Side Airbag Deployment Research Articles

Estimation of Injury Limits at Vulnerable Impact Locations Along the Forearm Via THUMS AM50 Finite Element Model at Airbag Loading Rates.

Side and frontal airbag deployment represents the main injury mechanism to the upper extremity during automotive collisions. Previous dynamic injury limit research has been limited to testing the forearm at either the assumed most vulnerable location to fracture, the distal 1/3rd, or the midpoint. Studies have varied the surface to which impacts were applied, with no clear consensus on the site of greatest vulnerability. The unpredictability of airbag impact location, especially with altered hand positioning, limits the effectiveness of existing forearm injury limits determined from impacts at only one location. The current study quantified the effect of impacts at alternative locations on injury risk along the forearm using the THUMS FE model. Airbag-level impacts were simulated along the forearm on all four anatomical surfaces. Results showed the distal 1/3rd is not the most vulnerable location (for any side), indicating forearm fracture is not solely driven by area moment of inertia (as previously assumed). The posterior forearm was the weakest, suggesting that current test standards underestimate the fracture risk of the forearm. Linear regression models showed strong correlation between forearm fracture risk and bone geometry (cross-sectional area and area moment of inertia) as well as soft-tissue depth, potentially providing the ability to predict forearm injury tolerances for any location or forearm size. This study demonstrated the forearm's vulnerability to fracture from airbag deployments, indicating the need for safety systems to better address injury mechanisms for the upper limb to effectively protect drivers.

Injury risk curves in far-side lateral motor vehicle crashes by AIS level, body region and injury code

Objective The objective of this study was to develop injury risk curves as a function of change in vehicle velocity for occupants in far-side lateral motor vehicle crashes (MVCs) by AIS level, body region, and specific AIS codes that commonly occur in this crash mode. Methods The National Automotive Sampling System-Crashworthiness Data System (NASS-CDS) years 2000–2015 database was queried, resulting in 4,495 non-weighted far-side crashes. For each case, occupant age, sex, and the following metadata were collected: vehicle model year, vehicle body type, lateral delta-v, normalized PDOF, multiple impacts, belt use, seat position, object contacted, striking vehicle body type, maximum crush extent and side airbag deployment. Multivariable logistic regression was used to develop risk curves for AIS 2+ through 5+ injuries, AIS 2+ injuries by body region (head, thorax, lower extremity), and for each of the 10 most frequent far-side AIS 2+ injuries. Significant covariates were determined by backwards elimination (p < 0.05). The full dataset and a subsampled dataset of only cases with side airbag deployment were used to develop risk curves. Results For AIS 2+ through 5+ injury, greater delta-V was associated with greater injury risk (OR’s: 2.48–3.66 per 11.9 kph increase) and belt use was associated with lower risk (OR’s: 0.04–0.36 compared to unbelted). Multiple impacts were significant predictors of increased AIS 3+, 4+ and 5+ injury risk (OR’s: 2.56, 2.27 and 2.83 compared to single impact). For AIS 2+ body region injuries, lateral delta-V and maximum CDC extent were positively associated with increased head, thorax and lower extremity injury risk while belt use was associated with lower risk. Increased lateral delta-v, unbelted status, and greater maximum CDC extent frequently increased injury risk for the most common far-side injuries. Side airbag deployment was not a significant covariate for the injury risk models. Conclusions The resulting risk models expand upon previous literature gaps to provide a more comprehensive view of contributors to injury risk for occupants in far-side MVCs. This study yields risk curves based on the latest available NASS-CDS data.

A Case of Acoustic Trauma Caused by Side-airbag Deployment

A Case of Acoustic Trauma Caused by Side-airbag Deployment

Influence of curtain side airbag deployment to the occupant seated in child restraint system

Influence of curtain side airbag deployment to the occupant seated in child restraint system

Numerical modelling and experimental analysis of the passenger side airbag deployment in out-of-position

ABSTRACTIn recent years, many accidents happened with passengers who were out of position when their airbag deployed. Therefore, new safety regulations have come into effect and an airbag now has to meet several requirements that concern out of positioning. In meeting these requirements, simulations of folding and deploying airbags are very useful and are widely used. This paper presents a simulation method for the deploying airbags using three materials in different working conditions. The main aim of this study is evaluate the performance of deploying of passenger side airbag using finite-element methods (FEMs). The model has been validated with experimental tests specifically designed for this task. Although the analysis was limited to linear elastic model, excellent agreements were obtained.

A numerical study of passenger side airbag deployment based on arbitrary Lagrangian-eulerian method

The passenger side airbags (PAB) are usually larger than the driver airbags. Therefore, the inflator of PAB is more powerful with high mass rate. In this paper, an Arbitrary Lagrangian-Eulerian (ALE) method based computational method is developed to simulate the deployment of a PAB. The tank test is used to test the property of the inflator. Through comparison of numerical and experimental results, the ALE method is validated. Based on a failed airbag test, a smaller sub-airbag is placed inside PAB to disperse the gas flow to directions which are less damaging. By applying dynamic relaxation, the initial mesh corresponding to the experimental terms is obtained. The results indicate that the interior pressure and impact force coincide with the test data, and the method in this paper is capable of capturing airbag deploying process of the PAB module accurately.

