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Technical Paper

Lateral Injury Criteria for the 6-year-old Pedestrian - Part II: Criteria for the Upper and Lower Extremities

2004-03-08
2004-01-1755
Pediatric pedestrians are frequently involved in Pedestrian versus Motor Vehicle Collisions (PMVCs). While in recent years, the automotive industry has worked towards making cars less aggressive to pedestrians, the efforts have mainly focused on adult pedestrian safety. When they have included considerations for children, only head injuries have been evaluated. The development of automotive countermeasures that provide protection for both adult and pediatric pedestrians requires access to injury criteria for the entire body that specifically account for both the age-dependent tissue properties and the pedestrian's size. The objective of the present study is to derive lateral injury criteria for the upper and lower extremities that can be used in finite element and multi-body simulations of PMVCs involving the 6-year-old pedestrian (corresponding injury criteria for the head, neck, thorax, abdomen and pelvis are derived in part I of this study).
Technical Paper

Lateral Injury Criteria for the 6-year-old Pedestrian - Part I: Criteria for the Head, Neck, Thorax, Abdomen and Pelvis

2004-03-08
2004-01-0323
Pediatric pedestrians are frequently involved in Pedestrian versus Motor Vehicle Collisions (PMVCs). While in recent years, the automotive industry has worked towards making cars less aggressive to pedestrians, the efforts have mainly focused on adult pedestrian safety. When they have included considerations for children, only head injuries have been evaluated. The development of automotive counter-measures that provide protection for both adult and pediatric pedestrians requires access to injury criteria for the entire body that specifically account for both the age-dependent tissue properties and the pedestrian's size. The objective of the present study is to derive lateral injury criteria for the head, neck, thorax, abdomen and pelvis that can be used in finite element and multi-body simulations of PMVCs involving the 6-year-old pedestrian (corresponding injury criteria for the upper and lower extremities are derived in part II of this study).
Technical Paper

Interaction of the Hand and Wrist with a Door Handgrip During Static Side Air Bag Deployment: Simulation Study Using the CVS/ATB Multi-Body Program

2001-03-05
2001-01-0170
This paper presents a parametric study that utilized the CVS/ATB multi-body simulation program to investigate the interaction of the hand and wrist with a door handgrip during side air bag loading. The goal was to quantify the relative severity of various hand and handgrip positions as a guide in the selection of a test matrix for laboratory testing. The air bag was represented as a multi-body system of ellipsoidal surfaces that were created to simulate a prototype seat-mounted thorax side air bag. All simulations were set in a similar static test environment as used in corresponding dummy and cadaver side air bag testing. The occupant mass and geometric properties were based on a 5th percentile female occupant in order to represent a high-risk segment of the adult population. The upper extremity model consisted of wrist and forearm rotations that were based on human volunteer data.
Technical Paper

Dynamic Response Corridors of the Human Thigh and Leg in Non-Midpoint Three-Point Bending

2005-04-11
2005-01-0305
Current standards and test devices for pedestrian safety are developed using results from impact tests where inertial considerations have dominated and the vehicle pedestrian loading environment has not been properly replicated. When controlled tests have been conducted to evaluate the biofidelity of anthropometric test devices, current designs have faired poorly. The objective of the current study was to develop dynamic force-deflection and moment-deflection response corridors for the 50th percentile adult male thigh and leg subjected to non-midpoint 3-point bending at rates characteristic of the vehicle-pedestrian loading environment. Six thigh and eight leg specimens were harvested from eight adult male human cadavers and ramped to failure in dynamic 3-point bending in the latero-medial direction.
Technical Paper

The Tolerance of the Femoral Shaft in Combined Axial Compression and Bending Loading

2009-11-02
2009-22-0010
The likelihood of a front seat occupant sustaining a femoral shaft fracture in a frontal crash has traditionally been assessed by an injury criterion relying solely on the axial force in the femur. However, recently published analyses of real-world data indicate that femoral shaft fracture occurs at axial loads levels below those found experimentally. One hypothesis attempting to explain this discrepancy suggests that femoral shaft fracture tends to occur as a result of combined axial compression and applied bending. The current study aims to evaluate this hypothesis by investigating how these two loading components interact. Femoral shafts harvested from human cadavers were loaded to failure in axial compression, sagittal plane bending, and combined axial compression and sagittal plane bending.
Technical Paper

