Search

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 valuation 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.

A total of 20 full-scale frontal sled tests were conducted using the Hybrid III (HIII), THOR-M and post-mortem human surrogates (PMHSs) to evaluate the thoracic biofidelity of the HIII and THOR-M under various belted restraint conditions. Each surrogate was tested under three belted restraint conditions: knee bolster, knee bolster and steering wheel airbag, and knee bolster airbag and steering wheel airbag. In order to assess the relative biofidelity of each ATD, external thoracic deflections were quantitatively compared between the ATDs and PMHSs using an objective rating metric. The HIII had slightly higher biofidelity than the THOR-M for the external thoracic deflections. Specifically, the THOR-M lower chest was more compliant compared to the other surrogates. However, the THOR-M exhibited expansion of the lower chest opposite belt loading, which was also observed to some degree in the PMHSs. The efficacy of the current injury risk prediction instrumentation and criteria were also evaluated for each surrogate. The THOR-M and its proposed injury risk criteria predicted the injuries observed in the PMHS tests better than the HIII. The PMHS injury criteria over-predicted the amount of chest deflection necessary to produce a severe injury and, consequently, under-predicted injury risk. The results of this study indicate that further testing should be performed to evaluate the biofidelity of the THOR-M thorax under more conditions. Furthermore, current thoracic injury risk criteria, which were developed using censored data, may not be effective at predicting injuries for all restraints and experimental conditions.

Accident emergency calling systems (AECSs) are signaled by the deployment of airbags, which causes them to automatically emit information providing the location of the accident site to a public service answering party (PSAP). In some realworld accidents, airbags have failed to deploy. This study clarifies the factors that influence the nondeployment of front airbags in vehicle-vehicle collisions, investigating nondeployment of the driver-side front airbags in sedans and light passenger cars (LPCs) from Japanese accident data. The component rates of deployment for front airbags tend to be higher than those of nondeployment at higher values of pseudo-ΔV in vehicle-vehicle frontal impacts. For both sedans and LPCs, the transition zones between nondeployment and deployment of the front airbag occur at pseudo-ΔV values of 30-50 km/h (ΔV ≈ 21-35 km/h). For mutual impact locations where sedans and LPCs impact opponent vehicles at pseudo-ΔV ≥ 40 km/h (ΔV ≈ 28 km/h) in frontal impacts, the component rate of front airbag nondeployment is higher than that of deployment in right-to-right impacts. The results indicate that factors influencing front airbag nondeployment in vehicle-vehicle collisions are ΔV, impact offset configuration, and crossing angle. Considering front airbag nondeployment in real-world accidents, AECSs should have other functions, such as a manual button, to emit information in addition to automatic emission via airbag signaling.

Recent field data have shown that the occupant protection in vehicle rear seats failed to keep pace with advances in the front seats likely due to the lack of advanced safety technologies. The objective of this study was to optimize advanced restraint systems for protecting rear seat occupants with a range of body sizes under different frontal crash pulses. Three series of sled tests (baseline tests, advanced restraint trial tests, and final tests), MADYMO model validations against a subset of the sled tests, and design optimizations using the validated models were conducted to investigate rear seat occupant protection with 4 Anthropomorphic Test Devices (ATDs) and 2 crash pulses. The sled tests and computer simulations were conducted with a variety of restraint systems including the baseline rear-seat 3-point belt, 3-point belts with a pre-tensioner, load limiter, dynamic locking tongue, 4-point belts, inflatable belts, Bag in Roof (BiR) concept, and Self Conforming Rear seat Air Bag (SCaRAB) concept. The results of the first two sled series demonstrated that the baseline 3-point belt system are associated with many injury measures exceeding injury assessment reference values (IARVs); showed the significance of crash pulse and occupant size in predicting injury risks; and verified the potential need of advanced restraint features for better protecting the rear-seat occupants. Good correlations between the tests and simulations were achieved through a combination of optimization and manual fine-tuning, as determined by a correlation method. Parametric simulations showed that optimized belt-only designs (3-point belt with pre-tensioner and load limiter) met all of the IARVs under the soft crash pulse but not the severe crash pulse, while the optimized belt and SCaRAB design met all the IARVs under both the soft and severe crash pulses. Two physical prototype restraint systems, namely an "advanced-belt only" design and an "advanced-belt and SCaRAB" design, were then tested in the final sled series. With the soft crash pulse, both advanced restraint systems were able to reduce all the injury measures below the IARVs for all four ATDs. Both advanced restraint systems also effectively reduced almost all the injury measures for all ATDs under the severe crash pulse, except for the THOR. The design with the advanced-belt and SCaRAB generally provided lower injury measures than those using the advanced belt-only design. This study highlighted the potential benefit of using advanced seatbelt and airbag systems for rear-seat occupant protection in frontal crashes.

