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Technical Paper

Vehicle-to-Vehicle Frontal Impacts: 2D Numerical Study

A 2D model for vehicle-to-vehicle impact analysis that was presented in an earlier paper [1], has been used to study several two-vehicle frontal impacts with different incidence angles, frontal overlap offsets, and mass ratios. The impacts have been evaluated in terms of energy and momentum change in the bullet vehicle and the target vehicle. Based on comparisons between pre- and post-impact longitudinal, lateral, and angular components of kinetic energy, and linear and angular momenta, the impacts experienced by the target vehicle and the bullet vehicle have been classified as collinear or oblique. These results have been used to propose a definition of frontal impact based on vehicle kinematics during a crash.
Technical Paper

The Influence of Superficial Soft Tissues and Restraint Condition on Thoracic Skeletal Injury Prediction

The purpose of this study is to evaluate the hard tissue injury -predictive value of various thoracic injury criteria when the restraint conditions are varied. Ten right-front passenger human cadaver sled tests are presented, all of which were performed at 48 km/h with nominally identical sled deceleration pulses. Restraint conditions evaluated are 1) force-limiting belt and depowered airbag (4 tests), 2) non-depowered airbag with no torso belt (3 tests), and 3) standard belt and depowered airbag (3 tests). Externally measured chest compression is shown to correspond well with the pre sence of hard tissue injury, regardless of restraint condition, and rib fracture onset is found to occur at approximately 25% chest compression. Peak acceleration and the average spinal acceleration measured at the first and eighth or ninth thoracic vertebrae are shown to be unrelated to the presence of injury, though clear variations in peaks and time histories among restraint conditions can be seen.
Technical Paper

Technical Specifications of the SID-IIs Dummy

The SID-IIs is a small [s], second-generation [II] Side Impact Dummy [SID] which has the anthropometry of a 5th percentile adult female. It has a mass of 43.5 kg, a seated height of 790 mm, and over 100 available data channels. Based on the height and mass, this is equivalent to an average 12-13 year old adolescent. The state-of-the-art SID-IIs has special application in evaluating the performance of side impact airbags. The dummy has undergone prototype testing and will shortly be available for worldwide evaluation. This paper describes the technical details of the dummy, its biomechanical design targets, how well it met those targets, its validation requirements, and its instrumentation. The dummy is the product of a joint development agreement between the Occupant Safety Research Partnership (OSRP) of USCAR and First Technology Safety Systems.
Technical Paper

Reinventing Safety Systems: Roadblocks; Organizational Structure, Data Analysis Bias, and Systems Integration

The automotive environment, within which original equipment manufacturers (OEM's) design, develop, and produce safety initiatives is fluid in light of regulatory and non-regulatory safety initiatives, and other competitive market realities. As current passive safety systems are being refined and expanded to include the general population, active safety systems covering accident avoidance are presenting a “new frontier” for engineers to explore. Other competitive hurdles include cost, weight, quality, and customer acceptance criteria. To effectively address this complexity, OEM's must completely reinvent safety system design and development processes. Specifically this paper outlines safety system design and development roadblocks encountered due to organizational structure, data analysis bias, and the need for component system integration.
Technical Paper

OOP Response of THOR and Hybrid-III 50th% ATDs

The responses of the THOR and the Hybrid-III ATDs to head and neck loading due to a deploying air bag were investigated. Matched pair tests were conducted to compare the responses of the two ATDs under similar loading conditions. The two 50th percentile male ATDs, in the driver as well as the passenger positions, were placed close to the air bag systems, in order to enhance the interaction between the deploying air bag and the chin-neck-jaw regions of the ATDs. Although both ATDs nominally meet the same calibration corridors, they differ significantly in their kinematic and dynamic responses to interaction with a deploying air bag. The difference between the structural designs of the Hybrid-III's and the THOR's neck appears to result in significant differences in the manner in which the loads applied on the head are resisted.
Technical Paper

Kinematic FCW System Modeling and Application for FCW Warning Strategy Evaluation

