Refine Your Search

Topic

Author

Affiliation

Search Results

Technical Paper

Materials Modeling for Engineering Thermoplastics in FEA Under High-Strain Loading

2000-03-06
2000-01-1167
Accurate predictive finite-element models can help engineers meet cost and timing targets in vehicle development. For components made of engineering thermoplastics, accurate materials characterization in finite-element models is an essential component of predicting part performance. Accurate materials modeling is especially important in applications where there are high speeds and high loading conditions, such as with airbag doors, knee bolsters, and pillar trim. This paper addresses materials modeling of engineering thermoplastics for finite-element models that are subjected to high-impact and high-speed loading. Here, the basics of polymeric behavior are introduced and a comparison of the accuracy of different materials characterization techniques in an impact loading is presented. The material under analysis here is polycarbonate (PC), an amorphous thermoplastic.
Technical Paper

An Application of Magnesium Alloy to Passenger Air Bag Housing

2000-03-06
2000-01-1115
To achieve a mass goal and minimize the bell mouthing phenomenon of Passenger Air Bag Housing which takes place when the air bag is in explosive action and detrimental to the safety of passenger side because excessive canister bell mouthing may distort and crash the top surface of instrument panel, a study on the replacing process of a PAB housing to a different material and process was performed. The explosive action of current steel PAB housing was firstly analized to evaluate the reaction forces transferred through the PAB and find out the adaptable material for replacing process. Due to the properties among the die casting alloys, the AM60B alloy was chosen for our new material for PAB housing. Then, stress analysis by the finite element method was performed for a design modification of magnesium one piece housing.
Technical Paper

Information Flow Analysis for Air Bag Sensor Development

2000-03-06
2000-01-1388
A statistical theory is used to quantify the amount of information transmitted from a transducer (i.e., accelerometer) to the air bag controller during a vehicle crash. The amount of information relevant to the assessment of the crash severity is evaluated. This quantification procedure helps determine the effectiveness of different testing conditions for the calibration of sensor algorithms. The amount of information in an acceleration signal is interpreted as a measure of the ability to separate signals based on parameters that are used to assess the severity of an impact. Applications to a linear spring-mass model and to actual crash signals from a development vehicle are presented. In particular, the comparison of rigid barrier (RB) and offset deformable barrier (ODB) testing modes is analyzed. Also, the performance of front-mounted and passenger compartment accelerometers are compared.
Technical Paper

5th Percentile Driver Out of Position Computer Simulation

2000-03-06
2000-01-1006
A finite element model of a folded airbag with the module cover and steering wheel system was developed to estimate the injury numbers of a 5th percentile female dummy in an out-of-position (OOP) situation. The airbag model was correlated with static airbag deployments and standard force plate tests. The 5th percentile finite element dummy model developed by First Technology Safety Systems (FTSS) was used in the simulation. The following two OOP tests were simulated with the airbag model including a validated steering wheel finite element model: 1. Chest on air bag module for maximum chest interaction from pressure loading (MS6-D) and 2. Neck on air bag module for maximum neck interaction from membrane loading (MS8-D). These two simulations were then compared to the test results. Satisfactory correlation was found in both the cases.
Technical Paper

Driver Fatalities in Frontal Crashes of Airbag-Equipped Vehicles: A Review of 1989-96 NASS Cases

2000-03-06
2000-01-1003
Using data from the National Automotive Sampling System/Crashworthiness Data System (NASS/CDS) for1995-96, this study updates previous analyses of driver fatalities in airbag-equipped vehicles in the NASS/CDS database for 1989-93 and 1989-94. A total of 59 cases of frontal crashes of airbag-equipped vehicles with driver fatalities were identified in these 8 years of NASS/CDS data, but in 9 cases the fatalities were not related to the impacts (e.g., fire, medical condition). Vehicle intrusion was the cause of the fatal injuries in 27 cases, and 7drivers died from injuries sustained when they were either partially or totally ejected from their vehicles. There was one case in which the airbag did not deploy, although the crash conditions indicated it should have. One driver died from contact with a nonintruding vehicle surface, and the causes of the fatal injuries in 5 cases were unknown.
Technical Paper

Comparison of Vehicle Structural Integrity and Occupant Injury Potential in Full-frontal and Offset-frontal Crash Tests

