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application/pdf, International Journal of Crashworthiness. 2020

application/pdf, International Journal of Crashworthiness. 2019, 25 (3), P.242-251

In this study, a comprehensive theoretical model of an in-position occupant restrained by seatbelt and airbag in an in-line frontal vehicle barrier impact is proposed. A novel approach is adopted in formulating the occupant motion based on occupant interaction with the seatbelt and airbag. Also, the airbag model developed in this paper simulates for airbag deflation both before and during occupant interaction. The proposed model is validated against test results by the system identification method through parameter optimisation. The optimisation problem is stated as a mixed integer non-linear programming problem to be solved by genetic algorithm. The results obtained with the proposed model are in good agreement with test results with a root mean square deceleration error of 0.13837 g. Furthermore, the computational time for the model has been estimated to be exceptional.

In 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 s...

Placental abruption accounts for more than half of fetal mortality in automobile collisions. In most of the pregnancies, placenta is located at the fundus position of the uterus. However, in real life, placenta can also be found at different locations in the uterus.The goal of this study is to investigate whether the location of the placenta in the uterus of pregnant driver has a role on the risk of placental abruption in motor vehicle accidents. In addition to the most common fundus position, four other placental locations, namely anterior, posterior, lateral left and lateral right, are considered within the computational pregnant driver model ‘Expecting’, and used in collision simulations with impact severities from 15 to 30 kph with 5-kph increments. Scenarios also include four cases where the pregnant driver is fully restrained with three-point seatbelt and airbag, three-point seatbelt only, airbag only and no restraint at all. The maximum strains developed in the utero-placental interface of ...

The chest deflection and chest acceleration (3 ms) have been used as chest injury measures of Hybrid III dummy in frontal crash tests. In this research, the relationship between two chest injury measures was investigated based on finite element analysis of Hybrid III in a frontal impact. The equation of motion of the chest was established using the external (seatbelt force and airbag contact force) and internal forces (neck, shoulder joint, lumbar spine force) that are exert on the chest. Based on this formula, the mechanism of the chest acceleration that was generated can be examined with time. The chest deflection is related to the external forces (seatbelt and airbag force), and the chest acceleration is related to the external and internal forces. The influence that the restraint conditions (seatbelt path and force limiter) has on the chest acceleration and chest deflection was also investigated. The seatbelt path affected the rib cage deformation mode and the chest sternum deflection, but it ...

Computational modelling is an effective way of estimating the risk of injuries and fatalities in road traffic accidents. Computational pregnant occupant modelling has an additional important role in the investigation of the risk of fetus mortality in crash test simulations. In this paper, the effect of including the fetus in the uterus of the pregnant occupant model is investigated. First, isolated drop test simulations with the uterus of the computational pregnant occupant model, ‘Expecting’, with and without a fetus are used to show the effect of the presence of fetus in the uterus model. Then ‘Expecting’ with and without the fetus is used with varying levels of restraint system use, such as fully restrained, ‘seatbelt only’, ‘airbag only’ and ‘no restraint’, in frontal crash simulations, representing five levels of impacts. Maximum strains developed in the uteroplacental interface with and without a fetus are compared in every case. Both simulations predict higher risks of placental abruption w...

The recent implementation of new federal regulations on injury criteria for occupants in side-facing seats greatly decreases the risk for these passengers. One of these new requirements limits the amount of leg flail allowed to the occupant. While the limit of rotation is defined at 35°, the method of measurement of this angle is left open to the end user. Photometric analysis and angular rate sensor data are analysed and evaluated, first, on a pendulum fixture to determine any difference between the two and then, second, on an ES-2re anthropomorphic test device (ATD) in a side-facing seat. The leg flail or leg rotation is measured in three different configurations: an unrestrained leg, a rigid block to restrain the leg, and with an airbag deployed to restrain the leg. Various targets are tracked from the high-speed video, and the photometric results for each are compared to the angular rate sensor data during the impact test.

