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Determination of the triggering conditions for automobile airbags is a complex problem because vehicles often run under transient conditions due to the dynamic influence from varying road conditions. The research into malfunctions of automobile airbags is an important and challenging topic. In this work, the peak acceleration and moving window integration algorithms were used to obtain the high-risk abuse items from a test matrix that consisted of 111 items which were under multiple road environment excitation, including condition categories for typical roads, curb striking, potholes and drains, and roadblocks. A novel multi-channel data reduction method and improved clustering method based on abuse probability sorting were proposed, and based on the specific characteristic constraints for the automobile airbag malfunction test results, by construction of a false triggering probability model and discussion of the weight factors of the two algorithms, importance rankings for the high-risk false action items were realized based on the relative probability. Finally, 53 high-risk abuse items were identified from a large set of 111 test items through 10-channel acceleration sensors. After analysis and comparison of the test condition details, conclusions of high-risk items are drawn with regard to the vehicle-road excitation that affects airbag abuse. The consistency of the identification results with the Chinese national standard verifies the accuracy and effectiveness of the proposed method.

Due to increase in fabric thickness and decrease compactness in packing, film bonding is unfavorable for airbag fabrics, furthermore, the uncoated fabric fabricated with a high density but it still has hot gas leakage problems. This study focuses on enhancement of vehicle airbag nylon 66 fabric properties by using a combination of different concentration of silica nanoparticles (SiO2 NPs) and low-density adhesion polyvinyl alcohol (PVA). The results illustrated that the nylon 66 fabric, which coated with PVA and SiO2 NPs presents an excellent property such as a thin layer reached at (0.009 mm), also thermal and mechanical properties have been enhanced to include better mechanical properties according to commercial guidelines airbag of Federal Motor Vehicle Safety Standards (FMVSS). Additionally, the weight per square meter of nylon 66 fabric coated with the PVA and high concentration of SiO2 NPs is 9.9 grams. Besides, the final dry weight of the coating (PVA/SiO2) material taken by the nylon 66 fabric is just 0.4 grams per square meter. The coated fabric demonstrated a hydrophobicity property in addition to the air-permeability has decreased by increasing the amount of SiO2 NPs in the composite material. The PVA and SiO2 NPs dispersed on the surface of the fabrics without any aggregation, as well, the coated fabric is gradually changed from flexible to hard which resulted in the better final performance in the proper and regular thickness along the whole fabric.

For closed-hole panels such as hat-stiffened panels, it is inevitable to use mandrels during the manufacturing process. However, the uniformity of pressure transmission of the silicone rubber mandrel with the prefabricated hole is not good, the vacuum bag mandrel is easy to be broken and wrinkled, the water-soluble mandrel is high in cost, and the invar steel metal mandrel is difficult to demold. To solve these problems, this article proposed a new method for co-curing carbon fiber-reinforced resin matrix composite hat-stiffened panels by using a silicone airbag as a mandrel through autoclaves. Firstly, the thermo-force-flow multi-field coupling finite element model of co-curing carbon fiber-reinforced polymer (CFRP) hat-stiffened panels was established by using finite element software. The co-curing process of hat-stiffened panels was simulated and studied. The influence of different thickness of silicone airbag mandrels on the wall thickness and pressure of the workpiece were found to be relatively uniform in the new process. Then, the autoclave experiment was carried out to verify the correctness of the finite element model. Lastly, the interfacial bonding strength test was carried out to verify the mechanical properties of the parts. In summary, the practicability of co-curing CFRP hat-stiffened panels with silicone airbag male mandrels was proved in this article. The precision of CFRP hat-stiffened panel was efficiently promoted by this new process.

With the rapid development of car crash sensing and identification technology, the application of pre-triggering airbag system is becoming an important option to improve vehicle safety. Thus, the present study aims to investigate the injury protection ability of pre-triggering airbag system and optimize its performance in frontal crashes regarding the key physical parameters. A driver restraint system model established and validated by National Crash Analysis Center was employed and validated for studying the injury protection ability of pre-triggering airbag system. Then, the influences of airbag triggering time, airbag volume scaling factor, inflator mass flow, and exhaust orifice size of pre-triggering airbag system on driver’s head and chest injuries were analyzed. Finally, the weighted injury criterion was selected as the evaluation index to optimize the pre-triggering airbag system. The results show the pre-triggering airbag should be designed with a larger airbag volume and inflator mass flow rate and smaller exhaust orifice. The optimized restraint system design presents a reduction of weighted injury criterion values in 100% and 40% overlapped frontal impacts reaching 25.63% and 42.23%, respectively.

