3D Printable Piezoelectric Composite Sensors for Guided Ultrasonic Wave Detection

Abstract

Commercially available photopolymer resin is combined with Lead Zirconate Titanate (PZT) micrometer size piezoelectric particles to form 3D printable suspensions that solidify under UV light. This in turn allows achieving various non-standard sensor geometries that might bring benefits, such as increased piezoelectric output in specific conditions. However, it is unclear whether piezoelectric composite materials are suitable for Guided Ultrasonic Wave (GUW) detection, which is crucial for Structural Health Monitoring (SHM) in different applications. In this study, thin piezoelectric composite sensors are tape casted, solidified under UV light, covered with electrodes, polarized in a high electric field and adhesively bonded onto a wave guide. This approach helps to understand the capabilities of thin piezoelectric composite sensors for GUW detection. In an experimental study, thin 2-dimensional rectangular, circular and annulus segment shaped piezoelectric composite sensors with an effective surface area smaller than 400 mm2 applied to an aluminum plate with a thickness of 2 mm demonstrate successful detection of GUW up to 250 kHz. An analytical calculation of the maximum and minimum amplitude for the ratio of the wavelength and the sensor length in wave propagation direction shows good agreement with the sensor-recorded amplitude. The output of the piezoelectric composite sensors is compared to commercial piezoelectric discs to evaluate their performance.