2000-03-06
2000-01-0879
The frontal crash standard in the USA specifies that the full front of a vehicle impact a rigid barrier. Subsequently, the European Union developed a frontal crash standard that requires 40 percent of the front of a vehicle to impact a deformable barrier. The present study conducted paired crashes of vehicles using the full-frontal barrier procedure and the 40 percent offset deformable barrier procedure. In part, the study was to examine the feasibility of adding an offset test procedure to the frontal crash standard in the USA. Frontal-offset and full-frontal testing was conducted using both the mid-size (50th percentile male Hybrid III) and the small stature (5th percentile female Hybrid III) dummies. Five vehicle models were used in the testing: Dodge Neon, Toyota Camry, Ford Taurus, Chevrolet Venture and Ford Contour. In the crash tests, all dummies were restrained with the available safety belt systems and frontal air bags.
Technical Paper

Air Bag Parameter Study with Out-Of-Position Small Female Test Devices

2000-06-19
2000-01-2204
The development of the Advanced Restraint System has lead to an innovative way in which we evaluate the systems effect on the occupant. This paper presents some initial investigation into the driver airbag system that consists of an inflator, cushion fold, tear seam pattern, and offset of the airbag cover to steering wheel rim plane. An initial DOE is reviewed to establish significant parameters and to identify equations for further investigation.
Technical Paper

STATIC OUT-OF-POSITION TEST METHODOLOGIES: IDENTIFYING A REALISTIC WORST CASE FOR SMALL STATURE FEMALE DRIVERS

2001-06-04
2001-06-0228
The NHTSA’s final interim rule on advanced airbags describes two static out-of-position test procedures for the 5th percentile female dummy. Recent testing by Transport Canada suggests that the procedure described for the positions may not be representative of the worst case condition and may include elements that are not realistic for a 5th percentile driver. A modified positioning procedure which prioritizes chest placement and positions the steering wheel in a location that is compatible with the visibility and comfort requirements of a 5th percentile female driver is described. A modified chin on hub procedure is also described. Results of the modified procedures are compared to the NHTSA procedures for a number of late model vehicles.
Technical Paper

Study of Airbag Interference with Out of Position Occupant by the Computer Simulation

2001-06-04
2001-06-0233
In the past few years many cases of serious injury to out of position occupants caused by airbag deployment have been reported in the United States. FMVSS208, which requires equipping automobiles with airbags, was revised to reduce the risk of deployment injury by airbags. The new regulation defines some new test procedures and several performance requirements regarding the out of position tests. The uniform gas pressure analysis has been a general analysis method for airbag deployment with computer simulations up to this point. However the membrane force of the airbag is a major parameter for the interference between the airbag and an out of position occupant, and the gas used for airbag deployment has the characteristics of a compressible fluid which is difficult to model. Therefore the general Euler-Lagrange coupling method will be necessary for the computer simulation of out of position occupant interference.
Technical Paper

TOR (TOTAL OCCUPANT RECOGNITION) SYSTEM

2001-06-04
2001-06-0242
The TOR-system is based on a sensor combination using 2 different physical properties independent of each other, in order to realise an occupant detection system. Purpose of the system is to fulfill the NHTSA FMVSS 208 regulation for an automatic suppression system. It includes an additional feature for an automatic suppression zone of 15 – 20 cm around the airbag cover. The system consists of a force sensitive matrix-mat under the seat-cover and an EFD-system (Electrical Field Detection), with sensors in the seatplain, the backrest and the dashboard. Additionally, two sensors installed at the seat-frame provide the information on seat-position and backrest-angle.
Technical Paper

DIFFICULTIES IN DETERMINING THE CAUSE OF REAL-WORLD CRASH INJURIES: A CASE STUDY OF A NASS INVESTIGATION

2001-06-04
2001-06-0065
This paper describes a National Automotive Sampling System (NASS) case in which a parked 1958 Chevrolet Bel Air was rear-ended by a 1991 Dodge Grand Caravan whose unbelted driver sustained fatal chest injuries despite the presence of an airbag. This particular case was chosen because different reviewers of the information from the crash investigation have proposed conflicting conclusions about the role of the airbag in the fatal injuries. The NASS investigators and others concluded that the driver bottomed out the airbag resulting in fatal chest injuries. Insurance Institute for Highway Safety researchers concluded that the driver either was out of position due to late firing of the airbag or was slumped over the wheel due to a high blood alcohol concentration; in either case they attributed the fatal injuries to airbag inflation forces. Thus, in one scenario the airbag had insufficient power, and in the others it had too much power.
Technical Paper

