ULTRASONIC STIMULUS AND RESPONSE TESTS LEVERAGING MODULAR INSTRUMENTATION

Abstract -Ultrasonic testing is being used increasingly across many industries and engineers are turning to modular instrumentation as a solution for these complex and dynamic challenges. The most common categories of automated ultrasonic tests are flaw detection and evaluation, dimensional measurements, and material characterization. These techniques can be applied to a diverse set of applications such as oil pipeline inspection to detect or prevent leaks, the identification of abnormalities in military/aerospace aircrafts that could result in failures, and for diagnosis and therapy research in the biomedical field. Most ultrasonic test systems consist of a stimulus created by a source capable of producing high voltage electrical signals which are then converted to ultrasonic energy waves by a transformer and propagated through the material or unit under test. The reflected energy wave or response is converted with a transducer to an electrical signal. The electrical signal is then digitized by an instrument so that it can be processed, analyzed, and displayed within a computing environment. Most traditional ultrasonic test systems use a pulser-receiver instrument to generate the stimulus and to acquire the response. Recently, engineers have begun replacing the traditional Pulser/Receiver instrumentation with modular instruments which provide a more flexible and cost effective solution. For instance, an arbitrary waveform generator paired with an amplifier can provide the stimulus to the unit under test. In addition to the common sinusoidal and pulsed waveforms, the user can design and generate any shape of ultrasonic waveform such as multitone, chirp, or enveloped signals. By producing these custom signals, many different types of transducers can be used, resulting in a better characterization of certain materials. The receiver can be replaced with a modular digital oscilloscope which can acquire the reflected signal at greater sampling rates and with more precision. This enables the acquisition of more detailed information about the unit or material under test. The computer contained within the modular system then allows for the instant display, analysis, and storage of data. This paper will provide a history and the basics of ultrasonic tests and then outline the benefits of a modular approach to solving these problems