An active bonnet and pedestrian airbag are effective in providing a high level of pedestrian head protection. For triggering the activation of these systems, a reliable sensor that distinguishes a pedestrian collision from collisions against other colliding objects is necessary. In this research, a pedestrian contact sensor based on the pressure of a deformable chamber was investigated from finite-element (FE) analysis. In a simulation of a component test of a chamber impact, the internal pressure of the chamber increased with the volume deformation of the chamber according to Boyle's law. The chamber was installed above the top plane of the bumper energy absorber of a simple car model, and FE simulations of a car–pedestrian collision were conducted. The chamber deformed and its internal pressure increased as the bumper energy absorber deformed during contact with the pedestrian leg. It was shown that the pressure response of the chamber could be detected, irrespective of vehicle shape and structure. This...

In this paper, the approximation non-linear interval number programming (A-NINP) method is suggested to obtain the optimal buffering characteristics of a landing airbag in manned airdrop. The landing velocities of airdrop equipment and ground friction coefficient are regarded as the uncertain parameters, and an uncertain objective function that represents the human neck injury index is created. Based on an order relation of interval number, the uncertain objective function is transformed into two deterministic objective functions. Through a modified possibility degree, the uncertain inequality constraints are changed to deterministic inequality constraints. In order to reduce the computational cost, radial basis function approximation models are used, and a local-densifying method is suggested to guarantee the accuracy of the approximation models. The intergeneration projection genetic algorithm is employed to solve the finally obtained deterministic and non-constraint optimisation problem. The results in...

Passive safety has for many years reduced the number of fatalities on the roads. However, its effect on occupants' safety has now stabilised, meaning that new active safety features are needed to reduce further the number of casualties. These active safety features, like autonomous emergency braking (AEB), aim to prevent vehicle collisions and reduce the vehicle kinetic energy on impact. A previous study has shown that unbelted occupants kinematics are affected by the pre-braking phase, suggesting that the occupant's hand positions on the steering wheel, combined with a bracing behaviour, could cause the occupant to miss the deploying airbag in the case of a secondary rigid wall impact. This paper will investigate the variations of the secondary vehicle impact crash patterns by calculating crash pulses based on typical vehicle frontal accident scenarios and conclude on these effects on the human occupant's neck, head and thorax injuries.

Airbag landing system has recently been used more and more extensively in industry for its excellent energy absorption capacity as well as extremely light weight. Firstly, we investigate a single-chamber airbag (SCA) under dynamic loading through experiment by using the Dynatup 9200 impact testing machine. Then, the corresponding non-linear finite element (FE) model of the SCA is established through LS-DYNA. From the comparison between the numerical results and the experimental results, we find that the FE model of the SCA is accurate enough for the engineering application. According to the FE modelling method of the SCA, the non-linear FE model a double-chamber airbag (DCA) landing system is established. Based on the FE numerical results, the polynomial function meta-models of the peak acceleration and the peak rebound velocity of the landing equipment of the DCA landing system are obtained by employing the error reduction ratio (ERR) structure-selection techniques. Finally, the DCA landing system is opt...

This paper reports on the work of computer simulations carried out at Coventry University as part of the European 6th Framework HeliSafe TA project, which considered the potential improvements in occupant safety for civil helicopters. A multi-body systems approach with additional use of finite elements for critical components such as a pilot airbag and the harnesses was adopted in the computer models to simulate helicopter crash/rollover scenarios and to investigate the effectiveness of occupant protection systems deployed during helicopter crash scenarios. ADAMS and Madymo simulations of helicopter impact/rollover events were demonstrated. A cabin/cockpit model of a Bell UH-1D helicopter was developed to replicate the physical crash test setup and a parametric study for the pilot airbag and a range of harness concepts was performed. The use of validated multi-body systems-based cabin/cockpit models has proved to be effective in the development of new restraint system concepts for occupant protection.

