Together with the Fraunhofer Institute for High-Speed Dynamics, the Ernst Mach Institute (EMI) in Freiburg, Mercedes-Benz says it has now carried out the world’s first “X-ray crash” with a real car. On board the test vehicle were two dummies of the SID IIs model on the left side facing the impact. These are test specimens with female anatomy, specially designed for side impact tests, as Mercedes-Benz explains.
The crash test
At 60 km/h, a device with a shock barrier rams the orange C-Class sedan and hits it square in the side. That’s not unusual, but in this crash test there is a frame on the hall ceiling above the vehicle: a linear accelerator serves as the X-ray source.
Mercedes-Benz is the first car manufacturer in the world to conduct an X-ray crash test
Mercedes Benz
Why even use X-rays in a crash test?
Mercedes-Benz: “Highly dynamic internal deformation processes can be depicted using short-term X-ray technology. Previously invisible deformations and their exact processes become transparent. The numerous, high-resolution images allow precise analysis”.
The aim of the whole thing: make cars even safer and improve the survival potential of the occupants.
The technology of the X-ray in detail
A linear accelerator with 1 kHz technology is used as the radiation source. The photon energy of the linear accelerator is up to nine megaelectron volts. According to Mercedes-Benz, this means that all materials commonly used in vehicle construction can be examined. The duration of the X-ray pulse is only a few microseconds.
This makes it possible to record deformation processes in crash tests without motion blur, as Mercedes-Benz explains. In addition, the linear accelerator generates a continuous stream of these X-ray pulses. This allows up to 1,000 images per second. That is said to be around 1,000 times as many as with conventional X-ray procedures.
During the crash test, the beams shine through the body and any dummies from above. An X-ray detector is located under the test vehicle. It serves as a digital image receiver in the X-ray system: When the radiation hits the detector, an electrical signal is generated.
How intense this is depends on how strongly the radiation was previously absorbed by the vehicle and dummy structure. This influences the gray value that is visible later – you may be familiar with this from X-ray images of your luggage at the airport or from the corresponding images taken by the doctor.
In the actual impact time of one tenth of a second, the X-ray system shoots around 100 still images. Put together into a video, they provide insights into what happens inside safety-relevant components and in the body of the dummy during the crash.
This allows you to observe in great detail how the dummy’s thorax is compressed or a component is deformed. Important: The X-ray crash does not affect other analysis tools. The crash test vehicle’s interior cameras also record undisturbed.