Lateral Collision with Side Airbag: A Literature Review

The paper presents a literature review of the efficacy of side passive safety in the event of lateral collision and the latest development of side airbag. According to the latest Global Status Report on Road Safety 2013, the total number of death every year due to road accident still maintained in a huge number of 1.24 million. Malaysia is one of the countries having highest estimated road traffic death rate of 25 per 100,000 populations. Moreover, 5% growth annually of fatalities rate forecasted. In general, lateral collision or side impact is the second most common vehicle crash type which takes almost 10,000 occupant deaths each year. Side airbags were introduced into vehicle firstly in 1995 in order to improve occupants injury. It is statically proven that combination of head with thorax side airbag is very effective in reducing occupants fatalities rate, however thorax only airbag is less significant. With the aid from Computer Aided Engineer (CAE) software, designer can further improve airbag design and optimize its performance in order to find the best combination of design parameter such as of area of air vent, Time-To-Fire (TTF), operating pressure of the inflator gas and many more, while design cycle time can be reduced significantly up to 40%. Nevertheless, people are afraid that side airbag deployment load may hurt children and small size female seated in Out-Of-Position (OOP). Researcher could resolve it by adopting the latest Computer Fluid Design (CFD) airbag simulation technique which have a better simulation result of OOP load, since CFD method provide more realistic airbag deployment simulations especially in the first few milliseconds which are significant in OOP test.

Door velocity and occupant distance affect lateral thoracic injury mitigation with side airbag

The relationship between thoracic injury risk and parameters of door velocity and occupant distance was delineated in blunt lateral impact with side airbag deployment. A sled impact model was exercised with the validated MADYMO fiftieth percentile facet occupant model and a generalized finite element torso side airbag. Impact velocity was incremented from 4.0 to 9.0m/s; occupant–airbag distance (at time of airbag activation) was incremented from 2.0 to 24.0cm; simulations without airbag were also examined. Using compression, deflection rate, and the Viscous Criterion, airbag performance was characterized with respect to occupant injury risk at three points of interest: occupant distance of most protection, distance of greatest injury risk, and the newly defined critical distance. The occupant distance which demonstrated the most airbag protection, i.e., lowest injury risk, increased with increasing impact velocity. Greatest injury risk resulted when the occupant was nearest the airbag regardless of impact velocity. The critical distance was defined as the farthest distance at which airbag deployment exacerbated injury risk. This critical distance only varied considering chest compression, between 3 and 10cm from the airbag, but did not vary when the Viscous Criterion was evaluated. At impact velocities less than or equal to 6m/s, the most protective occupant location was within 2cm of the critical distance at which the airbag became harmful. Therefore, injury mitigation with torso airbag may be more difficult to achieve at lower ΔV.

Thoracic Injury Metrics With Side Air Bag: Stationary and Dynamic Occupants

Objective: Injury risk from side air bag deployment has been assessed using stationary out-of-position occupant test protocols. However, stationary conditions may not always represent real-world environments. Therefore, the objective of the present study was to evaluate the effects of torso side air bag deployment on close-proximity occupants, comparing a stationary test protocol with dynamic sled conditions. Methods: Chest compression and viscous metrics were quantified from sled tests utilizing postmortem human specimens (PMHS) and computational simulations with 3 boundary conditions: rigid wall, ideal air bag interaction, and close-proximity air bag deployment. PMHS metrics were quantified from chestband contour reconstructions. The parametric effect of ΔV on close-proximity occupants was examined with the computational model. Results: PMHS injuries suggested that close-proximity occupants may sustain visceral trauma, which was not observed in occupants subjected to rigid wall or ideal air bag boundary conditions. Peak injury metrics were also elevated with close-proximity occupants relative to other boundary conditions. The computational model indicated decreasing influence of air bag on compression metrics with increasing ΔV. Air bag influence on viscous metric was greatest with close-proximity occupants at ΔV = 7.0 m/s, at which the response magnitude was greater than linear summation of metrics resulting from rigid impact and stationary close-proximity interaction. Conclusions: These results suggest that stationary close-proximity occupants may not represent the only scenario of side air bag deployment harmful to the thoraco-abdominal region. The sensitivity of the viscous metric and implications for visceral trauma are also discussed.