The purpose of this research is to analyse the influence of steering control devices for disabled people on passive safety. It is based on the advances made in the modelling and simulation of the driver position and in the suit verification test. The influence of these devices is studied through airbag deployment and/or its influence on driver safety. We characterise the different adaptations that are used in adapted cars that can be found mounted in vehicles in order to generate models that are verified by experimental test. A three-dimensional design software package was used to develop the model. The simulations were generated using a dynamic simulation program employing LS-DYNA finite elements. This program plots the geometry and assigns materials. The airbag is shaped, meshed and folded just as it is mounted in current vehicles. The thermodynamic model of expansion of gases is assigned, and the contact interfaces are defined. Static tests were carried out on the deployment of the airbag to contrast with and to validate the computational models and to measure the behaviour of the airbag when there are steering adaptations mounted in the vehicle. © 2011 Taylor & Francis.

One of the key components of inflatable restraint systems is the gas generator (inflator). This relevance of the generator is mainly due to the fact that it is the only active component on most airbag systems. Each new car model requires a new process of developement and system integration to set up the performance of the restraint system. This process usually demands a performance adjustment of the gas generator to optimise the overall behaviour of the whole system. Often, the number of gas generator configurations available from serial or prototype manufacturing does not cover the whole range of each design parameter. Also, the time needed to manufacture a prototype definition of a gas generator can be delayed from some days to several months, depending on the extent of the required modifications. This process can be significantly shortened by a simulation approach that provides the performance at the output of a particular gas generator. The present work describes a new analytical model of a pyrotechnical gas generator developed in Matlab/Simulink code. The advantage of the selection of this software is that it can be linked with most of the vehicle crash simulation softwares currently available in the market. Also, the utilisation of the block modelling technique of Simulink allows the easy implementation of new capabilities to the model. The model has been built to reproduce the performance of the inflator measured on the widely accepted closed tank test. Finally, to guarantee the predictability of the model it has been validated by means of (1) the comparision, made at three different test temperatures, of the theoretical results with the baseline of the results of the tank pressure tests performed during one year of serial production of a particular gas generator model; (2) comparing gas generator variability limits for tank test performance, calculated with the same serial production gas generators, with the variability limits obtained by means of a Monte Carlo analysis using the analytical model. It is demonstrated by means of this validation of robustness of the presented model.

The head impact in the windscreen area is currently the focus of the research regarding pedestrian protection by the Institute of Automotive Engineering (IKA) of RWTH Aachen University. Head injuries are the most relevant cause for severe and fatal injuries. Only consumer testing and - within a limited area - phase I of the European Directive on pedestrian protection considers the testing in this area, where in most cases involving an average sedan-shaped vehicle the head of the 50th percentile male will contact. For representation of the typical sedan-shaped vehicle, Opel Signum was chosen as the model. In the first test series the experimental vehicle has been tested using the European Enhanced Vehicle Safety Committee Working Group 17 (EEVC WG 17) adult-head impactor. For the triggering and timing of the head impactor in the airbag test, the previously determined head-impact time from numerical simulations has been used. In the second test series, Polar-II pedestrian dummy tests have been performed. In parallel to these test series an airbag developed by TAKATA has been tested. The airbag is able to lift the rear end of the hood and in addition cover the windscreen surrounding. The development of the necessary hinge modifications, to get an additional degree of freedom, and adjustments of the airbag mounting area were carried out by the IKA. The results of these tests should lead to an evaluation of and methods to test future protection systems for the head impact of pedestrians in the windscreen area.

Airbags have been widely used in passenger vehicles to protect occupants from vehicle collisions. Although the airbag is an advanced protective device, it has been continuously improved to minimise occupant injuries for true safety. The current study developed a new sandwiched tube-type airbag (STAB) consisting of two flat layers and a middle layer with a tube-type structure. The objective of designing this new type of airbag is to enhance occupant safety in passenger car collisions by reducing injury risks for small and out-of-position (OOP) occupants. A prototype of the new airbag was built using a volume of 40 L. The performance of the prototype airbag was investigated using static deployment test and sled crash test with a Hybrid III dummy. A finite element model of the new airbag was developed and validated using results from the airbag deployment test and sled crash test. A parametric study and STAB optimisation were subsequently conducted to study the influence of eight design variables on STAB. The design of experiment (DOE) was used to generate the virtual test matrixes; results were analysed to determine significant design variables and STAB's protective efficiency. A series of virtual tests involving the OOP occupant and STAB airbag as well as the normal driver-side airbag (DAB) were conducted with a 5th percentile female dummy and a 50th percentile male dummy. Results indicated that the STAB airbag needs less gas than the DAB to get the same load and displacement curve. In the deployment process, STAB's leading velocity was lower than that of DAB's. Thus, STAB could decrease the risk of OOP occupant's injury and provide better protection performance.

