Nondestructive testing of carbon-fibre-reinforced plastics - a study of an ultrasonic resonance method

An ultrasonic resonance technique has been used in the nondestructive testing of a set of carbon-fibre-reinforced plastic specimens. Both compressional and shear wave resonance as well as internal damping were measured. The results were compared with static modulus measurements, and repeated after the specimens had been cracked in torsion. The measurements lead to some important inferences about the effects of surface treatment on the fibres and their adhesion to the matrix. The method may have some applications where rapid nondestructive tests of fibre type, alignment and density, or of structural integrity are required.