Browse Topic: Airbag systems

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Evaluation of General Motors Event Data Recorder Performance in Semi-Trailer Rear Underride Collisions2020-01-13284/14/2020
The objective of this study was to analyze the validity of airbag control module data in semi-trailer rear underride collisions. These impacts involve unusual collision dynamics, including long crash pulses and minimal bumper engagement [1]. For this study, publicly available data from 16 semi-trailer underride guard crash tests performed by the Insurance Institute for Highway Safety (IIHS) were used to form conclusions about the accuracy of General Motors airbag control module (ACM) delta-V (ΔV) data in a semi-trailer rear underride scenario. These tests all utilized a 2009 or 2010 Chevrolet Malibu impacting a stationary 48’ or 53’ semi-trailer at a speed of 35 mph. Nine tests were fully overlapped collisions, six were 30% overlapped, and one was 50% overlapped [2]. The IIHS test vehicles were equipped with calibrated 10000 Hz accelerometer units. Event Data Recorder (EDR) data imaged post-accident from the test vehicles were compared to the reference IIHS data. For each test, root mean square error (RMSE), the percent error over time, and the difference between the EDR ΔV and the IIHS ΔV, was quantified, plotted, and related to crash pulse. This analysis revealed a general trend of decreasing EDR ΔV parity with an increasing crash pulse duration, although overall differences remained low for most tests. Eleven tests, all with airbag deployments, converged towards an average of 3.3% error at the end of the crash pulse, which were 150-270 ms. EDR recorded ΔVs were in the range of 29.8-39.9 mph. Five tests, three of which were non-deployments, diverged to higher percentage error averaging 12.7% at an EDR ΔV of 31.8-40.0 mph. All higher error tests were 30% overlapped and had the highest crash pulse durations of 240-300 ms. One fully overlapped test generated highly unusual EDR data due to failure of the rear underride guard mounting bolts and plates.
Famiglietti, Nicholas, Hoang, Ryan, Fatzinger, Edward, Landerville, Jon
Innovative Active Head Restraint System in a Car: Safety Assessment with Virtual Human Body Model2020-01-09794/14/2020
The aim of this study is to use numerical simulations for safety assessment of an innovative active head restraint system. This system was developed to protect the head and neck of an occupant in a car without a head airbag during a side impact. Its FE model is created and embedded it in a model of a small car with a side airbag. The dynamics of the head restraint activation are also taken into account. The virtual human body model Virthuman is used to represent occupants. The model is scaled for pre-selected human individuals to cover large numbers of occupants of different sizes. It extends conventional virtual evaluation of new safety designs via existing pre-defined mono-purpose side dummies and their FE models. The benefit of the head restraint system is evaluated in side impact scenarios inspired by the pole tests performed by EuroNCAP. Transversal impacts to a pole at 29 and 32 km/h are considered at 90° and 75° angles from driver and the opposite side. Also, the far side impact prescribed with an acceleration pulse according to EuroNCAP is considered. Various initial driver sizes in standard seated positions are tested. To extend the study beyond standard testing protocols, out-of-position of driver is also considered, leading to more than 100 simulations of impact scenarios in total. The effect of the innovative head restraint system is assessed from the point of view of driver injury risk.
Vychytil, Jan, Hlucha, Jana, Kovar, Ludek, Kostikova, Martina, Moravcova, Pavlina, Bucsuhazy, Katerina
The Effects of Small Seat Swiveling Angles on Occupant Responses during a Frontal Impact2020-01-05714/14/2020
In highly automated vehicles (HAVs), new seat configurations may be desirable to allow occupants to perform new activities. One of the current HAV concepts is the swiveled seat layout, which might facilitate communication between occupants. The main objective of this study was to investigate the effects of seat swiveling angles on occupant kinematics and injury risk predicted by a Human Body Model (HBM) during a frontal impact. A detailed 50th percentile male HBM (GHBMC M50-O) was subjected to two frontal crash pulses in a sled setup. The model was positioned on a semi-rigid seat and restrained using a pre-inflated airbag and a three-point seatbelt. Simulations included four seat swiveling angles (0, -10, -20, and -30 degrees), three occupant positions (Sedan driver, large VAN driver or Laptop user), two airbag initial locations (nominal or matching the head Y location), and the inclusion of lateral supports on the seat pan. The effects of the seat swiveling angle were similar for all occupant positions. With the airbag in the nominal location, higher seat swiveling angles led to a higher head lateral displacement and a higher risk of head injury, especially for the BrIC criterion. The Sedan driver position had higher BrIC and a larger head lateral excursion than the other two positions. This could be mitigated by aligning the airbag location with the head. Pelvic fractures were also predicted for the configurations with the highest swiveling angles. These fractures were limited by the use of seat pan lateral supports. Overall, the model responses were sensitive to both seating configurations and occupant postures, and the results suggest that swiveled seating may increase the injury risk, especially for the head and pelvis. However, simple countermeasures, such as adapted airbag location or adding lateral seat pan supports, seemed possible to mitigate the risk.
Grébonval, Cyrille, Trosseille, Xavier, Petit, Philippe, Wang, Xuguang, Beillas, Philippe
The Effects of Front-Mounted Accessories on Air Bag Sensors and CrashworthinessJ2431_201910 (Current)10/9/2019
Almost all light trucks now are being manufactured with at least a driver side air bag and all will have dual air bags by 1998. The driving forces behind this feature are occupant safety, federal regulations, and competition in the industry. Along with the booming popularity of pickups and SUVs, they are commonly accessorized with a wide variety of products. Many accessories for four-wheel drives in particular are mounted on the front of the vehicle. These products include grille/brush guards, winches, snow plows, replacement bumpers, bicycle carriers, etc. Concerns have arisen over the compatibility of these accessories with the vehicle’s air bag system. The vehicle manufacturers are concerned because of their huge investment in design and crash test verification of the complete vehicle system and keen awareness of the federal regulations. The crushability of the front bumper and supporting structure are key elements in the system, so alterations to that area become logical concerns. The accessory manufacturers, dealers, and installers are concerned because the very core of their business could be at risk. The unknowns can range from fear of setting off an airbag while working on the vehicle to liability issues in an injury accident situation. In some cases, the installation of the product is contrary to recommendations from the vehicle manufacturer and may void the warranty. The ultimate customers (end users) are in a unique situation and are not being well served in some situations. Their dilemma stems from the conflict between what a manufacturer is willing to certify for sale and what the customer needs and expectations are. Their needs in vehicle equipment can vary widely from making a living to recreational lifestyle issues to simplify the desire to individualize. The precedent for front-mounted accessories is well established. The customers for both the vehicle and the equipment are there, so finding ways for them to coexist safely is beneficial to all.
Motor Vehicle Council
Machining Capabilities Enhance Space-Related ProgramsTBMG-347367/1/2019
Insaco Quakertown, PA
Innovative Knee Airbag (KAB) Concept for Small Overlap and Oblique Frontal Impacts2019-01-06214/2/2019
Considerable research has been conducted in terms of attempting to reduce lower leg injury risk in full frontal impacts, in some cases by the use of a knee airbag (KAB). However, there has been limited research into the performance of KAB systems during a crash test with increased oblique loading, such as the IIHS small overlap frontal test, an oblique moving deformable barrier test (OI) being researched by NHTSA, and a mobile progressive deformable barrier test (MPDB) that is expected to be implemented by Euro NCAP in the next few years. The objective of the current numerical study was concentrated on the evaluation of an innovative KAB concept design intended to reduce ATD right inboard lower leg/foot responses under small overlap and oblique loading conditions. A novel appendage KAB concept design was developed with the help of morphing and computational studies which were performed with different ATD sizes. In the study, one of the lower leg/foot responses was monitored and compared over a conventional KAB design. Cases investigated in the study showed that the novel appendage KAB concept design acts as a conventional KAB in full frontal impact modes (similar right inboard femur responses) and has the potential to reduce right inboard lower leg/foot responses by an average 16% (small overlap impact mode) and 20% (oblique impact mode) over the conventional KAB design. Furthermore, it was noted that the novel design could potentially be adapted to achieve targeted right inboard lower leg responses in full, offset and oblique frontal crash tests with minimal impact on the left outboard responses.
