PZT-based SHM

The majority of MDC’s extensive SHM experience has made use of piezoelectric material. These elements can be used as sensor by measuring the voltage difference across two electrodes when cyclically strained, or alternatively they can be used as actuators by inducing expansion and contraction with an applied alternating electric field. Materials with piezoelectric properties are particularly attractive for SHM applications due to their high-frequency response and overall wide-bandwidth characteristics. Most research at MDC has indicated piezoceramic elements, specifically PZT (lead zirconate titanate), to be the most suitable for practical SHM efforts since these wafers have balanced actuator and sensor constants, they are accessible, have well vetted properties, and reasonable thermal stability.

A core business for MDC has been the assembly of custom PZT packages for customers. MDC’s world-class piezoelectric expert can assist customers with material selection. Wafers can be purchased flat or curved, they can be diced round, rectangular or in rings, and can range from 0.02” to 2.70” in size. These elements can be coated with a variety of electrodes to prevent oxidation or promote solder or adhesive bond strength, including gold, silver or nickel. Wafers can be poled in a variety of orientations including through thickness, in-plane, in-shear, or with interdigitated electrodes. Flexible circuits are designed to precisely align PZT elements in any configuration of actuators and sensors, including for single elements, phased arrays, and concentric pairs (MDC patented). An unlimited selection of connectors can also be chosen to mate with these PZT flex-assemblies ranging from micro-miniature coaxial to traditional SMA or BNC. Assemblies are often sold in fixed-price lots due to minimum vendor costs, and a non-recurring design fee will be applied for first-time orders of custom parts. The overall goal of this custom assembly service is to provide customer with robust PZT packages for repeatable testing, using proven techniques to eliminate electrical interference, cross-talk, signal attenuation, and non-uniformities caused by typical fabrication and installation practices such as direct-soldering.