Airbags are safety devices in vehicles effectively suppressing passengers’ injuries during accidents. Although there are still many cases of eye injuries reported due to eye-airbag impacts in recent years. Biomechanical approaches are now feasible and can considerably help experts to investigate the issue without ethical concerns. The eye-airbag impact–induced stresses/strains in various components of the eye were found to investigate the risk of injury in different conditions (impact velocity and airbag pressure). Three-dimensional geometry of the eyeball, fat and bony socket as well as the airbag were developed and meshed to develop a finite element model. Nonlinear material properties of the vitreous body and sclera were found through the in vitro tests on ovine samples and for the other components were taken from the literature. The eye collided the airbag due to the velocity field in the dynamic explicit step in Abaqus. Results of compression tests showed a nonlinear curve for vitreous body with average ultimate stress of 22 (18–25) kPa. Tensile behavior of sclera was viscoelastic nonlinear with ultimate stresses changing from 2.51 (2.3–2.7) to 4.3 (4–4.6) MPa when loading strain rate increased from 10 to 600 mm/min. Sclera, ciliary body, cornea and lens were the eye components with highest stresses (maximum stress reached up to 9.3 MPa). Cornea, retina and choroid experienced the highest strains with the maximum up to 14.1%. According to the previously reported injury criteria for cornea, it was at high risk of injury considering both stress and strains. Reduced pressure of the airbag was beneficial decreased stress of all components. Comprehensive investigations in this area can disclose biomechanical behavior of the eye during eye-airbag impact. Effective guidelines can be drawn for airbag design for instance the airbag pressure which reduces risk of eye injury.

The airbag is an occupant protection device widely used in the automotive industry. Federal Motor Vehicle Safety Standard 208 requires the low-risk deployment airbag system to be utilized in vehicles to protect out-of-position occupants. This paper presents a design-for-six-sigma low-risk deployment passenger airbag optimized by adding a passenger protection wrap. The passenger protection wrap reduces the cushion impact force on the passenger by ensuring pressure dispersion. A series of static tests were conducted to demonstrate the proposed system using Federal Motor Vehicle Safety Standard 208 test procedures. The test results shows that the proposed passenger airbag satisfies the criteria established by Federal Motor Vehicle Safety Standard 208 and also presents a significant improvement over conventional airbag systems.

In this paper the current generation of 350 dtex airbag coated and uncoated fabrics are examined experimentally under a multitude of simple and complex deformations. The geometric dimensions of the fabric architecture and the load–elongation behavior of the yarn constituents are studied. Furthermore, deformational shear behavior of airbag fabrics, which have not previously been investigated, are examined here. The stress–strain behavior of the yarn as well as the fabrics with and without coating are found to be highly nonlinear. Under uniaxial loading, nonlinearities of the fabric occur at lower strains due to crimp of the fabric, whereas under biaxial loading, the nonlinearity occurs at low and intermediate strain levels resulting from a combination of the inherent nonlinear material response of the yarn and geometric changes in the fabric structure. The data generated not only provide the basis for structural analysis of the airbag, but can also be used to develop more sophisticated definitions of the constitutive behavior of the fabric.

The safety of vehicles has been studied in the past on the basis of the safety of passengers. Recently, pedestrian safety has also attracted attention. The pedestrian protection performance of vehicles has gradually improved but is still not sufficiently good. Devices such as the pop-up hood and the pedestrian protection airbag system are generally used to protect pedestrians. Since these devices are relatively newer than other parts of an automobile, a standard design process has not yet been rigorously established. There have been studies that demonstrated how to determine the design parameters of the devices using computer simulations. In this research, a novel design process for a pedestrian protection airbag is proposed, which utilizes the results of the experiments. Some parameters of the pedestrian protection airbag system, which cannot be determined by simulations, are selected and obtained using experiments. They are the folding method of the airbag, the height type of the airbag and the inflator type. The design results using simulations are incorporated in the initial design of the proposed process. The experimental facilities are prepared on the basis of a mid-sized passenger vehicle, and the headform tests are performed according to the protocol of the European New Car Assessment Programme test. The proposed design process selects the rolling and folding method, the small height type and the bottom spurt inflator type. The resultant design is evaluated and analysed using experiments, and it is found to be satisfactory.

