In 2017, TÜV SÜD Czech invested a huge amount into the all-new airbag laboratory in the new vehicle passive safety test centre in Bezděčín near Mladá Boleslav. In the period of coming autonomous vehicles and overall activities of the Vision Zero strategy – measures to eliminate road traffic accident victims and occurrence of severe injuries – the investment into a costly system for testing airbag systems could seem to be not entirely appropriate; after all, as vehicles will completely avoid accidents in future, the passive safety systems shall thus not be necessary at all.
Is this really the case?
We do not wish for anything else. Nevertheless, for instance, certain levels of vehicle automation shall require more intensive airbag and passive safety system tests than apply at present. Is this possible? One of the reasons is sitting of passengers in a non-standard position – so-called Out of Position, hereinafter OoP. Already partially during the second, but mainly during the third and higher level of vehicle automation (as explained in TÜV SÜD Journal 3/2017) the driver sits in a position that does not comply with the safety position defined by current standards. However, in future the crew with seat backs comfortably inclined backwards (automation level 4 – the vehicle does not require any intervention from the driver, e.g. on a motorway section) or facing opposite the driving direction (automation level 5 – e.g. robotised taxi) shall not be an exception. It is clear that for these cases, the locations, dimensions and dynamics of the airbags shall be substantially different.
In addition to the above-stated, we must count on the fact that the renewal of most of the vehicle fleet shall take more than a decade and it shall certainly not be one hundred percent.
The OoP airbag tests are already being done to a certain extent at present on the basis of the internal methodologies of the vehicle manufacturers or according to non-European legislation and consumer tests. The manufacturers want to be sure that even in case of an incorrect sitting position, the airbags shall not be the cause of severe injuries.
Currently, we find the airbags in many positions in the vehicles and apart from the standard frontal and knee airbags (in the dashboard and steering wheel), side airbags (in the seats, in the rear upholstery and doors), head airbags (in the roof structure) also in the safety seat belts, headrests, between the passengers, in the child retention systems, in external vehicle parts, etc.
The number of places with airbags is increasing substantially, and because it is safety element to which the developers and manufacturers devote great attention above the legislative framework, they test it not only in normal conditions, but also in extreme conditions where the vehicle is, for instance, tempered at temperatures from –40 °C to 100 °C. The design of the individual components in the vehicle is changing and, taking the dashboard as an example, we can clearly see how we are shifting from the previous/standard to minimalist design, but with large touch-screen displays and various alternative materials. In spite of all the new trends in design, the developers must not forget that the carrier part of the dashboard must be adequately dimensioned for correct absorption of the reactive forces from the activated airbags and avoid creation of sharp edges and flying of dangerous parts in the direction of the crew. When it comes to combination of the activation of two knee airbags with activation of the large front passenger’s airbag, extreme temperature of 100 °C and the effort to achieve the lowest weight, we have a difficult design task ahead of us.
Hi-tech testing technologies at the service of customers
The new airbag test centre is conceived to cope with all the tests required by the manufacturers of vehicles and components at the stages of development and release for series production as well as regular testing during the life-cycle of the vehicle model, i.e. Conformity of Production (CoP).
The centre is equipped with a large climate chamber with a volume of almost 70 m3 from the firm WEISS with the following temperature and humidity parameters: –40 to 100 °C and 10 to 95% RH. For control of the airbag activation tests, heads of the tests use the newest generation HuDe system, which allows the independent activation of up to six airbags or a corresponding smaller number of multi-stage airbags at various moments in time. Because we are talking about events with a maximum duration of only a few tens of milliseconds, the centre is equipped with the latest high-speed cameras from the Japanese manufacturer Photron with a standard frame rate of 5,000 images/s. In case of special requirements, we use equipment from the company iX Cameras with a high-resolution frame rate of 20,000 images/s. All the cameras are installed on a mobile positioning system that allows quick adaptation for another test and addition of a high performance LED lighting system. Because the chamber has special large windows, it is possible to do a test and record it inside or outside the chamber by so-called exit and activation of the airbags within 10 seconds of leaving the extremely tempered environment. Both methods have their advantages and disadvantages and it is up to the customer to choose his preferred variant.
In order for us to be able to provide the customer with the maximum volume of information from the test, the laboratory is also equipped with a corresponding number of measuring devices for measurement of physical variables, for instance, forces, torques, pressures including their distribution, and analytical SW tools for evaluation of the measured data and high-speed camera recordings.
What is the result?
The result of our test comprises analyses of the interactions of the airbags with the interior parts of the vehicle, for instance, the dashboards, seats, roof parts and pillar trims. Regardless of whether it is at the stage of development or CoP testing, many parameters are evaluated after the test and various measures are subsequently applied that eliminate the negative impact on the crew. Our independent test laboratory with colleagues who have long-term experience often figures as the moderator of discussions between the OEM and suppliers where the causes of any problems are analysed and suitable remedial measures are suggested
What are the advantages for the customers?
Above the framework of long-term experience with the preparation, execution and evaluation of these types of tests, the newest technologies and impartiality of the accredited test laboratory, it is the already strong network of airbag centres. In Bezděčín, apart from the newest centre we have also commissioned and calibrated the initial airbag laboratory. Together with the laboratories in Nymburk and Nizhny Novgorod in Russia, we are capable of flexibly responding to customer needs and in case of emergency we also perform tests in another laboratory and meet the requirements of the development time schedules and series testing times.