Measurement of Ultrasonic Guided Waves in Plates using Low-Cost Equipment

Abstract

Abstract Guided wave ultrasound can be used to efficiently inspect and monitor large, thin-walled structures where the boundaries of the structure guide the propagation of wave energy, such as pipes and plates. In these structures the guided wave propagation can be used to inspect a large volume of the structure from a limited number of sensor locations, making permanently installed monitoring systems for Structural Health Monitoring (SHM) possible. Guided wave ultrasound, however, is complicated due to the presence of multiple modes of propagation and dispersion, causing the signals to become distorted as they propagate. This complexity makes both analytical analysis and experimental measurements essential for performing research in this area. Specialized laboratory equipment such as non-contact laser vibrometers, power amplifiers, or high specification oscilloscopes can be very expensive and unaffordable. This contribution presents a preliminary investigation on what can be achieved experimentally using low-cost (USD 1000) equipment, suitable for research and teaching in circumstances with limited budgets. Using the example of low frequency guided wave propagation (A0 mode) in an isotropic plate, the influence of different measurement configurations on the accuracy of phase velocity quantification was investigated. Results from two different experimental setups employing high or low-cost equipment and different settings were evaluated and quantified. Accuracy of sensor movement and signal-to-noise ratio (SNR) were found to have a significant influence on measurement repeatability and methods to reduce these effects were applied.