Effectiveness Of Restraint Systems Research Articles

A two degrees of freedom model–based optimization method for occupant restraint systems in vehicle crash

This paper presents a two degrees of freedom model–based optimization method for occupant restraint systems (ORS), applied before the finite element analysis in a vehicle crash. The method considers the effects of restraint systems (seatbelt, airbag, seat, and knee baffle) on the occupant and establishes the analytical models of them. The method reveals the effect essence of the ORS and takes the occupant response as the target to optimize the restraint system parameters rapidly. The multi-rigid body model of a Toyota Camry vehicle is established to verify the validity and reliability of two degrees of freedom model (TDFM). Comparing the results of the two models, the trends of acceleration-time curves are consistent, and the 85% errors of occupant responses are within 20%. Then, the practicality and effectiveness of the optimization method are confirmed by the instance of Camry ORS. The errors of results solved by optimization and the MADYMO model are all less than 20%. The optimization method can be used to provide an initial parameter range for the finite element simulation to improve the efficiency of the traditional optimization process.

Road Restraint Systems as a Basis for Roadside Safety Improvement

Roadside-related crashes occur when vehicles run off the road. The majority of the crashes have severe outcomes, especially when an object is hit (tree, pole, supports, front wall of a culvert, barrier). These accidents represent app. 19% of all of Poland’s road deaths. Roadside crashes involve: hitting a tree, hitting a barrier, hitting a sign or utility pole, vehicle roll-over on the roadside, vehicle roll-over on a slope and vehicle roll-over into a ditch. Understanding the effects of roadside factors on road safety requires in-depth research. The problem was partly addressed at the WMCAUS conference in 2017 [1]. Key to understanding the needs and tools of road infrastructure management for preventing run-off-road crashes or minimising their consequences is to identify the hazards and sources of hazards caused by wrong or improper use of road safety devices. It is also important to identify errors in the design, structure, construction and operation of road safety devices. Studying such an extended scope of the problem required fieldwork. Site tests had to be conducted such as hitting a wire rope barrier and a steel barrier on curve (test TB32), light and heavy vehicles hitting a bridge parapet (tests TB11 and TB51), hitting a transition between a steel and wire rope barrier (TB32) and crashes into a lighting column placed within the barrier’s working width. In addition, the project includes numerical tests validated on the basis of site tests. This helps to assess the behaviour of road restraint systems when selected parameters are changed. The work is part of the RID Programme (Development of Road Innovation) and the RoSE project (Road Safety Equipment). In the article the authors present the effects of building a road restraint system database for a selected test site (about 3,000 km of Poland’s national roads). An outline of new road restraint system guidelines could only be developed after understanding the effects of restraint systems, the design, additional elements, type of road and safety barrier location on a road or engineering structure and the road and traffic conditions on their functionality and safety. The paper will present the preliminary results of this research. Once complete, the research will offer tools to help with the implementation of road restraint systems. The tools will ensure that road infrastructure is safer and that the most common mistakes are eliminated.

The effects of vehicle restraint systems on road safety

Key to understanding the needs and tools of road infrastructure management for preventing runoff-road crashes or minimising their consequences, is to identify the hazards and sources of hazards caused by wrong or improper use of road safety devices and identify errors in the design, structure, construction and operation of road safety devices. Studying such an extended scope of the problem required fieldwork and surveys with road authorities, designers, road safety auditors and road maintenance services. An outline of new guidelines could only be developed after understanding the effects of restraint systems, the design, additional elements, type of road and safety barrier location on a road or engineering structure and the road and traffic conditions on their functionality and safety. The paper will present the preliminary results of this research (research project – ROSE). One way to understand the functionality of road safety devices is to build numerical models and conduct simulation tests of virtual crash tests. The article presents the scope of work conducted as part of an effort to develop new vehicle restraint system guidelines.

