Thick fiber-reinforced composites will be obtained and evaluated using an advanced ultrasonic inspection method to characterize the material for cracks and delaminations, porosity and density variations. The advanced ultrasonic inspection method is based upon synthetic pulse technology, which was originally developed for radar applications. A short, high energy, broadband pulse is replaced with a much longer frequency-modulated burst, covering the same bandwidth with much greater energy. This leads to improved sensitivity and resolution. Conventional transient-pulse techniques will be used for comparison. Advanced and conventional methods will be applied in both through-transmission and pulse-echo geometries. Through-transmission provides attenuation information which can be related to porosity and to density variations. Pulse-echo inspection provides size and location information for cracks, delaminations and pores. X-ray radiography will also be used to provide additional information on porosity and density variations for technique evaluation. Destructive testing will provide the necessary information to correlate the ultrasonic and radiographic test results and will provide quantitative assessment of the inspection techniques.