The rate of fatalities in vehicle-to-pedestrian crashes is high with respect to the frequency of occurrence. In recent years, a pedestrian safety system, which consists of a pop-up hood and a pedestrian airbag, was developed to reduce pedestrian injuries. However, the effects of the system and a reasonable design direction were not clearly established. In this research, the protection performance of the pedestrian safety system was investigated using actual impact tests. The pedestrian safety system was installed in a mid-size vehicle and tested according to the headform test of the New Car Assessment Program. The necessity and usefulness of the safety system using the test results are discussed. These results are incorporated into the simulation modelling process. The airbag system is designed to reduce head injuries by using computational impact analysis. Two categories are considered when designing the system: the design of the airbag housing and the design of the airbag itself. The airbag housing is designed by selecting appropriate materials. The design flow for the pedestrian airbag employs the orthogonal array and the response surface method. The newly designed airbag system reduces the severity of head injuries.

A vehicle–dummy multidisciplinary design optimization problem is treated as a multilevel system composed of structural and occupant restraint system design elements. The vehicle-based responses and the dummy-based responses are obtained from nonlinear transient dynamic finite element simulations of full frontal impacts and side impacts. The wall thicknesses of a set of energy-absorbing components together with the occupant restraint system control parameters associated with the seat belt and the airbag are treated as design variables and used to optimize the multilevel system to minimize both the structural mass and the selected injury criteria. Each element optimization problem is modeled using the augmented Lagrangian with exponential penalty function formulation. A single-loop coordination strategy is used to solve the multilevel optimization problem. To maximize the computational efficiency, surrogate models are used to approximate the vehicle-based responses and the dummy-based responses. The results of the vehicle–dummy design problem are used to examine the computational efficiency and the accuracy of the decomposed multilevel optimization methodology.

The role of automotive textile materials is of great importance and therefore this paper analyses the properties of such materials – airbag fabrics and upholstery fabrics. Fundamental characteristics and construction parameters of airbag fabrics and artificial leather with bonded textile fabric on the back side, as well as joining (sewing) and quality of joining places of cut parts are crucial for durability, comfort and aesthetics of the automotive interior design, and therefore were analysed. Airbag fabric specificity and extreme values of several parameters are achieved by manufacturing process, with extremely high densities in the warp and weft direction, resulting in a great strength and air permeability properties of very low level. The most important parameters for upholstery fabrics (artificial leather) durability are breaking force and elongation at break, and they were tested in different circular directions. Tests showed the direction with greater breaking properties, what is of paramount importance.

A side collision of an automobile poses a higher risk of injury than a frontal collision does. Throughout the world, governments and insurance companies tend to establish and implement new safety standards for side collisions in order to ensure the safety of the occupants of vehicles. Most of the standards aim to reduce the head injury criterion. Currently, curtain-airbag systems are widely used and known to be the most effective means to reduce the head injury criterion in the event of a side collision. A curtain-airbag design procedure which uses modern optimization methods based on a newly defined design scenario to reduce the head injury criterion risks of the occupants of vehicles is introduced in this paper. The design scenario has two phases. In phase 1, various elements of the curtain airbag are defined as the design parameters. The variables are determined in a discrete space using an orthogonal array as well as in a continuous space using optimization where each function is approximated. In phase 2, important variables are extracted via a statistical method and those variables are determined in the same manner as in phase 1. As a result, the head injury criterion of the occupant is decreased significantly. The final design is discussed from a practical viewpoint.

Pedestrian safety is of keen interest because the vulnerability of pedestrians leads to severe injuries in pedestrian-vehicle crashes. Various countermeasures for protecting pedestrians have been developed in the field of traffic and vehicular safety engineering. The pedestrian protection airbag system (PPAS) is one of the recently developed vehicular technologies for pedestrian protection. PPAS is a promising, passive safety technology for reducing the severity of pedestrian injury. The purpose of this study was to evaluate the safety benefits of PPAS. A probabilistic pedestrian fatality model and a set of linear regression models were employed to estimate the effectiveness of PPAS in reducing the severity of pedestrian injury. Head injury criteria data, which represented the level of severity of pedestrian head injury, were obtained from indoor experimental collisions. The number of pedestrian fatalities was estimated for two cases on the basis of the pedestrian fatality model: one with PPAS and one wit...

