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Technical Paper

Load Path Considerations for Side Crash Compatibility

2007-04-16
2007-01-1176
Heavier, larger pickups and SUVs are bound to encounter lighter, smaller passenger vehicles in many future accidents. As the fleet has evolved to include more and more SUVs, their frontal structures are often indistinguishable from pickup fronts. Improvements in geometric compatibility features are crucial to further injury prevention progress in side impact. In corner crashes where modern bullet passenger car (PC) bumpers make appropriate geometrical overlap with target PC rocker panels, concentrated loads sometimes disrupt foam and plastic bumper corners, creating aggressive edges. In situations where sliding occurs along the structural interface, these sharp edges may slice through doors, panels and pillars. End treatments for such bumper beams should be designed to reduce this aggressive potential.
Technical Paper

Pulse Shape and Duration in Frontal Crashes

2007-04-16
2007-01-0724
Understanding of events within the history of a crash, and estimation of the severity of occupant interior collisions depend upon an accurate assessment of crash duration. Since this time duration is not measured independently in most crash test reports, it must usually be inferred from interpretations of acceleration data or from displacement data in high-speed film analysis. The significant physical effects related to the crash pulse are often essential in reconstruction analyses wherein the estimation of occupant interior “second collision” or airbag sensing issues are at issue. A simple relation is presented and examined which allows approximation of the approach phase and separation phase kinematics, including restitution and pulse width. Building upon previous work, this relation allows straightforward interpretation of test data from related publicly available test reports.
Technical Paper

Fatal and Severe Injuries in Rear Impact; Seat Stiffness in Recent Field Accident Data

2008-04-14
2008-01-0193
A decade ago, James, et.al. published a detailed study of the available NASS data on severe rear impacts, with findings that “… stiffened or rigid seat backs will not substantially mitigate severe and fatal injuries in rear impacts.” No field accident study has since been advanced which refutes this finding. Advocates of rigidized seat backs often point to specific cases of severe rear impacts in which MAIS 4+ injuries are associated with seat back deformation, coupled with arguments supporting stiffer seatback designs. These arguments are generally based upon laboratory experiments with dummies in normal seating positions. Recent field accident data shows that generally, in collisions where the majority of societal harm is created, yielding seats continue to provide benefits, including those associated with whiplash associated disorders (WAD).
Technical Paper

Derivation of Vehicle-to-Vehicle Frontal Crash Pulse Estimates from Barrier Crash Data

2008-04-14
2008-01-0174
The BSAN crash pulse model has been shown to provide useful information for restraint sensing evaluation and for structural force-displacement studies in flat fixed rigid barrier (FFRB) crashes. This paper demonstrates a procedure by which the model may be extended for use with central and offset vehicle to vehicle (VTV) crashes through appropriate combinations of vehicle parameters.
Technical Paper

Interrelationship of Velocity and Chest Compression in Blunt Thoracic Impact to Swine II

1986-10-27
861881
Results of two studies concerning the interrelationship of velocity, compression and injury in blunt thoracic impact to anesthetized swine have been combined to provide a data base of forty-one experiments. impact velocity ranged from ∼8-30 m/s and applied normalized chest compression from ∼0.10-0.30. Experimental subjects were suspended in the spine-horizontal position and loaded midsternally through a 150 mm diameter, flat rigid disk on an impacting mass propelled upward from below. Measurements and computations included sternal and spinal accelerations, intracardiovascular overpressures, physiological responses, injury, as assessed by necropsy, and different forms of the velocity and compression exposure severity parameters. The significance of both compression and velocity as parameters of impact exposure severity is clearly demonstrated. Qualitatively, exacerbation of injury was seen when either variable was increased with the other held constant.
Technical Paper

Crash Protection in Near-Side Impact - Advantages of a Supplemental Inflatable Restraint

1989-02-01
890602
Collision Safety Engineering, Inc. (CSE), has developed a test prototype system to protect occupants during lateral impacts. It is an inflatable system that offers the potential of improved protection from thoracic, abdominal and pelvic injury by moving an impact pad into the occupant early in the crash. Further, it shows promise for head and neck protection by deployment of a headbag that covers the major target areas of B-pillar, window space, and roofrail before head impact. Preliminary static and full-scale crash tests suggest the possibility of injury reduction in many real-world crashes, although much development work remains before the production viability of this concept can be established. A description of the system and its preliminary testing is preceded by an overview of side impact injury and comments on the recent NHTSA Rule Making notices dealing with side-impact injury.
Technical Paper