Development of Performance Specifications for the Occupant Classification Anthropomorphic Test Device (Ocatd)

2001-06-04
2001-06-0063
Advanced airbag systems use a variety of sensors to classify vehicle occupants so that the airbag deployment can be modulated accordingly. One potential input to such systems is the distribution of pressure applied to the seat surface by the occupant. However, the development of such systems is hindered by the lack of suitable human surrogates. The OCATD program has developed two new surrogates for advanced airbag applications representing a small adult woman and a six-year-old child. This paper describes the development of performance specifications for the OCATDs based on a study of the seat surface pressure distributions produced by vehicle occupants. The pressure distributions of sixty-eight small women and children ranging in body weight between 23 and 48 kg were measured on four seats in up to twelve postures per seat. The data were analyzed to determine the parameters of the pressure distribution that best predict occupant body weight.
Technical Paper

Development and validation of the urgency algorithm to predict compelling injuries

2001-06-04
2001-06-0051
The URGENCY algorithm uses data from on-board crash recorders to assist in identifying crashes that are most likely to have time critical (compelling) injuries. The injury risks projected by using the NASS/CDS data are the basis for the URGENCY algorithm. This study applied the algorithm retrospectively to a population of injured occupants in the database from the University of Miami School of Medicine, William Lehman Injury Research Center (WLIRC). The population selected was adult occupants in frontal crashes that were protected by three-point belts plus an air bag. For the cases with greater than 50% predicted MAIS 3+ injury probability, 96% of the occupants in the study had MAIS 3+ injuries. For the cases with less than 10% predicted MAIS 3+ injury probability, 63% did not have MAIS 3+ injuries. Most of the of MAIS 3+ injuries not predicted involved injuries in multiple impact crashes, pole crashes or close-in occupants injured by air bag deployment.
Technical Paper

DEVELOPMENT OF A CRASHWORTHY SYSTEM: INTERACTION BETWEEN CAR STRUCTURAL INTEGRITY, RESTRAINT SYSTEMS AND GUARDRAILS

2001-06-04
2001-06-0052
In the development of a crashworthy road transport system, guard-rails could play an important role in preventing frontal collisions on roads without separated lanes and in avoiding collisions with roadside objects. Crash pulses in crashes into guard rails may differ from e.g. car-to-car collisions, concerning the duration and mean acceleration. If the characteristics of crash pulses into guard-rails differ from those used in the design of vehicle interior restraint systems, it may influence the performance of these systems.. Collisions with soft guardrails, such as wire ropes, may often have pulse duration of 200 ms or more. The performance of e.g. airbag systems in collisions with such duration is rarely studied. This study presents the results of six crash tests, carried out with identical vehicles running into three types of guard rails at two different test speeds, 80 and 110 km/h, and at two different impact angles, 45° and 20° respectively.
Technical Paper

DEVELOPMENT OF AN OCCUPANT POSITION SENSOR SYSTEM TO IMPROVE FRONTAL CRASH PROTECTION

2001-06-04
2001-06-0058
In motor vehicle crashes where an occupant has been seriously or fatally injured from a deploying air bag, a common finding has been that the occupant was in close proximity to the air bag (or out-of-position) at the time of deployment. The occupant may have been out-of-position for a variety of reasons including: driver loss of consciousness, pre-impact braking, multiple impacts, rear facing child seat installation, or late firing of the air bag after the occupant has already been forced against the air bag by the crash deceleration. Considerable research has been initiated to develop new or enhanced injury countermeasures to mitigate injuries to persons, particularly children, who are out-of-position at the time of air bag deployment. This paper reports on the development of an occupant position sensor that might be used in conjunction with dual stage or multi-stage inflation technologies for modulating air bag deployment.
Technical Paper

Body part study from real life accidents for a new SID (side impact dummy)