Makwana, Rahul, Jindal, Pardeep
Performance of Event Data Recorders Found in Toyota Airbag Control Modules in High Severity Frontal Oblique Offset Crash Tests2019-01-06334/2/2019
This paper presents an in-depth analysis of the performance of Event Data Recorders (EDRs) found in the Airbag Control Modules (ACMs), as tested in support of the National Highway Traffic Safety Administration’s Frontal Oblique Offset Program. Previous studies have examined EDR performance in high severity full-frontal barrier crash tests and moving deformable barrier side impact tests. This paper presents data from a high severity oblique frontal impact test in which the vehicle was struck by a moving deformable barrier. This paper examines the results of EDR data downloaded from two 2015 model year Toyota Highlanders, and the results of EDR reported change in velocity (delta-v), to vehicle mounted accelerometers and reference instrumentation. This paper will analyze EDR performance in reporting: Seatbelt buckle status, Occupant Size Classification, Front Passenger, Airbag and seatbelt pretensioner deployment time(s), Longitudinal delta-v, and Lateral acceleration/crash pulse.
Bortles, William, Hostetler, Ryan
Probability of Frontal Airbag Deployment in Bumper-Bumper and Underride Collisions2019-01-06204/2/2019
Airbag deployment thresholds can be a useful metric of collision severity in accident reconstruction applications. The National Automotive Sampling System (NASS) has provided a publicly-available database of real-world motor vehicle collisions, including more than 10,000 event data recorder (EDR) reports retrieved from airbag control modules. These reports typically indicate the airbag deployment status and the corresponding Delta-V of each recorded event. A prior study analyzing crash data in the NASS database demonstrated the airbag deployment threshold varies between vehicle manufacturers and over time. However, the analysis was limited to Ford and GM vehicles due to insufficient data. This paper expands on the prior study of frontal airbag deployment thresholds by analyzing newer years of NASS EDR data (4,000 additional reports). We found that the Delta-V threshold for a 50% probability of deployment event is higher for Toyota than for GM and Ford vehicles. Moreover, SUVs and pickup trucks had higher deployment thresholds than sedans. An increase in Delta-V thresholds was observed for more recent vehicle model years. A higher Delta-V is required for frontal airbag deployment in underride collisions, in which a sedan contacted a vehicle with higher ground clearance (SUV, pickup truck, or van), compared to collisions with direct bumper-bumper engagement. Based on the findings, we developed a logistic regression model that predicts the probability of frontal airbag deployment with a known change in velocity (ΔV = 0 to 45 mph), vehicle manufacturer (GM, Toyota, Ford), vehicle type (sedan, SUV, pickup truck), model year (1994-2001, 2002-2016), and impact configuration (underride, bumper-bumper) with 82% accuracy. This study provides information about airbag deployment behavior beyond what is reported in owner’s manuals and National Highway Traffic Safety Administration (NHTSA) guidelines.
Lee, Felix, McCleery, Caitlin H., Ngo, Christina, Limousis-Gayda, Manon, Hashish, Rami
The Swedish Word for AV Tech19AVEP03_083/1/2019
Veoneer, a new Tier 1 supplier with well-established roots, is moving rapidly into AI, says veteran research boss Ola Boström. The first automotive camera with built-in Deep Learning-considered to be a significant step forward in autonomous-vehicle sensor technology-is due to launch this year. It was developed and will be manufactured by a Tier 1 whose name is still seeking broader recognition in the industry. “What is a…Veoneer?” asked an engineer waiting in the taxi line at this year's CES, when a monorail train wrapped with the company's logo flashed past above. Building brand cred among countless other spin-offs and tech start-ups who are clawing for visibility takes time, of course, even for the independent, publicly-traded Swedish company with 8,600 employees, formerly known as Autoliv's Electronics segment.
Brooke, Lindsay
Products of Tomorrow: January 2019TBMG-335941/1/2019
This column presents technologies that have applications in commercial areas, possibly creating the products of tomorrow. To learn more about each technology, see the contact information provided for that innovation.
Device Detects Subatomic-Scale MotionTBMG-3339712/1/2018
It is relatively easy to measure small movements of large objects, but is much more difficult when the moving parts are on the scale of nanometers, or billionths of a meter. The ability to accurately measure tiny displacements of microscopic bodies has applications in sensing trace amounts of hazardous biological or chemical agents, perfecting the movement of miniature robots, accurately deploying airbags, and detecting extremely weak sound waves traveling through thin films.
Autonomous vehicles present passive-safety challenges18AUTP10_0810/1/2018
Reclined and rotated seating positions are commonly depicted for autonomously driven vehicles. But for the Autoliv engineers tasked with developing occupant safety for tomorrow's self-driving vehicles, those previously improbable seating positions dictate innovative new passive safety protections. “Passive safety for autonomous vehicles is a pretty complicated problem to solve, which is why we're starting out with the simplest scenario: a frontal crash with a front occupant in a partial-recline position,” E. Scott Dershem, Autoliv's Vice President of Product Development, said in an interview with Automotive Engineering at the safety supplier's Auburn Hills, Michigan technical center.
Buchholz, Kami
Potential Effects of Deceleration Pulse Variations on Injury Measures Computed in Aircraft Seat HIC Analysis Testing2017-01-20529/19/2017
Aircraft seating systems are evaluated utilizing a variety of impact conditions and selected injury measures. Injury measures like the Head Injury Criterion (HIC) are evaluated under standardized conditions using anthropomorphic dummies such as those outlined in 14 CFR part 25. An example test involves decelerating one or more rows of seats and allowing a lap-belted dummy to impact components in front of it, which typically include the seatback and its integrated features. Examples of head contact surfaces include video monitors, a wide range of seat back materials, and airbags. The HIC, and other injury measures such as Nij, can be calculated during such impacts. A minimum test pulse, with minimum allowable acceleration vs time boundaries, is defined as part of the regulations for a frontal impact. In this study the effects of variations in decelerations that meet the requirements are considered. A series of Finite Element simulations of a generalized aircraft seat were performed to determine the variation in HIC and Nij observed based on variations in the deceleration pulse. The results indicate that the pulse characteristics affect the resulting head motions and can influence the ability to pass the HIC analysis test.
Friedman, K, Mattos, G, Bui, K, Hutchinson, J, Jafri, A, Paver PhD, J
Avoiding Safety Scandals by Controlling the Risk of Material Changes2017-01-03733/28/2017
Achieving functional safety in mechatronic systems with growing product functionality is a major challenge in systems engineering. Following the current discussion, this challenge is mostly allocated to electronics and software development. For most of the scenarios this focus is feasible. Product design - the construction of the product - defines the properties and the appearance of the product by shape, material and assembly. So, the product design is often not under control of the safety management system. A hazardous deviation of part shape can be easily identified after the parts product or at least at its mounting. A wrong assembly is controlled by assembly documentation or data (e.g. screw torques) and identified at end of assembly line checks. The identification of a hazardous material choice depends on the product material class. Product materials can be separated into two classes: passive or active materials. Passive materials (e.g. car body) can be distinguished in as passive materials with constant shape (stiff) and variable shape (flexible) (e.g. damper, spring). The liability of those materials regarding their usage in the product is tested in labs in prototypes in prior. Active materials (e.g. fluids, gases), or functional materials fulfill, trigger or directly influence the functionality of the product. The choice of a functional material is not always made by the electronics engineering. Therefore, it is not under control of safety management processes. Never the less functional material, especially with radical behavior, underlie other safety regulation. Explosives for example, can be integrated in a product or system and are restricted by specific standards. This technology report reflects the verification methods of functional materials today. The responsibility of the product design engineer is discussed as well as the relevant standards. The challenge of achieving complete product compliance with functional materials is shown by the technology analysis of the Takata airbag recall. The required and available methods to control risks of functional materials choice and change are listed and rated. Gaps in existing engineering processes and regulations are identified. A strategy to close those gaps is explained.
Koark, Fabian Jorg Uwe, Beul, Christian
Bolt EV seat design cuts weight, delights taller passengers16AUTP08_088/1/2016
Stepping into the back seat of Chevrolet's 2017 Bolt EV, one attribute of the car is immediately evident: the designers and engineers didn't neglect the outsized physical dimensions of tall passengers. In fact, even those whose height and inseam length are well beyond the 90th percentile-that would include the author-will appreciate the Bolt EV's surprisingly easy ingress and egress. That's because the car's front seats were designed with the back-seaters in mind, as well as being designed to reduce mass.
