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Technical Paper

Development of Brain Injury Criteria (BrIC)

2013-11-11
2013-22-0010
Rotational motion of the head as a mechanism for brain injury was proposed back in the 1940s. Since then a multitude of research studies by various institutions were conducted to confirm/reject this hypothesis. Most of the studies were conducted on animals and concluded that rotational kinematics experienced by the animal's head may cause axonal deformations large enough to induce their functional deficit. Other studies utilized physical and mathematical models of human and animal heads to derive brain injury criteria based on deformation/pressure histories computed from their models.
Technical Paper

Field Demonstration of a Camera/Video Imaging System for Heavy Vehicles - Driver Lane Change Performance Preliminary Results

2010-10-05
2010-01-2020
On-board Camera/Video Imaging Systems (C/VISs) for heavy vehicles display live images to the driver of selected areas to the sides, and in back of the truck's exterior using displays inside the truck cabin. They provide a countermeasure to blind-spot related crashes by allowing drivers to see objects not ordinarily visible by a typical mirror configuration, and to better judge the clearance between the trailer and an adjacent vehicle when changing lanes. The Virginia Tech Transportation Institute is currently investigating commercial motor vehicle (CMV) driver performance with C/VISs through a technology field demonstration sponsored by the National Highway Traffic Safety Administration (NHTSA) and the Federal Motor Carrier Safety Administration (FMCSA). Data collection, which consists of recording twelve CMV drivers performing their daily employment duties with and without a C/VIS for four months, is currently underway.
Technical Paper

Dynamic Properties of the Upper Thoracic Spine-Pectoral Girdle (UTS-PG) System and Corresponding Kinematics in PMHS Sled Tests

2012-10-29
2012-22-0003
Anthropomorphic test devices (ATDs) should accurately depict head kinematics in crash tests, and thoracic spine properties have been demonstrated to affect those kinematics. To investigate the relationships between thoracic spine system dynamics and upper thoracic kinematics in crash-level scenarios, three adult post-mortem human subjects (PMHS) were tested in both Isolated Segment Manipulation (ISM) and sled configurations. In frontal sled tests, the T6-T8 vertebrae of the PMHS were coupled through a novel fixation technique to a rigid seat to directly measure thoracic spine loading. Mid-thoracic spine and belt loads along with head, spine, and pectoral girdle (PG) displacements were measured in 12 sled tests conducted with the three PMHS (3-pt lap-shoulder belted/unbelted at velocities from 3.8 - 7.0 m/s applied directly through T6-T8).
Technical Paper

Rear Seat Occupant Safety: An Investigation of a Progressive Force-Limiting, Pretensioning 3-Point Belt System Using Adult PMHS in Frontal Sled Tests

2009-11-02
2009-22-0002
Rear seat adult occupant protection is receiving increased attention from the automotive safety community. Recent anthropomorphic test device (ATD) studies have suggested that it may be possible to improve kinematics and reduce injuries to rear seat occupants in frontal collisions by incorporating shoulder-belt force-limiting and pretensioning (FL+PT) technologies into rear seat 3-point belt restraints. This study seeks to further investigate the feasibility and potential kinematic benefits of a FL+PT rear seat, 3-point belt restraint system in a series of 48 kmh frontal impact sled tests (20 g, 80 ms sled acceleration pulse) performed with post mortem human surrogates (PMHS). Three PMHS were tested with a 3-point belt restraint with a progressive (two-stage) force limiting and pretensioning retractor in a sled buck representing the rear seat occupant environment of a 2004 mid-sized sedan.
Technical Paper

Impact Response of Restrained PMHS in Frontal Sled Tests: Skeletal Deformation Patterns Under Seat Belt Loading

2009-11-02
2009-22-0001
This study evaluated the response of restrained post-mortem human subjects (PMHS) in 40 km/h frontal sled tests. Eight male PMHS were restrained on a rigid planar seat by a custom 3-point shoulder and lap belt. A video motion tracking system measured three-dimensional trajectories of multiple skeletal sites on the torso allowing quantification of ribcage deformation. Anterior and superior displacement of the lower ribcage may have contributed to sternal fractures occurring early in the event, at displacement levels below those typically considered injurious, suggesting that fracture risk is not fully described by traditional definitions of chest deformation. The methodology presented here produced novel kinematic data that will be useful in developing biofidelic human models.
Journal Article

