Belt Restraint Systems Research Articles

Comparison of Head, Neck, and Chest Injury Risks between Front and Rear-Seated Hybrid III 50th-Percentile Male ATDs in Matched Frontal NCAP Tests

<div>The objective of this study was to compare head, neck, and chest injury risks between front and rear-seated Hybrid III 50th-percentile male anthropomorphic test devices (ATDs) during matched frontal impacts. Seven vehicles were converted to rear seat test bucks (two sedans, three mid-size SUVs, one subcompact SUV, and one minivan) and then used to perform sled testing with vehicle-specific frontal NCAP acceleration pulses and a rear seated (i.e., second row) Hybrid III 50th male ATD. Matched front seat Hybrid III 50th male ATD data were obtained from the NHTSA Vehicle Crash Test Database for each vehicle. HIC15, Nij, maximum chest acceleration, and maximum chest deflection were compared between the front and rear seat tests, as well as between vehicles with conventional and advanced three-point belt restraint systems in the rear seat. Additionally, a modified version of the NCAP frontal star rating was calculated for the front and rear seat tests. All injury metrics, except for chest acceleration, were higher in the rear seat compared to the front. In addition, injury thresholds were exceeded or nearly exceeded in the rear seat for Nij in three vehicles, chest acceleration in one vehicle, and chest deflection in three vehicles, while no thresholds were exceeded in the front seat. When comparing advanced and conventional restraints in the rear seat, all injury metrics were higher in the vehicles with conventional restraints. All vehicles with conventional restraints in the rear had a star rating of 1, while those with advanced restraints in the rear ranged from 2 to 3. Conversely, all vehicles had 5 stars for the front seat, except one that had 4 stars. Overall, these data highlight the disparity between front and rear seat occupant protection and the benefits of advanced rear seat safety restraints, and the need for future testing.</div>

Seat Belt Restraint Evidence Generated by Unrestrained Occupant Interaction in a Rollover

<div class="section abstract"><div class="htmlview paragraph">Assessment of the physical evidence on a seat belt restraint system provides one source of data for determining an occupant’s seat belt use or non-use during a motor vehicle crash. The evidence typically associated with loading from a restrained occupant has been extensively researched and documented in the literature. However, evidence of loading to the restraint system can also be generated by other means, including the interaction of an unrestrained occupant with a stowed restraint system. The present study evaluates physical evidence on multiple stowed restraint systems generated via interaction with unrestrained occupants during a full-scale dolly rollover crash test of a large multiple passenger van. Unbelted anthropomorphic test devices (ATDs) were positioned in the driver and right front passenger seats and in all designated seating positions in the third, fourth, and fifth rows. Occupant kinematics during the dolly rollover were evaluated through on-board and off-board real-time and high-speed video, and physical evidence on the restraint systems was documented. Analysis of the occupant kinematics demonstrated multiple ATD interactions with stowed restraint systems in the vehicle, which generated corresponding physical evidence on those restraint systems. The findings of the present study demonstrate that the presence of physical evidence on the restraint system alone is insufficient for determination of occupant seat belt usage. A methodology for assessing restraint webbing and hardware evidence in the context of occupant seat belt use versus non-use is detailed. Thorough documentation of the restraint system physical evidence, evaluation of the occupant kinematics and injury patterns, and evaluation of the restraint system evidence as it relates to the body habitus of the occupant of interest can provide an objective scientific basis for the determination of occupant restraint status.</div></div>

Experimental-theoretical method for studying the vehicle airbag modules functioning