Brooke, Lindsay
Development of Plastic Fracture Simulation Technology for Passenger Airbag Tear Line2015-01-13414/14/2015
The explicit methods analysis solver LS-DYNA was used to create technology for simulating airbag deployment and plastic airbag lid tear-away in the front passenger seat. The present study clarified the mechanical properties and the transitions in fracture pattern of the material at low temperature plastic this way, an appropriate modeling method was developed and the prediction accuracy of the simulation of airbag lid tear-away on deployment was increased. Tensile testing of the material was carried out where there were differences in thickness of the tear-away section and the fracture characteristics were determined. A material model was created by analyzing changes in fracture characteristics and collapse patterns, taking into consideration the effects of strain and strain rate localization on fracture strain as well as ductile-brittle fracture transition. Next, airbags were subjected to the impactor testing. It was confirmed that the reaction force characteristics with that impactor had a good correlation with the simulation model. Finally, the airbag that matched the reaction force characteristic and the instrument panel model were combined. The simulation result was compared with the experimental results of the tear-away deployment, leading to good correlations with the tear-away process in simulations and experiments. It was also found that the two factors were important with regard to the reproducibility of the progressive tear-away process. They were changes in fracture mode due to the strain rate and strain rate dependence of fracture strainIn addition, it is necessary to pay careful attention to the modeling method due to the varying material thickness. More over prototypes with various significant parameters were created and subjected to accuracy verification. These prototypes also yielded good results for reproducibility. The sufficient accuracy aimed to reduce the number of prototypes in the vehicle development was confirmed.
Sugaya, Hisaki, Tosa, Yoshiyuki, Imura, Kazuo, Mae, Hiroyuki
Simplification of the Variable Vent Structure of the Passenger Airbag by Applying a Slit-Type Vent2015-01-14554/14/2015
The reaction force of a traditional passenger airbag tends to reduce after the initial inflation and before contact with the occupant, since the vent structure discharging the internal gas is always open. A potential means to prevent this drop in the airbag reaction force includes the addition of a variable vent structure which keeps the vent hole closed until occupant contact to maintain the airbag internal pressure and then opens to vent gas after the contact. However, variable vent structures may involve issues from a complicated structure due to additional parts in its construction. The goal of this study was to develop a simplified variable vent structure. A slit-type vent structure was investigated. This structure incorporates no additional parts to a conventional airbag with a hole-type vent. Static deployment tests and impactor tests were conducted to measure the effect of the slit-type vent structure and to compare it with the conventional airbag. Additionally, the correlation between slit length/depth and the airbag reaction force was investigated by performing impactor tests to clarify the potential contribution of this vent structure to the optimization of the overall restraint system. The results of this study showed that a simple variable vent concept was achieved with the slit type vent structure. It was also found that the slit length and depth correlates with the airbag reaction force.
Torikai, Kenshi, Higuchi, Hitoshi, Seki, Kazuhiro
Effects of Crash Pulse, Impact Angle, Occupant Size, Front Seat Location, and Restraint System on Rear Seat Occupant Protection2015-01-14534/14/2015
In this study, two sled series were conducted with a sled buck representing a compact vehicle. The first series of tests focused on the effects of crash pulse, impact angle, occupant size, and front seat location on rear seat occupant restraint with a generic rear-seat belt system without pre-tensioner or load limiter. The second series of tests focused on investigating the benefit of using advanced features for rear-seat occupant restraint in the most severe crash condition in the first sled series. The first series of tests include 16 test conditions with two impact angles (0° and 15°), two sled pulse (soft and severe), and four ATD sizes (HIII 6YO, HIII 5th female, HIII 95th male, and THOR-NT) with two ATDs in each test. The driver seat was located at the mid position, while the front passenger seat was positioned such that a constant distance between the ATD knee and the front seat is achieved. In all the tests, a generic rear-seat belt system without pre-tensioner, load limiter or dynamic locking tongue (DLT) was used. Test results from the first sled series showed that crash pulse and occupant size are the two dominating factors affecting the ATD kinematics and injury measurements, while impact angle and front-seat location are not statistically significant. Although no head-to-front-seat contact occurred in any of the tests, in general, the severe crash pulse would result in chest deflections over the injury criteria for adult ATDs with higher ATD excursions than for the soft crash pulse. These results are consistent to those from the field data in that chest injuries are the most common injuries in rear-seat adult occupants. The HIII 6YO ATD sustained submarining kinematics in all the tests due to the slouching pre-crash posture. In an attempt to help further reduce the chest loading while managing the head excursion, 3-point belts with pre-tensioner and load limiter, 4-point belts, DLT, inflatable belts, Bag in Roof (BiR) concept, and Self Conforming Rear-seat Air Bag (SCaRAB) concept were investigated in the second series of sled tests, in which only the most severe testing condition (0° and severe pulse) in the first sled series was used. Reductions in occupant loading were shown with these advanced restraint systems, especially the airbag features, to help reduce head, neck, and chest injury measures for rear-seat occupants. This study demonstrated the importance of considering the effects of occupant size and crash pulse on rear-seat occupant protection. Advanced restraint systems including features such as a pre-tensioner, a load limiter, and an airbag, may have the potential to help provide additional protection for rear-seat occupants with diverse occupant sizes.
Hu, Jingwen, Fischer, Kurt, Lange, Paul, Adler, Angelo
Low Light Image Enhancement Using Color Transfer2015-01-03124/14/2015
Advanced Driver Assistance System (ADAS) in combination with other active safety features like air bags etc. is gaining popularity. Vision based ADAS systems perform well under ideal lighting, illumination and environmental conditions. However, with change in illumination and other lighting related factors, the effectiveness of vision based ADAS systems tend to deteriorate. Under conditions of low light, it is therefore important to develop techniques that would offset the effects of low illumination and generate an image that appears as if it were taken under ideal lighting conditions. To accomplish this, we have developed a method, that uses local color statistics from the host image with low illumination, and enhance the same using an adaptive color transfer mechanism. By taking cues from the properties of ideal images that are saved in a database, the proposed method tends to recreate the input scene (with low illumination), into a near ideal scene, based on the database images. Visual and quantitative evaluation of our method confirms that it performs well under very low light conditions as well, where standard algorithms tend to fail.
Gangadharan, Jiji, Mani, Shanmugaraj, Kutty, Krishnan
Development of Prediction Method for Dynamic Strain on Windshield during Passenger Airbag Deployment2015-01-13304/14/2015
The objective of this study is to accurately predict the dynamic strain on the windshield caused by the deployment of the airbag in a short term without vehicle tests. The following assumption is made as to the dynamic pressure distribution on the windshield: The deployment of the airbag is fast enough to ignore spatial difference in the patterns of the pressure time histories. Given this assumption, significant parameters of the dynamic pressure distribution are as follows: 1) the distribution of the maximum pressure during contact between the airbag and the windshield, and 2) the characteristic of the force time histories applied to the windshield by the deploying airbag. In this study, the prediction method consists of a simplified airbag deployment test and an FE simulation. The simple deployment test was conducted to measure the peak pressure distribution between the airbag and a flat panel simulating the windshield. The pressure time history curves were determined by scaling the force time histories from the load cells. The scale factor was identified for each of the measuring points on the pressure measurement film. Prescribed pressure time histories were directly applied to the part of the FE mesh specifically used to load the windshield. In order to validate the developed prediction method, the strain from the FE simulation was compared with that from strain gauges in the vehicle tests. The results showed that the predicted strain on the windshield caused by the airbag deployment correlated well with the data measured in the vehicle tests, suggesting that the prediction method developed in this study can be a valuable tool for improving the efficiency of development.
