Impacting of fast flying fragments or projectiles on a protection shield as well as high-speed rotating machineries like jet engine turbines or turbo chargers store high kinetic energies. When such impacting fragments respectively components burst caused by material fatigue failure that energy is released by local loading protection shields like ballistic armor systems or enveloping casings. The path of travel behind the armor shield and the fragmentation of the impacting objects provides engineers and designers useful information to evaluate failure risks. Ballistic testing by registration the fragments using flash X-ray technology (FXR) is a method to study the behavior of fragments or projectiles in front and behind the shield after interaction especially under harsh conditions. The path of travel as well as the residual velocity will be determined and analyzed. These results could also be used to support numerical simulation. We present a simple method to reconstruct the three-dimensional trajectory of fast-moving objects after impacting with protection shields or casings using a three-channel flash X-ray system each channel with dual remote tube heads triggered simultaneously to get three orthogonal X-ray images. These images are calibrated to reduce optical distortion. To calculate the 3D trajectory and the residual velocities the coordinates of the objects registered by the image plates of the vertical and horizontal plane will be descripted by two-dimensional vectors for each plane.
Flash X-ray radiography (FXR) is one of the electro-optical imaging methods and the most important diagnostic tool in the field of homeland security to detect explosive materials or drugs, terminal ballistics and detonation research to register and study such high-speed phenomena even under the roughest conditions like humidity, dust, smoke, debris, and metal. Physical principles of FXR technology and imaging with hard X-rays are presented. In order to take image sequences of high-velocity impacts using FXR and intensified high-speed cameras for image separation fast solid-state scintillator screens are necessary to convert the X-ray radiation into detectable visible light. The thickness of a scintillator screen is a significant parameter because there is a trade-off between the spatial resolution and the sensitivity. A low thickness means a high spatial resolution but also a lower sensitivity. In a study we investigated the influence of scintillator thickness on the FXR image quality and the emission decay of the scintillation response called decay time. Physical parameters like spatial resolution, signal-noise ratio and contrast are used to characterize image quality. High-speed sequences of FXR images at frame rates up to 50kfps of experimental investigations on the ballistic impact behavior of various protective components against projectiles and applications in the field of military and security agencies are presented. Finally, as a result of a literature study, some applications of X-ray backscatter technology in the field of homeland security and border control are shown to detect suspicious organic materials such as explosives, drugs using and landmines fast decay solid-state scintillators.
For understanding the interaction between projectiles and target structures at impact velocities up to 2000 m/s and higher, a fast-multi-flash X-ray system is needed to look through materials. For that reason a fast optical diagnostic system was developed which is equipped with a multi-flash X-ray system, a fast decay scintillator screen and a fast gating intensified multi-frame CCD camera. The already low parallax caused by the compact annular installed RXanodes was eliminated by mathematical affine transformation. A first basic version of an image processing and analysing software was developed to eliminate the already low parallax, to improve the image quality, detect fragments and debris, as well as calculating the object velocity. This high-speed diagnostic system was used for ballistic testing to investigate the ballistic performance of composite body armour, ballistic helmets and laminated armour.
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