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The paper gives an evaluation of the performance of lap and shoulder belt restraint systems currently being used in American-built automobiles. Comparisons are made of the response characteristics of a volunteer, an anthropometric dummy, and a cadaver when subjected to identical collision environments while wearing a three or four point torso restraint system as occupants of the right front seat. Simulated frontal force barrier collisions in a modified automobile provided the realistic environment for the restraint system performance study. Human tolerances, interior vehicle geometry, and the interaction of the restrained occupant with the vehicle during the collision are reported in detail.

Traditionally, Knee Air Bag (KAB) is constructed of a woven nylon or polyester fabric. Recently, Ford developed an injection molded air bag system for the passenger side called Active Glove Box (AGB). This system integrates a plastic bladder welded between the glove box outer and inner doors. This new system is smaller and lighter, thus improving the roominess and other creature comforts inside the passenger cabin while providing equivalent restraint performance as traditional knee airbag system. This patented technology allows positioning of airbags in new locations within the vehicle, thus giving more freedom to designers. The first application of this technology was standard equipment on the 2015 Ford Mustang. Given that this technology is first in the industry, it was a challenge to design, test and evaluate the performance of the system as there is no benchmark to compare this technology. A CAE driven design methodology was chosen to overcome this challenge.

This paper reports a study of the dynamic characteristics of body mounts in body on frame vehicles and their effects on structural and occupant CAE results. The body mount stiffness and damping are computed from spring-damper models and component test results. The model parameters are converted to those used in the full vehicle structural model to simulate the vehicle crash performance. An effective body mount in a CAE crash model requires a set of coordinated damping and stiffness to transfer the frame pulse to the body. The ability of the pulse transfer, defined as transient transmissibility[1]1, is crucial in the early part of the crash pulse prediction using a structural model such as Radioss[2]. Traditionally, CAE users input into the model the force-deflection data of the body mount obtained from the component and/or full vehicle tests. In this practice, the body mount in the CAE model is essentially represented by a spring with the prescribed force-deflection data.

For more than 30 years, field research and laboratory testing have consistently demonstrated that properly wearing a seat belt dramatically reduces the risk of occupant death or serious injury in motor vehicle crashes. In severe rollover crashes, deformation to vehicle body structures can relocate body-mounted seat belt anchors altering seat belt geometry. In particular, roof pillar mounted shoulder belt anchors (“D-rings”) are subject to vertical and lateral deformation in the vehicle coordinate system. The ROllover Component test System (ROCS) test device was utilized to evaluate seat belt system performance in simulated severe rollover roof-to-ground impacts. A mechanical actuator was designed to dynamically relocate the D-ring assembly during a roof-to-ground impact event in an otherwise rigid test vehicle fixture. Anthropomorphic test device (ATD) kinematics and kinetics and seat belt tensions were compared between tests with and without D-ring relocation.

The dilemma of using a shoulder belt force limiter with a 3-point belt system is selecting a limit load that will balance the reduced risk of significant thoracic injury due to the shoulder belt loading of the chest against the increased risk of significant head injury due to the greater upper torso motion allowed by the shoulder belt load limiter. However, with the use of air bags, this dilemma is more manageable since it only occurs for non-deploy accidents where the risk of significant head injury is low even for the unbelted occupant. A study was done using a validated occupant dynamics model of the Hybrid III dummy to investigate the effects that a prescribed set of shoulder belt force limits had on head and thoracic responses for 48 and 56 km/h barrier simulations with driver air bag deployment and for threshold crash severity simulations with no air bag deployment.

In order to provide an improved countermeasure for occupant protection, a new type of active reversible preload seatbelt (ARPS) is presented in this paper. The ARPS is capable of protecting occupants by reducing injuries during frontal collisions. ARPS retracts seatbelt webbing by activating an electric motor attached to the seatbelt retractor. FCW (Forward Collision Warning) and LDW (Lane Departure Warning) provide signals as a trigger to activate the electric motor to retract the seatbelt webbing, thus making the occupant restraint system work more effectively in a crash. It also helps reduce occupant’s forward movement during impact process via braking. Four important factors such as preload force, preload velocity and the length and timing of webbing retraction play influential roles in performance of the ARPS. This paper focuses on studying preload performance of ARPS under various test conditions to investigate effects of the aforementioned factors.