Tosa, Yoshiyuki, Mae, Hiroyuki
Finite-Element-Based Transfer Equations: Post-Mortem Human Subjects versus Hybrid III Test Dummy in Frontal Sled Impact2015-01-14894/14/2015
Transfer or response equations are important as they provide relationships between the responses of different surrogates under matched, or nearly identical loading conditions. In the present study, transfer equations for different body regions were developed via mathematical modeling. Specifically, validated finite element models of the age-dependent Ford human body models (FHBM) and the mid-sized male Hybrid III (HIII50) were used to generate a set of matched cases (i.e., 192 frontal sled impact cases involving different restraints, impact speeds, severities, and FHBM age). For each impact, two restraint systems were evaluated: a standard three-point belt with and without a single-stage inflator airbag. Regression analyses were subsequently performed on the resulting FHBM- and HIII50-based responses. This approach was used to develop transfer equations for seven body regions: the head, neck, chest, pelvis, femur, tibia, and foot. All of the resulting regression equations, correlation coefficients, and response ratios (FHBM relative to HIII50) were consistent with a set of test-based results. The HIC15 transfer equation was used to transform the cadaver-based risk curve into the HIII50 domain.
El-jawahri, Raed E., Laituri, Tony R., Kim, Agnes S., Rouhana, Stephen W., Weerappuli, Para V.
Evaluation of Air Bag Electronic Sensing System Collision Performance through Laboratory Simulation2015-01-14844/14/2015
Since their inception, the design of airbag sensing systems has continued to evolve. The evolution of air bag sensing system design has been rapid. Electromechanical sensors used in earlier front air bag applications have been replaced by multi-point electronic sensors used to discriminate collision mechanics for potential air bag deployment in front, side and rollover accidents. In addition to multipoint electronic sensors, advanced air bag systems incorporate a variety of state sensors such as seat belt use status, seat track location, and occupant size classification that are taken into consideration by air bag system algorithms and occupant protection deployment strategies. Electronic sensing systems have allowed for the advent of event data recorders (EDRs), which over the past decade, have provided increasingly more information related to air bag deployment events in the field. To further aid in the evaluation of air bag field performance and interpretation of EDR downloads, a test methodology was developed so that controlled actuation of air bag system sensing elements could be achieved that accurately simulates vehicle collision dynamics. This was accomplished with the air bag control module removed from the vehicle and installed on physical actuators (linear and/or rotary) while still connected to the vehicle wiring harness. Controlled excitation of air bag sensing elements while simultaneously monitoring the outputs of the air bag system control module allows for assessment of system performance under various collision pulses and state sensor conditions. The presented test methodology provides a tool for evaluating field performance and EDR reporting in a controlled laboratory environment, without a priori knowledge of the underlying air bag algorithm or the expense and difficulty of running vehicle crashes.
Toomey, Daniel E., Winkel, Eric S., Krishnaswami, Ram
Interior Trims Design Considerations for Roof Mounted Curtain Airbag2015-26-01571/14/2015
Curtain airbag design offers protection in side crash and it plays a critical role in safety of the vehicle. Curtain airbag provides protection to the occupant in many impact events like frontal offset, side barrier, and side pole and rollover condition. For a vehicle to be safe for any side impact condition, the curtain airbag should deploy and take its final shape before any injury happens to the occupant. During deployment, it is important that the airbag chooses a path of minimum resistance and does not get entangled in interior trims. In reality, the trims always do obstruct the path of airbag deployment in some way. Hence, special care has to be taken care for designing areas surrounding curtain like providing hinges, deflector components etc. to avoid being caught. There are about ten different factors on this deployment is dependent upon. This paper discusses these factors and the effect of the factors on the trims and airbag development. Proper care needs to be taken while designing the airbag mounting locations and the protrusions from the trims.
Hendre, Kedar Madhukar, Purohit, Yogesh
Airbag Deployment Thresholds from Analysis of the NASS EDR Database2014-01-04964/1/2014
Accident reconstructionists and others use airbag non-deployment thresholds as an indicator of severity in minor- to moderate-severity accidents. The National Automotive Sampling System (NASS) has accessed and recorded the data stored in the airbag control modules of nearly 6,300 vehicles since 2000 and has made these data publicly available. The goal of this study is to ascertain thresholds from the data based on delta-V and seatbelt use, studying how they may differ among manufacturers and over time. Other data is also examined, such as seatbelt pre-tensioner fire times and airbag deployment signal times. These data have been analyzed for use in accident reconstruction for vehicles which may or may not be supported by a publicly available module download tool. While manufacturers at one point published deployment data in owner's manuals, this has not been the case for approximately five to ten years. The dataset analysis will compare the published data for deployment thresholds to real world accidents. Over time, with the addition of occupant classification systems and dual-stage airbags, there has been an increase in variability for airbag deployment times and thresholds. The analysis thus far shows the thresholds from the dataset to be in general agreement with published data.
Wood, Matthew, Earnhart, Nicholas, Kennett, Kelly
A Proposal of Middle Speed Hybrid III 50 th Dummy Chest Calibration Test2014-01-08104/1/2014
The Hybrid III 50th male dummy is widely used in front impact crash tests in the world to evaluate the vehicle safety performance. The chest impact calibration test should be conducted after certain amount of crash tests to ensure that the dummy has the right performance during the crash tests. The impact velocity in the current chest calibration tests is 6.71 m/s and the chest displacement corridor is 63.5 mm to 72.6 mm, which was based on the cadaver tests carried out in 1970s. After over forty years' development, the vehicle safety has been improved significantly with applications of seat belt and airbag technologies. In the European and China new car assessment program (ENCAP and CNCAP), the higher performance limit for the front impact dummy chest compression is 22mm and the lower performance limit is 50 mm, which is much lower than the dummy chest calibration corridor. In this paper, the dummy rib assembly structure is analyzed and the rib impact FEA simulation was also conducted. It is found the high speed impact will cause the damping material fracture, which is glued on the rib steel, and the glue de bonding. A proposal of middle speed chest calibration test with compression of about 50 mm was made to match the ENCAP and CNCAP lower performance limit.
Zhao, Youmei
Curtain Airbag Linear Impact Simulation Method for FMVSS 226 and NCAP Side Impact2014-01-08054/1/2014
In current inflatable curtain airbag development process, the curtain airbag performance is developed sequentially for the airbag coverage, FMVSS 226, FMVSS 214 and NCAP. Because the FMVSS 226 for the ejection mitigation and the NCAP side impact test require the opposite characteristics in terms of the dynamic stiffness of the inflatable curtain airbag, the sequential development process cannot avoid the iteration for dynamic stiffness optimization. Airbag internal pressure characteristics are can be used to evaluate the airbag performance in early stage of the development process, but they cannot predict dynamic energy absorption capability. In order to meet the opposite requirements for both FMVSS 226 and NCAP side impact test, a test and CAE simulation method for the inflatable curtain airbag was developed. The purpose of this study is to standardize the test setup for comparing the energy absorption capability of inflatable curtain airbag and to make criteria for meeting both FMVSS 226 and NCAP early in the program. This test and CAE simulation method can be used for A to B comparison between curtain airbags and for quantifying the dynamic restraint capability of inflatable curtain airbag. The robust design considering the real crash environment was conducted to determine the best test parameters, for example the shape of the impactor, impact velocity and impactor mass. The developed criteria of the linear impact simulation can be used to meet both FMVSS 226 and NCAP in early stage of the program.
Lee, Jeong Keun, Ahn, Byung-Jae, Hong, Ye Ri
Analysis of High-Speed Sideswipe Collisions Using Data from Small Overlap Tests2014-01-04694/1/2014
Little experimental data have been reported in the crash reconstruction literature regarding high-speed sideswipe collisions. The Insurance Institute for Highway Safety (IIHS) conducted a series of high-speed, small overlap, vehicle-to-barrier and vehicle-to-vehicle crash tests for which the majority resulted in sideswipe collisions. A sideswipe collision is defined in this paper as a crash with non-zero, final relative tangential velocity over the vehicle-to-barrier or vehicle-to-vehicle contact surface; that is, sliding continues throughout the contact duration. Using analysis of video from 50 IIHS small overlap crash tests, each test was modeled using planar impact mechanics to determine which were classified as sideswipes and which were not. The test data were further evaluated to understand the nature of high-speed, small overlap, sideswipe collisions and establish appropriate parameter ranges that can aid in the process of accident reconstruction. An example reconstruction of a small overlap, sideswipe collision using optimization methods based on the planar impact mechanics model is included in the paper. The results of the example reconstruction show that the reconstruction method developed in the paper, using the physical evidence and EDR data, produces useful results.