The deployment of an airbag is most fatal and dangerous to a passenger when it is in an out of position (OOP) situation, with the airbag making contact before it is fully inflated. This can lead to severe, if not life threatening, injuries to the passenger. This situation is more commonly associated with small females and children who are positioned near to the airbag module, i.e. in an OOP load case. The aim of this research is to assess the response of a Hybrid III 5th percentile female anthropomorphic dummy positioned in an FMVSS 208 low risk static airbag deployment OOP load cases using a transient dynamic finite element program called LS-DYNA. The simulation considers the standard procedures utilised in the LS-DYNA, where assumptions such as uniform airbag pressure and temperature are made, along with a more recently developed procedure that takes into account the fluid-structure interaction between the inflating gas source and the airbag fabric, referred to as arbitrary Lagrangian Eulerian (ALE) theory. Both simulations were compared to test data received by Jaguar, indicating satisfactory results in terms of correlation, with the more recently developed procedure, ALE theory, showing the greatest accuracy, both in terms of graphical and schematic comparison, especially in the very early stages of the inflation process. As a result, the new simulation procedure model was utilised to research into the effects of changing the designs of the airbag module.

In recent years there have been many airbag-related injuries and fatalities. These have been due to the airbag interacting with the occupant during out-of-position (OOP) states. Numerical simulation of this situation is currently under investigation. This article reviews the mathematical models that have been developed and utilised for in-position (IP) occupant analysis, showing their capabilities in crash simulations and their inefficiency for OOP occupant interaction. The review then describes a new simulation technique, fluid structure interaction, which can possibly model the OOP occupant interaction. The capabilities of this new method are described and how it can be utilised for this type of simulation, along with recommendations of future work in this area.

New simulation tools and modelling techniques have been developed in recent years to predict injury risks for Out-Of-Position (OOP) occupants. These developments include the integration of Computational Fluid Dynamics (CFD) into Finite-Element simulations of airbag deployment, realistic folding of airbag models and refined models for dummies and humans. This contribution surveys the current state of these new techniques and discusses their strengths and weaknesses. In the first part of the paper, the integration of the Finite-Point-Method (FPM) for CFD analysis within FEM simulations is discussed and demonstrated for the deployment of a curtain airbag manufactured by Autoliv B.V. & Co. KG. In the second part, the influence of the generator housing on the unfolding process is presented for the impact of an inflating passenger bag against a body block. Simulation results clearly show the current limiations of CFD methods for airbag inflation problems. In the third section, several aspects of the co...

Airbag simulations have emerged as an important means to study their efficiency in occupant safety. The situation in which the occupant deviates from the nominal position is commonly referred to as an out-of-position (OOP) situation. The focus in this paper is on developing simulation models that can be used for OOP studies in the future. To capture the initial stages of inflation of the airbag in OOP simulations, the focus has now shifted towards discretizing the fluid flow inside the airbag using the Arbitrary Lagrangian Eulerian (ALE) approach. The interaction between the fluid (Eulerian mesh) and the structural elements (Lagrangian mesh) is defined through a coupling. In this work, a description of the process for generating the mesh for the folded airbag is presented. Some strategies adopted to resolve penetration and time step issues in folding have been highlighted. The folded airbag is inflated in simulation using both the CV (Control Volume) and ALE approach, and the results are compared. For validation, the inflation of the airbag was recorded using high-speed photography and a tank test conducted to characterise the inflator. The performance of the ALE method and CV method for the purpose of OOP simulations is compared with the experimental observations.

