1a), the piezoelectric element, which converts electrical energy into mechanical energy and vice versa, is mechanically attached to a backing material, most often called the damping block. In the vertical or straight beam probe ( Fig. 1 shows the basic construction of four fundamental probe types. Today, ultrasonic probes work almost exclusively according to the piezoelectric effect. In any case is the choice of the correct probe is decisive for the quality and the reliability of inspection results. In numerous cases, especially if a workpiece has a complicated geometry or the inspection has to be done under unusual conditions, ultrasonic inspection becomes only feasible by use of probes, which have appropriate acoustic properties. Probes form the actual core in all non-destructive ultrasonic inspection procedures: The fact whether a workpiece can be inspected or not depends upon them. The choice of the correct type of probe is often made easier through this knowledge.ģ. if a probe is coupled to a specimen, which it is not designed for. Knowing about these details however does not only contribute towards a better technical understanding of the basic action of the probe, but it does also help towards understanding the behaviour of the probe under certain operation conditions, e.g. Although the overall characteristics of probes, such as pulse shape, frequency and sound field are given in data sheets and are basically well understood, the knowledge about constructional details with regard to the utilised piezoelectric materials is less common.
Depending on the application and the required probe characteristics, the one or the other material is more advantageous, sometimes for acoustic or technical reasons, sometimes even for economic reasons. These materials differ in their physical properties.
RiesĪ series of powerful piezoelectric materials are available to generate ultrasound in ultrasonic probes. Piezoelectric materials for ultrasonic probes NDTnet - September 1996, Vol.1 No.09 Piezoelectric materials for ultrasonic probes Authors: M.