Preliminary Evaluation Methodology in Front-Front Vehicle Compatibility

2008-04-14
2008-01-0814
The injury outcome of a front-front two-vehicle crash will be a function of crash-specific, vehicle-specific, and occupant-specific parameters. This paper focuses on a preliminary methodology that was used to evaluate the potential for benefits in making vehicle-specific changes to improve the compatibility of light vehicles across the fleet. In particular, the effect on injury rates of matching vehicle frontal stiffness was estimated. The front-front crash data for belted drivers in the lighter vehicles in the crash from ten years of NASS-CDS data were examined. The frontal stiffness of each vehicle was calculated using data taken during full frontal rigid barrier tests for the U.S. New Car Assessment Program (NCAP), and only crashes coded in the CDS as “no override” were considered.
Technical Paper

Simulator Study of Heavy Truck Air Disc Brake Effectiveness During Emergency Braking

2008-04-14
2008-01-1498
In crashes between heavy trucks and light vehicles, most of the fatalities are the occupants of the light vehicle. A reduction in heavy truck stopping distance should lead to a reduction in the number of crashes, the severity of crashes, and consequently the numbers of fatalities and injuries. This study made use of the National Advanced Driving Simulator (NADS). NADS is a full immersion driving simulator used to study driver behavior as well as driver-vehicle reactions and responses. The vehicle dynamics model of the existing heavy truck on NADS had been modified with the creation of two additional brake models. The first was a modified S-cam (larger drums and shoes) and the second was an air-actuated disc brake system. A sample of 108 CDL-licensed drivers was split evenly among the simulations using each of the three braking systems. The drivers were presented with four different emergency stopping situations.
Journal Article

Pedestrian Lower Extremity Response and Injury: A Small Sedan vs. A Large Sport Utility Vehicle

2008-04-14
2008-01-1245
Vehicle front-end geometry and stiffness characteristics have been shown to influence pedestrian lower extremity response and injury patterns. The goal of this study is to compare the lower extremity response and injuries of post mortem human surrogates (PMHS) tested in full-scale vehicle-pedestrian impact experiments with a small sedan and a large sport utility vehicle (SUV). The pelves and lower limbs of six PMHS were instrumented with six-degree-of-freedom instrumentation packages. The PMHS were then positioned laterally in mid-stance gait and subjected to vehicle impact at 40 km/h with either a small sedan (n=3) or a large SUV (n=3). Detailed descriptions of the pelvic and lower extremity injuries are presented in conjunction with global and local kinematics data and high speed video images. Injured PMHS knee joints reached peak lateral bending angles between 25 and 85 degrees (exceeding published injury criteria) at bending rates between 1.1 deg/ms and 3.7 deg/ms.
Technical Paper

Development and Design of Thor-Lx: The Thor Lower Extremity

1999-10-10
99SC09
A new lower extremity has been developed to be used with Thor, the NHTSA Advanced Frontal Dummy. The new lower extremity, known as Thor-Lx, consists of the femur, tibia, ankle joints, foot, a representation of the Achilles' tendon and the associated flash/skins, it has been designed to improve biomechanical response under axial loading of the femur during knee impacts, axial loading of the tibia, static and dynamic dorsiflexion, static plantarflexion and inversion/aversion. Instrumentation includes a standard Hybrid ill femur load cell, accelerometers, load cells, and rotary potentiometers to capture relevant kinematic and dynamic information from the foot and tibia. The design also allows the Tnor-Lx to be attached to the Hybrid III, either at the hip, or at the knee.
Technical Paper

Closed Loop Steering System Model for the National Advanced Driving Simulator

2004-03-08
2004-01-1072
This paper presents the details of the model for the physical steering system used on the National Advanced Driving Simulator. The system is basically a hardware-in-the-loop (steering feedback motor and controls) steering system coupled with the core vehicle dynamics of the simulator. The system's torque control uses cascaded position and velocity feedback and is controlled to provide steering feedback with variable stiffness and dynamic properties. The reference model, which calculates the desired value of the torque, is made of power steering torque, damping function torque, torque from tires, locking limit torque, and driver input torque. The model also provides a unique steering dead-band function that is important for on-center feel. A Simulink model of the hardware/software is presented and analysis of the simulator steering system is provided.
Technical Paper

