Temperature- and load-sensing via acoustic emission of shape memory alloy particles

Abstract

The experimental fact that the acoustic emission (AE) of a shape memory alloy (SMA) isconfined well in the temperature range of the martensitic transformation hysteresis suggeststhe possibility of there being an SMA that is suitable for use as a temperature-sensingdevice sending AE signals out. This study has proposed a method to measure thetemperature at the point of a small SMA particle in a solid body by detecting the AEsignals from the particle. Moreover, a two-sensor method, which is the technique forlocating the source of AE signals by measurement with two AE sensors, has been applied.It allows us to monitor the temperatures at many points in the solid body withmany SMA particles in it. The proposed method was examined using a modelcomposite material that was composed of five SMA particles lying in an array in analuminum plate. It is shown that the method could locate the positions of theparticles having emitted AE signals by martensite transformation. It has also beenproposed that the AE during deformation of the SMA can be used for sensingstress. When a point load was applied at various positions on the surface of anepoxy–SMA particle composite plate, the AE method located the point loadcorrectly.