Use of a modified HYBRID III 50th dummy to estimate the effectiveness of market restraint systems for forklift truck drivers

This study concerns the development of an experimental method intended to estimate the effectiveness of restraint systems for forklift truck drivers during a lateral tip-over.Tests performed on human subjects placed in situations of partial lateral tip-over were used to modify a HYBRID III dummy and to validate its performance. Another more realistic test setup was used to simulate a 90° lateral tip-over and assess the effectiveness of market restraint systems. The results show that systems that kept the dummy inside the cab (door-bar systems, seat-belt, etc.) would considerably increase the driver's chances of survival. Conversely, other poorly dimensioned equipment might not block the dummy's movement or might break. Head injury criteria (HIC15) calculation gave values lower than the threshold of 560 that was set in our approach for impacts inside the cab, whereas our assessments showed that impacts with the ground could be very serious or fatal.

Study of a device for controlling the pulses of sled testing

Improving the effectiveness of restraint systems (seat belts, air bags,) requires the development of experimental means capable of testing different crash types. Sled testing offers the advantage of improving the test conditions and consequently the repeatability of the crash pulse. The paper focuses on the deceleration device and on how to control the deceleration of the sled. The deceleration device includes a fixed part composed of four cylinders maintaining a steel bar and a spur attached to the front part of the sled. The dissipation mechanism is due to the plastic deformation of the steel bar impacted by the spur. The mechanism is stationary, leading to a constant force on the spur and therefore leading to a constant deceleration of the sled. The paper includes an experimental study and presents an analytical and a numerical model (FE model) to predict the deceleration of the sled. Comparisons between experimental results and predicted results point out the reliability of the models.

Effectiveness of Child Safety Seats vs Seat Belts in Reducing Risk for Death in Children in Passenger Vehicle Crashes

To provide an estimate of benefit, if any, of child restraint systems over seat belts alone for children aged from 2 through 6 years. Cohort study. A sample of children in US passenger vehicle crashes was obtained from the National Highway Transportation Safety Administration by combining cases involving a fatality from the US Department of Transportation Fatality Analysis Reporting System with a probability sample of cases without a fatality from the National Automotive Sampling System. Children in tow-away [corrected] crashes occurring between 1998 and 2003. Use of child restraint systems (rear-facing and forward-facing car seats, and shield and belt-positioning booster seats) vs seat belts. Potentially confounding variables included seating position, vehicle type, model year, driver and passenger ages, and driver survival status. Death of child passengers from injuries incurred during the crash. Compared with seat belts, child restraints, when not seriously misused (eg, unattached restraint, child restraint system harness not used, 2 children restrained with 1 seat belt) were associated with a 28% reduction in risk for death (relative risk, 0.72; 95% confidence interval, 0.54-0.97) in children aged 2 through 6 years after adjusting for seating position, vehicle type, model year, driver and passenger ages, and driver survival status. When including cases of serious misuse, the effectiveness estimate was slightly lower (21%) (relative risk, 0.79; 95% confidence interval, 0.59-1.05). Based on these findings as well as previous epidemiological and biomechanical evidence for child restraint system effectiveness in reducing nonfatal injury risk, efforts should continue to promote use of child restraint systems through improved laws and with education and disbursement programs.

Effect of restraint systems on maxillofacial injury in frontal motor vehicle collisions