Introduction (problem statement and relevance). The airbag belongs to the passive vehicle safety system (SRS - Supplementary Restraint System) and is the most important (together with the seat belt) restraint system that protects the driver and passengers in a collision with static or moving objects. The main task of the SRS is to minimize injuries to the driver and passengers and reduce deaths in various road traffic accidents. For the development and testing of modern high-tech airbag modules, it is necessary to have informative theoretical and experimental methods for studying the non-stationary processes of their functioning.The purpose of the study was to develop an experimental-theoretical research method based on modern highly informative tools of experimental physics of fast processes and numerical methods for continuous media dynamics.Methodology and research methods. To study the functioning dynamics of vehicle airbag modules, an experimental method for determining the kinematic and acoustic parameters has been developed and implemented, and a mathematical model of an airbag functioning process has been formulated and implemented in the LS-DYNA environment with the help of corpuscular particles method.Scientific novelty and results. The created experimental-theoretical method allowed both to simulate the functioning processes of the developed and tested airbag modules, and to carry out field tests of these modules. In addition, the experiment made it possible to carry out a detailed verification of the numerical method for calculating the airbag operation, on the basis of which it was also possible to perform numerical calculations interaction of the airbag and an anthropometric dummy model.Practical significance. The developed method for studying the processes of airbag modules functioning is an important and necessary component of creating a scientific, technical and experimental base for the development and production of passive safety systems.

Frontal crash seat belt restraint effectiveness and comfort accessories used by older occupants

Objective: Around a quarter of older occupants use some type of comfort or orthopedic aftermarket accessory on the vehicle seat while traveling in a vehicle. The aim of this study was to investigate the effect of comfort accessories on the performance of the seat belt restraint system in a frontal crash in terms of potential injury implications for older occupants.Methods: Eight frontal sled tests (43 km/h, 32 g) were carried out on a deceleration sled fitted with a three-point lap-sash seat belt and a front passenger seat from a common Australian passenger car for each test. A 5th percentile Hybrid III anthropometric test device (ATD) was positioned in the seat and measurements were recorded for head center of gravity acceleration, chest acceleration, neck forces and moments and sternal deflection. Tests were carried out in a baseline condition and with seven comfort accessories. Each comfort accessory was inserted between the ATD and vehicle seat as it is intended to be used, with the ATD otherwise positioned as close as possible to the baseline test position.Results: Initial distance between the seat belt anchor and ATD hip was associated with a statistically significant decrease in Head Injury Criterion and increase in sternal deflection. Submarining was related to the ATD torso recline angle and angle of the lap belt from the seat belt anchor.Conclusions: Accessories placed between the seat back and the lumbar region of an occupant have the potential to increase the risk of submarining due to a change in posture and should be avoided if such a change in posture when seated with an accessory is excessive. Sitting on seat cushions resulted in the greatest increase in seat belt anchor to hip distances and hence largest increase in sternal deflection. Given the fragility, frailty and particular importance of chest injuries among older vehicle occupants, further investigation is needed to determine whether these changes in ATD sternal deflection observed with seat cushion use results in injury threshold limits being exceeded and whether pretensioners and load limiters would ameliorate these effects without causing other negative changes in occupant response or kinematics.

Numerical Low-Back Booster Analysis on a 6-Year-Old Infant during a Frontal Crash Test

This work studies descriptively the Head Injury Criterion (HIC) and Chest Severity Index (CSI), with a finite element model of the Hybrid III dummy type, for six-year-old subjects in a frontal vehicular collision, using the low-back booster (LBB) passive safety system. The vehicle seats and the passive safety systems were modelled in CAD (computer aided design) software. Then, the elements were analysed by the finite element method (FEM) in LS-DYNA® software. The boundary conditions were established for each study, according to the regulations established by the Federal Motor Vehicle Safety Standard (FMVSS), following the FMVSS 213 standard. The numerical simulations were performed during an interval of 120 ms and recording results every 1 ms. In order to analyse the efficiency of the system, the restraint performance of the LBB system is compared with the restraint configuration of the vehicle safety belt (VSB) only. The obtained injury criteria with the LBB system shows its ability to protect children in a frontal collision. The analyses allow obtaining the deceleration values to which the dummy head and chest was subjected. Of the studies herein performed, Study I: VSB obtained a HIC36 of 730.4 and CSI of 315.5, while Study II: LBB obtained a HIC36 of 554.3 and CSI of 281.9. The outcome shows that the restraint efficiency of each studied case differs. Used materials, the attachment system of the LBB, and the belt restraint system properly placed over the infant trunk are the main factors reducing the injury criteria rate.

