Multiparameter Ultrasonic Evaluation of Thick Composite Materials
Traditional pulse-echo ultrasonic NDE techniques are useful in the evaluation for structural flaws in components manufactured from homogeneous materials (i.e. most metals). However, composite materials are often neither homogeneous nor isotropic which decreases the sensitivity of traditional techniques by making the resultant data difficult to interpret. Composite materials also tend to attenuate the ultrasonic energy to a greater degree than metals decreasing the signal-to-noise ratio needed for confident flaw detection. The attenuation is attributed to the absorption of energy by the matrix and the scattering of energy due to the inherent scatterers in the system such as fibers and small voids or porosity. For very thick composites these difficulties are amplified. In addition, a component of the attenuation due to ultrasonic beam spreading increases with thickness. As the beam spreads, spatial resolution is lost as well.
KeywordsScattered Amplitude High Attenuation Impact Damage Dual Frequency Beam Spread
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