Johnson Controls invests 3 million Euro (2.43 million GBP) in state-of-theart crash test facility Crash test facility simulates frontal, rear-end and side collision with acceleration pulses of up to 65 g and 85 km/h (53 mph) Burscheid, Germany 8 December 2010. We ve all seen images of crash tests: a car accelerating automatically and crashing head on into a barrier or another vehicle. Johnson Controls Automotive Experience, a renowned global supplier of seating systems, interiors and electronics to the automotive industry, also performs crash tests, not on complete vehicles however but rather on interior systems such as car seats. These seats which are usually occupied by dummies are accelerated on a sled at a force of up to 65 g and a speed of up to 85 km/h (53 mph). Such highprecision tests ensure optimum control accuracy and enable designers to gain new insights into the stability and dynamic behavior of seat structures, discover how effective head restraints are in preventing whiplash and find potential areas for improvement. The supplier recently set up a second crash test facility at its European headquarters in Burscheid in order to perform frontal, rear-end and, in the near future, side crash tests with even more detailed results. As Dr. Detlef Jürss, Vice President Product Development, Sales & Innovation at Johnson Controls Automotive Experience explained: Our new crash test facility is state-of-the-art. There are only four other comparable facilities in the whole of Europe and we are the only supplier to have this kind of sled test facility. Thanks to a very realistic acceleration pulse this pneumatic facility provides very detailed results on the force exerted on the seats and dummies. These results feed into series development and production and help optimize Johnson Controls seats, also in terms of safety. Johnson Controls crash tests focus on rear impact Unlike in a frontal collision, where the emphasis lies on restraint systems such as the airbag and seatbelt, as a designer of seating systems Johnson Controls is focused on simulating rear impact scenarios. The new test facility consists of two guide rails on which a sled can travel approx. 16 meters (52.5 ft.) in a straight line. The actual sled test is performed over a
distance of approx. 2 meters (6.5 ft.). The sled is accelerated by the piston rod of a huge pneumatic cylinder. This cylinder is filled with air on both sides of the piston before the crash test begins. This air is taken from the area surrounding the facility and compressed to a pressure of 345 bar (5 000 PSI). 220 bar (3 190 PSI) of operating pressure is now available on one side of the piston, while some 125 bar (1 810 PSI) of compressed air on the other serves as a pneumatic brake for the piston. In accordance with regulations, the sled is slowed down by a separate brake. In the event that this brake fails, the sled will crash into a crash tube at the end of the track and come to a standstill. The acceleration process is crucial to the tests and this is where a whole arsenal of disc brakes plays a key role. Metal tracks, so-called blades, run below and alongside the sled in the direction of travel, explained Georg Müller, Engineering Manager Product Validation at Johnson Controls Automotive Experience. Hydraulic brakes clasp these blades like caliper brakes clasp the brake discs on the wheel of a car and hold the sled against 220 bar (3 190 PSI) of operating pressure. A rear-end collision with another car is then simulated in the crash test by metering the opening and closing of the brakes several times in an acceleration process of approx. 100 milliseconds by means of a proportioning valve. Therefore, the sled is not accelerated by a single pulse, as in a launcher, but by short, non-linear applications of force. The sled is thus given precisely the pulse we need, as in a real-life situation, while the deformations in the front end of the impacting vehicle and the rear end of the impacted vehicle also cause a non-linear pulse, explained Georg Müller. All information relevant for a realistic crash test is summarized in Excel spreadsheets, which are used by the sled test facility to calculate the necessary acceleration, relevant speed, required pressure and the exact metering of the brakes, said Georg Müller, explaining the procedure. As a preparatory measure this also includes the weighing of the sled; the force of acceleration must be metered according to how many seats and dummies are mounted, whether they are connected directly to the sled or have been pre-mounted onto a model of a body structure. The maximum loading capacity of the sled is two tons (4 400 lbs). Theoretically, this is enough to accelerate an entire car including occupants.