Approximately 66 per cent of all airbag deployments in the USA result in at least one skin injury, with 47 per cent of these skin injuries attributed directly to the airbag deployment. The purpose of the present study was to evaluate the risk of skin abrasions from the airbag fabric seam design by using a new shear testing methodology. High-rate shear loading was performed with a pneumatic impactor that propelled a section of airbag fabric across porcine skin at 85 m/s. Twenty-seven tests (three control and 24 with fabric) were performed using eight different seam designs. A 40 cm × 10 cm section of airbag fabric with each seam was forced across a 5 cm × 5 cm section of fresh porcine skin that was acquired within 2 h post-mortem. No abrasions were observed in the three control tests, but abrasions were observed in all 24 of the tests conducted using airbag fabric. The unturned, sewn seam orientation resulted in significantly more severe abrasions than the woven, unturned seam orientation ( P = 0.01). This new system and results illustrate that different seam designs can result in different skin abrasion risk. Moreover, the data show that severe abrasions can be caused by normal pressures well below the 1.75 MPa injury threshold previously published.

In order to improve the impact ejection performance of the flexible airbag and to reveal the airbag inflating mechanism, a simulation model was built and verified by carrying out the flexible airbag impact ejection test. Based on this model, the influence of mass flow, compression displacement, and airbag thickness on flexible airbag ejection impact performance were studied. The results show that the ejection velocity of the flexible airbag increases as mass flow increases, but the excessive air mass flow does not improve the impact ejection performance of the airbag. The simulation results also demonstrate that the flexible airbag will oscillate reciprocally after it has no more contact with the moving rigid body and every node in the flexible airbag model has the same oscillating displacement. The analysis of compression displacement shows that it has a significant effect on the improvement of ejection performance. In conclusion, to improve the impact ejection performance of flexible airbag, the mass flow and compression displacement should be changed in a certain scope, which can provide reference for the topological structure design of the flexible airbag.

This overview paper summarizes the status of design and analysis of small and large, complex, flexible and adaptable industrial membrane structures in architecture, automotive and space industries, with the numerical tools developed and implemented by the authors and their affiliations. Examples from aero-space membranes, airbag simulations used by car makers, and from impact biomechanics, enlarge the field of application beyond structural engineering.

A computational model of the pregnant occupant, which is capable of simulating the dynamic response to acceleration impacts, is introduced. The occupant model represents a 5th percentile female at around the 38th week of pregnancy. A finite element uterus and multi-body fetus is integrated into an existing female model to incorporate pregnant female anthropometry. The complete model, ‘Expecting’, is used to simulate a range of frontal impacts of increasing severity from 15km/h to 45km/h. Three levels of occupant restraint, completely unrestrained, three-point seat belt, and three-point seat belt with an airbag, are investigated. The strains developed in the uterus because of loading from the seat belt and steering-wheel unit are presented, together with an analysis of stress distribution due to inertial loading of the fetus on the uterus. The unrestrained cases are shown to be the most dangerous to the fetus, owing to the large interaction with the vehicle steering wheel at the level of the placenta. The use of a three-point seat belt together with a driver airbag appears to offer the greatest protection to the fetus.

The paper explores an adaptation of a messy genetic algorithm (mGA) and back-propagation neural network (BPN) in the context of a global approximate optimization of an occupant safety system in automotive design. The design objective is to determine the airbag vent hole size, seatbelt load limiter, steering column collapse load, and airbag tether length by minimizing both the head injury criterion (HIC) and thorax injury criterion (centre-of-gravity criterion (CGC)) for passenger protection. The analysis of the occupant safety system is highly non-linear, thus an mGA is adopted as a global optimizer in the present study. For global function approximations, BPN models are established to represent output responses of the HIC and CGC. A design of experiments is conducted to examine the interaction effect between the design variables and to generate training data for use in the BPN. The paper develops new schemes of adaptive random seed selection and adaptive operation probability to enhance the mGA performance. A number of benchmarking problems are first explored to support proposed mGA strategies, and approximate optimization is performed for the design of occupant safety system.