A Comparative Analysis of the Pedestrian Injury Risk Predicted by Mechanical Impactors and Post Mortem Human Surrogates

2008-11-03
2008-22-0020
The objective of this study is to compare the risk of injury to pedestrians involved in vehicle-pedestrian impacts as predicted by two different types of risk assessment tools: the pedestrian subsystem impactors recommended by the European Enhanced Vehicle-Safety Committee (EEVC) and post-mortem human surrogates (PMHS). Seven replicate full-scale vehicle-pedestrian impact tests were performed with PMHS and a mid-sized sedan travelling at 40 km/h. The PMHS were instrumented with six-degree-of-freedom sensor cubes and sensor data were transformed and translated to predict impact kinematics at the head center of gravity, proximal tibiae, and knee joints. Single EEVC WG 17/EuroNCAP adult headform, upper legform and lower legform impactor tests of the same vehicle were selected for comparison based on the proximity of their impact locations to that of the PMHS.
Technical Paper

On the Importance of Nonlinearity of Brain Tissue Under Large Deformations

2003-10-27
2003-22-0005
Linear shear properties of human and bovine brain tissue were determined from transient stress-relaxation experiments and their material functions were compared. Quasi-linear viscoelastic theory was then utilized to determine material constants for bovine brain tissue subjected to large deformations. The range of applicability for linear and quasi-linear constitutive models of brain tissue was determined. A nonlinear Green-Rivlin constitutive model was subsequently applied to characterize temporal nonlinearity of bovine brain tissue in shear. Overall, 10 brain specimens from 5 fresh human cadavers and 156 brain specimens from 26 fresh bovine cadaver brains were used to quantify and compare shear brain responses under various loading conditions. The assumptions of homogeneity, isotropy, and incompressibility of brain material were made in order to reduce the required number of experiments.
Technical Paper

Evaluation of lower limb injury mitigation from inflatable carpet in sled tests with intrusion using the Thor Lx

2001-06-04
2001-06-0092
Real-world crash investigations have suggested that lower limb injury risk is increased with the occurrence of toepan intrusion in a frontal collision. In order to more closely evaluate the effects of different modes of toepan intrusion, a rotational and translational intrusion device was built for the test sled at the University of Virginia. Sled tests were performed at a velocity of 56 km/h with a belted Hybrid III occupant and a simulated knee bolster and steering wheel air bag. Lower limb injury risk measures were obtained with Hybrid III and Thor Lx dummy lower extremities. Dummy response variables of interest included tibia axial and shear loads, tibia bending moments, ankle rotations and foot and tibia accelerations. The tests were conducted with no intrusion and with a translational intrusion with a peak deceleration of approximately 175 g's with 14 cm of translation.
Technical Paper

THE EFFECT OF ACTIVE MUSCLE TENSION ON THE AXIAL INJURY TOLERANCE OF THE HUMAN FOOT/ANKLE COMPLEX

2001-06-04
2001-06-0074
Axial loading of the foot/ankle complex is an important injury mechanism in vehicular trauma that is responsible for severe injuries such as calcaneal and tibia pilon fractures. Axial loading may be applied to the leg externally, by the toepan and/or pedals, as well as internally, by active muscle tension applied through the Achilles tendon during pre-impact bracing. In order to evaluate the effect of active muscle tension on the injury tolerance of the foot/ankle complex, blunt axial impact tests were performed on 44 isolated lower legs with and without experimentally simulated Achilles tension. The primary fracture mode was calcaneal fracture in both groups, but tibia pilon fractures occurred more frequently with the addition of Achilles tension. Acoustic emission demonstrated that fracture initiated at the time of peak local axial force.
Technical Paper

Occupant Kinematics in Laboratory Rollover Tests: ATD Response and Biofidelity

2014-11-10
2014-22-0012
Rollover crashes are a serious public health problem in United States, with one third of traffic fatalities occurring in crashes where rollover occurred. While it has been shown that occupant kinematics affect the injury risk in rollover crashes, no anthropomorphic test device (ATD) has yet demonstrated kinematic biofidelity in rollover crashes. Therefore, the primary goal of this study was to assess the kinematic response biofidelity of six ATDs (Hybrid III, Hybrid III Pedestrian, Hybrid III with Pedestrian Pelvis, WorldSID, Polar II and THOR) by comparing them to post mortem human surrogate (PMHS) kinematic response targets published concurrently; and the secondary goal was to evaluate and compare the kinematic response differences among these ATDs.
Technical Paper