One method of reducing the number and/or severity of vehicle crashes is to warn the driver of a potential crash. The theory is that there will be driving conditions in which the drivers are unaware of a potential crash and a warning system will allow them to, in some manner, avoid the accident or reduce the severity. In an attempt to develop an analytical understanding of Forward Collision Warning systems (FCW) for frontal impacts a 2-d mathematical/kinematic model representing a set of pre-crash vehicle dynamic maneuvers has been built. Different driving scenarios are studied to explore the potential improvement of warning algorithms in terms of headway reduction and minimization of false alarm rates. The results agree with the field data. NHTSA's new NCAP active safety criteria are evaluated using the model. The result from the analysis indicates that the NHTSA criteria may drive higher false alarm rates. Opportunities of minimizing false positive rates are discussed.
Journal Article

Hybrid III Head/Neck Analysis Highlighting Nij in NCAP

Nij, a function of upper neck forces and moment, plays a dominant role in the vehicle's star rating under the new NHTSA NCAP front impact program. This is mainly due to an artifact in the mapping of the Nij into the “risk” value used in the star rating, and the fact that the neck region is not weighted appropriately to reflect its real world significance relative to the other body regions in the NCAP rating. New test data also show that compared with the 50th male driver Nij, the 5th female passenger Nij is significantly more challenging to contain and therefore it is more dominant in the star rating. This paper describes the Hybrid III dummy head and neck impact response and provides a method to determine the external force acting on the head. The force and its acting point on the head are determined from head acceleration, angular acceleration, and the upper neck forces.
Technical Paper

Hybrid III Dummy Neck Issues

While the Hybrid III anthropomorphic test device (ATD) family has experienced a lengthy period of development, and is an essential part of vehicle safety regulation, several issues associated with the ATD's head/neck design and the neck dynamic response due to airbag loading have been identified. As a result, the response of the Hybrid III neck under a number of airbag loading conditions could be an “artifact” of the ATD and not representative of the live human. One area of concern relates to the method of incorporating the human neck muscles into the neck response and how this affects the out-of-position (OOP) tests mandated in the new FMVSS 208. The results of a series of sled and OOP tests are presented in this paper to elaborate on the nature and the magnitude of the ATD's neck response “artifact”. In addition, the complication associated with balancing in-position and OOP requirements as a result of this “artifact” is highlighted.
Technical Paper


This paper discusses issues related to the Hybrid III dummy head/neck response due to deploying air bags. The primary issue is the occurrence of large moment at the occypital condyles of the dummy, when the head-rotation with respect to the torso is relatively small. The improbability of such an occurrence in humans is discussed in detail based on the available biomechanical data. A secondary issue is the different anthropometric characteristics of the head/neck region of the Hybrid III dummy when compared to humans. Different modes of interaction between the deploying air bag and the Hybrid III dummy’s neck are discussed. Key features of the dummy’s response in these interaction modes have been described in light of the laxity of the atlanto-occypital joint and the effect of the neck muscle pairs. Issues for improving the biofidelity of the Hybrid III dummy’s neck response due to deploying air bags are discussed.
Technical Paper

Extraction of Information From Noisy 3-Year-Old Atd Response Signals in Static Out-Of-Position Airbag Tests

This paper presents an approach to analyze experimental data contaminated with noise from Anthropomorphic Test Devices (ATDs). This approach is based on information extraction procedures and they are illustrated through an analysis of Hybrid III 3-year-old and Q3 ATDs test data. The methodology used for extracting information and ATD test data analysis includes optimized filtering, spectral coherence, auto- and cross-correlation analysis, and Kalman filtering. This work investigates promising techniques of extracting information from noisy ATD signals that are not commonly used in the automotive industry.
Technical Paper

Evaluation of the Hybrid III 10-year-Old Dummy Chest Response in the Sled Test Environment

