Seat Belt Systems Research Articles

A Review of the effectiveness of seat belt systems: design and safety considerations

Following a description of seat belt components, this paper presents a review, analysis, and discussion of the effectiveness and limitations of seat belt systems. Causes of malfunction are identified. The paper also discusses expected findings in post-accident inspections of seat belt systems. Finally, a brief discussion of current and future design improvements is given.

Limiting Performance of Seat Belt Systems for the Prevention of Thoracic Injuries

The theoretically optimal performance of seat belt systems for occupants in automobile frontal crashes is investigated based on a two-mass injury model of the thorax. The performance is measured by thoracic injury criteria which include the maximum chest acceleration, compression and viscous response. The relationship between the best possible performance (limiting performance) of the seat belt system and the distance between the occupant and the interior components of the vehicle is displayed in the form of trade-off curves, which can be used for the evaluation of seat belt performance. The characteristics of the optimal seat belt force and the kinematics of the system are illustrated. The results indicate that the optimal seat belt force is not constant during an impact and that an initial impulse is required. However, constant seat belt force can provide thoracic restraint that is close to the optimal solution.

Limiting performance of seat belt systems for the prevention of thoracic injuries

The theoretically optimal performance of seat belt systems for occupants in automobile frontal crashes is investigated based on a two-mass injury model of the thorax. The performance is measured by thoracic injury criteria which include the maximum chest acceleration, compression and viscous response. The relationship between the best possible performance (limiting performance) of the seat belt system and the distance between the occupant and the interior components of the vehicle is displayed in the form of trade-off curves, which can be used for the evaluation of seat belt performance. The characteristics of the optimal seat belt force and the kinematics of the system are illustrated. The results indicate that the optimal seat belt force is not constant during an impact and that an initial impulse is required. However, constant seat belt force can provide thoracic restraint that is close to the optimal solution.

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.

Development of a side facing seat and seat belt system for the Australian Army Perentie 4×4

The survivability of soldiers in the rear of military vehicles when involved in a crash has been identified as an area of major concern. The Australian Army via Project TRANSAFE has developed and evaluated a range of side facing Seat and Seat Belt Systems (SSBS) for the Perentie 4x4 to improve crash survivability. Options which have been evaluated include; bench seat with lap seat belt, bench seat with lap sash seat belt, individual seat with harness, wooden seat with lap sash seat belt and a plastic seat with lap sash seat belt. Tests were conducted on isolated single seating systems and on multiple seating systems simulating the internal structure of the Perentie 4x4. Wooden and plastic prototype SSBS demonstrated a low probability for life threatening head, neck and chest injuries while the bench seat options and individual seat and harness SSBS have a high probability of serious, if not life threatening, head, neck and chest injuries. A set of three-dimensional MADYMO models were also developed and validated, simulating the SSBS with seated 50th percentile Hybrid Ill dummies subjected to a mid-severity crash pulse. The dummy kinematics and injury parameters from the simulation were compared to tests and fairly good agreement was found.

Airbag Deployments

Transport Canada is undertaking an in-depth study of motor vehicle collisions involving airbag deployments. University-based collision investigation teams across Canada are used to collect crash data. The primary objective of the study is to gain a better understanding of the injuries and the injury mechanisms associated with airbag deployments among both restrained and unrestrained occupants. Preliminary results show an exceptionally high level of seatbelt use in conjunction with the supplemental air cushion restraints. Most crashes are, however, of only minor to moderate severity, in which the seatbelt systems alone would be expected to provide adequate occupant protection. Initial findings indicate that, at the lower end of the collision severity spectrum, deployment of an airbag may, in some circumstances, increase the overall likelihood of injury to a restrained occupant. This suggests that the current deployment threshold is set too low, at least for belted occupants.

Estimating trends in the effectiveness of seat belts in saving lives, 1975-1985.

We examine the effectiveness of seat-belt systems for preventing mortality in automobile crashes. In particular, we examine whether seat-belt effectiveness has been constant over this period and conclude that there has been a trend toward an increased effectiveness of seat-belt systems. The relative odds of death associated with wearing seat belts dropped from 0.80 in 1975 to 0.34 in 1985. This trend results from improvements in both the type and design of seat belts and from additional design changes, such as padded dashboards and collapsible steering columns, that protect occupants at the time of collision.

Prevention of nervous system trauma from travel in motor vehicles.

Brain and spinal cord injuries are a frequent cause of death and long-term disability in motor vehicle accidents. Helmet use reduces death and head injury severity in motorcycle accidents. Proper use of child restraints can prevent death from falls and vehicle crashes. Auto lap and shoulder restraints, when in use, reduce death from accidents and falls from cars. Passive protections, such as air bags, vehicle design for crashworthiness, and automatic seatbelt systems are less available for economic reasons. Voluntary use of available devices is the remaining viable option. One-to-one education may help promote use of protective devices. The greatest impact lies in legislative requirements for self-protection. It is ethically justifiable to require use of devices such as child restraints, seatbelts, and motorcycle helmets to prevent death and disability.

Letter: New seat belt systems as a cause of meralgia paresthetica.

To the Editor.— The lateral femoral cutaneous nerve, which transmits cutaneous sensation to the anterolateral aspect of the thigh, may be involved at the point of passage medial to the anterosuperior part of the iliac spine, with subsequent painful paresthesias known as meralgia paresthetica. This condition is often caused by trauma, obesity, increased intra-abdominal pressure, occupational posture requiring hip flexion, and pressure by a belt or truss. There appears to be little doubt that the automatic lap belt retractor, recently introduced with other safety devices in the automotive industry, is a new and avoidable cause for the production of this syndrome. New cars are equipped with a starter interlock that prevents starting the car until all front seat occupants are buckled in. Consequently, buckling of the lap belt is mandatory. The belt restraint buckle, which is fixed to the seat and is located close to it, maintains the lap belt