Automobile manufacturers will invest heavily in crash tests to understand the damage suffered by the body structure and internal dummies during a collision, and related technologies are also constantly improving.
Over the past year, Mercedes-Benz has become the first manufacturer to crash-test two electric cars against each other, and the first to perform X-rays of the vehicles at the moment of impact, Autocar reports.
The X-ray test was carried out at the Ernst Mach Institute in Freiburg, Germany, using a C-Class sedan and a linear accelerator as an X-ray camera. This was a side impact test, meaning the car remained stationary and then a heavy barrier hit the vehicle at 59km/h. The seat closest to the impact side (left) holds a SID II dummy, which is designed for side impact testing and is used to simulate a female body.
In Mercedes’ system, X-ray images are taken by a linear accelerator operating at 1kHz that shines down on the car from above. A flat-panel detector under the car acts as a digital receiver and produces an electrical signal when hit by X-rays.
As the X-rays pass through the car structure and dummy, they are absorbed to varying degrees by different materials, so the intensity changes across the flat panel, producing different tones to create a black and white image. The end result is similar to an X-ray machine in a hospital or a luggage scanner in an airport.
The X-ray pulses last only a few microseconds, allowing still images of deforming structures to be taken without blur due to movement. Because the linear accelerator generates a continuous stream of X-ray pulses, up to 1,000 images per second can be generated. Within milliseconds of the impact, approximately 100 still images can be captured, which can be viewed individually or combined into a video.
The results can provide an accurate insight into the damage suffered by the car and the dummy during the collision. For example, it could give researchers a detailed look at how a dummy’s ribcage is compressed during a side impact, or how a car’s structural components deform precisely.
The X-ray system does not interfere with other analysis tools, such as conventional cameras mounted inside the vehicle, and the facility has been modified to ensure staff and any outsiders are not exposed to potentially harmful radiation. Dosimeters monitor radiation levels, and additional physical protection measures are in place, such as 40cm-thick concrete walls around the building and a German government-approved 45-ton protective gate at the entrance to the factory.