Purpose Motor vehicle collisions (MVCs) are the leading cause of maxillofacial fractures. Additionally, maxillofacial injuries are the most common injury related to air bag deployment. We sought to characterize the occupant restraint system (seat belt and air bag) and collision characteristics associated with MVC-related maxillofacial injuries. Materials and methods The 1991–2000 National (United States) Automotive Sampling System Crashworthiness Data System (CDS) data files were used. The CDS is a national probability sample of passenger vehicles involved in police-reported tow-away MVCs. Analysis was limited to front seat occupants involved in frontal collisions of delta-V (estimated change in velocity) of greater than 15 km/hr. The risk of facial injury was calculated according to occupants’ restraint use (unrestrained, seat belt only, air bag only, and seat belt and air bag combined) and compared using risk ratios (RRs) and associated 95% confidence intervals (CIs). Results Occupants restrained with a seat belt only (RR, 0.48; 95% CI, 0.40 to 0.57) or a seat belt and an air bag (RR, 0.83; 95% CI, 0.73 to 0.94) had a significantly reduced risk of any facial injury compared with completely unrestrained occupants. There was no association for those restrained with an air bag only (RR, 1.19; 95% CI, 0.82 to 1.73). A similar pattern of results was observed for moderate to severe facial injuries and for facial fractures. Conclusion Seat belt use significantly reduces the risk of facial injury in frontal MVCs. Air bag use was not associated with the risk of facial injury.

Radiographic Detection of Rib Fractures: A Restraint-Based Study of Occupants in Car Crashes

Twenty-nine human cadavers were subjected to frontal impacts using two restraint conditions:: torso belt-only (14 tests), and torso belt-and-airbag (15 tests). Five radiologists independently evaluated post-test chest films, and their results were compared with detailed necropsy results. The radiologists' ability to identify rib fractures was influenced by the restraint system, rib number, aspect (right or left), circumferential location of the fracture, and the number of fractures on the rib. The probability of fracture detection (sensitivity) was significantly higher for the torso belt-only group (0.44) than for the belt-and-airbag group (0.24). Knowledge of fracture locations increased the overall (both restraint groups) sensitivity from 0.40 to 0.49. It is concluded that the sensitivity is dependent on the restraint system used. Since rib fractures are the injuries most commonly used to describe AIS 2+ thoracic injury severity, this dependence may bias field data-based comparative studies of restraint system effectiveness.

Rear seat restraint system effectiveness in preventing fatalities

Restraint system effectiveness for rear seat adult (16 years or older) car occupants is estimated by applying the double pair comparison method to Fatal Accident Reporting System (FARS) data for 1975 through 1985. As this data set contains information on fatal crashes only, the results apply exclusively to fatalities, and should not be generalized to other levels of injury. Rear seat occupants coded as using any restraint system are assumed to be using the lap belt only. Occupants in all four outboard seating positions (that is, driver and right front passenger, right and left rear passengers) serve as “other” occupants. Disaggregating the “other” occupant by restraint use generates six estimates of restraint system effectiveness for each of the two rear outboard positions. Insufficient data precluded estimating effectiveness for the center rear (or center front) positions, and also use of these occupants as “other” occupants. Average restraint system effectiveness for the two outboard rear seating positions is estimated as (18 ± 9)%, where the error limit indicates one standard error. These estimates suggest that there is a 39 in 40 chance that rear lap belts reduce fatality likelihood, but a less than 1 in 10 chance that the reduction exceeds 30%.

Empirical estimates of seat belt effectiveness in two-car collisions

The objective of this research is to quantify occupant protection afforded by restraint systems in two-car head-on collisions. An accepted measure of occupant protection is “Restraint System Effectiveness” (RSE). This quantity is defined as the percent reduction in the probability of an occupant injury due to the use of a restraint system. RSE estimates are calculated in the present paper using a previously developed mathematical model of occupant injuries in two-car collisions and obtaining parameter estimates from two data sets. The two sets of data used for estimating RSE are: New York police accident data and data collected by various multidisciplinary accident investigation teams. Both these data sets have been reported in the literature. The RSE estimates obtained from the two data sets range from 29 to 40%. These estimates are shown to increase as the mass of the occupant's vehicle increases, but decrease as the mass of the other colliding vehicle increases. On the average, the use of a restraint system can offset the decrease in occupant protection that would result from a 40% reduction in car weight. Consequently, the use of restraint systems to reduce occupant risk is estimated to be even more important as the number of small vehicles in the U.S. vehicle fleet increases.