Determination of elastoresistance of some nonmagnetic metals and alloys with the aid of alternating eddy currents

Abstract

The measurements of elastoresistance of some nonmagnetic metals and alloys, the results of which are reported in the present paper, were carried out by means of a method relying on the use of eddy currents of various frequencies. In the subsequent paragraphs we shall describe a contactless method of measuring quite small changes in the electrical conductivity of metals under the influence of external factors, in particular elastic stresses; using this method, we have determined the sign and magnitude of the stress coefficient of rod specimens of some nonmagnetic metals and alloys prepared in the usual manner. The method we have used to measure the electrical conductivity of metals is based on the application of air-core coils (Fig. t). It is known that the emf induced in the measuring coils of pick-ups of the solenoid type [6] and expressed in relarive units is, in the case of nonmagnetic materials, described by the formula