This work presents a novel algorithm for generating a geometric mesh of an airbag after a series of folds are defined on it, for use in crash simulations. The process of airbag folding is simulated as a series of geometric transformations to the airbag mesh, which is modeled as a stack of connected planar layers. Along with these transformations, optimisation techniques are used to minimise change in the geometry and the area of the airbag post-inflation. The results from this approach are compared with commercially available airbag folding software. It is observed that the algorithm is effective in limiting change in the area and geometry of the airbag in the folding process. The change in surface area is only 0.1% of the surface area of the airbag against the change of 11% in the commercial package. The current paper is a sequel to authors' 'Development of FE meshes for folded airbags', (International Journal of Crashworthiness, 2005 10(3) 259-266), which reports initial results of the folding process.

Today, numerical simulation is used all over the world to develop and optimise the restraint system performance. But more than just helping engineers to design restraint systems fulfilling the homologation and ratings requirements, the numerical simulation enables them to extend their field of investigation by going beyond the laboratory test conditions, making their first steps in "real life safety". This paper presents the simulation of a concept of an adaptive restraint system for the passenger side. Its restraint capacity is continuously adjustable to the occupant, by an airbag whose shape and volume can be varied. In addition to this, the airbag outflow hole characteristics have also been optimised. The performance of this restraint system has been evaluated using the three standard adult dummies (5th, 50th and 95th percentile), each one in various seating positions for both US and Euro-NCAP pulses. The results will be shown with respect to a state-of-the-art restraint system. The design process, starting from the 95th percentile dummy, will be explained as well as the problems encountered during the optimisation process.

Since its invention in the early 1990's, the side curtain airbag has become an important part of the occupant restrain system. In order to optimize the design of these devices more efficiently, Computer Aided Engineering (CAE) is often used. While usual simulation tools have proven their usefulness with certain types of airbags, the specificity of a side curtain airbag highlighted some of their limitations. The widely adopted uniform pressure method can simulate the behavior of a side curtain airbag after its full deployment, but is unable to capture the correct inflation kinematics at the early stage due to the great difference of pressure and temperature from one end of the airbag to the other end. As the result of coupling a Computational Fluid Dynamics (CFD) code with a Finite Element (FE) code, the Finite Point Method (FPM) is able to simulate the gas dynamics inside the airbag, thus results in more realistic inflation kinematics. In this paper, the simulation of a side curtain airbag by FPM...

A novel algorithm for generating Finite Element meshes of folded airbags for use in crash simulations is proposed and evaluated. The algorithm models the airbag folding process through geometric transformations on a given airbag mesh, followed by a series of numerical optimizations in order to achieve a folded state. An airbag model as a stack of connected planar layers is the input. It is shown that the proposed approach compares favorably with existing airbag folding techniques when evaluated quantitatively with the area and volume of the airbag post folding.

The function of the head restraint system is to prevent injurious hyperextension of the neck following a vehicle rear end impact. The nature and severity of the head and neck injuries attributed to rear end impacts are the result of many factors including the manner in which the head is supported throughout the impact process. A well-designed head restraining system will prevent neck hyperextension and accomplish this with the minimum risk of consequential injury to the head. Also, it must not present a safety hazard in itself and its effectiveness should not depend on precise adjustment. This paper discusses the approach taken in the design and development of a low impact airbag head restraint system.

Recent development in computer hardware technology and software advancement has made it possible to develop large and detailed finite element models, which include vehicle structures, interior, seats, airbags, and hybrid-III dummies, for crashworthiness evaluation. This paper presents some recent effort of developing an approach for crashworthiness using integrated vehicle structural, interior, occupant, and airbag finite element models. A case study using integrated finite element models of vehicle structure and interior, airbag, seats, and hybrid-III dummy is discussed to demonstrate the potential benefit of the integrated simulation and analysis approach. This new integrated approach will further improve the engineering practice with cost saving in engineering resources and producing more accurate and consistent analysis results.

