Bill D. Cook
Dept. of Mech. Eng., Univ. of Houston, 4800 Calhoun, Houston, TX 77204-4792
A simple model has been developed that accounts for the excitation signal to the transducer, the transducer characteristics, and the diffraction of the sound for the purpose of flaw sizing. The goal has been to seek the ramp response that is the second integral of the impulse response. The ramp response yields volume and cross-sectional area information about the flaw. This research has demonstrated that all of the above mechanisms are high-pass frequency filters whereas the frequency content needed for the ramp response is low, namely ka<2. Unfortunately the physical mechanisms reduce the low-frequency content well below the noise levels and it is impossible to extract the information required even though the transducer is driven with a signal that contains a large amount of low-frequency content.