2001-06-04
2001-06-0022
The purpose of this paper is to review injuries found in real-world lateral collisions and determine the mechanisms responsible for certain kinds of biomechanical failure. During the last years the distribution of deaths among the different types of accidents has changed. Lateral collisions now are the most frequent cause of fatal and other serious injuries. Every third accident is an impact from the side, while every second fatality is the result of a lateral accident. Just a few years ago this value was no higher than 30%. This is probably the result of increasing safety standards for frontal collisions (airbags, seatbelt usage, structural improvements of cars, etc.). Although the number of registered vehicles increased, the total amount of fatalities decreased during the same period. Thus it is now necessary to pay greater attention to the lateral accident situation in order to improve road safety and decrease the number of traffic injuries.
Technical Paper

ANALYTICAL EVALUATION OF AN ADVANCED INTEGRATED SAFETY SEAT DESIGN IN FRONTAL, REAR, SIDE, AND ROLLOVER CRASHES

2001-06-04
2001-06-0017
Analytical computer simulations were used to optimize and fabricate an Advanced Integrated Safety Seat (AISS) for frontal, rear, side, and rollover crash protection. The AISS restraint features included: dual linear recliners, pyrotechnic lap belt pretensioner, 4 kN load-limiter, extended head restraint system, rear impact energy absorber, seat-integrated belt system, and side impact air bag system. The evaluation and optimization of the AISS design was achieved through analytical simulations using MADYMO multi-body analysis software, LS-DYNA3D finite element software, and through LS-DYNA3D/MADYMO coupling. Frontal and rear impact sled tests were also conducted with physical AISS prototypes and baseline integrated seats to verify performance. Both the analytical modeling and the experimental sled testing demonstrated safety improvements over the baseline integrated seat.
Technical Paper

ANALYSIS OF OCCUPANT PROTECTION PROVIDED TO 50TH PERCENTILE MALE DUMMIES SITTING MID-TRACK AND 5TH PERCENTILE FEMALE DUMMIES SITTING FULL-FORWARD IN CRASH TESTS OF PAIRED VEHICLES WITH REDESIGNED AIR BAG SYSTEMS

2001-06-04
2001-06-0015
Historically, the United States Federal Motor Vehicle Safety Standard No. 208 (FMVSS No. 208) has used 50th percentile male dummies seated in the mid-track position to evaluate occupant protection in frontal crashes. As a result of field investigations of air bag-related fatalities and serious injuries involving short-stature female drivers, more recent research has focused on improving crash protection using the 5th percentile female dummy in a full-forward seat position. A series of 48 kmph (30 mph) full frontal rigid barrier crash tests were conducted with belted and unbelted 5th percentile female dummies in the full-forward seat position of Model Year (MY) 1999 vehicles with redesigned air bags (certified to the FMVSS No. 208 sled test). Tests were also conducted using identical vehicles with the 50th percentile male dummies seated mid-track.
Technical Paper

Air bag crash investigations

2001-06-04
2001-06-0009
The performance of air bags, as an occupant protection system, is of high interest to the National Highway Traffic Safety Administration (NHTSA or Agency). Since 1972, the NHTSA has operated a Special Crash Investigations (SCI) program which provides in-depth crash investigation data on new and rapidly changing occupant protection technologies in real-world crashes. The Agency uses these in-depth data to evaluate vehicle safety systems and form a basis for rulemaking actions. The data are also used by the automotive industry and other organizations to evaluate the performance of motor vehicle occupant protection systems such as air bags. This paper presents information from NHTSA's SCI program concerning crash investigations on air-bag-equipped vehicles. The paper focus is on data collection and some general findings in air bag crash investigations including: air-bag-related fatal and life-threatening injuries; side air bags; redesigned air bags and advanced air bags.
Technical Paper

Development of a Hybrid III 5th Percentile Facet Dummy Model

2001-03-05
2001-01-1050
A MADYMO multibody model of the Hybrid III 5th percentile female dummy has been developed. Most attention is placed on modelling the thorax, pelvis-abdomen, head and neck. Those parts are modelled with facet surfaces and deformable bodies are used for the thorax. The remaining dummy parts are identical to an existing ellipsoid model. The facet component models have a more detailed geometry and are therefore more realistic than the ellipsoid model. The model enables accurate interaction with a FE lap belt, or seat, or airbag. The dummy model has been tested and validated using component tests and full dummy tests. From the results, it can be concluded that the model is an improved tool, which will give engineers more confidence concerning predictability. The model is slightly slower than the ellipsoid model, but still fast enough to perform parametric studies and optimizations.
X