3D printable piezoelectric composite sensors for guided ultrasonic wave detection

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 which might bring benefits, such as increased piezoelectric output in specific conditions. However, it is unclear if 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 high electric field and adhesively bonded onto a waveguide. This approach helps to understand the capabilities of thin piezoelectric composite sensors for GUW detection. In a proof of concept, thin 2-dimensional rectangular and circular 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.