Brach, R. Matthew, Brach, Raymond M., Pongetti, Katherine
Validation of Event Data Recorders in Side-Impact Crash Tests2014-01-05034/1/2014
This study evaluated the accuracy of 75 Event Data Recorders (EDRs) extracted from model year 2010-2012 Chrysler, Ford, General Motors, Honda, Mazda, and Toyota vehicles subjected to side-impact moving deformable barrier crash tests. The test report and vehicle-mounted accelerometers provided reference values to assess the EDR reported change in lateral velocity (delta-v), seatbelt buckle status, and airbag deployment status. Our results show that EDRs underreported the reference lateral delta-v in the vast majority of cases, mimicking the errors and conclusions found in some longitudinal EDR accuracy studies. For maximum lateral delta-v, the average arithmetic error was −3.59 kph (−13.8%) and the average absolute error was 4.05 kph (15.9%). All EDR reports that recorded a seatbelt buckle status data element correctly recorded the buckle status at both the driver and right front passenger locations. For equipped vehicles that reported side torso, side curtain, and frontal airbag deployment information, all vehicles recorded the correct status. Although only model year 2013 and later EDRs must meet Code of Federal Regulations Title 49 Part 563, seatbelt buckle status and frontal airbag deployment time are required data elements.
Tsoi, Ada, Johnson, Nicholas, Gabler, H.
Repeatability of a Small Overlap and an Oblique Moving Deformable Barrier Test Procedure2013-01-07624/8/2013
NHTSA has developed two different moving deformable barrier-to-vehicle test procedures to assess the vehicle and occupant response in narrow overlap motor vehicle crashes. An assessment of test repeatability is one of the requirements necessary to accept the test procedure as viable. Previous methodologies, coefficient of variation (CV) and similarity analysis were developed to assess the repeatability of vehicle and occupant response in motor vehicle crash tests for full frontal and 40% overlap tests procedures. These will be used for this assessment. Three repeat tests were performed in each test procedure, with all other factors held constant: vehicles of the same make, model, and model year; moving deformable barriers of the same mass, velocity, and barrier face properties; and the same occupant - a THOR 50th percentile adult male in the driver's seat. In general, for this one vehicle make and model the repeatability of both vehicle and occupant response metrics were good for both test modes. In isolated cases, differences in occupant response resulted from the timing of side curtain air bag deployment.
Saunders, James, Parent, Daniel
Comparison of Dummy Kinematics and Injury Response between WorldSID and ES-2 in Side Impact2013-01-05994/8/2013
A new highly biofidelic side impact dummy, the WorldSID 50th percentile male, has been developed under the supervision of the International Organization for Standardization in order to harmonize a number of existing side impact dummies in one single dummy. Momentum is growing for using the WorldSID in safety tests in the EU and the US. In the present study, two Euro-NCAP pole side impact tests were conducted to compare ES-2 and WorldSID responses in a mid-size SUV with respective seating positions as stipulated in the Euro-NCAP test conditions and fitted with the same side airbag. It was found that, compared with ES-2, the chest, abdomen and pelvis accelerations of WorldSID are more sensitive to variation in the applied external load transmitted by the deployed side airbag and door intrusion.
Iwata, Kazuya, Tatsu, Kaoru, Saeki, Hidetsugu, Okabe, Tomosaburo
A New Approach to Input and Output Monitoring for Microcontrollers Supporting Functional Safety2013-01-01854/8/2013
It is very common that a microcontroller is used in a safety relevant system to acquire data from sensors, process the data and then control actuators. With the shrink of technology every few years it becomes ever more common to use digital serial interfaces and high speed PWM links for both inputs and outputs. The microcontroller vendors have responded to the need for functional safety in the CPU cores by lock-stepping them and adding ECC to buses and memories. They are also implementing highly flexible and complex timer peripherals to be able to automate much of the real-time processing of the digital signals. However these timers are becoming significantly large, and many have their own embedded sequence engines or microkernels, which although powerful, often lack the rigorous diagnostic mechanisms required to reach ASILD. Currently the only solution is to use an application level measure to detect timer failures, but the large quantity of signals can lead to a substantial CPU load just for the monitoring tasks. This paper describes how a new I/O Monitoring peripheral can be used to ‘lockstep’ digital input and output signals, using two redundant or diverse timer peripherals. It will outline the problems, the current state of the art, and the proposed new solution, together with some typical use-cases of braking, electrical power steering and airbag.
Brewerton, Simon P.
Validation of Event Data Recorders in High Severity Full‑Frontal Crash Tests2013-01-12654/8/2013
This study evaluates the accuracy of 41 Event Data Recorders (EDR) extracted from model year 2012 General Motors, Chrysler, Ford, Honda, Mazda, Toyota, and Volvo vehicles subjected to New Car Assessment Program 56 kph full-frontal barrier crash tests. The approach was to evaluate (1) the vehicle longitudinal change in velocity or delta-V (ΔV) as measured by EDRs in comparison with the high-precision accelerometers mounted onboard test vehicles and (2) the accuracy of pre-crash speed, seatbelt buckle status, and frontal airbag deployment status. On average the absolute error for pre-crash speed between the EDR and reference instrumentation was only 0.58 kph, or 1.0% of the nominal impact speed. In all cases in which the EDRs recorded the seatbelt buckle status of the driver or right front passenger, the modules correctly reported that the occupants were buckled. EDRs reported airbag deployment correctly in all of the tests. The average absolute error was 4.20 kph (6.6%) for final longitudinalΔV and 4.32 kph (6.6%) for maximum longitudinal ΔV. Our results show that EDRs underreport the reference instrumentation ΔV in the vast majority of cases.
Tsoi, Ada, Hinch, John, Ruth, Richard, Gabler, Hampton
The Front Center Airbag2013-01-11564/8/2013
General Motors and the Takata Corporation have worked together to bring to production a new, industry first technology called the Front Center Airbag which is being implemented on General Motors' 2013 Midsize Crossover Vehicles. This paper reviews field data, describes the hardware, and presents occupant test data to demonstrate in-position performance in far side impacts. The Front Center Airbag is an airbag that mounts to the inboard side of the driver front seat. It has a tubular cushion structure, and it deploys between the front seating positions in far side impacts, near side impacts and rollovers, with the cushion positioning itself adjacent the driver occupant's head and torso. This paper includes pictures of the technology along with a basic description of the design. In-position occupant performance is also described and illustrated with several examples. Single occupant and two front occupant far side impact test data are included, both with and without the airbag present. Resulting performance differences are discussed leading to the following test observations: a) In a far side impact with a single driver occupant present, the deployed airbag functions as a restraint to help keep the occupant away from the intruded passenger compartment structure. b) When two occupants are present, the deployed airbag functions as a cushion between the front occupants. In addition, field data from the Fatal Analysis Reporting System and National Automotive Sampling System - Crashworthiness Data System are initially presented to illustrate the challenges that this technology attempts to address.
Thomas, Scott D., Wiik, Richard A., Brown, Jacqueline E.
