Monitoring wear using the high accurate alternating current potential drop method

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A surface damage evaluation system was developed. The alternating current potential drop (ACPD) method was used in this system. This system consists of a personal computer, a frequency generator, a power current amplifier which has capacity of 5 A maximum current and high frequency 600 kHz, two signal conditioner and two high speed A/D converters and has a compensating technique for inductive pick-up of AC voltage. The inductive pick-up is the most important cause of measurement error at ACPD method. We could develop a compensate algorithm using Kalman filter technique. Model damage evaluate tests were carry out. Middle carbon steel and bearing steel were used for rolling wear specimens, and reciprocating rolling wear tests were carried out. Signals of ACPD from surface which damaged with rolling wear and applied alternating current were measured. These signals were analyzed by computer program and the phase difference between these signals was detected. Then the inductive pick-up was compensated.The conclusions which were obtained in this research are summarized in the following.(1) Using the compensation technique, the true value of ACPD could be estimated successfully.(2) In model damage evaluate tests, the length of model crack and the measured potential drop value was shown the proportional relation.(3) Reciprocating rolling wear proceeded with producing small flaky wear particles.(4) From the change in estimated ACPD values against the number of cycles, it can be seen to the tendency of decreasing before about 105 cycles and increasing after about 105 cycles. The reason seems to change in the electrical properties of materials and current path caused from wear of lower specimens.