Electromechanical characterization of ultrasonic NDE systems

An ultrasonic nondestructive evaluation (NDE) measurement system is a complex collection of many elements such as the pulser/receiver, the cabling, the transducers, and the material configuration being tested. To completely model an ultrasonic measurement system, a system model, called the electroacoustic measurement (EAM) model , was developed. This model allows one to analyze the measurement system at many different levels, ranging from individual details to the entire system itself. The EAM model has been implemented in software using the MATLAB development environment such that one has control over the specification of the detailed system components. On the other hand, the practical use of the EAM model for commercial systems, whose explicit internal construction details are not known, requires that the model be expressed in terms of elements that can either be obtained experimentally or modeled. Thus, the EAM model has also been characterized in terms of a small number of system parameters that can either be explicitly modeled or obtained from purely electrical measurements. This advance is important, since it lays the foundation for new, quantitative transducer characterization procedures and new methods for evaluating and compensating for system variabilities

Electromechanical characterization of ultrasonic NDE systems

An ultrasonic nondestructive evaluation (NDE) measurement system is a complex collection of many elements such as the pulser/receiver, the cabling, the transducers, and the material configuration being tested. To completely model an ultrasonic measurement system, a system model, called the electroacoustic measurement (EAM) model , was developed. This model allows one to analyze the measurement system at many different levels, ranging from individual details to the entire system itself. The EAM model has been implemented in software using the MATLAB development environment such that one has control over the specification of the detailed system components. On the other hand, the practical use of the EAM model for commercial systems, whose explicit internal construction details are not known, requires that the model be expressed in terms of elements that can either be obtained experimentally or modeled. Thus, the EAM model has also been characterized in terms of a small number of system parameters that can either be explicitly modeled or obtained from purely electrical measurements. This advance is important, since it lays the foundation for new, quantitative transducer characterization procedures and new methods for evaluating and compensating for system variabilities.</p

Use of an Electroacoustic Measurement Model for Ultrasonic Transducer Characterization

Ultrasonic transducers are electromechanical devices that covert electrical inputs (voltage, current) into mechanical outputs (force, velocity) and vice-versa. To completely characterize the relationship between these four parameters in general requires knowledge of all the elements of a 2×2 complex-valued “transduction” matrix as a function of frequency. In the literature it has typically been assumed that to obtain all the elements of this transduction matrix it is necessary to perform a combination of both electrical and mechanical measurements (see Sachse and Hsu [1], for example), which makes such a complete characterization rather difficult and expensive. Here, we will show that, by using an electroacoustic measurement model that completely characterizes an entire ultrasonic measurement system, it is possible in principle to set up a practical measurement method where the complete transduction matrix can be obtained by purely electrical measurements at the electrical port of the transducer. Having a practical procedure to completely characterize an ultrasonic transducer is important since it will allow one to make quantitative estimates of the influence of the transducer properties on an ultrasonic measurement process.</p