Results of Feasibility Study on Computer Assisted Tomography for Ballistic Applications.
ARMY BALLISTIC RESEARCH LAB ABERDEEN PROVING GROUND MD
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Tomography, a noninvasive technique relying on the use of x-ray absorption characteristics of a body taken at multiple angles, allows, through the use of mathematical reconstruction techniques, the determination of unknown density distributions within an object. Here we describe the requirements on such a system for ballistic applications, especially for the study of two-phase flow in a chamber under actual firing conditions. The results of experiments on a static mock-up were used to illustrate the possibilities and limitations of the proposed system. The mock-up consisted of a fiberglass chamber loaded with inert granular propellant. 180 sets of projectile data were taken by moving in a semicircle around the object and stepping by one degree each time. Two different algorithms were used to reconstruct the cross-sectional image of the chamber and propellant grain distribution. Transient ballistic requirements dictate that as few as possible views, ie.e., x-ray sources, be used in the actual system design. with 180 views, excellent reconstruction images were obtained. Details such as propellant perforations 1.0 mmare easily observed. Even with 15 to 20 views, reasonable reconstruction can be achieved and will be the basis of the initial BRL design. The quality deteriorated when only nine views were used in the reconstruction.