Analysis of upper extremity response under side air bag loading

2001-06-04
2001-06-0016
Computer simulations, dummy experiments with a new enhanced upper extremity, and small female cadaver experiments were used to analyze the small female upper extremity response under side air bag loading. After establishing the initial position, three tests were performed with the 5th percentile female hybrid III dummy, and six experiments with small female cadaver subjects. A new 5th percentile female enhanced upper extremity was developed for the dummy experiments that included a two-axis wrist load cell in addition to the existing six-axis load cells in both the forearm and humerus. Forearm pronation was also included in the new dummy upper extremity to increase the biofidelity of the interaction with the handgrip. Instrumentation for both the cadaver and dummy tests included accelerometers and magnetohydrodynamic angular rate sensors on the forearm, humerus, upper and lower spine.
Technical Paper

The Effects of Axial Preload and Dorsiflexion on the Tolerance of the Ankle/Subtalar Joint to Dynamic Inversion and Eversion

2002-11-11
2002-22-0013
Forced inversion or eversion of the foot is considered a common mechanism of ankle injury in vehicle crashes. The objective of this study was to model empirically the injury tolerance of the human ankle/subtalar joint to dynamic inversion and eversion under three different loading conditions: neutral flexion with no axial preload, neutral flexion with 2 kN axial preload, and 30° of dorsiflexion with 2 kN axial preload. 44 tests were conducted on cadaveric lower limbs, with injury occurring in 30 specimens. Common injuries included malleolar fractures, osteochondral fractures of the talus, fractures of the lateral process of the talus, and collateral ligament tears, depending on the loading configuration. The time of injury was determined either by the peak ankle moment or by a sudden drop in ankle moment that was accompanied by a burst of acoustic emission. Characteristic moment-angle curves to injury were generated for each loading configuration.
Technical Paper

Whole-body Response for Pedestrian Impact with a Generic Sedan Buck

2015-11-09
2015-22-0016
To serve as tools for assessing injury risk, the biofidelity of whole-body pedestrian impact dummies should be validated against reference data from full-scale pedestrian impact tests. To facilitate such evaluations, a simplified generic vehicle-buck has been recently developed that is designed to have characteristics representative of a generic small sedan. Three 40 km/h pedestrian-impact tests have been performed, wherein Post Mortem Human Surrogates (PMHS) were struck laterally in a mid-gait stance by the buck. Corridors for select trajectory measures derived from these tests have been published previously. The goal of this study is to act as a companion dataset to that study, describing the head velocities, body region accelerations (head, spine, pelvis, lower extremities), angular velocities, and buck interaction forces, and injuries observed during those tests.
Technical Paper

Biofidelity Improvements to the Polar-II Pedestrian Dummy Lower Extremity

2007-04-16
2007-01-0757
Experimental tests were performed on the modified Polar-II pedestrian dummy lower extremity components to evaluate their biofidelity in lateral impact loading corresponding to a 40 km/h pedestrian-car collision. The bending moment-angle response from a newly developed knee joint, dynamically loaded in four-point valgus bending, was compared against previously published postmortem human subject (PMHS) response corridors. In addition to the stiffness characteristics of the knee joint, individual ligament forces were also recorded during the bending tests. The evaluated force-relative elongation response of the medial collateral ligament (MCL) in the new knee was compared against PMHS data on MCL tensile stiffness. Lower extremity long bones developed for improved anthropometrical accuracy and deformability were dynamically loaded in latero-medial three-point bending.
Journal Article

A Computational Study of Rear-Facing and Forward-Facing Child Restraints

2008-04-14
2008-01-1233
A recent study of U.S. crash data has shown that children 0-23 months of age in forward-facing child restraint systems (FFCRS) are 76% more likely to be seriously injured in comparison to children in rear-facing child restraint systems (RFCRS). Motivated by the epidemiological data, seven sled tests of dummies in child seats were performed at the University of Virginia using a crash pulse similar to FMVSS 213 test conditions. The tests showed an advantage for RFCRS; however, real-world crashes include a great deal of variability among factors that may affect the relative performance of FFCRS and RFCRS. Therefore, this research developed MADYMO computational models of these tests and varied several real-world parameters. These models used ellipsoid models of Q-series child dummies and facet surface models of American- and Swedish- style convertible child restraints (CRS).
Technical Paper