Occupant protection systems for automobiles are currently highly publicized. An airbag inflating at high speed impacts an occupant with great force. Airbag safety relies on its construction with primarily woven fabrics. We have referred to a typical pressure-time history of an airbag and developed a device to measure impact load when the fabric airbag inflates at high speed. When interior pressure in the airbag increased, impact load increased. Also, the impact load on a body increased as the distance between the body and airbag decreased. The impact force of an airbag inflating at high speed was simulated by a non-linear finite element method (FEM) combined with an incremental method, where the sample was modeled by a thin elastic shell. An experiment was conducted to verify the theory and this calculation method. Good agreement was obtained between the theoretical and experimental values for two types of fabric sample. This demonstrated that the mathematical technique developed here can satisfactorily predict the impact force when an airbag inflates at high speed and that the impact force depends appreciably on the mechanical properties of fabrics., Article, TEXTILE RESEARCH JOURNAL. 79(9):837-843 (2009)

Engineered fabric manufacturing needs a thorough understanding of the functional properties and their key control construction parameters. When the relationship between a set of interrelated properties goes out of the complete comprehension of human brain, neural networks could be used to find the unknown function. This article describes the method of applying the artificial neural network for the prediction performance parameters for airbag fabrics. The results of the ANN performance prediction had low prediction error i.e., 12% with all the samples and the artificial neural network based on Error Back-propagation were found promising for a new domain of design prediction technique. The prediction performance of the neural network was based on the amount of training given to it, i.e., the diversity of the data and the amount of data; resulting in better the mapping of the network, and better predictions. Airbag fabrics could be successfully engineered using artificial neural network.

This paper presents efforts made on the computational modelling, simulation, and optimization of a new type of airbag, namely a sandwiched tube-type airbag, which deploys more rapidly than the traditional airbag using less gas mass inflow and can decrease the risk of head injury of an out-of-position passenger. The airbag is modelled using the finite element method with MADYMO. A static airbag deployment test is performed to support and validate the computational modelling efforts. The considered variables for airbag optimization design are as follows: the collocation of the tether, the length of the tether, the mass flowrate, and the size and location of the vent hole. The simulation is performed using an orthogonal array, within the range of given control levels. Finally, the simulation results are analysed by iSIGHT, and the relationships between the design variables could help to design the airbag cushion.

The airbag is a widely accepted device for occupant protection in the automotive industry. Both restraint and automobile manufacturers have to come up with a proper airbag design to reduce the injuries from static and dynamic tests in the FMVSS 208 regulation. The objective of this study is to investigate the injury characteristics of the Hybrid III fifth percentile female dummy according to airbag inflation. In order to study the injury patterns, tests are performed for the dummy with the out-of-position (OOP). The test conditions are varied with various airbag parameters such as inflators, airbag folding methods, and cover tear lines. The relationships are investigated further by using computer simulations. The guidelines for the airbag design with the OOP are established and the injury patterns are identified.

An approach based on the shock tube experiment is proposed to evaluate the permeability of airbag fabrics. Shock tube experiments were conducted to imitate airbag inflation by fixing an airbag fabric sample near the end of an open driven section. When a plane shock wave impinges the airbag fabric, it will be reflected. Meanwhile, an increase in pressure will form at the front face of the airbag fabric and this will lead to a flow through the fabric, due to the permeable structure of the fabrics. The air permeability of airbag fabrics can therefore be determined by measuring the velocity of the reflected shock wave. It was found that at relatively high pressure the dynamic permeability results from the shock tube experiment were lower than the static results from the conventional permeability testing method. This phenomenon appears to be related to the different influences on the airbag fabric structure of the steady pressurization that occurred in the static experiments and the instantaneous pressurization that occurred in the shock tube experiments.

Multidisciplinary design optimization based on independent subspaces (MDOIS), which is a multidisciplinary design optimization (MDO) algorithm, has been recently proposed. Since MDOIS is relatively simple compared with other MDO algorithms, it is easy to apply MDOIS to practical engineering problems. In this research, an MDO problem is defined for the design of a belt-integrated seat (BIS) while considering crashworthiness. The crash model consists of an airbag, a BIS, an energy-absorbing steering system, and a safety belt. It is found that the current design problem has two disciplines - structural non-linear analysis and occupant analysis. The interdisciplinary relationship between the disciplines is identified. Interdisciplinary variables between the two disciplines are stiffness of the seat back frame and the belt load. The interdisciplinary relationship is addressed in the system analysis step in MDOIS. Prior to each independent subspace design, values of interdisciplinary variables at a given design point are determined in the system analysis step. The determined values are passed to corresponding subspaces, and the subspaces treat the received values of the interdisciplinary variables as constant parameters throughout the subspace design. For the present example, the belt load is passed to the structural analysis subspace and the stiffness of the seat back frame is passed to the occupant analysis subspace. Determined design variables in each subspace are passed to the system analysis step. In this way, the design process iterates until the convergence criterion is satisfied. As a result of the design, the weight of the BIS and the head injury criterion (HIC) of an occupant are reduced while the specified constraints are satisfied. Since the system analysis cannot be formulated in an explicit form in the current example, an optimization problem is formulated to solve the system analysis. The results from MDOIS are discussed.

