Enhancing repeatability in the measurement of potential drop using an adjustable four-point-probe measuring system

The article describes an effective method of measurement for enhancing the repeatability in the experimental determination of electrical potential drop for the evaluation of materials. In the present approach, an averaging scheme is adopted for measuring the potential drop using a DC four-point-probe measuring system, where the associated probe contact distances on the material surface are adjusted in successive measurements by refreshing the individual contacts of the spring-loaded probes to the measuring surface. Statistical considerations are discussed in the context of repeatability of results using this method. Finally, the application of the method is demonstrated and discussed for a practical problem of interest, namely, the evaluation of rear-wall flaws (cracks and slots) in thick-walled structures. In an attempt to verify the accuracy, measured results are compared with the corresponding finite-element predictions of the potential drop. Results of the present study and also the comparative analysis firmly establish the appropriateness as well as reliability of the present potential-drop measuring system for obtaining repeatable measurements in the evaluation of materials.