Side Crash Pressure Sensor Prediction for Body-on-Frame Vehicles: An ALE Approach2013-01-06664/8/2013
In an attempt to assist pressure sensor algorithm and calibration development using computer simulations, an Arbitrary Lagrangian Eulerian (ALE) approach was adopted in this study to predict the responses of side crash pressure sensors for body-on-frame vehicles. Acceleration based, also called G-based, crash sensors have been used extensively to deploy restraint devices, such as airbags, curtain airbags, seatbelt pre-tensioners, and inflatable seatbelts, in vehicle crashes. With advancements in crash sensor technologies, pressure sensors that measure pressure changes in vehicle side doors have been developed recently and their applications in vehicle crash safety are increasing. The pressure sensors are able to detect and record the dynamic pressure change when the volume of a vehicle door changes as a result of a crash. Due to the nature of pressure change, data obtained from the pressure sensors exhibits lower frequency and less noise in the responses which are significantly different from those of the acceleration-based crash sensors. This technology is very suitable for side crash applications due to its ability to discriminate crash severities and deploy restraint devices earlier in the event. The lower frequency and less noise in the responses are also more suitable for non-linear finite element codes to simulate. To help understand the responses of pressure sensors and the capabilities of the ALE method in the prediction of pressure sensor responses, fifteen different benchmark tests were designed and performed in previous research. The fifteen benchmark tests were divided into three groups so that the capabilities of the ALE method could be examined in detail. The first group of benchmark tests included a rectangular steel container with one side being compressed while all other sides were fixed to simulate a piston compression condition. Two different gases were tested in the first group of benchmark tests. Solutions for the first group of benchmark tests can be derived theoretically. The second group of benchmark tests, a series of eight, involved a rigid impactor or a deformable barrier hitting a rectangular steel box with and without a hole. In addition, different speeds were chosen in the second group of component tests to obtain their corresponding responses. The third group of benchmark tests, a series of five, involved a rigid impactor or a deformable barrier hitting a vehicle side door with different openings. Similar to the second group of benchmark tests, different speeds were chosen to create different crash severities. Computer simulations conducted employing the ALE method for all fifteen benchmark tests were compared to their corresponding theoretical solutions or test data. Reasonable correlations had been found between the benchmark tests and the computer simulations as presented and discussed in a previous paper. The success of the benchmark study allowed the advancement of the research into its final stage, full vehicle tests. The full vehicle tests contained both body-on-frame and unitized vehicles which are the two main vehicle architectures used in the automotive industry. This paper focused on the body-on-frame vehicles with fifteen tests, including a combination of different body styles, powertrains, drive-trains, wheel bases, test modes, and impact speeds, being investigated. In this study, an approach was developed to correlate the structural responses and to predict the pressure sensor responses for body-on-frame vehicles. The results obtained from the developed method are compared to those obtained from tests. Contrary to common thoughts, it was found that the pressure responses of the low speed test conditions are more challenging to predict than those of the high speed test conditions. This is because the pressure responses for the low speed test conditions are usually very weak. The errors obtained from the numerical simulations become predominant when the magnitudes of the pressure responses are small. The numerical fluctuations induced by the coupling of Lagrangian and Eulerian calculation need to be distinguished and ignored (or filtered) when processing the pressure information. Overall, the slopes, peak values, and shapes of the predicted pressure responses correlate reasonably well with those of the fifteen full vehicle tests selected. The pre-peak responses seem to correlate better to those of the tests than the post-peak responses which involve air leakage. The door pressure changes due to the impacts of oblique pole, IIHS MDB, and FMVSS 214 MDB, can be captured reasonably by the computer simulations.
Tyan, Tau, Arthurs, Kirk, Rupp, Jeffrey, Ko, Charles, Sherwood, Bill, Shaner, Leonard, Barbat, Saeed, Kochhar, Nand, Fazio, John, Bauch, David
A Study of Layout Regarding Integrated Controls on the Steering Wheel2013-01-00363/25/2013
In order to utilize in-vehicle systems efficiently, many vehicles are becoming equipped with integrated controls near the center fascia or the control box. However, the placement of these control systems can cause safety issues and risks due to visual distractions. In this study, we proposed a new integrated touch screen on the steering wheel. For this experiment, a control system was placed on the steering wheel or the center fascia. 15 participants were required to drive while utilizing vent and navigation control tasks regarding four different locations. Three of these locations were based on the steering wheel (center, upper right, lower right) and one location on the center fascia. Afterwards, the task completion time and visual distraction rate of the different locations were measured and compared. The results showed that a touch screen placed on the upper right section of the steering wheel had better performance and lower user discomfort.
Lee, Yong, Nam, Jongyong, Jung, Eui-seung, Lim, Youngjae, Jung, Sung wook, Chung, David
Procedure and Instrumentation for Measuring Acoustic Impulses from Deployment of Automotive Inflatable DevicesJ247_201211 (Historical)11/1/2012
The purpose of this SAE Recommended Practice is to provide guidelines for selection of transducers, data acquisition systems, and other instrumentation as well as analysis methods to help ensure proper measurement and evaluation of acoustic impulses in automobiles. While this Recommended Practice focuses on automotive inflatable devices, such as, frontal airbag systems, pretensioners, inflatable curtains, side airbags, etc, it can be used for measurement of other impulsive sounds in a vehicle if needed. The objective is to achieve uniformity in instrumentation practice and reporting of test measurements. Use of this recommended practice should provide a basis for meaningful comparisons of test results from different sources. This recommended practice specifies procedures for static measurement of acoustic impulses, but due to the much more complicated nature of crash testing, does not specify procedures for measuring impulses in vehicles during crash tests.
Inflatable Restraints Committee
Hybrid III Head/Neck Analysis Highlighting Nij in NCAP2012-01-01024/16/2012
Nij, a function of upper neck forces and moment, plays a dominant role in the vehicle's star rating under the new NHTSA NCAP front impact program. This is mainly due to an artifact in the mapping of the Nij into the “risk” value used in the star rating, and the fact that the neck region is not weighted appropriately to reflect its real world significance relative to the other body regions in the NCAP rating. New test data also show that compared with the 50th male driver Nij, the 5th female passenger Nij is significantly more challenging to contain and therefore it is more dominant in the star rating. This paper describes the Hybrid III dummy head and neck impact response and provides a method to determine the external force acting on the head. The force and its acting point on the head are determined from head acceleration, angular acceleration, and the upper neck forces. This paper also analyzes the neck bending mechanism and the associated forces, and how the thorax rotation and translation can affect the upper neck forces. It discusses how the airbag shape and stiffness can affect the external force acting point and direction, and how the force affects the neck internal forces. The analyses have focused on the response of the 5th female dummy neck due to the aforementioned practical difficulty with its Nij. The analytical methods presented should aid in the understanding of vehicle restraint systems.
Wu, Jianping, Shi, Yibing, Beaudet, Brian, Nusholtz, Guy
Side Crash Pressure Sensor Prediction: An ALE Approach2012-01-00464/16/2012
An Arbitrary Lagrangian Eulerian (ALE) approach was adopted in this study to predict the responses of side crash pressure sensors in an attempt to assist pressure sensor algorithm development by using computer simulations. Acceleration-based crash sensors have traditionally been used to deploy restraint devises (e.g., airbags, air curtains, and seat belts) in vehicle crashes. The crash pulses recorded by acceleration-based crash sensors usually exhibit high frequency and noisy responses depending on the vehicle's structural design. As a result, it is very challenging to predict the responses of acceleration-based crash sensors by using computer simulations, especially those installed in crush zones. Therefore, the sensor algorithm developments for acceleration-based sensors are mostly based on physical testing. With the advancement in the crash sensor technology, pressure sensors that detect pressure change in door cavities have been developed recently and production vehicle applications are increasing. The pressure sensors detect pressure change when there is a change in the door volume. Due to the nature of pressure change, the data obtained from side crash pressure sensors exhibits lower frequency and less noisy responses which are quite different from those of the acceleration-based crash sensors. The technology is most promising for side crash applications due to its ability to discriminate crash severities and deploy airbags earlier. The lower frequency and less noisy responses are also more suitable for non-linear finite element codes to predict. To help understand the responses of pressure sensors and obtain reliable test data for model developments, fourteen different benchmark tests were designed and performed in this research. The first set of benchmark tests included a rectangular steel container with one side being compressed while all other sides were fixed to simulate a piston compression condition. The second set of benchmark tests, a series of eight, involved a rigid impactor or a deformable barrier hitting a rectangular steel box with and without a hole. Different speeds were chosen in the second set of component tests to obtain the corresponding responses. The third set of benchmark tests, a series of five, involved a rigid impactor or a deformable barrier hitting a vehicle side door with different openings. Similar to the second set of the benchmark tests; different speeds were chosen to create different crash severities. Computer simulations for all fourteen benchmark tests were conducted by employing the ALE method as one of the studies in this research. The results obtained from the benchmark tests and the computer simulations are presented and discussed in this paper.