Although airbags have been shown to reduce the incidence of life-threatening injuries, they have increased the risk of minor injuries such as those to the skin. Based on the distribution of injuries that can be directly attributed to the airbag itself, it is believed that shear loading exists as a mechanism for these skin injuries. The purpose of this study was to develop a new methodology designed to assess the injury potential from different types of airbag with respect to shear loading. This new methodology utilized a high-speed impactor to accelerate the airbag fabric past a sample of skin. Contact normal forces were monitored by the use of pressure sensors, and fabric velocity was determined from a high-speed video. The abraded skin samples were analysed using light microscopic analysis and ultraviolet light source photography. A new abrasion rating method was developed called the total abrasion score, which allows for quantifiable differentiation between the abrasions caused by different airbag fabric and seam types.

A finite element model of a seven-month pregnant uterus was created and integrated into a multibody human model. The pregnant occupant model was validated using known abdominal response corridors. Tests of occupants with no restraint, a three-point belt and a three-point belt plus airbag at 35 km/h were simulated to evaluate the effects of four support ligaments connected to the uterus. The primary injury predictor, the peak uterine strain on the anterior uterus, was not found to change appreciably by the absence of the support ligaments; however, high local stress concentrations were found at the ligament attachment sites. Based on these results, it is recommended that computational models of the pregnant occupant contain the supporting ligaments since the stress concentrations may result in increased injury risk in other test configurations or loading conditions.

Restrained driver and passenger kinematics and injury outcome in frontal collisions are compared using US fatality field data and post-mortem human surrogate sled tests. The fatality data indicate that a frontal airbag may provide greater benefit for a passenger than for a driver. The thoracic injuries sustained by passenger-side surrogates restrained by a force-limited, pre-tensioned belt and airbag are evaluated, and kinematics are compared with driver-side subjects exposed to a similar impact. Driver and passenger kinematic differences are identified and the implications are discussed with respect to the injury-predictive ability of existing thoracic injury criteria. The chest acceleration of the passenger-side subjects exhibited a bimodal profile with an initial (and global) maximum before the subject loaded the airbag. A second acceleration peak occurred as the subject loaded both the belt and the airbag. A similarly restrained driver-side subject loaded the belt and airbag concurrently at the time of peak chest acceleration and therefore did not exhibit this biomodal chest acceleration. While the injury-causing or injury-mitigating significance of this bimodal response is not known, its significance with respect to thoracic injury prediction is discussed.

This study examined how people allocate blame for injuries sustained from the deployment of a driver-side airbag. Participants read one of several versions of a fictitious scenario in which the driver of an automobile is injured by a deploying airbag after a driver swerves into oncoming traffic to avoid striking a child who has run into the road. The scenarios depicted a driver sitting within the airbag's deployment zone and varied in the following ways: the stature of the injured driver (small or large); severity of the injury resulting from the deployment of the airbag (permanent blindness in one eye versus quadriplegia); vehicle speed at impact (15 m.p.h. above versus driving at the posted speed limit); and the safety-worthiness of the vehicle (an elaborate system of safety features versus the absence of these features). When assigning blame for the injuries sustained in the crash, participants appeared sensitive to both the quality of the vehicle's safety system and the driving behavior of the injured party. The manufacturer of the “safe” vehicle was held significantly less responsible than the manufacturer of the vehicle lacking these safety features. However, driver behavior also exerted a significant effect on allocation of blame. Injured drivers depicted as traveling significantly above the speed limit were assigned significantly more blame than their counterparts depicted as driving at the speed limit. This finding suggests that people take other factors into account, including personal responsibility, when assigning blame. Perhaps the most important finding of this research, and one that supports previous research on this topic, is that safety pays. When companies are perceived as making a good faith attempt to look out for the safety of their customers, their customers, in return, may be less likely to hold them responsible when injuries do occur.