Experimental Steering Feel Performance Measures

2004-03-08
2004-01-1074
This paper discusses techniques for estimating steering feel performance measures for on-center and off-center driving. Weave tests at different speeds are used to get on-center performances for a 1994 Ford Taurus, a 1998 Chevrolet Malibu, and a 1997 Jeep Cherokee. New concepts analyzing weave tests are added, specifically, the difference of the upper and lower curves of the hysteresis and their relevance to driver load feel. For the 1997 Jeep Cherokee, additional tests were done to determine steering on-center transition properties, steering flick tests, and the transfer function of handwheel torque feel to handwheel steering input. This transfer function provides steering system stiffness in the frequency domain. The frequency domain analysis is found to be a unique approach for characterizing handwheel feel, in that it provides a steering feel up to maximum steering rate possible by the drivers.
Technical Paper

NHTSA's Frontal Offset Research Program

2004-03-08
2004-01-1169
The National Highway Traffic Safety Administration (NHTSA) is conducting a research program to investigate the use of the 40 percent offset deformable barrier (ODB) crash test procedure to reduce death and injury, in particular debilitating lower extremity injuries in frontal offset collisions. This paper presents the results of 22 ODB crash tests conducted with 50th percentile male and 5th percentile female Hybrid III (HIII) dummies fitted with advanced lower legs, Thor-Lx/HIIIr and Thor-FLx/HIIIr, to assess the potential for debilitating and costly lower limb injuries. This paper also begins to investigate the implications that the ODB test procedure may have for fleet compatibility by evaluating the results from vehicle-to-vehicle crash tests.
Technical Paper

Response Corridors of Human Surrogates in Lateral Impacts

2002-11-11
2002-22-0017
Thirty-six lateral PMHS sled tests were performed at 6.7 or 8.9 m/s, under rigid or padded loading conditions and with a variety of impact surface geometries. Forces between the simulated vehicle environment and the thorax, abdomen, and pelvis, as well as torso deflections and various accelerations were measured and scaled to the average male. Mean ± one standard deviation corridors were calculated. PMHS response corridors for force, torso deflection and acceleration were developed. The offset test condition, when partnered with the flat wall condition, forms the basis of a robust battery of tests that can be used to evaluate how an ATD interacts with its environment, and how body regions within the ATD interact with each other.
Technical Paper

Development of THOR-FLx: A Biofidelic Lower Extremity for Use with 5th Percentile Female Crash Test Dummies

2002-11-11
2002-22-0014
A new lower leg/ankle/foot system has been designed and fabricated to assess the potential for lower limb injuries to small females in the automotive crash environment. The new lower extremity can be retrofitted at present to the distal femur of the 5th percentile female Hybrid III dummy. Future plans are for integration of this design into the 5th percentile female THOR dummy now under development. The anthropometry of the lower leg and foot is based mainly on data developed by Robbins for the 5th percentile female, while the biomechanical response requirements are based upon scaling of 50th percentile male THOR-Lx responses. The design consists of the knee, tibia, ankle joints, foot, a representation of the Achilles tendon, and associated flesh/skins. The new lower extremity, known as THOR-FLx, is designed to be biofidelic under dynamic axial loading of the tibia, static and dynamic dorsiflexion, static plantarflexion and inversion/eversion.
Technical Paper

Development of a New Biofidelity Ranking System for Anthropomorphic Test Devices

2002-11-11
2002-22-0024
A new biofidelity assessment system is being developed and applied to three side impact dummies: the WorldSID-α, the ES-2 and the SID-HIII. This system quantifies (1) the ability of a dummy to load a vehicle as a cadaver does, “External Biofidelity,” and (2) the ability of a dummy to replicate those cadaver responses that best predict injury potential, “Internal Biofidelity.” The ranking system uses cadaver and dummy responses from head drop tests, thorax and shoulder pendulum tests, and whole body sled tests. Each test condition is assigned a weight factor based on the number of human subjects tested to form the biomechanical response corridor and how well the biofidelity tests represent FMVSS 214, side NCAP (SNCAP) and FMVSS 201 Pole crash environments.
Technical Paper