The relation cost versus performance in the design of an automobile is crucial for its success. These two characteristics, much like the project development timing, are closely related to the attributes that the new design must achieve (e.g. weight, fuel economy, torsional stiffness, NVH, safety, etc.). In this respect, the design optimization of body reinforcements (i.e. part thickness, quantity of reinforcements, and number of spot welds) contributes greatly to a sound and robust project concept. This paper describes one application of 6-Sigma methodology to evaluate the performance of different configurations of seat belt reinforcements resulting in an optimized concept that achieved the proposed performance targets with weight and sub-assembly complexity reduction. Using a Design of Experiments (DOE) and Finite Element Analysis (FEA), each proposal was evaluated for its resistance to plastic deformation.

The Hybrid III dummy is an anthropomorphic (humanlike) test device, generally used in crashworthiness testing to assess the extent of occupant protection provided by the vehicle structure and its restraint systems in the event of vehicle crash. Lumped-parameter analytical models are commonly used to simulate the dummy response. These models, by virtue of their limited number of degrees of freedom, can neither represent accurate three-dimensional dummy geometry nor detailed structural deformations. In an effort to improve the state-of-the-art in analytical dummy simulations, a set of finite element models of the Hybrid III dummy segments - head, neck, thorax, spine, pelvis, knee, upper extremities and lower extremities - were developed. The component models replicated the hardware geometry as closely as possible. Appropriate elastic material models were selected for the dummy “skeleton”, with the exterior “soft tissues” represented by viscoelastic materials.

Occupant protection in side impacts, in particular for near-side occupants, is a challenge due to the occupant’s close proximity to the impact. Near-side occupants have limited space to ride down the impact. Curtain and side airbags fill the gap between occupant and the side interior. This analysis was conducted to provide insight on the characteristics of side impacts and the relevancy of currently regulated test configurations. For this purpose, 2007-2015 NASS-CDS and 2017-2021 CISS side crash data were analyzed for towed light vehicles. 2008 and newer model year vehicle data was selected to ensure that most vehicles were equipped with side/curtain airbags. The results showed that side impacts accounted for approximately 26.7% of the vehicles involved and 18.9% of the vehicles with at least one seriously injured occupant. Most side impacts involved damage to the front and front-to-center of the vehicle.

This paper updates the findings of prior research addressing the relationship between seatback strength and likelihood of serious injury/fatality to belted drivers and rear seat occupants in rear-impact crashes. Statistical analyses were performed using 1995-2014 CY police-reported crash data from seventeen states. Seatback strength for over 100 vehicle model groupings (model years 1996-2013) was included in the analysis. Seatback strength is measured in terms of the maximum moment that results in 10 inches of seat displacement. These measurements range from 5,989 in-lbs to 39,918 in-lbs, resulting in a wide range of seatback strengths. Additional analysis was done to see whether Seat Integrated Restraint Systems (SIRS) perform better than conventional belts in reducing driver and rear seat occupant injury in rear impacts. Field data shows the severe injury rate for belted drivers in rear-impact crashes is less than 1%.

Squeak and rattle is an important sub Noise and Vibration attribute which can be easily noticed by the costumer. A rattle was observed at seat belt retractor during subjective evaluation at a special test on a rough road It was developed an objective metric, in laboratory, with the aim to establish an acceptance criteria for the part. The objective of this paper is to show how noise, vibration and harshness engineers worked on the correlation between subjective and objective evaluation concerning this rattle.

This study examined occupant and seat responses with ABTS (all-belts-to-seat) in rear end collisions. Some have claimed improved ABTS seat performance and retention in rear impacts than conventional seats. ABTS seats tend to have higher ultimate yield strengths than conventional yielding seats. Most ABTS seats have asymmetric seatback stiffness due to the need for additional structure on one side of the seat to support shoulder belt loads. Many designs use a single-side recliner and single stanchion that anchors the D-ring. This asymmetry results in twisting of the seatback in severe rear impacts. Seatback twist can allow the occupant to move away from the shoulder belt. Rearward pull tests on ABTS seats also demonstrates seatback twisting and in some cases large drops in load during the test. The added strength and stiffness of ABTS seats lead to designs that are vulnerable to sudden force drops from separated parts.

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.