Collision related data stored in the airbag control modules (ACM's) of Toyota vehicles can provide useful information to collision investigators, including both front and rear collision severity. Previous studies of ACM's from other manufacturers found that the devices underestimated the actual speed change in low speed frontal collisions. To quantify the accuracy and sensitivity of select 2005 to 2008 Toyota ACM's, in-vehicle crash tests and linear sled tests were performed in both front and rear impact orientations. A 2005 Toyota Corolla with five extra ACM's mounted in the right front seat position underwent a series of vehicle-to-barrier collisions with speed changes of up to 10 km/h. Next, the same six Toyota ACMs underwent a range of crash pulses using a linear sled. In all in-vehicle tests, the speed change reported by the ACM underestimated the actual speed change for frontal collisions, and overestimated the actual speed change for rear-end collisions. The speed change underestimates ranged from 1.3 to 2.6 km/h and the speed change overestimates ranged from 0.6 to 2.2 km/h. The magnitude of the error varied with collision duration and peak acceleration. Threshold accelerations required to initiate the recording of an event were found to be between 2.0 and 2.1g for all of the ACM's tested. A model using the threshold accelerations and a bias was generated to explain the speed change error. This study provides an understanding into the accuracy of the Toyota ACM reported speed change at low speeds and the collision parameters which can affect it. Language: en

Prior EDR testing methodologies required setting events in the airbag control module in the vehicle during controlled driving behavior. Duplicating events was nearly impossible, and it was difficult to separate how much differences in recorded speeds to reference speeds was due to measurement error, wheel slip, reporting time delays, or data truncation within the EDR. Recording thresholds have also increased making non-deployment and deployment events closer in magnitude, increasing the risk of accidentally exceeding the deployment threshold while setting events. The new methodology eliminates the risk of accidentally deploying airbags while gathering GPS and CAN bus data in the test vehicle. The techniques presented in this paper also allows gathering of data in vehicle without tampering with the airbag control module, which reduces the potential liability to testers using rental or borrowed test vehicles. The new methodology allows for repeatable testing and mapping the transfer function between the vehicle CAN bus data and the EDR. Should a manufacturer make a design change to an ACM EDR, identical inputs can be given to exemplar ACM's from before and after the changes to document any change in the transfer function. This methodology allows researchers the ability to re-create events of interest in a low-cost, repeatable manner. The accuracy of the 2012 Honda CR-V and 2012 Honda Civic event data recorders were tested using this new two part methodology. First, the test vehicles were instrumented with both a Racelogic VBOX differential GPS speed measurement system and a Vector CAN data logger. The measurements from the VBOX were transmitted onto the vehicle's Controller Area Network (CAN) bus that also contained messages reflecting indicated vehicle speed, brake status, accelerator pedal position, steering wheel angle, individual wheel speeds and other signals. This put the GPS speed data on the same time base as the vehicle CAN speed signal such that no additional synchronization was required. This permitted analysis of the accuracy and update rate of the vehicle speed CAN signal, which is the source for speed data used in the Event Data Recorder (EDR). Second, a system was developed to replay the recorded CAN data to an exemplar airbag control module in the laboratory, such that the exemplar was receiving data exactly as if it were in a moving vehicle. A pneumatic fixture with a slide was built to allow the exemplar module to be accelerated to nearly 10 km/h (6 mph) and then stopped in about 80 msec. to create a non-deployment event that met the minimum 5 mph delta-V over 150ms threshold. Actuation of the event setting fixture was computer controlled (using LabVIEW) and synchronized with the CAN replay system so that the desired test condition could be replicated precisely. An external accelerometer was mounted to the airbag control module to mark when the ACM began recording and the accelerometer data was matched to the acceleration and delta-V data in the EDR. The desired test conditions were replayed to the airbag control module and a series of non-deployment events were set. Each event on the EDR data was read using the Bosch Crash Data Retrieval system. The EDR data was compared to the inputs, and it was determined that the two byte vehicle CAN bus signal was truncated to the next lower whole km/h when recorded in the EDR. Under steady state conditions the speed data was accurate within 2%. The vehicle CAN signal published new values every 0.1 seconds, and the CR-V updated values every 0.1 seconds, but the Civic only updated every 0.6 seconds during hard brake events. During hard ABS braking events the expected wheel slip led to the vehicle speed signal under-reporting ground speed, but the delay in the CAN bus update rate resulted in over-reporting ground speed in many of the tests. Language: en