Tyan, Tau, McClain, Ben, Arthurs, Kirk D., Rupp, Jeffrey, Ghannam, Mahmoud Yousef, Bauch, David, Clark, Todd, Bhalsod, Dilip M., Wang, Jason
Side Crash Pressure Sensor Prediction: An Improved Corpuscular Particle Method2012-01-00434/16/2012
In an attempt to predict the responses of side crash pressure sensors, the Corpuscular Particle Method (CPM) was adopted and enhanced in this research. Acceleration-based crash sensors have traditionally been used extensively in automotive industry to determine the air bag firing time in the event of a vehicle accident. The prediction of crash pulses obtained from the acceleration-based crash sensors by using computer simulations has been very challenging due to the high frequency and noisy responses obtained from the sensors, especially those installed in crash zones. As a result, the sensor algorithm developments for acceleration-based sensors are largely based on prototype testing. With the latest advancement in the crash sensor technology, side crash pressure sensors have emerged recently and are gradually replacing acceleration-based sensor for side impact applications. Unlike the acceleration-based crash sensors, the data recorded by the side crash pressure sensors exhibits lower frequency and less noisy responses which is more conductive for CAE prediction. In the attempt to predict the side crash pressure sensor responses, fourteen different benchmark tests were designed and conducted to provide data for model validations. The fourteen benchmark tests can be divided into three sets based on the structure designs. The first set of benchmark tests included a rectangular rigid container with one side being compressed while all other sides were fixed to simulate a piston compression condition. The second set of benchmark tests contained a rigid impactor or a deformable barrier hitting a rectangular steel box with and without a hole. Different speeds were chosen in the second set of benchmark tests to obtain the corresponding pressure responses. The third set of benchmark tests involved a rigid impactor or a deformable barrier hitting a real vehicle side door with different openings. In the baseline door test, the window weather strip and speaker were kept and all holes in door inner were closed to represent a production door. To ensure the robustness of CAE predictions for different door designs, the window weather strip was removed and some holes in the door inner were opened in some of the door benchmark tests. Computer models were created according to the corresponding test conditions. The CPM method originally developed in LS-DYNA to simulate the deployments of side air bags and side air curtains was adopted and improved in this research to predict the responses of the side crash pressure sensors. One of the main purposes of adopting such method in this project is trying to expand the application of the CPM method to problems that do not involve inflators. With major improvements in the CPM method through this research in the past two years, not only the responses of side crash pressure sensor can be predicted but also the computation time required to complete such simulations has been shortened. The development of the modeling methodology to predict the responses of the side crash pressure sensors will also make it possible to use computer simulations as part of side crash sensor development and results in more robust sensor firing algorithm.
Tyan, Tau, McClain, Ben, Arthurs, Kirk, Rupp, Jeffrey, Ghannam, Mahmoud, Bauch, David, Clark, Todd, Bhalsod, Dilip, Wang, Jason
Influence of Complying with FMVSS 226 (Ejection Mitigation) on Side Airbag Occupant Out of Position Injury Assessment2012-01-04664/16/2012
The National Highway Traffic Safety Administration (NHTSA) has identified ejection mitigation as a top priority, issuing a final rule for FMVSS 226, Ejection Mitigation, in January of 2011 to set performance standards for a vehicle's ejection mitigation countermeasures to mitigate the risk of ejection through a vehicle's side window openings. The most likely countermeasures to be used for compliance with this standard are rollover activated curtain airbags that deploy from a vehicle's roof rail. However, this rule will most likely result in increases in the coverage area and inflator outputs of the curtain airbag; which may influence out-of-position occupant injury as measured in the test methods that have been outlined by the Side Airbag Out-of-Position Injury Technical Working Group (TWG). This paper presents a case study in which the out-of-position performance of a curtain airbag optimized for both ejection mitigation and side impact protection, as outlined per FMVSS 226 and FMVSS 214 respectively, is compared with that of one developed for side impact protection only for the same vehicle. Furthermore, the authors present a design concept that can be used to balance the requirements of FMVSS 226 with the injury risk from the deploying curtain airbag for out-of-position occupants.
Dix, Jeff, Hammoud, Selim, Cardinali, Alex, Mitchell, Abe, Fulk, Daniel
Technical Feasibility Study on Avoidance or Mitigation of Side Collisions at Intersections2012-01-00904/16/2012
Side collisions at intersections account for 30-40 % in vehicle-to-vehicle accidents in most countries. Side collisions usually become unavoidable due to human response time even though drivers in collided vehicles perceive an imminent risk of collision. Side collisions at intersections become often fatal because impacted vehicles have little space to absorb impact energy. Vehicle manufacturers utilize side airbags and curtain airbags to mitigate injuries to occupants in impacted vehicles to overcome structural design constraints. In the past decade advanced technologies become available to improve vehicle safety. For example, a cruise control system adopted radar technology from aero industry, evolved into an adaptive cruise control system and further into automatic emergency brake system. In this study the technical feasibility of a system to avoid or mitigate side collisions at intersections has been explored by utilizing advance technologies, such as radar technology and electronic stability control system. The following factors were taken into consideration; acceleration and average speed of the vehicles approaching to intersections, human behavior in approaching to and starting from intersections, and characteristics of road structures. Based on investigated facts, a side collision accident situation was assumed at a 4-way intersection. An algorithm for determining anticipated side impacts was developed. Mathematical calculations showed that avoiding or mitigating side collisions could be achieved by forced deceleration or acceleration activated by determination algorithm. This study showed that side collision avoidance or mitigation system was feasible by utilizing current advanced technologies.
KIM, Jongsoo, LEE, Jaewan, KIM, Eunsook
Airbag System Applied to Microvans2012-01-00474/16/2012
Today, microvans (a cost effective version of minivans) in China provide transportation for people as well as for goods. Due to their lower prices, airbags for the driver and the front passenger are not standard but only an option in some high end models. This paper describes the procedures that were used in an airbag system development based on a contract with one of the microvan makers to install front airbags in the majority of microvans in production. Front impact tests demonstrated that when airbags were installed for the driver and the front passenger, head injury parameters were reduced significantly. It also shows that front impact characteristics of microvans are different from other vehicles. In particular, the peak accelerations and the rates in high speed impacts are high, and the times to reach the peaks are early as compared to SUVs and other small passenger cars. The development of the airbag system control algorithm for microvans is summarized here. Impact verification tests have shown that the algorithm based on a combined “Time Window+Acceleration Change + Angled Impact Recognition” method satisfied the requirements of the microvans must-not-deploy and must-deploy conditions. Additionally, the important purpose of this work is to emphasize that airbag systems should not be optional and encourage other microvan makers to install front airbag systems as the standard safety measure.
Zhang, Daqing, Wang, Xinming, Huang, Jialiang, Zhou, Zongma, Wang, Yanqing, Zhang, Xiaoyan, Wang, Chenlei, Wang, Huayong, Nie, Xiaohui, Zhang, Wenlin
Single Stage Driver Airbag Module Development for OOP2012-01-00834/16/2012
A driver airbag module has been developed with single stage inflator in an attempt to determine the 05th% ATD measured dummy injury response (“MDIR”) in out-of-position scenarios (two NHTSA positions). Through computer simulations, dynamic MDIRs for in-position 05th%ile and 50th%ile dummies were evaluated as well. It typically takes many design iterations to finalize a driver side module configuration to meet FMVSS208 regulatory conditions. Some typical parameters are tear seam cover design, cushion folding pattern and inflator output. In this paper, a Taguchi design of experiments was used to evaluate the influence of module design parameters. A MDIR comparison between a proposed new driver airbag module with a single stage inflator and a baseline module with a dual stage inflator was made not only for out-of-position tests, but also in-position crash simulations. Currently in the US market, a majority of driver airbag modules use dual stage inflators to meet the injury assessment reference value (“IARV”) criteria set by federal regulation. This driver airbag module with single stage inflator will give car manufacturers an option to eliminate the seat track position sensor and to reduce the number of wire harnesses which are required to connect the dual stage inflator. An additional benefit would be a simplified airbag control unit involving both algorithm and hardware. This simplification should be accomplished while providing comparable MDIR for both in-position and out-of-position scenarios over a baseline module with a dual stage inflator.