Evaluation of the effectiveness of toe board energy-absorbing material for foot, ankle, and lower leg injury reduction

ABSTRACTObjective: Since 2000, numerous improvements have been made to the National Association for Stock Car Auto Racing, Incorporated (NASCAR®) driver restraint system, resulting in improved crash protection for motorsports drivers. Advancements have included seats, head and neck restraints (HNRs), seat belt restraint systems, driver helmets, and others. These enhancements have increased protection for drivers from severe crash loading. Extending protection to the driver's extremities remains challenging. Though the drivers’ legs are well contained for lateral and vertical crashes, they remain largely unrestrained in frontal and frontal oblique crashes.Method: Sled testing was conducted for the evaluation of an energy-absorbing (EA) toe board material to be used as a countermeasure for leg and foot injuries. Testing included baseline rigid toe boards, tests with EA material–covered toe boards, and pretest positioning of the 50th percentile male frontal Hybrid III anthropomorphic test device (ATD) lower extremities. ATD leg and foot instrumentation included foot acceleration and tibia forces and moments.Results: The sled test data were evaluated using established injury criteria for tibial plateau fractures, leg shaft fractures, and calcaneus, talus, ankle, and midfoot fractures.Conclusion: A polyurethane EA foam was found to be effective in limiting axial tibia force and foot accelerations when subjected to frontal impacts using the NASCAR motorsport restraint system.

A Pilot Study of Three-Dimensional Child Anthropometry for Vehicle Safety Analysis

The publicly available anthropometric data for U.S. children were published in 1977, lack body shape data, and do not include measurements in supported sitting postures that are needed for vehicle safety applications. A pilot study was conducted of methods using standard anthropometry, laser scanning, and three-dimensional coordinate measurement to develop the data needed to improve the sizes and shapes of crash dummies and other design tools used to develop and assess child restraints, belt-positioning boosters, and vehicle seat and belt restraint systems. A total of 15 children ages 4 to 11 were measured in this pilot study.

Seat Belt Restraint Evidence Generated in the Presence of Fractured Glass

Physical evidence on the seat belt restraint system is one source of data used by investigators to determine whether or not an occupant was wearing their seat belt during a crash. Evidence of occupant loading on seat belts generated during crash events has been thoroughly researched and is well documented in the literature. However, there is a paucity of data regarding the physical evidence produced when fractured glass is introduced into the restraint system during occupant loading events. The objective of this study is to characterize the physical evidence generated by glass-to-seat belt interaction during low-level impact loading, and compare this evidence with the types of seat belt marks that can be generated inadvertently by accident scene bystanders, emergency responders, and crash investigators. The presence of glass particles in and around the vehicle at the end of a crash event may contribute to the inadvertent generation of physical evidence. Movable side windows composed of tempered safety glass and laminated safety glass were fractured via impactor loading representative of occupant impact. The resulting glass fracture fragments were separated by size using a series of sieves, and the distribution of glass fragments size was quantified. New service-replacement seat belt retractor assemblies (including D-ring, latch plate, anchor, and webbing) were tested using a Seat Belt Load Simulator (SBLS) fixture, which simulates occupant loading by applying a repeatable load pulse to the restraint system. Each retractor assembly was mounted onto the SBLS fixture in a position representative of belt routing when installed in a vehicle. A repeatable lap-shoulder belt stroke pulse, representative of low-level restraint loading and consistent in magnitude and duration with loads produced during rollover, was applied using the SBLS with glass fragments of varying sizes introduced onto the webbing surface adjacent to the D-ring and latch plate surfaces. Additional test series were run to investigate the types of physical evidence generated in the presence of glass under non-crash loading scenarios. These scenarios included the extraction of webbing with glass fragments present adjacent to the D-ring and latch plate, extraction of webbing over glass fragments captured or fixed in a window seal, and the compression of webbing with various sizes of glass fragments interposed between the webbing and a reaction surface. Documentation of each restraint system was performed post-test. Seat belt loading events that occurred in the presence of fractured safety glass produced characteristic markings on the restraint system hardware and webbing. The tests conducted to examine non-crash loading evidence generated in the presence of fractured safety glass revealed markings on the restraint system that differed from those generated in a simulated loading event. Language: en