A number of variations may include a front center airbag system comprising: a first airbag mounted on an inboard side of a first front seat and a second airbag mounted on an inboard side of a second front seat, wherein the first airbag and the second airbag are constructed and arranged so that in a deployment condition the first airbag and the second airbag fill a space between and partially forward of the first front seat and the second front seat.

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 midsize 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. Language: en

Independent verification of the accuracy of data from Event Data Recorders (EDRs) is useful when using the information to help reconstruct a crash. To this end, the accuracy of the EDR function of the Airbag Control Module (ACM) was tested on 2010 and 2011 Toyota Camry sedans during straight line operation. During steady state operation, and maximum ABS-braking runs starting from approximately 80 km/h (50 mph), and 113 km/h (70 mph), non-deployment events were artificially induced to store event data. Following each run, the EDR was imaged using the Bosch Crash Data Retrieval (CDR) system. The CDR reported speed values were compared to Racelogic VBox differential GPS speed records. Data recorders were also used to monitor the vehicle Controller Area Network (CAN) bus traffic, including the indicated speed, brake pressure, engine RPM, and accelerator pedal position. The speed and RPM reporting algorithms stated in CDR Data Limitations were confirmed. Exemplar graphs of EDR-reported speed/brake/RPM/accel pedal data versus GPS speed and CAN bus data are presented and discussed. The timing of the reported data with respect to the event is also discussed. The difference between vehicle speed recorded by the EDR and the GPS speed during steady state operation varied from +0.4 to −2.3 km/h, with the EDR typically reporting lower than the GPS. During heavy braking the difference in speed was observed to be from −7 to +15 km/h, with wheel slip causing negative differences, and time delay since the last CAN bus update causing positive differences. Language: en

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. Language: en

Electroimpact has developed a second generation of mobile robots with several improvements over the first generation. The frame has been revised from a welded steel tube to a welded steel plate structure, making the dynamic response of the structure stiffer and reducing load deflections while maintaining the same weight. The deflections of the frame have been optimized to simplify position compensation. The caster mechanism is very compact, offers greater mounting flexibility, and improved maneuverability. The mechanism uses a pneumatic airbag for both lifting and suspension. The robot sled has been improved to offer greater rigidity for the same weight, and dual secondary feedback scales on the vertical axis further improve the rigidity of the overall system. Maintenance access has been improved by rerouting the cable and hose trays, and lowering the electrical cabinet. The mobile robot is sized so it can be shipped complete on a lowboy trailer for deliveries that can be completed by truck. It can also be broken down for container shipping, and reassembly at the customers' site is a straightforward process. The mobile robot can now be placed in position over obstructions by raising the robot on its vertical axis prior to moving it into the final assembly position.

An overview NASS study of US frontal crashes was performed to investigate crash involvement, driver injury distributions and rates in airbag equipped vehicles by vehicle class and structural engagement. Frontal crash bins were based on taxonomy of structural engagement, i.e., Full Engagement, Offset, Between Rails and Corner impact crashes. A new classification of Corner impacts included frontal small overlap impacts with side damage as coded by NASS CDS. Belted drivers of two age groups, between 16 and 50 and over 50 years old, were considered. Vehicles were grouped into light and heavy passenger cars and lights trucks, and vans. A method to identify and address overly influential NASS weights was developed based on considerations of weighting factor statistics. The new taxonomy, with an expanded definition of corner impacts, allowed a more comprehensive classification of frontal crash modes. Results highlight the need to address upper extremities injuries and to better address lower extremities injuries for both the younger and older drivers. For all body regions studied, the vast majority of all serious and moderate injuries occurred in Full Engagement and Offset crash modes for both the younger and older drivers. Corner impacts, which have been the focus of recent research and testing programs, are the smallest contributors to serious and moderate injuries in frontal crashes. Greater opportunities to mitigate injuries in frontal crashes for vehicles have been shown to exist in lower speed full frontal and offset crash modes.