Large-scale accident studies are an indispensable tool to idente the focal points of crash occurrence and the benefits of active and passive safety systems. This report describes the requirements on data quality and presents results of retrospective large-scale studies concerning collision types in real-world accidents, effect of safety systems and possibility and limits of car safety assessment. Large-scale studies of the German Motor Insurers (GDV), covering close to 20,000 accidents, indicate that 6 crash configurations cover the majority of fatal car crashes. A weighting procedure of car-to-car and single car crashes, integrated assessment of collision types is described. The effectiveness of safety systems is a typical research field of large-scale accident studies. An analysis of 249 airbag cases showed that driver airbags reduce Serious/fatal injuries by more than 40% compared with seat belt only cases. For passenger airbags, up to now, no clear evidence of injury reduction has been found in general, but their effect in very serious front crashes is thought to be unquestionable. Accident studies with children in cars showed a seven times lower risk for fatal and serious injuries to restrained than to unrestrained children. But Child Restraint Systems (CRS) could be still more efficient. In a study carried out on CRS, it was noticed that serious misuse was found in 33% of cases, misuse including minor faults amounted to 63%. A further study, based on 150 persons, showed that a standardised rigid connection between CRS and vehicle, the ISOFIX-system, would reduce misuse by at least a factor ten. Large-scale studies are a pre-requisite for safety rating systems, which promote the consumer's interest in car safety. In a GDV-research project, the experience with existing safety rating systems has been analysed. Calculations based on uniform accident material, selected from the GDV database, showed that ranking differences mainly relate to the procedure of the rating systems and less to different traffic circumstances in different countries. Language: en

Although airbags have proven to be effective in high severity crashes, they can cause unintended injuries in certain deployment scenarios in low severity crashes. Most airbag-induced injuries occur while airbag is still inflating, particularly, for unbelted occupants who may be closer to the airbag at the time of deployment. Many factors in airbag deployment affect the severity of injuries that need to be analyzed. In this paper the effect of occupant position and airbag inflation parameters on driver injury measures is investigated using finite element simulation models of a vehicle, airbag, and Hybrid III dummy. The influence of steering column characteristics as well as the relative velocity (ΔV) between the dummy and vehicle interior is also investigated. Simulations are conducted at both static and dynamic test environments for two different critical dummy vertical positions and for two additional horizontal alignments. Airbag deployment is considered for three different mass flow rate curve...

This research investigated whether the performance of vehicle secondary safety systems could be enhanced if the physical characteristics of the occupant and their position in relation to the interior of the vehicle were known. The system could then tailor its performance in terms of e.g. airbag firing times, airbag inflation, to the characteristics of the occupant. User trials were conducted to find the measures required to identify reliably occupant sizes and seated position in the vehicle. MADYMO modelling studies investigated the benefits to different sizes of drivers. A technology demonstrator incorporated seat mounted sensors to provide the required measurements. The project has shown that it is feasible to obtain data about the characteristics of vehicle occupants and their seating position from seat mounted sensors and that this information can be used to enhance the performance of secondary safety systems, providing benefit especially for people who sit close to the steering wheel.

The principal objective of head restraint systems is to minimise the severity of injuries to the occupant's head and neck in the event of rear impact. This can be achieved if the headrest is of adequate stiffness, appropriately absorbs the kinetic energy through the deformation of the material ahead of the support frame, allows a steady sinking of the head relative to the torso and eliminates the head rotation. This paper assesses these attributes and develops a criterion for qualifying head restraint systems. It presents some experimental results obtained from eighteen randomly selected existing headrests and compares the mechanics of failure, energy absorption capabilities and the HIC values with the developed mechanical airbag head restraint systems proposed herein for the first time. The study shows that airbag headrests protect occupants better than the existing stiff head restraint systems found in current vehicles.

