Restraint Systems and Seat Belts

Our experts have participated in many cases involving Restraints and Seat Belts.

 

Related Papers and Presentations

Mitigation of Head and Neck Trauma, ASME Biomechanics of Trauma Conference
 
In conjunction with its development of high performance air bags for small cars in the early 1970's, Minicars, Inc. attempted to provide truly passive protection in all accident modes. The passive interior concept was epitomized in the design for NHTSA of the Minicars Research Safety Vehicle (RSV) (1, 2), the Large Research Safety Vehicle (3), then applied to the Chevrolet Citation in the Modified Production
Vehicle program (MIV) (4) and incorporated and publicized to some extent in General Motors X and J cars (5) in the late 70's and early 80's.

The extent to which the initial implementation of passive interiors could be expanded and its effectiveness in reducing AIS 4 to 6 injuries increased has been the subject of a seven year Research effort using real world injury accident case data, NHTSA and other published research results, manufacturer's crash test data and computer simulations and analysis. The analytical protocol was previously described in reference. The present paper describes and summarizes the effectiveness of passive interior modifications in mitigating head and neck injuries in frontal, side and rollover accidents as well as in helmets. One case in each accident mode are discussed with and without alternative restraints, comparing the injuries to the manufacturer's as-built test results and the injuries which would have resulted in  improved passive interior components had been installed.

Frontal Offset and Angled Impact Passive Protection, Society of Automotive Engineers (SAE) International Congress
 
ABSTRACT

Occupant protection in offset and strongly angled frontal impacts represents a crash mode in which a significant number of severe and fatal injuries occur each year in the United States. To date, no United States auto manufacturers have acknowledged dealing with or addressing the problem. The following discussion provides an overview literature review, describing the recognition by researchers for more than 20 years that this impact configuration represents a significant and foreseeable accident situation.
Following a discussion of the literature review, a brief overview of the frequency of occurrence is      provided, followed by an example of cases studies, and a description of the countermeasure analysis for a selected case. A discussion of the countermeasures we have generally found to be applicable is then provided. Conclusions and recommendations follow.

Restraint Effectiveness During Rollover Motion, International Research Council on Biomechanics of Impact Conference


ABSTRACT
 
A large number of restrained occupants of vehicles in the United State suffer severe head and neck injuries during rollover accidents. Occupant protection in rollover impacts can be provided through the use of many components, one of which is the restraint system. The ability of various restraint systems to control occupant kinematics and keep occupant heads away from potential injurious loading conditions is important in providing protection to restrained occupants in rollover impacts. An experimental study was conducted to assess the ability various restraints to control human volunteer vertical motions.

Improved Vehicle Design for the Prevention of Head and Neck Injuries to Restrained Occupants In Rollover Accidents, International Enhanced Vehicle Safety (ESV) Conference

ABSTRACT

We analyzed the 1988 through 1992 NASS field accident data on rollover and injuries to occupants in these crashes. The data show that more than 96 percent of all occupants in rollovers do not receive serious head or neck injuries. The authors discuss why most restrained occupants do not suffer serious head or neck injuries in rollovers and how that helps us understand the injuries that do occur. Based on those data, the authors further developed the rollover injury parameter "residual headroom" to identify the likelihood of severe head/face or neck injury and the vehicle design measures that can mitigate those injuries. A theory of rollover head and neck injury causation is proposed that is supported by all available evidence and observations. In particular, we will discuss how minor modifications of the roof structure and occupant protection systems of most contemporary passenger cars, light trucks and vans can prevent severe injuries in rollovers.

The Ability of 3 Point Safety Belts to Restrain Occupants in Rollover Crashes, International Enhanced Safety Vehicle (ESV) Conference

ABSTRACT

Three point safety belts are intended to restrain front seat occupants in motor vehicle crashes. Their purpose is to reduce the severity of occupant collisions with the interior of a vehicle and thus to reduce occupant injury. Manufacturers and the government test occupant protection in frontal collisions both for compliance with federal requirements and under a federal consumer information program. No consensus exists for a test of the ability of seat belts to prevent harmful contact with the roof and roof structure of vehicles. This paper describes simple test procedure and provides data from tests of some common production safety belt systems. These tests demonstrate that most of the production belts place the head and neck in potentially injurious positions in a rollover. These tests also show that simple geometric improvements could provide substantial head and neck protection in rollover crashes.