On the Development of the SIMon Finite Element Head Model

2003-10-27
2003-22-0007
The SIMon (Simulated Injury Monitor) software package is being developed to advance the interpretation of injury mechanisms based on kinematic and kinetic data measured in the advanced anthropomorphic test dummy (AATD) and applying the measured dummy response to the human mathematical models imbedded in SIMon. The human finite element head model (FEHM) within the SIMon environment is presented in this paper. Three-dimensional head kinematic data in the form of either a nine accelerometer array or three linear CG head accelerations combined with three angular velocities serves as an input to the model. Three injury metrics are calculated: Cumulative strain damage measure (CSDM) – a correlate for diffuse axonal injury (DAI); Dilatational damage measure (DDM) – to estimate the potential for contusions; and Relative motion damage measure (RMDM) – a correlate for acute subdural hematoma (ASDH).
Technical Paper

Development of Side Impact Thoracic Injury Criteria and Their Application to the Modified ES-2 Dummy with Rib Extensions (ES-2re)

2003-10-27
2003-22-0010
Forty-two side impact cadaver sled tests were conducted at 24 and 32 km/h impact speeds into rigid and padded walls. The post-mortem human subjects were instrumented with accelerometers on the ribs and spine and chest bands around the thorax and abdomen to characterize their mechanical response during the impact. Load cells at the wall measured the impact force at the level of the thorax, abdomen, pelvis, and lower extremities. The resulting injuries were determined through detailed autopsy and radiography. Rib fractures with or without associated hemo/pneumo thorax or flail chest were the most common injury with severity ranging from AIS=0 to 5. Full and half thorax deflections were computed from the chest band data. The cadaver test data was analyzed using ANOVA and logistic regression. The age of the subject at the time of death had influence on injury outcome while gender and mass of the subject had little or no influence on injury outcome.
Technical Paper

Design and Development of a Thor-Based Small Female Crash Test Dummy

2003-10-27
2003-22-0024
This paper describes the design and development of a small female crash test dummy, results of biofidelity tests, and preliminary results from full-scale, 3-point belt and airbag type sled tests. The small female THOR was designed using the anthropometric data developed by Robbins for the 5th percentile female and biomechanical requirements derived from scaling the responses of the 50th percentile male. While many of the mechanical components of the NHTSA THOR 50th percentile male dummy were scaled according to the appropriate anthropometric data, a number of improved design features have been introduced in the new female THOR. These include; improved neck design, new designs for the head and neck skins: and new designs for the upper and lower abdomen. The lower leg, ankle and foot, known as THOR-FLx, were developed in an earlier effort and have been included as a standard part of the new female dummy.
Technical Paper

Biomechanical Responses of PMHS Subjected to Abdominal Seatbelt Loading

2016-11-07
2016-22-0004
Past studies have found that a pressure based injury risk function was the best predictor of liver injuries due to blunt impacts. In an effort to expand upon these findings, this study investigated the biomechanical responses of the abdomen of post mortem human surrogates (PMHS) to high-speed seatbelt loading and developed external response targets in conjunction with proposing an abdominal injury criterion. A total of seven unembalmed PMHS, with an average mass and stature of 71 kg and 174 cm respectively were subjected to belt loading using a seatbelt pull mechanism, with the PMHS seated upright in a free-back configuration. A pneumatic piston pulled a seatbelt into the abdomen at the level of the umbilicus with a nominal peak penetration speed of 4.0 m/s. Pressure transducers were placed in the re-pressurized abdominal vasculature, including the inferior vena cava (IVC) and abdominal aorta, to measure internal pressure variation during the event.
Technical Paper

The Large Omnidirectional Child (LODC) ATD: Biofidelity Comparison with the Hybrid III 10 Year Old

2016-11-07
2016-22-0017
When the Hybrid III 10-year old (HIII-10C) anthropomorphic test device (ATD) was adopted into Code of Federal Regulations (CFR) 49 Part 572 as the best available tool for evaluating large belt-positioning booster seats in Federal Motor Vehicle Safety Standard (FMVSS) No. 213, NHTSA stated that research activities would continue to improve the performance of the HIII-10C to address biofidelity concerns. A significant part of this effort has been NHTSA’s in-house development of the Large Omnidirectional Child (LODC) ATD. This prototype ATD is comprised of (1) a head with pediatric mass properties, (2) a neck that produces head lag with Z-axis rotation at the atlanto-occipital joint, (3) a flexible thoracic spine, (4) multi-point thoracic deflection measurement capability, (5) skeletal anthropometry representative of a seated child, and (6) an abdomen that can directly measure belt loading.
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