Methodology for Measuring Tibial and Fibular Loads in a Cadaver

2002-03-04
2002-01-0682
Crash test dummies rely on biomechanical data from cadaver studies to biofidelically reproduce loading and predict injury. Unfortunately, it is difficult to obtain equivalent measurements of leg loading in a dummy and a cadaver, particularly for bending moments. A methodology is presented here to implant load cells in the tibia and fibula while minimally altering the functional anatomy of the two bones. The location and orientation of the load cells can be measured in all six degrees of freedom from post-test radiographs. Equations are given to transform tibial and fibular load cell measurements from a cadaver or dummy to a common leg coordinate frame so that test data can be meaningfully compared.
Technical Paper

Comparative Evaluation of Dummy Response with Thor-Lx/HIIIr and Hybrid III Lower Extremities

2002-03-04
2002-01-0016
Multiple series of frontal sled tests were performed to evaluate the new Thor-Lx/HIIIr lower extremity developed by the National Highway Traffic Safety Administration for retrofit use on the 50th percentile male Hybrid III. This study's objective was to compare the Thor-Lx/HIIIr to the existing Hybrid III dummy leg (HIII) from the standpoint of repeatability and effects on femur and upper body response values.\ The test-to-test repeatability of the dummy responses, as measured by the coefficient of variation (CV), was generally acceptable (CV < 10%) for all of the test conditions for both legs. Overall, tests with the Thor-Lx/HIIIr legs produced upper body movement and injury criteria values for the head and chest that were acceptably consistent and were generally indistinguishable from those produced with the HIII leg. Low right femur loads, which ranged from 4 to 25 percent of the injury assessment reference value, varied substantially test-to-test for tests with both types of legs.
Technical Paper

Biomechanical Response and Physical Properties of the Leg, Foot, and Ankle

1996-11-01
962424
The anatomical dimensions, inertial properties, and mechanical responses of cadaver leg, foot, and ankle specimens were evaluated relative to those of human volunteers and current anthropometric test devices. Dummy designs tested included the Hybrid III, Hybrid III with soft joint stops, ALEX I, and the GM/FTSS lower limbs. Static and dynamic tests of the leg, foot, and ankle were conducted at the laboratories of the Renault Biomedical Research Department and the University of Virginia. The inertial and geometric properties of the dummy lower limbs were measured and compared with cadaver properties and published volunteer values. Compression tests of the leg were performed using static and dynamic loading to determine compliance of the foot and ankle. Quasi-static rotational properties for dorsiflexion and inversion/eversion motion were obtained for the dummy, cadaver, and volunteer joints of the hindfoot.
Technical Paper

An Evaluation of a Fiber Optic Based Sensor for Measuring Chest and Abdominal Deflection

2005-04-11
2005-01-0745
The objective of this study was to investigate the use of a fiber optic based sensor, ShapeTape, as an instrument for measuring abdominal and chest deflection, and to compare it to the current instrument used in impact biomechanics applications, the chestband. Drift, pressure, and temperature tests were conducted for ShapeTape alone, whereas quasi-static and dynamic loading tests were conducted as comparison tests between the chestband and ShapeTape. The effects of drift and temperature on ShapeTape were very small, averaging 0.26% and 1.2% full scale changes respectively. During the pressure test at a load of 1000 N the ShapeTape sensor tested experience a 7.47% full scale voltage change. The average errors in reporting maximum deflection of the chest form during the quasi-static loading tests were 3.35% and 1.64% for ShapeTape and the chestband respectively.
Technical Paper

Experiments for Establishing Pedestrian-Impact Lower Limb Injury Criteria

2003-03-03
2003-01-0895
Previous lateral knee bending and shear tests have reported knee joint failure moments close to failure bending moments for the tibia and femur. Eight tibias, eight femurs and three knee joints were tested in lateral bending and two knee joints were tested in lateral shear. Seven previous studies on femur bending, five previous studies on tibia bending, two previous studies on knee joint bending, and one on shear were reviewed and compared with the current tests. All knee joint failures in the current study were either epiphysis fractures of the femur or soft tissue failures. The current study reports an average lateral failure bending moment for the knee joint (134 Nm SD 7) that is dramatically lower than that reported in the literature (284-351 Nm), that reported in the current study for the tibia (291 Nm SD 69) and for femur (382 Nm SD 103).
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