Human Drop Tests of Restrained Occupants in a Small Passenger Car Compartment, ASME Conference

ABSTRACT

The paper describes experiments involving restrained human volunteer tests in drop tests involving velocities up to 4.2 meters/sec. The effect of roof crush on restrained occupants has often been discussed without regard to the headroom available, effectiveness of belts, and location of roof crush.
In this paper the question of the ability to protect a simply restrained occupant in an environment in which the roof does not crush is addressed.
The results show that, with an effectively designed occupant rollover protection system, restrained occupants of various sizes do not experience serious injurious neck injuries without roof crush.

An Investigation of Hybrid III and Living Human Drop Tests, Critical Review in Biomedical Engineering

ABSTRACT 

The effect of roof crush on restrained occupants has often been discussed without regard to the headroom available, effectiveness of belts, and location of roof crush. In this article, the question of the ability to protect a simply restrained occupant in an environment in which the roof does not crush is addressed. The subjects were inverted and dropped vertically in no crushable production vehicle compartments and a specially designed drop fixture. Data collected includes head accelerations, vehicle accelerations, head displacements, belt angles, anchor point location, seat position, and belt tension for a variety of occupant sizes. To our knowledge, these are the first inverted living human vertical studies to be scientifically documented and reported. It was found that no head or neck injuries resulted from drops of up to 91 cm and velocities up to 4.2 m/sec for restrained occupants in the absence of roof crush.

Experimental Comparison of Inverted Dummy and Living Human Drop Tests, ASME Summer Bioengineering Conference

This study was conducted to evaluate the potential for neck injury when restrained, inverted living humans are dropped vertically in non-crushable production vehicle compartments and in a specially designed drop fixture. The drop fixture arid the subjects were instrumented in some of the tests and standard and high speed video cameras were used to record the motion of the subjects.

Two questions were of interest. The first was whether an effectively restrained occupant with adequate headroom can avoid serious neck injury in the absence of roof crush when dropped from heights up to 9lcm. The second was whether an effectively restrained occupant whose head is on a non-deforming roof need sustain serious neck injury when dropped from height up to 30.5cm.

Experimental Investigation and Finite Element Analysis of Vehicle Restraint Systems, ASME Summer Bioengineering Conference

ABSTRACT

This study was conducted to develop a finite element model of a Type-1 buckle. The model was used to evaluate the unlatching sensitivity  of the buckle to various interface materials, webbing tensions and spring strengths. Various force and acceleration input pulses were used. The studies demonstrate the finite element model can predict buckle unlatching under various conditions.

Biomechanical Simulation for Evaluation of Alternative Rollover Occupant Protection Systems Designs, IASTED Biomedical Engineering 2005

ABSTRACT

The evaluation of the biomechanical performance that can be expected from alternative designs for restrained occupant rollover protection was approached through the use of finite element modeling. Finite element models o vehicle designs and the Hybrid III dummy were used to evaluate elements of alternative rollover occupant protection system designs. Results from rollover crash tests of a production vehicle were used to validate the baseline models. The alternative designs were then incorporated into the vehicle designs and comparisons of various biomechanical injury measurements of the neck were made.

Restrained Occupant Protection Performance Under Rollover Conditions Using an Intelligent Rollover Protection Subsystem, International Crashworthiness (ICRASH) Conference

ABSTRACT

The evaluation of the biomechanical performance that can be expected by restrained occupants from the incorporation of an intelligent rollover protection subsystem (IRPS) into a production vehicle has been conducted. This paper reports on the evaluation of such a system based on finite element modeling. Finite element models of vehicle designs and the Hybrid III dummy were used to evaluate the subsystem under manufacturer created rollover conditions for a production roof structure. Results from a rollover crash test of a production vehicle were utilized to validate the model using the production vehicle crash test. The IRPS design was then integrated with the production vehicle and the results compared with the baseline neck biomechanical injury measures. Neck loads were utilized to validate the model against the test results. The results of the study show that the IRPS resulted in substantial reduction of neck loads with the production roof and even greater reductions with a strengthened roof. The results illustrate opportunities available to improve rollover crashworthiness performance for restrained occupants.