Is Bigger Better? The Effect of Obesity on Pelvic Fractures After Side Impact Motor Vehicle Crashes

Previous research has identified nearside impacts, intrusion, gender, age, and body mass index (BMI) as associated with pelvic fractures in motor vehicle crashes. This study assesses the role of BMI in predicting pelvic fracture and whether BMI modifies the effect of other potential risk factors. The Crash Injury Research and Engineering Network data were queried to study occupant, vehicle, and crash factors predicting pelvic injury in occupants of nearside crashes. Occupants in different BMI categories were compared with assess odds of pelvic fracture during nearside impacts. Logistic regression was used to identify predictive variables for pelvic fracture controlling for age, gender, delta V, intrusion, side airbag deployment, seat position, vehicle curb weight, and safety belt use. Two hundred forty-four (57.5%) occupants in nearside impacts sustained pelvic fractures. Occupants with a normal BMI were more likely (unadjusted odds ratio = 1.80, adjusted odds ratio = 1.98) to have a pelvis fracture compared with overweight and obese occupants. Door panel intrusion >15 cm, female gender, and delta V were associated with pelvic fracture in univariate analyses. BMI was a predictor of pelvic fracture when controlling for potential confounding factors. BMI status influences other variables associated with pelvic fracture. Redesign of interior door panels, hardware, armrests, and the center console may be appropriate for motor vehicle manufacturers to consider in prevention of pelvic fracture during nearside impacts.

Injury risk function for the small female wrist in axial loading

Previous experiments with human cadavers and side airbags revealed the potential for wrist injuries as a result of the hand becoming entrapped in the handgrip. The purpose of this paper was to develop an injury tolerance for the small female wrist that may be used in the design phase of side airbags in order to reduce the risk of wrist injuries resulting from side air bag deployment. Small female cadaver upper extremities were used to develop the wrist tolerance as a conservative estimate of the most vulnerable section of the driving population. The energy source was a pneumatic impactor that was configured to match the force onset rate, impulse, and peak force in order to simulate the load profile of a deploying side airbag. A total of 17 ( n=17) axial impact experiments were performed on the wrists of small female cadavers. Post-test necropsy revealed that 9 of the 17 tests resulted in wrist injuries. The injury patterns were identical to those observed from cadaver tests with side airbags and included fractures of the scaphoid (AIS 2), lunate (AIS 1), distal radius (AIS 3), and distal ulna (AIS 2). Using the injury outcome as the binary variable, a logistic regression analysis was performed. When mass scaled to the fifth female, the analysis produced an injury risk function that predicts a 50% risk of injury at a wrist load of 1700 N ( P=0.0037). Risk of injury was found not to be dependent of subject bone mineral density ( P=0.49), age ( P=0.99), mass ( P=0.31), and stature ( P=0.69). Based on the similarities in impact load profile and observed injury patterns between the impactor tests and the side airbag tests, it is suggested that the injury risk function will accurately predict the risk of wrist injuries in the automobile crash environment.

Occupant position detection system (OPDS) for side airbag system

In order to prevent injury of the occupant of the passenger seat when a side airbag deploys, we have developed an occupant position detection system. It detects the occupant's head entering the side airbag deployment zone. If so, the side airbag operation is inhibited and an indicator light on the side airbag alerts the occupant to the improper sitting position. It detects accurately the occupant's size and the head entering the side airbag deployment zone, using an occupant identification algorithm and electrostatic capacity sensors under the seat trim cover which determine the dielectric around the seat surface.

Dynamic response of the Hybrid III three year old dummy head and neck during side air bag loading

This paper presents the results from 14 tests designed to evaluate the response and injury potential of a Hybrid III three year old dummy subject to loading by a deploying seat mounted side air bag. An instrumented Hybrid III three year old dummy was used for tests in two different occupant positions chosen to maximize head and neck loading. Four seat mounted thoracic side air bags were used that varied only in the level of inflator output. The National Highway Traffic Safety Administration's neck injury criteria for complex loading were modified to include moment values for both anterioposterior and lateral directions. The results indicate that side air bags may be designed so that the forces and moments in the child dummy's neck are below injury threshold values during a side air bag deployment. While there is considerable uncertainty as to the validity of published injury criteria owing to the lack of child biomechanical data, this study demonstrates the sensitivity of child response to initial position which provides insight into placement and geometry of side airbag systems. Furthermore, the data indicate a relationship between airbag inflator properties and child dummy response for a given airbag geometry.

PATTERNS OF FRACTURE AFTER AIR BAG DEPLOYMENT

The airbag restraint system has been described as a means of reducing fatalities in frontal crashes. This conclusion is based on crash investigations and statistical extrapolation, but few data exist to document specific fracture patterns and injuries after airbag deployment. Seven cases of driver's side airbag deployment after motor vehicle crashes were studied for extent of injury. Unrestrained (non-seatbelted) drivers demonstrated flexion injuries of the cervical and thoracic spine and direct impaction fractures of the face and sternum. One restrained (lap-shoulder belt) driver demonstrated an extension injury of the upper cervical spine. What may emerge from further study is a decrease in fatalities, but also a pattern of fractures specific to airbag use.