Influence of standing or seated pelvis on dummy responses in rear impacts

ObjectiveThere is a question whether the standing or seated pelvis should be used in Hybrid III dummy evaluations of seats and belt restraint systems in severe rear impacts. This study compares the standing and seated Hybrid III pelvis in matched rear sled tests. MethodsSixteen sled tests were found at 10, 16 and 24km/h rear delta V in Ford's archives where matched tests were run with the standing and seated pelvis in a belted Hybrid III dummy. Two new tests were conducted at 40km/h rear delta V to extend the severity range. The head, chest and pelvis were instrumented with triaxial accelerometers and the upper and lower neck, thoracic spine and lumbar spine had transducers measuring triaxial loads and moments. Belt Loads were measured. High-speed video recorded different views of the dummy motion. Dummy kinematics and biomechanical responses were compared for all of the data with the two different Hybrid III pelvic designs. ResultsIn the 40km/h sled tests, the dummy motion and excursion were essentially similar with the standing and seated pelvis. The similarities included the lap belt interaction with the pelvis and the leg movement upward flexing the hip joint. Overall, similar biomechanic and kinematic responses were found, including the pelvic acceleration, spinal forces and moments. For the lower speed tests at 10, 16 and 24km/h, the motion sequence was also similar with the two different pelvises, including the upward movement of the legs as the seat was loaded and rebound kinematics. The biomechanical responses were similar. The seated pelvis involves only a small portion of the upper leg molded into the vinyl skin of the pelvis and does not limit leg rotation at the hip joint. Furthermore, lap belt loads were minimal during the rearward movement of the dummy. ConclusionsThe matched testing showed no significant difference in occupant kinematics or biomechanical responses between the standing and seated pelvis in rear sled tests. The Hybrid III dummy with the seated pelvis is suitable for FMVSS 301 and other testing of seats and belt restraint systems in severe rear impacts.

Reference governors for controlled belt restraint systems

Today's restraint systems typically include a number of airbags, and a three-point seat belt with load limiter and pretensioner. For the class of real-time controlled restraint systems, the restraint actuator settings are continuously manipulated during the crash. This paper presents a novel control strategy for these systems. The control strategy developed here is based on a combination of model predictive control and reference management, in which a non-linear device – a reference governor (RG) – is added to a primal closed-loop controlled system. This RG determines an optimal setpoint in terms of injury reduction and constraint satisfaction by solving a constrained optimisation problem. Prediction of the vehicle motion, required to predict future constraint violation, is included in the design and is based on past crash data, using linear regression techniques. Simulation results with MADYMO models show that, with ideal sensors and actuators, a significant reduction (45%) of the peak chest acceleration can be achieved, without prior knowledge of the crash. Furthermore, it is shown that the algorithms are sufficiently fast to be implemented online.

Control-oriented modelling of occupants in frontal impacts

This paper presents manageable, mathematical models of a vehicle occupant and a belt restraint system. These low-order models are relevant in the development of controlled restraint systems, which aim at lowering injury criteria by real-time control of the occupant motion. The models can be employed for control design and real-time injury prediction, the main components of controlled restraint systems. Several low-order models are constructed with first principles of physics and through knowledge obtained from a sensitivity analysis of validated, complex occupant models. The biomechanical responses of the low-order models, related to neck and thoracic injury criteria are validated with the results of the complex models. They are found to be valid for 5th, 50th and 95th percentile Hybrid III dummies in a range of frontal impact scenarios. The conclusion of this study is that thoracic and neck injury criteria in frontal impact can be accurately assessed with relatively simple occupant models, which are required for real-time control of injury-related biomechanical responses.