Ten sled tests were conducted with a Hybrid III 10-year-old dummy under a 3-point belt only restraint condition to evaluate its performance. The results of the Hybrid III 10-year-old in these tests indicate that there are artifactural noise spikes observable in the transducer responses. A number of metal-to-metal contacts in the shoulder area were identified as one of the sources for the chest acceleration spikes. Noise spikes were also observed in the response from multiple body regions; however, the source of the spikes could not be determined. Compared to the other Hybrid III dummies, non-characteristic dummy chest deflection responses were also observed. This limited analysis indicates that the Hybrid III 10-year-old dummy requires additional development work to eliminate the metal-to-metal contacts in the shoulder area and to understand and correct the other sources of the noise spikes. More investigation is needed to determine if the chest deflection response is appropriate.
Technical Paper

Evaluation of the ES-2re Dummy in Biofidelity, Component, and Full Vehicle Crash Tests

This technical paper presents the results from tests conducted with the ES-2re, a version of the ES-2 side impact dummy that was modified by the National Highway Traffic Safety Administration (NHTSA) to improve its performance in crash tests. Through the series of biofidelity tests conducted on the ES-2re, described in International Standards Organization (ISO) Technical Report (TR)9790 (1999), the OSRP observed a final overall biofidelity ranking of 4.1 for the ES-2re, which corresponds to an ISO classification of “marginal.” The biofidelity of the ES-2re is compared to that of the ES-2 and the WorldSID. Repeatability was also evaluated on the ES-2re based on the biofidelity test data. Additional pendulum tests were performed to assess the response of the dummy in oblique loading conditions, and results indicate that oblique loading from the front leads to significantly reduced rib deflections.
Journal Article

Effects of Vehicle Mass and Other Parameters on Driver Relative Fatality Risk in Vehicle-Vehicle Crashes

Regression models are used to understand the relative fatality risk for drivers in front-front and front-left crashes. The field accident data used for the regressions were extracted by NHTSA from the FARS database for model years 2000-2007 vehicles in calendar years 2002-2008. Multiple logistic regressions are structured and carried out to model a log-linear relationship between risk ratio and the independent vehicle and driver parameters. For front-front crashes, the regression identifies mass ratio, belt use, and driver age as statistically significant parameters (p-values less than 1%) associated with the risk ratio. The vehicle type and presence of the ESC are found to be related with less statistical significance (p-values between 1% and 5%). For front-left crashes the driver risk ratio is also found to have a log-log linear relationship with vehicle mass ratio.
Journal Article

Effect of Operational Testing and Trim Manufacturing Process Variation on Head Injury Criterion in FMVSS 201 Tests

This paper analyzes the difference in impact response of the forehead of the Hybrid III and THOR-NT dummies in free motion headform tests when a dummy strikes the interior trim of a vehicle. Hybrid III dummy head is currently used in FMVSS201 tests. THOR-NT dummy head has been in development to replace Hybrid III head. The impact response of the forehead of both the Hybrid III dummy and THOR dummy was designed to the same human surrogate data. Therefore, when the forehead of either dummy is impacted with the same initial conditions, the acceleration response and consequently the head Injury criterion (HIC) should be similar. A number of manufacturing variables can affect the impacted interior trim panels. This work evaluates the effect of process variation on the response in the form of Head Injury Criterion (HIC).
Technical Paper

Effect of Airbag Porosity, Mass Flow and Load Limiter on the 5th and 50th Hybrid Dummies in a 35 Mph Crash

Restraint systems play an important role in managing the energy of occupants during a crash event. Belt and airbag systems complement each other in order to gradually decelerate the occupant. However, the seating position of the 5th percentile female and 50th percentile male occupants forces the need to manage this energy in different ways. MADYMO simulation of a generic vehicle-restraint system with a driver side 5th and a 50th percentile Hybrid III dummy were done for a typical frontal impact. The belt system had a retractor/load limiter, but no pretensioner. The effect of airbag fabric porosity, inflation rate and seat belt load limiting ability were evaluated for both occupants. Parameters examined that affect system rebalancing to achieve the highest star rating were HIC and 3ms Chest acceleration.
Technical Paper

