Predicting X-Rays for Dynamic Flaw Detection in Solid Rockets *

The principal objective of this study was to evaluate the potential of real-time radiography as a diagnostic tool for measuring propellant crack propagation speed. The scope addressed either a non-propagating or a propagating axial bore crack in a 6-in.-diam solid-propellant motor. Simulations of X-ray emissions from a low-energy source, a model of propellant burn recession, and analysis of the simulated images provided the basis of the results. The complete simulation was performed on an IBM RISC-based workstation and the resulting images were evaluated using an image processor. The results show that the transmitted X-ray intensity profiles can be analyzed to determine the velocity of the crack tip during motor operation. A crack that was modeled to propagate at 5.0 in./sec was “measured” to within ± 1.0 in./sec using the simulated data. The simulation included the effects of finite pixel resolution and finite (8-bit) intensity digitization.