Kim, Young Seok, Fischer, Kurt, Nayef, Eyad, Choi, Hyeong Ho
Simulation and Physical Measurement of Seamless Passenger Airbag Door Deployment2012-01-00824/16/2012
Seamless Passenger Airbag Door, which means the seam of the passenger airbag door is not visible to the passenger, is being frequently implemented in the instrument panel because of its good surface appearance. But it is always a challenge to design a robust passenger airbag door with an invisible seam because many kinds of failures are possible during the design, such as cracks of the substrate of instrument panel, hinge failure of airbag door, windshield breakage, etc. Besides the engineering difficulties, the simulation of seamless passenger airbag door deployment is challenging due to three aspects: 1. the simulation method of the early stage airbag deployment (0~20 msec after trigger), 2. the material model of the airbag door pre-weakening line (the invisible seam); and 3. the physical measurement of the reaction load between cushion and door. In this paper, the FPM (Finite Point Method) method in PAM-CRASH™ was used to simulate the early stage airbag deployment and the fabric material model was validated by a material sample tensile test. An airbag deployment test was designed to push a mass upwards and the acceleration of the mass was measured. The measured acceleration shows FPM method with the validated fabric material model is capable to give a good prediction of the early stage airbag deployment. The material model of door seam is also presented and validated with a physical test. To measure the reaction load between airbag cushion and door, Flexi-Force™ sensors, film-like pressure sensors, were used. To deal with the nonlinear signal output of the sensor in different pressure ranges, a calibration device was developed exclusively for this sensor. After the calibration, 32 Flexi-Force™ sensors were put into a seamless passenger airbag door on the IP structure, and then the reaction load between the airbag door and the cushion was measured in its deployment. The action point position of the resultant reaction load, its peak value and duration correlate with the physical tests. Finally, the limitations and future developments are discussed.
Guo, Qing, Liu, Bing
S-E-A Roll Simulator as a Parametric Test Device2012-01-11754/16/2012
The National Highway Traffic Safety Administration (NHTSA) has utilized acceleration sled testing for decades to allow for the evaluation of occupant kinematics, occupant protection systems, and occupant exposure in many modes of accidents. Such systems have the advantage of being non-destructive, having relatively low turnaround time between tests, and precise control of input parameters. These systems usually involve placing some portion of a vehicle occupant compartment on a rigid sled and then accelerating the sled with a desired linear acceleration pulse profile. Such systems have been effective in the development and evaluation of air bag systems, seat belt restraints, and occupant interior surfaces. A roll simulator has been developed to allow for similar parametric testing of vehicle/machine occupant compartments. Such occupant compartments range from those in which the operator is driving the vehicle in a similar arrangement to an on-highway vehicle, such as a recreational off-highway vehicle (ROV), to those on construction, maintenance or material handling equipment. The use of this roll simulator as an occupant kinematic and occupant protection system parametric evaluation tool relies on the ability of this system to first, provide repeatable and applicable dynamic inputs, and second, to allow for the discrimination between differing occupant protection systems. For the current work, a series of tests was completed with a recreational off-highway vehicle to determine the effects of varying occupant protection device configurations. Evaluation of the results shows that the roll simulator is an effective tool for observing subtle differences in occupant response and interaction with various restraint systems.
Castro, Elaine, Morr, Douglas, Tanner, C. Brian
Evaluation of Variation in the Excursion Measured in the FMVSS 226 Ejection Mitigation Test Resulting from Test Vehicle Setup2012-01-00974/16/2012
Federal Motor Vehicle Safety Standard 226 outlines a component test methodology that consists of a linear impact test that uses a featureless head-form with a mass of 18 kg to impact a vehicle's side windows' daylight openings at various positions. The test measures the excursion of the head-form beyond the plane of the window glazing. The intention is to evaluate the ability of a vehicle's ejection mitigation system, such as the curtain airbag or other vehicle features, to manage the impactor energy and limit excursion. However, there are several factors which may cause variation in the amount of excursion measured in the test. These factors include how the vehicle is restrained for the test, the friction of the linear impactor shaft and the lateral deflection of the impactor shaft among others. This paper will present background information from a previous study on variability involving the impactor shaft as well as a study which identifies the effects of vehicle restraint on the excursion measured in the Federal Motor Vehicle Safety Standard (FMVSS) 226 test.
Mueller, Joe, Stein, Douglas, Dix, Jeff
Numerical Simulation of Out-of-Position Front Passenger Injuries in Frontal Crashes Using an Accurate Finite Element Model of the Cockpit Module2012-01-05524/16/2012
While airbags are effective safety devices for reducing occupant injury level, front Out-of-Position (OOP) passengers can be injured by airbag deployment, for example, when a passenger's head is on the instrument panel surface at the time of the collision. Consequently, FMVSS 208 prescribes In-Position and OOP occupant safety performance, and vehicle manufacturers are continuing to develop optimal restraint systems for reducing injuries under both In-Position and OOP conditions. In this study, a numerical simulation method for OOP front passenger injuries in frontal crashes is presented by using accurate finite element (FE) models of the airbag and the cockpit module. The main characteristics of the airbag model are: (i) the Finite Point Method is employed to simulate the flow of gas; (ii) the initial airbag shape is represented by a folding model; (iii) nonlinear anisotropic material properties of the airbag fabric are identified considering the fiber directions and hysteresis. The major features of the cockpit module are: (i) part shapes are represented accurately by a fine mesh; (ii) rupture of the material is described by element elimination. This paper describes the simulation method along with several numerical simulation examples that are sufficiently accurate to provide design directions for occupant restraint systems, including OOP passenger safety. The simulation results show that the reaction force of the instrument panel has a significant influence on dummy injury readings as well as on the airbag pressure. This means that the deformation and rupture mode of the instrument panel surface are important factors affecting dummy injury readings.
Yamagishi, Michihiro, Iyama, Jun, Araki, Toshihiro, Natori, Sou
A Study on the Optimal Design of IP Module Considering Performance of LRD A/BAG Deployment2011-28-004610/6/2011
The current advanced airbag regulation (FMVSS208) requires passenger cars and MPV either to have an automatic suppression system or to meet the LRD requirement on the passenger side. Recently, the car makers are choosing LRD requirement option and developing new LRD passenger airbag system. This paper presents a new methodology for improvement of airbag deployment using experimental and analytical research. The significant parameters were determined from statistical analysis of the experiment data. Basically, to deploy airbag normally, the ultra sonic knife or laser is used to cut the skin layer inside along with the gate line partially, so that deploying airbag can tear gate on instrument panel surface easily. As a result of the number of tests conducted at different conditions, this study was able to determine the range of relevant parameters. Additionally, using LRD simulation model, a parametric study was done, to figure out, which design factors mainly affect the low risk deployment of the passenger airbag, and some design improvements are presented.
Hyun, Kim, Mo, Ku Jun, Moon, S. S.
Blood Pressure Monitoring ToolTBMG-99205/1/2011
The MDMouse system incorporates a pre-existing medical device into a conventional computer control mouse. The tool is designed to measure blood pressure outside of the medical environment, and to provide that information for use by individuals, clinical evaluation companies (CROs), healthcare providers, and healthcare payers.
Mandatory Air Bag Warnings: An Updated Evaluation2011-01-02614/12/2011
In a previous SAE paper (2001-01-0046), the authors reviewed the National Highway Traffic Safety Administration's (NHTSA) activities in the development of mandatory air bag warnings and analyzed those activities against the framework of the available human factors engineering (HFE) and warning literature. That analysis concluded that in both rulemaking procedures, NHTSA developed labeling requirements that appropriately addressed the respective injury prevention policies and strategies of those respective timeframes. In most regards, the agency properly identified and responded to HFE criteria although some methodological improvement could be obtained. Since the previous paper, the rulemaking process has continued and there have been significant changes to the mandatory air bag warnings. Some of these changes reflect the improvements in advanced air bag technologies. Other changes reflect an alternate warning scheme to continue to alert consumers to the dangers posed by passenger air bags to children and provide a means of distinguishing vehicles equipped with advanced air bags. The current paper is an extension of the SAE 2001-01-0046 paper and examines the agency's development of the current mandatory air bag warning requirements. It utilizes the full record of the rulemaking process including Federal Register notices and docket submissions to identify the analyses and decisions made by the agency in developing these rules. This analysis concludes that although the rulemaking process was somewhat inefficient, spanning over a five year period, NHTSA's analysis of relevant human factors issues appears to have been systematic and complete. The agency did not employ specific testing or formal evaluation as they did in the previous rulemakings, however, the current mandated warnings were subjected to a reasonable HFE analysis and the development process was consistent with the process likely used by most product manufacturers.
Dorris, Nathan T., Burke, Kelly A.
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