Crash Test Pulses for Advanced Batteries

This paper reports a 2010 study undertaken to determine generic acceleration pulses for testing and evaluating advanced batteries for application in electric passenger vehicles. These were based on characterizing vehicle acceleration time histories from standard laboratory vehicle crash tests. Crash tested passenger vehicles in the United States vehicle fleet of the model years 2005-2009 were used. The crash test data were gathered from the following test modes and sources: 1 Frontal rigid flat barrier test at 35 mph (NHTSA NCAP) 2 Frontal 40% offset deformable barrier test at 40 mph (IIHS) 3 Side moving deformable barrier test at 38 mph (NHTSA side NCAP) 4 Side oblique pole test at 20 mph (US FMVSS 214/NHTSA side NCAP) 5 Rear 70% offset moving deformable barrier impact at 50 mph (US FMVSS 301). The accelerometers used were from locations in the vehicle where deformation is minor or non-existent, so that the acceleration represents the “rigid-body” motion of the vehicle.
Technical Paper

Comparison of Frontal Crashes in Terms of Average Acceleration

The paper presents a comparison between the acceleration pulses of vehicle-to-vehicle crash tests with those of different single-vehicle crash tests. The severity of the full frontal rigid barrier test is compared with that of the vehicle- to-vehicle crash test based on average acceleration and time-to-zero-velocity. Based on this a 30mph full frontal rigid barrier test is found equivalent to a 41mph vehicle-to-vehicle crash. A reduced speed of 22mph for full frontal rigid barrier test is found to represent vehicle-to- vehicle crashes with 50%-100% overlap, with each vehicle travelling at 30mph. The paper also presents a comparison of the acceleration pulses from different crash tests based on the pulse shape and the pulse phase cross-correlation. None of the single-vehicle crash tests have been found to resemble vehicle-to-vehicle crashes in terms of the pulse shape and the pulse phase.
Technical Paper

Comparison of Energy Management Materials for Head Impact Protection

Energy management materials are widely used in automotive interiors in instrument panel, knee bolster, and door absorber applications to reduce the risk of injury to an occupant during a crash. Automobile manufacturers must meet standards set by the National Highway Traffic Safety Administration (NHTSA) that identify maximum levels of injury to an occupant. The recent NHTSA upgrade to the Federal Motor Vehicle Safety Standard (FMVSS) 201 test procedure(1) for upper interior head impact protection has prompted energy management materials' use in several new areas of affected vehicles. While vehicle evaluations continue, results to date show that energy management foams can be effective in reducing the head injury criterion [HIC(d)] to acceptable government and OEM levels.
Technical Paper

Comparative Performance Evaluation of THOR and Hybrid III

A comparison of the NHTSA advanced dummy, THOR, and the Hybrid III dummy is presented in this paper, based on their performance in four vehicle barrier tests, six HYGE sled tests and twenty two pendulum chest–impact tests. Various time–histories pertaining to accelerations, angular motions, deflections, forces and moments are compared between the two dummies in light of their design difference. In general, in the vehicle crash tests, the resultant head acceleration and chest deflection in THOR are greater than those in the HYBRID III. The shear, axial force and lateral moment in THOR's lumbar are less than those in the Hybrid III in frontal impacts. The differences in the head/chest acceleration and chest deflection could be due to the differences in the construction of the neck and the thorax of the THOR when compared to those of the Hybrid III. The THOR and the Hybrid III have the same level of repeatability in the rear impact sled tests.
Journal Article

Assessment of Similarity of a Set of Impact Response Time Histories

Two methods of assessing the similarity of a set of impact test signals have been proposed and used in the literature, which are cumulative variance-based and cross correlation-based. In this study, a normalized formulation unites these two approaches by establishing a relationship between the normalized cumulative variance metric (v), an overall similarity metric, and the normalized magnitude similarity metric (m) and shape similarity metric (s): v=1 − m · s. Each of these ranges between 0 and 1 (for the practical case of signals acquired with the same polarity), and they are independent of the physical unit of measurement. Under generally satisfied conditions, the magnitude similarity m is independent of the relative time shifts among the signals in the set; while the shape similarity s is a function of these.