The performance of belt, airbag, and force limited belt restraint systems for the driver were compared using frontal sled tests. Nine human cadaver and six dummy sled tests were conducted at 56 km/h using a test buck representing a mid-size vehicle. Subject instrumentation included upper and lower chestbands to measure local thoracic deformations and sternal and spinal accelerometers to record torso deceleration. Following the sled tests, radiographs and autopsy results were used to correlate cadaver injury with measured engineering parameters and dummy response. Chest compression, acceleration, change in curvature and Viscous Criteria were evaluated for all occupants. Occupant kinematics were determined from analysis of high speed film. Local differences in the chest loading behavior among the restraint systems were identified using the chestband contours. The results of the research indicate that improvements in thoracic occupant protection may be achieved with the use of force limited belt and...

A two-dimensional lumped-mass model of the BIOSID dummy was developed to be used as a complement to mechanical simulations. The software used was the crash victim simulation program MADYM02D. The mathematical BIOSID dummy consisted of eleven body parts; head, neck, arm, shoulder rib, thoracic ribs, abdominal ribs, spine, and pelvis. The spine and ribs were connected by a number of non linear springs and dampers. The model was used to evaluate the protective effects of side-airbags and interior padding in automobile side impacts. To validate the mathematical model, the mechanical BIOSID dummy was impacted by a pendulum at various impact speeds. In addition, tests were conducted with padding and pre-inflated airbags on the pendulum. Sled tests at impact velocities of 9 m/s and 6 m/s were also used to validate the model. The tested padding in the mechanical sled tests consisted of 50 mm of compliant padding at the thorax level, and 75 mm of the same padding at the pelvis level. The airbag used was an 8 1 bag at the thorax level with an internal pressure of approximately 1 bar. At the pelvis level it was used with the 75 mm padding. It was found that predictions of the model were in good agreement with the results from the mechanical sled tests. The lumped-mass model of the BIOSID dummy is a good tool for evaluating the protective effect of padding or airbags in the side door. Language: en

A mathematical sled model that included a BIOSID dummy was used to evaluate the potential injury reducing benefits of padding or airbags in side impacts. The side impact simulations were carried out using the crash victim simulation software MADYMO2D. The model has been validated against mechanical sled tests at two impact velocities: with padding, or with airbags mounted to the door. The airbags were filled with compressed air and had varying initial (over) pressures and ventilation areas. The protective system resulting in the lowest injury measures for the dummy was thus determined. The lowest TTI was obtained with the airbag with 0 kPa initial over pressure and 1500 mm2 ventilation area, while the lowest chest deflection and chest VC were obtained with an airbag with 40 kPa initial over pressure and 2000 mm2 ventilation area. The risk of the head impacting the side window was significantly reduced with the addition of an airbag. It was found that the airbag has to be at least 120 mm thick whe...

The current research efforts in airbag modeling are focused on improving airbag deployment and interaction with an out-of-position occupant. This is especially important when other than direct frontal impact is of concern. Thus, the airbag deployment models must address the gas flow dynamics, airbag unfolding and fabric characteristics. This paper discusses the existing capabilities in this field and compares the effect of including gas dynamic details such as inflator jet and airbag unfolding on the deployment predictions. The airbag deployment is simulated using a dynamic model in LS-DYNA3D interacting with a rigid body for 4 different configurations. The simulations were performed on a Silicon Graphics Power Challenge-XL with 10 parallel processors. The analysis shows that the deploying bag may have a much reduced interaction with an occupant positioned oblique to the axis of bag deployment. The inclusion of the inflator jet momentum reveals that it may increase the forces imparted on the occu...

‘Expecting’, a computational pregnant occupant model, developed to simulate the dynamic response to crash impacts, possesses anthropometric properties of a fifth percentile female at around the 38th week of pregnancy. The model is complete with a finite element uterus and a multi-body foetus which is a novel feature in models of this kind. In this paper, the effect of incorporating a foetus with a finite element head into ‘Expecting’ is investigated. The finite element head was developed using detailed anatomic geometry and projected material properties. Then it was integrated with the ‘Expecting’ model and validated using the lap belt loading and the rigid bar impact tests. The model is then used to simulate frontal impacts at a range of crash severities with seatbelt and airbag, seatbelt only, airbag only as well as no restraint cases to investigate the risk of placental abruption and compare it with the model featuring the original multi-body foetus. The maximum strains developed in the utero-p...