The Insurance Institute for Highway Safety (IIHS) is investigating small overlap crash test procedures for a possible consumer information program. Analysis of real-world small overlap crashes found a strong relationship between serious head and chest injuries and occupant compartment intrusion. The main sources of serious head injuries were from the A-pillar, dash panel, or door structure, suggesting head trajectories forward and outboard possibly bypassing the airbag. Chest injuries mainly were from steering wheel intrusion and seat belt loading. In developing this program, two test dummies were evaluated for predicting occupant injury risk: midsize male Hybrid III and THOR. In the collinear small overlap crash tests conducted here, results from the two dummies were similar. Both predicted a low risk of injury to the head and chest and sometimes a high risk of injury to the lower extremities. Head and torso kinematics also were similar between dummies. Other test scenarios might show larger differences between the dummies. Language: en

This study characterized thoracoabdominal response to posterolateral loading from a seat-mounted side airbag. Seven unembalmed post-mortem human subjects were exposed to ten airbag deployments. Subjects were positioned such that the deploying airbag first contacted the posterolateral thorax between T6 and L1 while stationary (n = 3 × 2 aspects) or while subjected to left lateral sled impact at ΔV = 6.7 m/s (n = 4). Chestband contours were analyzed to quantify deformation direction in the thoracic x–y plane (zero degrees indicating anterior and 180° indicating posterior), magnitude, rate, and viscous response. Skeletal injuries were consistent with posterolateral contact; visceral injuries consisted of renal (n = 1) or splenic (n = 3) lacerations. Deformation direction was transient during sled impact, progressing from 122 ± 5° at deformation onset to 90° following maximum deflection. Angles from stationary subjects progressed from 141 ± 9° to 120°. Peak normalized deflections, peak rates, and VCmax ranges were 0.075 – 0.171, 3.7 – 12.7 m/s, and 0.3 – 0.6 m/s with stationary airbag, respectively; ranges were 0.167 – 0.297, 7.4 – 18.3 m/s, and 0.7 – 3.0 m/s with airbag sled impact, respectively. Peak deflections were measured at angles between 99° – 135° and 98° – 125° for stationary and dynamic conditions, respectively. Because of deflection angle transience and localized injury response, both posterolateral and lateral injury metrics may be required for this boundary condition. Contrasted with flat rigid or anterolateral loading, biomechanical response to side airbag interaction may be augmented by peak normalized deflection or VCmax at 130°.

This paper describes how an ideal injury criterion should be predictive of the risk of injury across the range of loading conditions where it may be applied. The injury risk curve associated with this criterion should be applicable to all loading conditions. With respect to side impact, the injury risk curve should apply to pure lateral or oblique loading by rigid and padded walls, as well as airbags. Previous research reported that the number of fractured ribs was higher in pure lateral impact than in forward oblique interaction with an airbag. The paper describes how a good dummy criterion should be able to account for this difference. In order to evaluate various injury criteria with the WorldSID 50th and ES-2re dummies, the dummies were exposed to the same airbag loadings as the post-mortem highway surrogates (PMHS) and the criteria measured in the dummy tests were paired with the rib fractures from the PMHS tests. Regarding the effect of configuration, results of sled tests with the 50th percentile WorldSID and ES-2re have been paired with injuries found in the PMHS tested in the same conditions. The relationships obtained were compared with the relationships established in the same way for the subjects loaded in the airbag tests. Comparing the lateral and oblique lateral loading conditions, both the WorldSID and the ES-2re exhibited differences in peak lateral deflection of their ribs that were consistent with the different number of rib fractures for PMHS subjected to these loading conditions. For each dummy, the risk of rib fractures could be assessed from one injury risk curve, regardless of the loading angle and the same injury risk curve can be used to assess the risk of rib fractures from sled tests and airbag loading. However, because the WorldSID deflection measurements differed in the rigid and padded sled tests, it is recommended that the dummy's sensitivity to padding be further assessed prior to adopting injury risk curves for WorldSID. Rib deflections of the ES- 2re were not sensitive to padding. Finally, the paper shows how the VC should not be considered as a valid criterion to assess the risk of rib fractures.

