Mercedes-Benz, in conjunction with the Fraunhofer-Institute for High-Speed Dynamics EMI (Ernst Mach Institute), has conducted the world’s first crash test using an X-ray camera.
According to Mercedes-Benz, the technology demonstration (proof of concept) at the EMI research crash facility showed that high-speed X-ray technology can be used to visualise highly dynamic internal deformation processes that were previously invisible. The technology produced numerous high-resolution images, allowing precise analysis.
“The Mercedes-Benz X-ray crash sets a milestone in the development tools of the future,” said Markus Schaefer, Chief Technology Officer and member of the board of management of Mercedes-Benz Group. “With a direct view into the hidden interior, it can help to draw important conclusions for the further improvement of vehicle safety.”
Professor Dr Paul Dick, Director of Vehicle Safety at Mercedes-Benz, said the X-ray crash showed that the technology can provide revealing new insights. “We learn what happens inside a vehicle and to the dummies during an accident. The X-ray images also offer the opportunity to further improve the model quality of the digital prototypes,” he added.
For several years, the Mercedes-Benz vehicle safety division researched the use of X-ray technology in crash tests with colleagues from EMI. The breakthrough occurred through the use of a linear accelerator with 1 kHz technology as the radiation source. The device is more powerful than the X-ray flashes previously used in trials. The photon energy of the linear accelerator is up to nine megaelectron volts, allowing all materials commonly used in vehicle construction to be screened.
The duration of the X-ray pulse is only a few microseconds, making it possible to record deformation processes in the crash test without motion blur. The linear accelerator also generates a continuous stream of pulses, meaning that up to 1,000 images per second are possible – about 1,000 times as many as with conventional X-ray procedures.
Mounted on the facility ceiling, the device shines beams through the bodywork and dummies while a flat detector located under the test vehicle serves as a digital image receiver. When the radiation hits the detector, an electrical signal is generated. The intensity depends on how strongly the radiation was absorbed by the vehicle and dummy structure. This influences the grey value that is later visible – similar to the X-ray inspection of luggage at an airport or images taken by radiographers.
In the milliseconds of the impact time, the X-ray system shoots around 100 still images. Combined into a video, they provide insights into what happens inside safety-relevant components and in a dummy’s body during a crash. This makes it possible to observe in detail how the thorax of a dummy is pressed in or how a component is deformed.
The X-ray crash does not affect other analysis tools, with the interior cameras in the crash test vehicle recording without disturbance.
EMI experts drew up a comprehensive radiation protection concept for the X-ray crash. Dosimeters are used as monitors to ensure that employees are not exposed to radiation, while elaborate physical protection measures include an additional 40-centimetre-thick concrete wall around the building and a protection door weighing around 45 tonnes.