Crush Energy in Accident Reconstruction

1986-02-24
860371
Vehicle accident reconstruction methods based on deformation energy are argued to be an increasingly valuable tool to the accident reconstructionist, provided reliable data, reasonable analysis techniques, and sound engineering judgement accompany their use. The evolution of the CRASH model of vehicle structural response and its corresponding stiffness coefficients are reviewed. It is concluded that the deformation energy for an accident vehicle can be estimated using the CRASH model provided that test data specific to the accident vehicle is utilized. Published stiffness coefficients for vehicle size categories are generally not appropriate. For the purpose of estimating vehicle deformation energy, a straight-forward methodology is presented which consists of applying the results of staged crash tests. The process of translating crush profiles to estimates of vehicle deformation energies and velocities is also discussed.
Technical Paper

Roadway Asphalt Damage Force Analysis for Accident Reconstruction

2008-04-14
2008-01-0173
In reconstruction of on-roadway vehicle accidents, tire-road surface friction coefficient, mu (μ), can be estimated using a variety of available data. Common ranges and values for μ are used in calculations forming the foundation for most accident reconstruction techniques. When the roadway surface is gouged or disrupted by vehicle components, accounting of dissipated energy can be successful where supporting force data exists. Roadway gouge forces can vary widely depending upon such factors as road surface construction, surface temperature, and the velocity and geometry of the gouging mechanism. Such dissipated energy can be significant in accounting of total reconstruction energy. This paper presents experiments aimed at quantifying gouge force by controlled pavement gouging tests.
Technical Paper

Photogrammetry and Accident Reconstruction: Experimental Results

1994-03-01
940925
A controlled experiment involving road marks was conducted to compare various photogrammetry practices currently in use in the accident investigation community. The experimental controls and results are discussed for three variations of one 2-D scheme and for six 3-D photogrammetric schemes applied to a similar set of road marks and points. For measurements related to the most frequent issues in traffic accidents, all of the methods are capable of providing usable data. The experimental photographs and corresponding data represent a reference set for developing skills and for comparison with other photogrammetry schemes.
Technical Paper

Conservation of Momentum Analysis of Two-Dimensional Colliding Bodies, With or Without Trailers

1994-03-01
940566
This paper presents a method of automobile collision analysis based on conservation of momentum. The analysis is applied to the collision of two two-dimensional bodies, either or both of which may be attached to a trailer. Newton's laws of motion are employed to determine changes in linear and angular velocities for the two-dimensional colliding bodies. Knowing the masses and rotational inertias and the initial velocities of all bodies at impact, the post-impact velocities can be calculated if appropriate constraints are applied to the bodies' post-collision motion. Various motion constraints, including lock-up, slip, and restitution are examined, and a methodology for modeling vehicle motion experienced during a collision is presented. The full set of basic equations characterizing this conservation-of-momentum analysis is presented with sufficient detail to allow their implementation on a programmable calculator or personal computer.
Technical Paper

Lateral Load Sensing Hybrid III Head

1991-10-01
912908
Recent cadaver studies have provided data for the development of force and stiffness characteristics of the side of the human head. A Hybrid III Anthropomorphic Test Dummy (ATD) head was modified to allow direct measurement of impact forces on the parietal and temporal regions by recasting the upper left half of the skull and installing triaxial piezoelectric force transducers. Dynamic impact tests of this modified head were conducted and force/stiffness characteristics for the temporal and parietal areas were compared to existing data on cadaver subjects. It was found that the existing Hybrid III vinyl skin satisfactorily represents the force/stiffness characteristics of the human head in these areas. This modified Hybrid III dummy head was also impacted against typical interior components likely to be contacted during a side impact. The force and acceleration test results are presented.
Technical Paper

The Assessment of the Societal Benefit of Side Impact Protection

1990-02-01
900379
This paper summarizes work relating to the assessment of societal benefits of side impact protection. National Crash Severity Study (NCSS) and National Accident Sampling System (NASS) accident data technigues were reviewed with respect to the reliability of output information concerning the distribution of side impact accidents by impact severity and relationships between injury and impact severity. NCSS and NASS are confounded by errors and inadequacies, primarily as a result of improper accident reconstruction based upon the CRASH computer program. Based on review of several sample cases, it is believed that the NCSS/NASS files underestimate Lower severities and overestimate higher severities in side impact, with delta-V errors probably overestimated by 25-30 percent in the case of the more serious accidents. These errors cannot be properly quantified except on a case-by-case basis. They introduce unknown biases into NCSS/NASS.
Technical Paper

Application of Kinematic Concepts to Side Impact Injury Analysis

1990-02-01
900375
An understanding of fundamental kinematic relationships among the several deforming surfaces of side-impacting bullet and target vehicle, occupant protection system and occupant is fundamental to rational design of crash injury counter-measures. Unfortunately, such understanding is not easy to achieve. Side impacts address the full range of bodily contacts and injuries in a way that challenges analysis. Each bodily area and organ requires individual consideration for adequate injury protection. This paper presents a simplified graphical analysis of occupant kinematics and injury exposure applied specifically to the NHTSA-proposed crabbed moving deformable barrier (MDB) compartment impact, as described in NHTSA's Notice of Proposed Rulemaking (NPRM) for Federal Motor Vehicle Safety Standard (FMVSS) 214, issued in January of 1988 [NHTSA 1988 (1)*]. Projections are offered regarding the potential of thoracic injury counter-measures.
Technical Paper