In this study, an optimization methodology was developed to obtain design parameters for a frontal occupant impact protection problem using a statistical approach. The central composite design was applied to occupant simulations. On the basis of the design, a total of 25 simulations were performed. The second-order multiple regression injury functions about the head injury criterion (HIC), 3 ms chest acceleration, chest deflection, and right and left femur loads were constructed with high coefficient of determination values and statistical significance ( r2 > 0.8 and p 0.001). Then, the response surface method (RSM) was applied to this multicriterion optimization problem, and optimum design parameters about the airbag vent characteristics, triggering time, mass flowrate and knee foam stress-strain relationship were obtained. After the optimized design, the 3 ms chest acceleration, right and left femur loads were reduced by 25.5, 7.1 and 19.9 per cent respectively. These results suggest that the proposed method is useful and effective for automotive safety design problems.

The function of a head restraint system is to prevent injurious hyperextension of the occupant's neck in the event of a road vehicle rear end impact, and thus it must have adequate stiffness to limit the movement of the head relative to the torso. Also, it should absorb the kinetic energy progressively so that the head does not sustain any injury and does not roll on the cushion. Practically, a well-designed head restraint will have an optimum balance of these features and thereby offer adequate protection for both the head and the neck. This paper presents some pioneering thinking on head restraint design and develops criteria for qualifying the systems. It presents an airbag head restraint system that has optimum stiffness and good potential for reducing head and neck injuries suffered through rear end collisions. It also presents the results of experimental tests conducted on this novel airbag head restraint system and on several randomly selected existing head restraints. Furthermore, analysis of energy absorption capabilities, head injury criterion (HIC) values and a new criterion, called the equivalent impact power criterion (EIPC), is developed in order to quantify the relation between the rate at which energy is imparted to the head during the impact cycle and injury severity. Current test results show that, the lower the EIPC, the better is the head restraint system and the less is the risk of whiplash and head injuries. Moreover, the work has quantified a number of variables, including the optimum stiffness, as the factors governing the severity of injury to the occupant in a rear impact scenario.

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.

A novel dynamic air permeability tester (Textest FX3350) is designed to project air at high pressure through automotive airbag fabrics. The abilities of the machine are studied, and a standard operating procedure is defined. A series of fabrics is tested with the machine, and the results are correlated with readings obtained from the conventional static tester, which operates at a lower pressure. A nonlinear relationship exists between air pressure and fabric air permeability.

When airbag technology appeared on an industrial scale in the middle of the 1980s, the first bags were neoprene coated. Although the neoprene met initially the performance requirements of airbags, its efficiency was question able in the long term.

There are currently two principle material types which are used in the manufacture of airbags. They are uncoated nylon (polyamide 66) and coated nylon. Two types of commonly used coatings are Silicone and Neoprene. In general, coated materials are used for driver's side airbags and side impact bags, while passenger side airbags are made from uncoated nylon materials. Different cutting methods are needed for the two different classifications of mate rials. Coated nylon can be cut with traditional mechanical tools such as dies or reci procating knife cutters, due principally to the fact that the coating prevents fraying. On the other hand, uncoated nylon must be cut with a hot tool, such as a laser to pre vent fraying; fraying could compromise the airbag integrity during deployment.

Because the chassis, suspension and tyres of a tipping trailer unit are flexible, when standing on sloping ground, the body tilts more than the sideways slope of the ground on which it is standing. This changes the positions and directions of the resultant forces due to self-weight, payload and sideways wind relative to the hinge bar which allows the body to be tipped. These changes alter the magnitudes of the forces exerted on the chassis at the hinges and by the lifting ram; this changes the forces exerted through the air suspension on to the rear wheels. When the force exerted by a rear wheel becomes zero, rollover is imminent. All of the above changes have highly non-linear effects. Further non-linearities are due to the operation of the airbag suspension. This paper defines these effects and describes iterative methods to predict the position of the body relative to the ground for any trailer unit under specified conditions and to predict the ram length at which rollover would occur.

In an era when automotive safety sells and competition among safety component suppliers is fierce, the inflatable supplemental restraint or airbag system is undergoing a continual evolution in terms of its materials, design, and perfor mance.