A study was conducted by General Motors at its crash test facility located at the Milford Proving Ground. The intent of this study was to expand upon the currently available research regarding the safety belt buckle environment during full scale planar crash tests. Buckle accelerations and webbing tensions were measured and recorded to characterize, in part, buckle responses in a crash environment. Previous studies have focused primarily on the component level testing of safety belt buckles. The crash tests included a variety of vehicles, impact types, seating positions, Anthropomorphic Test Devices (ATDs), impact speeds, and impact angles. Also included were various safety belt restraint systems and pretensioner designs. This study reports on data recorded from 100 full scale crash tests with 180 instrumented end release safety belt buckles. Acceleration measurements were obtained with tri-axial accelerometers mounted onto the buckles.

This paper describes an analytical method to predict the sensor closure time for an airbag (Supplemental Inflatable Restraint - SIR) system in frontal impacts. The analytical tools used are the explicit finite element code, an in-house sensor closure time prediction program, and a full vehicle finite element model. Nodal point information obtained from the full vehicle finite element simulation is used to predict the sensor closure time of the airbag system. This analytical method can provide the important crash signature information for a SIR system development of a new vehicle program. In this paper, 0-degree frontal impacts at four different impact speeds with two different bumper energy absorption systems are studied using the non-linear finite element computer program DYNA3D. It is concluded that this analytical method is very useful to predict the SIR sensor closure time.

Although rollover crashes represent a small fraction (approximately 3%) of all motor vehicle crashes, they account for roughly one quarter of crash fatalities to occupants of cars, light trucks, and vans (NHTSA Traffic Safety Facts, 2004). Therefore, the National Highway Traffic Safety Administration (NHTSA) has identified rollover injuries as one of its safety priorities. Motor vehicle manufacturers are developing technologies to reduce the risk of injury associated with rollover collisions. This paper describes the development by General Motors Corporation (GM) of a suite of laboratory tests that can be used to develop sensors that can deploy occupant protection devices like roof rail side air bags and pretensioners in a rollover as well as a discussion of the challenges of conducting this suite of tests.

Computational analysis of occupant safety has become an efficient tool to reduce the development time for a new product. Multi-body computer models (e.g. Madymo models) that simulate vehicle interior, restraint system and occupants in various crash modes have been widely used in the occupant safety area. To ensure public safety, many injury numbers, such as head injury criteria, chest acceleration, chest deflection, femur loads, neck load, and neck moment, are monitored. Deterministic optimization methods have been employed to meet various safety requirements. However, with the further emphasis on product quality and consistency of product performance, variations in modeling, simulation, and manufacturing, need to be considered.

Sled tests simulating full-frontal rigid barrier impact were conducted using the Hybrid III 5th female and the 50th male anthropomorphic test devices (ATDs). The ATDs were positioned in the outboard rear seat of a generic small car environment. Two belt configurations were used: 1) a standard belt with no load limiter or pre-tensioner and 2) a seatbelt with a 4.5 kN load-limiting retractor with a stop function and a retractor pre-tensioner (LL-PT). In the current study, the LL-PT belt system reduced the peak responses of both ATDs. Probabilities of serious-to-fatal injuries (AIS3+), based on the ATDs peak responses, were calculated using the risk curves in NHTSA’s December 2015 Request for Comments (RFC) proposing changes to the United States New Car Assessment Program (US-NCAP). Those probabilities were compared to the injury rates (IRs) observed in the field on point estimate basis.

This paper summarizes the results of tests conducted with anesthetized animals that were exposed to a wide range of passenger inflatable restraint cushion forces for a variety of impact sled - simulated accident conditions. The test configurations and inflatable restraint system concepts were selected to produce a broad spectrum of injury types and severities to the major organs of the head, neck and torso of the animals. These data were needed to interpret the significance of the responses of an instrumented child dummy that was being used to evaluate child injury potential of the passenger inflatable restraint system being developed by General Motors Corporation. Injuries ranging from no injury to fatal were observed for the head, neck and abdomen regions. Thoracic injuries ranged from no injury to critical, survival uncertain.

Automotive industries are emphasizing more and more on occupant safety these days, due to an increase in awareness and demand to achieve high safety standards. They are dependent on simulation tools to predict the performance of subsystems more accurately. The challenges being encountered are designs which are getting more complex and limitations in incorporating all real-life scenarios, such as to include all manufacturing considerations like forming and welding effects. Latest versions of solvers are slowly introducing new options to include these actual scenarios. Ls-Dyna is one of the explicit solvers to introduce these possibilities. The process of including stamping details into crash simulation is already being performed in the automotive industry. However, for seatbelt pull analysis, this has not been explored much.