragada, Taewung Kim, Jeff Crandall, Jason Kerrigan
Published 2016-04-05 by SAE International in United States
Some rollover testing methodologies require specification of vehicle kinematic parameters including travel speed, vertical velocity, roll rate, and pitch angle, etc. at the initiation of vehicle to ground contact, which have been referred to as touchdown conditions. The complexity of the vehicle, as well as environmental and driving input characteristics make prediction of realistic touchdown conditions for rollover crashes, and moreover, identification of parameter sensitivities of these characteristics, is difficult and expensive without simulation tools. The goal of this study was to study the sensitivity of driver input on touchdown parameters and the risk of rollover in cases of steering-induced soil-tripped rollovers, which are the most prevalent type of rollover crashes. Knowing the range and variation of touchdown parameters and their sensitivities would help in picking realistic parameters for simulating controlled rollover tests. Additionally, understanding the sensitivity of the risk of rollover could potentially aid in developing countermeasures to prevent rollover. Monte Carlo simulations were performed using two multibody models (sedan and pickup) by varying the driving inputs (speed, steer angle, steer rate) for typical…
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Neck Validation of Multibody Human Model under Frontal and Lateral Impacts using an Optimization Technique

Tsinghua University-Yan Wang, Yibing Li
University of Virginia-Taewung Kim, Jeff Crandall
Published 2015-04-14 by SAE International in United States
Multibody human models are widely used to investigate responses of human during an automotive crash. This study aimed to validate a commercially available multibody human body model against response corridors from volunteer tests conducted by Naval BioDynamics Laboratory (NBDL). The neck model consisted of seven vertebral bodies, and two adjacent bodies were connected by three orthogonal linear springs and dampers and three orthogonal rotational springs and dampers. The stiffness and damping characteristics were scaled up or down to improve the biofidelity of the neck model against NBDL volunteer test data because those characteristics were encrypted due to confidentiality. First, sensitivity analysis was performed to find influential scaling factors among the entire set using a design of experiment. Second, the identified scaling factors were adjusted using a gradient-based optimization technique to minimize a Biofidelity rank score (smaller the better), which is one of common technique for correlation analysis between PMHS responses and ones of a dummy or a model. In the sensitivity analysis 4 scaling factors out of 7 were found to be influential to the…
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Occupant Kinematics in Laboratory Rollover Tests: PMHS Response

University of Virginia Center for Applied Biomechanics-David J. Lessley, Patrick Riley, Qi Zhang, Patrick Foltz, Brian Overby, Sara Heltzel, Mark Sochor, Jeff Crandall, Jason R. Kerrigan
Published 2014-11-10 by The Stapp Association in United States
The objective of the current study was to characterize the whole-body kinematic response of restrained PMHS in controlled laboratory rollover tests. A dynamic rollover test system (DRoTS) and a parametric vehicle buck were used to conduct 36 rollover tests on four adult male PMHS with varied test conditions to study occupant kinematics during the rollover event. The DRoTS was used to drop/catch and rotate the test buck, which replicated the occupant compartment of a typical mid-sized SUV, around its center of gravity without roof-to-ground contact. The studied test conditions included a quasi-static inversion (4 tests), an inverted drop and catch that produced a 3 g vertical deceleration (4 tests), a pure dynamic roll at 360 degrees/second (11 tests), and a roll with a superimposed drop and catch produced vertical deceleration (17 tests). Each PMHS was restrained with a three-point belt and was tested in both leading-side and trailing-side front-row seating positions. Whole-body kinematics were measured using a 3D motion capture system that quantified occupant displacement relative to the vehicle buck for the X-axis (longitudinal), Y-axis…
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Evaluation of Biofidelity of Side Impact Computational Surrogates (ES-2re, WorldSID, GHBMC)

Automotive Safety Honda R&D Americas-Andy Svendsen, Nathaniel Saunders, Craig Markusic
University of Virginia-Gwansik Park, Taewung Kim, Jeff Crandall
Published 2014-04-01 by SAE International in United States
The goal of this study was to evaluate the biofidelity of the three computational surrogates (GHBMC model, WorldSID model, and the FTSS ES-2re model) under the side impact rigid wall sled test condition. The responses of the three computational surrogates were compared to those of post mortem human surrogate (PMHS) and objectively evaluated using the correlation and analysis (CORA) rating method. Among the three computational surrogates, the GHBMC model showed the best biofidelity based on the CORA rating score (GHBMC =0.65, WorldSID =0.57, FTSS ES-2re =0.58). In general, the response of the pelvis of all the models showed a good correlation with the PMHS response, while the response of the shoulder and the lower extremity did not. In terms of fracture prediction, the GHBMC model overestimated bone fracture. The results of this study can be effectively utilized in a research that mainly relies on the response of computational surrogates without experimental tests, especially initial development stage of countermeasures for occupant protection from vehicular accidents.
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Rollover Initiation Simulations for Designing Rollover Initiation Test System (RITS)