Rib fractures are the most frequent types of AIS3+ chest injuries and constitute a good indication of severity. However, the behavior of the rib cage is not well documented, and though chest external measurements are often provided in the literature, the strains of the ribs themselves during a crash remain unknown. In order to address this issue, a test protocol was developed, where the ribs of 8 PMHS were equipped with up to 96 strain gauges. In a first series of 3 tests, the subjects were seated upright and their chests were loaded by a 23.4 kg impactor propelled at 4.3 m/s in 0 degrees (pure frontal), 60 degrees (oblique) and 90 degrees (pure lateral) directions. In a second series of 3 tests, the subjects were loaded by the deployment of an unfolded airbag in the same 3 directions. Finally, a third series of 2 tests was performed with airbags at different distances from the subjects, in a pure lateral direction. This paper presents the results of the tests and an analysis of the strain patterns. The differences between a pure frontal, a pure lateral and an oblique loading are explored. The airbag loading is compared to impactor loading and the severity effect is described. Finally, the time and location of the rib fractures are analyzed as a function of the test configuration.

When a car collides against a pole-like obstacle, the deformation pattern of the vehicle body-side tends to extend to its upper region. A possible consequence is an increase of loading to the occupant thorax. Many studies have been conducted to understand human thoracic responses to lateral loading, and injury criteria have been developed based on the results. However, injury mechanisms, especially those of internal organs, are not well understood. A human body FE model was used in this study to simulate occupant kinematics in a pole side impact. Internal organ parts were introduced into the torso model, including their geometric features, material properties and connections with other tissues. The mechanical responses of the model were validated against PMHS data in the literature. Although injury criterion for each organ has not been established, pressure level and its changes can be estimated from the organ models. Finite element simulations were conducted assuming a case where a passenger vehicle collides against a pole at 29km/h. Occupant kinematics, force-deformation responses and pressure levels were compared between cases with and without side airbag deployment. The results indicated that strain to the ribs and pressure to the organs was smaller with side airbag deployment. The side airbag widened the contact area at the torso, helping to distribute the force to the shoulder, arm and chest. Such distributed force helped generate relatively smaller deformation in the ribs. Furthermore, the side airbag deployment helped restrict the spine displacement. The smaller displacement contributed to lowering the magnitude of contact force between the torso and the door. The study also examined the correlations between the pressure levels in the internal organs, rib deflection, and V*C of chest. The study found that the V*C(t) peak appeared to be synchronized with the organ pressure peak, suggesting that the pressure level of the internal organs could be one possible indicator to estimate their injury risk.

The objectives of this study were to examine the response, repeatability, and injury predictive ability of the Hybrid III small-female dummy to static out-of-position (OOP) deployments using a depowered driver-side airbag. Five dummy tests were conducted in two OOP configurations by two different laboratories. The OOP configurations were nose-on-rim (NOR) and chest-on-bag (COB). Four cadaver tests were conducted using unembalmed small-female cadavers and the same airbags used in the dummy tests under similar OOP conditions. One cadaver test was designed to increase airbag loading of the face and neck (a forehead-on-rim, or FOR test). Comparison between the dummy tests of Lab 1 and of Lab 2 indicated the test conditions and results were repeatable. In the cadaver tests no skull fractures or neck injuries occurred. However, all four cadavers had multiple rib fractures. These results suggested that an older, osteoporatic, small-female driver would experience AIS>/=3 thoracic injury if exposed to this type of depowered airbag inflation for the three positions tested, but would be unlikely to experience any head or neck injury. The cadaver results provided no information about the possibility of AIS>/=3 rib fractures for the average small, female driver. The Hybrid III small-female dummy results suggest that a low percentage (15%) of small, female drivers would experience AIS>/=3 thoracic injuries if they had their chest on the module cover at the time of deployment of this depowered airbag. Also, for this position, the dummy results indicated a risk of an AIS=2 neck injury for some small, female drivers. For all positions tested, the dummy results predicted that head injury was unlikely for most small-female drivers. Language: en