Computational investigation of the effect of up-armouring on the reduction in occupant injury or fatality in a prototypical high-mobility multi-purpose wheeled vehicle subjected to mine blast

A comprehensive finite-element-based computational investigation of the ability of different measures (e.g. up-armouring, seat cushion, or seat belt restraint system) to protect the occupant(s) of a prototypical high-mobility multi-purpose wheeled vehicle in the event of an anti-vehicle mine detonation under the vehicle's front right wheel is carried out. While assessing the effectiveness of these protective measures, different injury criteria had to be defined and/or employed, their values calculated (during the initial response stage of the blast event), and compared with the limiting values corresponding to the critical levels of injury. The efficacies are compared both when these measures are implemented in isolation and in the presence of other protective measures with respect to specific injuries.

낙하 충격을 받는 다점 구속 장치를 착용한 헬기 승무원의 상해도 평가에 관한 연구

In this paper, a method of modeling seat belts on crew seat during dynamic seat testing was studied. The body segments of the occupant were modeled with joints. The joints consisted with various stiffnesses, dampings, and frictions. Three types of seat belt restraint systems were investigated. The analysis for on the injury assessment of helicopter's crew under drop impact was conducted. The effectiveness of the seat belt system for crashworthiness and safety was evaluated. As the results of impact analysis, head, neck and spine of the crew can be easily damaged in the vertical direction more than the longitudinal direction. Based on the verified model, behavior of human body was studied with three-point restraint systems. The displacement and injury level of the 12-point restraint system was the smallest.

A study on the modeling and analysis of a helicopter’s occupant seat belt for crashworthiness

In this paper, a method of modeling a seat belt on a crew seat during a dynamic seat testing was studied. The body segments of the occupant were modeled with joints that consisted of various stiffness, damping, and friction. Three types of seat belt restraint systems were investigated and an analysis on the injury assessment of the helicopter’s crew under a drop impact was conducted. The effectiveness of the seat belt system for crashworthiness and safety was likewise evaluated. From the impact analysis results, it was determined that the head, neck, and spine of the crew body can be easily damaged in the vertical direction more than the longitudinal direction. Based on the verified model, the human body’s behavior was studied using three point restraint systems. The displacement and injury level of the 12-point restraint system was the smallest.

Occupant behaviour simulation using DADS and design of seat belt for occupant safety

The occupant and seat belt restraint system were modelled mathematically using multi-body dynamics. The interactions between belt and dummy such as belt slip and energy dissipation were considered in three dimensional mathematical models of 50th percentile Hybrid111 dummy and 3-point seat belt system. In this study, the commercial software DADS (Dynamic Analysis and Design System) was used for dynamic simulation of occupant impact response in sled tests and barrier crash tests. Results from the sled test simulations were compared with those available in the literature in order to validate the mathematical model for occupant behaviour analysis. In order to simulate the occupant behaviour in barrier crash tests, simple models of car interior system and energy-absorbing steering system were also established. And the effect of seat belt systems on occupant protection was evaluated through the occupant behaviour simulation in barrier crash tests. Several factors, which were thought to be closely related to the performance of seat belt systems for occupant protection, were considered. Orthogonal array table was used for a systematic procedure to lay out the factors and conditions in the barrier crash test simulation. The various injury values were investigated in response to the change of seat belt variables such as shoulder belt slackness, lap belt slackness, belt stiffness, retractor performance, and outer D-ring position. The contribution of seat belt variables to occupant protection was analysed by ANOVA (analysis of variance). From this analysis, it was found that seat belt slackness had the most dominant effect on occupant injuries, and seat belt pretension can increase the occupant safety. Through the systematic applications of orthogonal array table and ANOVA to seat belt design, the modified combination of seat belt variables was obtained, and the initial occupant injury values could be decreased.

Perceived Risks and Injuries Associated with Non-Use of the Manual Lap Belt in Motorized Shoulder Belt Restraint Systems

An experiment was conducted in order to explore some of the perceived risks associated with automatic shoulder belt/manual lap belt restraint systems used without buckling the manual lap belt. Participants viewed videotaped clips that combined sequences of a person entering a car and using or not using the active component of the restraint system followed by an accident. Participants were then asked to estimate the severity of injury likely suffered by a person who was involved in that accident given the seat belt use they viewed. Participants did not perceive large differences in injury severity between scenarios when the manual lap belt was used and when it was not used. Additionally, participants seemed relatively unaware of the risks of submarining and ejection when the manual lap belt was not used.

