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.
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