Papers by Author: Lester W. Schmerr

Abstract: For the proper interpretation of ultrasonic measurement results from a side-drilled hole (SDH) using a rectangular transducer, it is very helpful to have a complete ultrasonic measurement model. A highly efficient ultrasonic beam model of a rectangular transducer and an accurate scattering model of a SDH are currently available. However, to develop such a complete measurement model, a reference model for the system efficiency factor is also needed. In this study a reference model suitable for a rectangular transducer is given and combined with existing models to develop a complete ultrasonic measurement model that can the predict ultrasonic signals from a SDH. Based on this model, we have calculated the ultrasonic signals from a SDH at different transducer orientations and compared the model-based predictions with experiments.

Abstract: The electroacoustic measurement model is an explicit model of an entire ultrasonic measurement system, including the pulser/receiver, cabling, and transducers. A summary is given of the measurement procedures needed for characterizing all the system elements contained in this measurement model, including a description of a new pulse-echo method for obtaining the sensitivity and impedance of an ultrasonic transducer. It is demonstrated that these models and measurement procedures can be combined to accurately simulate the measured voltage of a pulseecho immersion system.

Abstract: Over the past two and a half decades there has been considerable progress made in the modeling of ultrasonic nondestructive evaluation (NDE) inspections. These models have also been combined with models of the noise and variability present in an inspection to estimate probability of detection (POD) versus flaw size curves. An overview will be given of the past and present accomplishments made in ultrasonic NDE modeling, POD modeling, and the relationship of those advances to reliability modeling that incorporates explicitly the results of inspections. A brief look into the future of this modeling technology will also be given.