A Perspective on Side Impact Occupant Crash Protection

1990-02-01
900373
The NHTSA notices of proposed rulemaking on side impact protection have focused worldwide attention on one of the most difficult and frustrating efforts in automobile crash safety. Traditional vehicle design has evolved obvious structural contrasts between the side of the struck vehicle and the front of the striking vehicle. Protection of near-side occupants from intruding door structure is a most perplexing engineering challenge. Much useful and insightful engineering work has been done in conjunction with NHTSA's proposed rulemaking. However, there are many major engineering issues which demand further definition before reasonable side impact rulemaking test criteria can be finalized. This paper reviews recent findings which characterize the human factors, biomechanics, and occupant position envelope of the typical side impact crash victim.
Technical Paper

Facial Impact Response — A Comparison of the Hybrid III Dummy and Human Cadaver

1988-10-01
881719
Results indicate the need for a redesigned Hybrid III face capable of accurate force and acceleration measurements. New instrumentation and methods for facial fracture detection were developed, including the application of acoustic emissions. Force/ deflection information for the human cadaver head and the Hybrid III ATD were generated for the frontal, zygomatic, and maxillary regions.
Technical Paper

Estimating Vehicle Deformation Energy for Vehicles Struck in the Side

1998-02-23
980215
The reconstruction of accidental impacts to the side structure of one or more accident vehicles often incorporates estimates of the energy absorbed by laterally struck vehicle(s). Such estimates generally involve considerably more issues than does the assessment of frontal or rear impact deformation energy. The sides of vehicles are, compared to the usual striking object, relatively broad, and they contain zones of varying stiffness supported by collapsible box structures. Side stiffnesses can vary widely, depending upon impact geometry. Most side impact crash tests that can readily be used to make estimates of side stiffness have been conducted by the National Highway Traffic Safety Administration (NHTSA).
Technical Paper

LIMITATIONS OF ATB/CVS AS AN ACCIDENT RECONSTRUCTION TOOL

1997-02-24
971045
Occupant simulation models have been used to study trends or specific design changes in “typical” accident modes such as frontal, side, rear, and rollover. This paper explores the usage of the Articulated Total Body Program (ATB) as an accident reconstruction tool. The importance of model validation is discussed. Specific areas of concern such as the contact model, force-deflection data, occupant parameters, restraint system models, head/neck loadings, padding, and intrusion are discussed in the context of accident reconstruction.
Technical Paper

Proportional Braking of Solid-Frame Vehicles

1971-02-01
710047
An engineering analysis of vehicle braking is presented in terms of the utilization of available road friction. Physical relations are derived which allow the determination of optimum brake force distribution on front and rear wheels as a function of axle loading. Ideal braking distribution curves are shown for a typical vehicle in the loaded and unloaded conditions. A technique is suggested for rational design of braking system parameters. It is applied to the case of a two-stage proportioning system, and is validated by experimental data from tests using a specially equipped light truck. It is concluded that a proper design analysis can establish a combination of braking system parameters which results in improved utilization of available friction. A simple, self-adjusting brake proportioning system can be a highly cost-effective safety device for truck use.
Technical Paper

Comparative Thoracic Impact Response of Living and Sacrificed Porcine Siblings

1977-02-01
770930
Thoracic impact response and injuries of living and postmortem porcine siblings were investigated to quantify comparative differences. Thirteen male animals, averaging 61.4 kg, from five different porcine litters comprised the two animal samples. Porcine brothers were subjected to similar impact exposures for which at least one brother was tested live, anesthetized and another dead, post rigor with vascular repressurization. Statistically significant differences in biomechanical responses and injuries were observed between live and postmortem siblings. On the average the anesthetized live animals demonstrated a greater thoracic compliance, as measured by increased normalized total deflections (21% Hi), and reduced overall injuries (AIS 14% Lo and rib fractures 26% Lo) at lower peak force levels (13% Lo) than did the postmortem subjects. However, individual comparisons of “match-tested” siblings demonstrated very similar responses in some cases.
Technical Paper

Design, Development and Testing of a Load-Sensing Crash Dummy Face

1984-02-01
840397
This project covers one facet of a program to develop a mechanical model for characterizing the time history of local forces on the zygomatic, maxillary and mandible regions of the human face during a frontal collision. Two mechanical devices to measure the forces on crash dummies during testing were designed, constructed and tested. The devices employed cantilever beams equipped with strain gauges. Both devices were subjected to a series of drop tests onto various materials. Time histories were compared to those obtained from cadaver experiments. While the data obtained from this testing appears to be similar to the cadaver data, further improvements and modifications will make the model much more useful.
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