Alternating current potential drop crack detection

摘要

An alternating current potential drop (ACPD) system for detecting and measuring cracks on the surfaces of electrically conducting materials (10) comprises a constant current AC generator 9 for applying current to material (10), a receiving unit 8 and a self-contained potential drop (PD) transducer unit 7 for attaching directly onto material surface 13. Two sets of detection probes 11, 12 measure the PD over a test area and an uncracked reference area respectively. The receiving unit 8 may be a microprocessor controller, The PD transducer 7 detects the PD on the material surface 13, converts the resulting analogue signal to a digital signal and transmits it to the microprocessor 8 where it is converted to a crack depth value. The signal may be transmitted to the microprocessor 7 via an optical fibre link 14. The system is relatively immune to interferences and losses and is easily portable for use in the laboratory or in the field. IMAGE