Evaluation of Ultrasonic Scattering at LCF Cracks Including Optically Measured, Real Roughness Profiles

An approach is presented to theoretically study the effect of surface roughness of real defects on ultrasonic wave scattering. Using an optical measurement system, real roughness profiles are recorded for cracks generated e.g. during LCF testing. These measured profiles are then discretized and used as input for the theoretical model, which has been previously presented by Ogilvy. Having obtained realistic input data to characterize the crack surface roughness, it is possible to evaluate the scattered energy distribution in dependence of frequency, angle of insonification and wave type.