Official Project Website - ACPD Four-Point Probe
Client: Center for Nondestructive Evaluation
Advisors: Dr. Nicola Bowler and Dr. John Bowler
Alternating current potential drop (ACPD) testing is a relative newcomer to the area of non destructive evaluation (NDE). Developed in the 1980’s, ACPD testing currently uses two point probes for single frequency (typically 5kHz) measurements of crack depths, crack growth, and material properties. Although this type of testing is effective there are several limitations, especially when measuring materials of different types and reducing the inherent inductive pickup. It is also desirable to be able to perform tests over a range of frequencies. To counter these problems the intent of this project will be to design four point ACPD probes. One probe will be for used for lower frequencies (1 Hz to 10kHz) and the other for higher frequencies (100kHz to 10MHz). Both probes will be expected to reference the measured voltage to the current source, control the effect of the inductive pick-up, as well as the ability to analyze multifrequency data online. As a result of producing these probes, it will be easier for users to test materials more efficiently, accurately, and effectively.