Biomechanics of Side Impact Injuries: Evaluation of Seat Belt Restraint System, Occupant Kinematics and Injury Potential, IEEE Engineering in Medicine and Biology Society

ABSTRACT

Side impact crashes arc the second most severe motor vehicle accidents resulting in serious and fatal injuries. One of the occupant restraint systems in the vehicle is the three point lap/shoulder harness. However, the lap/shoulder restraint is not effective in a far-side crash (impact is opposite to the occupant location) since the occupant may slip out of the shoulder harness. The present comprehensive study was designed to delineate the biomechanics of far-side planar crasher. The first part of the study invokes a car-to-ear crash to study the crash dynamics and occupant kinematics; the second part involves an epidemiological analysis of NASS/CDS 1988-2003 database to study the distribution of serious injury; the third part includes the mathematical MADYMO analysis to study the occupant kinematics in detail; and the fourth part includes m in-depth analysis of a real world far-side accident to delineate the injury mechanism and occupant kinematics. Results indicate that the shoulder harness is ineffective in far side crashes. The upper torso of the belted driver dummy slips out of the shoulder harness and interacted with the opposite vehicle interior such as the door panel. The unbelted occupants had a similar head injury severity pattern compared to belted occupants. The present study is another step to advance towards better understanding of the prevention, treatment and rehabilitation of side impact injuries.

Restrained Occupant Protection Performance Under Rollover Conditions Using an Intelligent Rollover Protection Subsystem, International Journal of Crashworthiness

ABSTRACT

The evaluation of the biomechanical performance that can be expected by restrained occupants from the incorporation of an intelligent rollover protection subsystem (IRPS) into a production vehicle has been conducted. This paper reports on the evaluation of such a system based on finite element modeling. Finite element models of vehicle designs and the Hybrid III dummy were used to evaluate the subsystem under manufacturer-created rollover conditions for a production roof structure. Results from a rollover crash test of a production vehicle were utilized to validate the model, using the production vehicle crash test. The IRPS design was then integrated with the production vehicle and the results were compared with the baseline neck biomechanical injury measures. Neck loads were utilized to validate the model against the test results. The results of the study show that the IRPS resulted in substantial reduction of head and neck loads with the production roof and even greater reductions with a strengthened roof. The results illustrate opportunities available to improve rollover crashworthiness performance for restrained occupants.

Biomechanical Evaluation of a Rollover Occupant Protection Subsystem, 21st International Society of Biomechanics

The biomechanical performance of an intelligent rollover protection subsystem (IRPS) under previously published rollover impact conditions using a Hybrid III dummy is compared with that obtained from the baseline restraint system utilized in the same rollover impact conditions. The effect of improved roof strength on IRPS is also addressed.

Biomechanical Considerations in Automotive Rollover Accidents: Occupant Kinematics and Vehicular Restraint System, Annual Biomedical Engineering Society Conference

In rollover accidents, a better understating of occupant kinematics assists to advance biomechanical knowledge and to enhance the safety features in motor vehicles. The purpose of the study is to quantify and compare the occupant kinematics such as vertical head excursion in a simulated rollover accident under two restraint systems. The production restraint system included a fixed shoulder harness with a raised lap belt. The modified restraint system included the lowering of shoulder harness attachment and lowering the height of buckle towards the floor, and the use of hyper tensioner as an outboard attachment point. The hyper tensioner was used to increase the tension to move the occupant closer to the floor. Laboratory dynamic rollover test equipment was used to simulate the rollover environment in a controlled manner. Two human surrogate models with different anthropometric characteristics were used. The surrogate model was placed on the platform of the test equipment and rotated to 180 degrees quasi-statically and dynamically up to 147 degrees/second. A total of ten tests were conducted. The vertical occupant head excursion was measured using video cameras. Results show that the modified restraint system significant reduction of occupant movement with a proposed modification in restraint system assists to better protect occupants in rollover accidents.