Hyundai America Technical Center-Ravi Tangirala, Michael Guerrero
University of Virginia-Taewung Kim, Jason Kerrigan, Varun Bollapragada, Jeff Crandall
Published 2014-04-01 by SAE International in United States
Some rollover test methods, which impose a touchdown condition on a test vehicle, have been developed to study vehicle crashworthiness and occupant protection in rollover crashes. In ground-tripped rollover crashes, speed, steering maneuver, braking, vehicle inertial and geometric properties, topographical and road design characteristics, and soil type can all affect vehicle touchdown conditions. It is presumed that while there may be numerous possible combinations of kinematic metrics (velocity components and orientation) at touchdown, there are also numerous combinations of metrics that are not likely to occur in rollover crashes. To determine a realistic set of touchdown conditions to be used in a vehicle rollover crash test, a lateral deceleration sled-based non-destructive rollover initiation test system (RITS) with a fully programmable deceleration pulse is in development.A full-size SUV vehicle dynamics model was developed and validated with static test data and curb-trip rollover test data. Then, design constraints of the RITS were set considering available space and given range of vehicle mass and geometric properties. Since accelerating a test vehicle consumes the limited travel distance, the effect…
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Test Methodology and Initial Results from a Dynamic Rollover Test System

UVA Center for Applied Biomechanics-Jason R. Kerrigan, Jeremy Seppi, Jack Lockerby, Patrick Foltz, Brian Overby, Jim Bolton, Taewung Kim, Nate J. Dennis, Jeff Crandall
Published 2013-04-08 by SAE International in United States
The goal of this study is to present the methods employed and results obtained during the first six tests performed with a new dynamic rollover test system. The tests were performed to develop and refine test methodology and instrumentation methods, examine the potential for variation in test parameters, evaluate how accurately actual touchdown test parameters could be specified, and identify problems or limitations of the test fixture. Five vehicles ranging in size and inertia from a 2011 Toyota Yaris (1174 kg, 379 kg m₂) to a 2002 Ford Explorer (2408 kg, 800 kg m₂) were tested. Vehicle kinematic parameters at the instant of vehicle-to-road contact varied across the tests: roll rates of 211-268 deg/s, roll angles of 133-199 deg, pitch angles of -12 deg to 0 deg, vertical impact velocities of 1.7 to 2.7 m/s, and road velocities of 3.0-8.8 m/s. Vehicle instrumentation included three angular rate sensors and three linear accelerometers mounted near the vehicle CG; data from the sensor pack and a coordinate measurement machine facilitated analytical translation of the kinematics sensors to…
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Optical Measurement of High-Rate Dynamic Vehicle Roof Deformation during Rollover

UVA Center for Applied Biomechanics-Jack Lockerby, Jason Kerrigan, Jeremy Seppi, Jeff Crandall
Published 2013-04-08 by SAE International in United States
The goals of this study were to examine the dynamic force-deformation and kinematic response of a late model van subjected to an inverted drop test and to evaluate the accuracy of three-dimensional multi-point roof deformation measurements made by an optical system mounted inside the vehicle. The inverted drop test was performed using a dynamic rollover test system (Kerrigan et al., 2011 SAE) with an initial vehicle pitch of −5 degrees, a roll of +155 degrees and a vertical velocity of 2.7 m/s at initial contact. Measurements from the optical system, which was composed of two high speed imagers and a commercial optical processing software were compared to deformation measurements made by two sets of three string potentiometers. The optical and potentiometer measurements reported similar deformations: peak resultant deformations varied by 0.7 mm and 3 ms at the top of the A-pillar, and 1.7 mm and 2 ms at the top of the B-pillar. The top of the vehicle B-pillar sustained peak resultant deformation of 146.2 mm 116 ms after contact, and unloaded to 77.1 mm…
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Identification of Anatomical Landmarks for Whole-Body Kinematic Measurement in the THOR Mod Kit Frontal Impact ATD

US DOT-Daniel Parent
University of Virginia-David Lessley, Greg Shaw, Jeff Crandall
  • Technical Paper
  • 2012-08-0062
Published 2012-05-23 by Society of Automotive Engineers of Japan in Japan
Evaluating the kinematic response of the THOR Mod Kit frontal impact ATD to that of PMHS requires comparing consistent measurement locations. The current study identifies the 3D locations of anatomical landmarks to be used for kinematic response comparisons between the THOR ATD and restrained PMHS tested in the same impact condition. The anthropometry of eight male PMHS approximating a 50th percentile male were used to map the anatomical locations of T1, T8, L2, L4, pelvis center, and acromia to the THOR Mod Kit geometry. The identified locations are provided and will be immediately useful for whole-body kinematic comparisons with existing PMHS data.
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Development of an Alternative Frontal Impact Condition to Assess Thoracic Response Using the THOR Mod Kit Dummy

University of Virginia-Greg Shaw, David Lessley, Joseph Ash
University of Virginia Center for Applied Biomechanics)-Jeff Crandall
  • Technical Paper
  • 2012-08-0064
Published 2012-05-23 by Society of Automotive Engineers of Japan in Japan
In the course of developing an alternative test condition to explore torso response, the NHTSA's THOR Mod Kit Dummy was evaluated in two simulated frontal impact conditions. The recently proposed condition, which is less severe, produced less shoulder belt tension resulting in lower chest deflection. It also produced differences in the pattern of anterior ribcage deflection. The results of this study suggest that this less severe frontal impact test condition will produce sufficiently different PMHS response relative to that recorded in previous PMHS tests, including fewer rib fractures as well as an altered pattern of anterior ribcage loading.