Side Impact Protection - Occupants in the Far-Side Seat

Much of the applied vehicle side impact occupant protection research to date has concentrated on occupants seated beside the struck side of vehicles. These occupants are defined as ‘near-side occupants’. Regulatory side impact test standards focus exclusively on this scenario. Real world crash evidence however has shown that occupants seated on the side away from the struck side, defined as ‘far-side occupants’, are still subject to a risk of injury. Relatively little research literature is available that addresses the protection of far-side occupants. Existing three-pint seat belt restraint systems were primarily designed for frontal impacts. Consequently, there is an inability for these systems to perform as effectively under lateral loading, compared to longitudinal loading. This is particularly the case for far-side occupant restraints, where the occupant's upper tom has often been observed to slip out from under the sash part of the seat belt system. This paper examines side impact epidemiology from an injury causation perspective, and endeavours to explain evidence indicating head injuries and seat belt related injuries constitute a significant proportion of all far-side impact injuries. Injury mechanisms and key dynamic parameters governing injury severity are detailed. Computer models simulating the dynamic motion of vehicle far-side occupants are described. Occupant kinematics and injury parameters from the models are then compared with real world crash case studies. The paper finally suggests vehicle design strategies which are likely to reduce far-side injuries. Some alternative restraint systems are proposed as potential countermeasures to reduce occupant injuries.

Recurring Accidents in Transportation Systems

The four papers in this symposium all deal with events and accidents in surface transportation systems which display a continuing condition. The recurring aspect of these events allows patterns to emerge, associated environmental conditions to be reviewed and demographics to be considered. Human factors/ergonomics analyses and some suggested remedial actions are included for each of the accident types. All four papers deal with elements related to forensic and litigation contexts and provide insights, information and techniques for human factors practitioners in this field. Some observations and insights into the U.S. legal system are also included. The specific topics dealt with in this symposium are: 1) Automatic shoulder belt/manual lap belt restraint systems in late model automobiles and their effect on users and accidents, 2) Pedestrian accidents, repeating patterns, and the need for lawyer, prosecutors, and judges to be more sophisticated in the limitation of both drivers and pedestrians in these situations, 3) Individuals falling out of moving passenger trains in both the U.S. and the U.K. and Amtrak's response, and 4) Misconceptions about how the expectancies of drivers affect their detection and perception of objects in night driving conditions.

Thoracic response and injury with belt, driver side airbag, and force limited belt restraint systems

Abstract The performance of belt, airbag, and force limited belt restraint systems for the driver were compared using frontal sled tests. Nine human cadaver and six dummy sled tests were conducted at 56 km/h using a test buck representing a mid-size vehicle. Subject instrumentation included upper and lower chestbands to measure local thoracic deformations and sternal and spinal accelerometers to record torso deceleration. Following the sled tests, radiographs and autopsy results were used to correlate cadaver injury with measured engineering parameters and dummy response. Chest compression, acceleration, change in curvature and Viscous Criteria were evaluated for all occupants. Occupant kinematics were determined from analysis of high speed film. Local differences in the chest loading behavior among the restraint systems were identified using the chestband contours. The results of the research indicate that improvements in thoracic occupant protection may be achieved with the use of force limited belt and pretensioner systems.

Airbag safety: Deployment in an automobile crash with a fall from height

Airbag restraint systems have demonstrated a significant reduction in mortality in motor vehicle crashes (MVCs). While airbag devices are effective primarily in frontal or near-frontal impacts, little is known about the efficacy of these devices in nonfrontal types of collisions. Moreover, there are reports of injuries specific to airbag deployment that have led some investigators to question the benefit of such devices. This article reports a rollover MVC with a considerable fall from height in which lap/shoulder belts were used in addition to airbag deployment that resulted in protection of the driver from injury. The outcome of this case continues to support the combination of belt and airbag restraint systems as the most effective occupant protection in both frontal and nonfrontal types of MVCs.