Tubular structures fabricated from composite materials are used in advanced fuselages, rocket motor cases, space truss structures, landing gear and launch tubes etc. The tubes were fabricated using Resin Transfer Molding Technique (RTM) with a single cylindrical mold and a Teflon rod mandrel. The void content of the composite tubes were determined by use of a ultrasonic C-scan equipment with a specially designed fixture. The fixture enabled the indexing of the X-axis stepper motor that inturn rotates the composite tube in unison to the scanning action of the ultrasonic C-scan transducer. The relative void content of the inspected composite tubes, range between 0.00 to 0.09 percent, which is good quality standard.
The inspection of the structural properties of this materials is contingent on developing a non destructive method of evaluating their properties. The successful use of ultrasonic energy in non-destructive testing of composite materials, require an adequate knowledge of the propagation of sound waves in these materials.
The concept of ultrasonic testing is simple, the approach maps the variation in transmission or scattering of ultrasonic waves. Defects such as delaminations show up as reflection or loss of ultrasonic energy. Poor cure state, low quality adhesive or interlaminar bonding and porosity show up as signal attenuation.
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Simon Senibi shows Resin Tranfer Molding of Tubes 
Immersion Testing in C-Scan Tank