Biomechanical Analysis of Child Restraint System, Rocky Mountain Bioengineering Symposium & International ISA Biomedical Sciences Instrumentation Symposium

ABSTRACT

The purpose of the study is to test the hypothesis that potential for the head injury to child occupants is reduced with energy absorbing foam in a rear facing restraint system. The traffic safety of the pediatric population is improved with the child restraint system. However, the child restraint is effective only if advanced protective features are incorporated. One of the protective features is the energy absorbing padding on the side wings of the child seat wherein the child would interact during the crash. A hybrid computer model of the child restraint system was developed using the commercially available MADYMO and LS-DYNA software. A rear facing child seat in the rear compartment of the vehicle was simulated. The 9 months old anthropometric dummy was modeled. The dummy was restrained in the child seat and the child seat was restrained using the lap and shoulder harness. Two computer models with and without the padding on the side wing were simulated. The input included the acceleration at the center of gravity of the vehicle and the door intrusion into the vehicular interior and the child restraint system. Results indicate that the lack of padding allowed the child’s head to interact with the side wing in a concentrated manner while the padding allowed distributed contact to the head area. The padding also retained the head within the confines of the child seat with no exposure to outside environment. The head injury parameters (Head Injury Criteria and Angular Acceleration) were reduced two to three times due to padding on the extended side wing. The present study is an additional step towards a better understanding of the injury biomechanics of pediatric population involved in motor vehicle crashes.

Finite Element Modeling of Restrained Occupant Partial Ejection Under Rollover Conditions, International Crashworthiness (ICRASH) Conference

ABSTRACT

Rollover fatalities and serious injuries represent a large portion of the harm occurring in traffic accidents in the United States.  Restrained occupants whose heads are reported partially ejected have a much worse outcome than those whose heads are not partially ejected.  Prevention of partial ejection represents a significant objective in automotive design.   In this study two methods were investigated involving an empirical methodology and a finite element model methodology.  A finite element model of a production vehicle is utilized under rollover impact conditions in conjunction with a restrained occupant characterized by a Hybrid III dummy.  The properties of the model are compared with human volunteer characteristics in the production vehicle. The restrained occupant model is then utilized under rollover impact conditions with the baseline production vehicle and modified versions of the roof structure.  Comparison of the results associated with the empirical method and finite element method is provided as are the results of the effects of the modified roof structure on partial ejection.

Examination of the Ability of Conceptual Airbag Systems to Affect Restrained Occupant Kinematics and Associated Neck Loads During Rollover Impact Conditions, ASME International Mechanical Engineering Congress

ABSTRACT

Rollover occupant protection systems consist of many design elements such as various seat belt types, airbags, active and passive seats, and deployable systems in rollover impacts. In this study conceptual airbag systems intended to modify occupant kinematics were examined. The potential effects of these systems on occupant neck loads were evaluated. Finite element models of an LTV type vehicle and a 50th percentile dummy were utilized to evaluate the effects of alternative designs on neck loads under example rollover conditions. CAE representations of deployable airbag system types were created. Results of the study are summarized below.

Finite-Element Modelling of Restrained Occupant Partial Ejection Under Rollover Conditions, International Journal of Crashworthiness

ABSTRACT

Rollover fatalities and serious injuries represent a large portion of the harm occurring in traffic accidents in the United States.  Restrained occupants whose heads are reported partially ejected have a much worse outcome than those whose heads are not partially ejected. Prevention of partial ejection represents a significant objective in automotive design.  In this study two methods were investigated involving an empirical methodology and a finite element model methodology.  A finite element model of a production vehicle is utilized under rollover impact conditions in conjunction with a restrained occupant characterized by a Hybrid III dummy. The properties of the model are compared with human volunteer characteristics in the production vehicle.  The restrained occupant model is then utilized under rollover impact conditions with the baseline production vehicle and modified versions of the roof structure.  Comparison of the results associated with the empirical method and finite element method is provided as are the results of the effects of the modified roof structure on partial ejection.

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