Two Mega-Newton of thrust accelerates the sled to up to 85 km/h (53 mph) with up to 65 g With a thrust of 2 000 000 Newton (2 Mega-Newton or 450 000 lbf)) the new test facility can accelerate the sled at 65 times the force of gravity to a maximum of 85 km/h (53 mph) in just 20 milliseconds, depending on the mass and acceleration process. The highest speed required for a rear-end collision, however, is only around 35 km/h (22 mph). Although this may sound harmless, it is important to remember that this speed must be regarded in relative rather than absolute terms. In effect, 35 km/h (22 mph) means that the impacting vehicle crashes into the rear end of the vehicle simulated by the sled at an excess velocity of 35 km/h (22 mph). A crash at a relative speed of between 24 km/h (15 mph) and 35 km/h (22 mph) is classed as a high-speed impact. Crash tests are also carried out at relative speeds of around 16 km/h (10 mph) to 24 km/h (15 mph) to research low-speed impact. For these two crash scenarios the seats are mounted either in the direction of travel or the direction of impact (longitudinal). However, lateral collisions also occur on the roads e.g. when one car hits a corner of the body of another at an angle. Johnson Controls therefore also fixes the seats to be tested at a 30 angle to the direction of travel, in order to test the stability of the structure and to ascertain the force exerted on the dummies. Dummy family and high-speed cameras provide accurate data Valuable data is provided by seven high-speed cameras which take up to 4 000 shots a second. An independent lighting system with three batteries of floodlights provides optimum lighting of up to 250 000 lux. The cameras are attached to an arm on the sled and, on subsequent analysis using special software, show extremely detailed images of how the bodies of the dummies move in certain phases and where they might come into contact with interior components. Naturally, such data is extremely important for static tests in which a dummy head is equipped with sensors and launched onto the instrument panel, head restraints, door panels or seats. The dummies are basically just a family of dolls that wear clothes and shoes for crash tests. Johnson Controls uses four different dummies with a body weight of between 11 kg (24 lbs) and 32 kg (70 lbs) to test the stability of ISOFIX attachment points. These dummies cover a range of 18-
month to 10-year-old children. Adult protection is optimized using Hybrid III dummies starting from the weight and height of the 5th percentile female (152 cm or 5.0 ft. in height, 54 kg or 119 lbs in weight) and ending with the 95th percentile male at 188 cm (6.2 ft.) in height and weighing 101 kg (223 lbs). The percentages represent the normal distribution of all adults assumed by the dummy manufacturer. According to Georg Müller, This means the 5th percentile female is larger than the manufacturer assumes 5% of female drivers to be, and the 95th percentile male is larger than the manufacturer assumes 95% of male drivers to be. However, the 50th percentile male is most often used because at 175 cm (5.7 ft.) tall and weighing 78 kg (172 lbs) he comes closest to the average driver. Tests are also performed with the BioRID-II, a dummy specially designed for low-speed rear impact in accordance with EuroNCAP and IIWPG (International Insurance Whiplash Prevention Group). This dummy is a very detailed biomechanical replica of the human body, equipped with acceleration sensors at specific points along the vertebral column, in the pelvic region and head, and load cells in the neck, thigh bones, and around the knees, ankles and heels. At our crash test facility, which opened in 1998 and is still in operation, the data measured by the sensors is also recorded on up to 56 channels linked to the data recorder on the sled, explained Georg Müller. The new facility enables the data to be recorded digitally; meaning only one cable with up to 96 channels need to be connected to transmit the data from the recorder on the dummies to the recorder on the sled. While the crash test takes less than a second, considerably more time is required for analysis because the wealth of data obtained from the acceleration sensors and load cells are analyzed just as meticulously as the camera shots and the data from the test facility itself. Only once an overview has been provided by the analysis software can data be obtained as to at which stage of the impact and to what extent force is exerted on specific areas of the body and how the design engineers could perhaps minimize this force by modifying the structure of the seat frame, its upholstery, seatbelt mountings or ISOFIX attachment points. The job of Georg Müller and his team is only done once the force exerted on dummies is below all limits set by Johnson Controls, its customer and the law. Digital images are available online from www.johnsoncontrols.co.uk/press.
Please do not hesitate to contact us if you would like more information: Johnson Controls GmbH Automotive Experience Industriestraße 20 30 51399 Burscheid Germany Ulrich Andree Tel.: +49 2174 65-4343 Fax: +49 2174 65-3219 E-mail: ulrich.andree@jci.com Astrid Schafmeister Tel.: +49 2174 65-3189 Fax: +49 2174 65-3219 E-mail: astrid.schafmeister@jci.com Johnson Controls Automotive Experience is a global leader in automotive seating, overhead systems, door and instrument panels, and interior electronics. We support all major automakers in the differentiation of their vehicles through our products, technologies and advanced manufacturing capabilities. With more than 200 plants worldwide, we are where our customers need us to be. Consumers have enjoyed the comfort and style of our products, from single components to complete interiors, in over 200 million vehicles.