METHOD FOR MEASURING EFFECTIVE DETECTING DEPTH OF LOW-FREQUENCY VORTEX-FLOW PROBE

摘要

PURPOSE:To make it possible to measure the accurate effective detecting depth of a probe by potting the curve of the relationship between the thickness of overlapped plates and the amount of the information of a vortex flow under the constant flaw detecting conditions, and measuring the effective detecting depth based on this curve. CONSTITUTION:A low-frequency vortex-flow probe 1 is set on a flaw detecting fastener 3 of a body under test 2. The defect such as a fatigue crack 5 which is formed from the fastner hole of overlapped plates is detected based on the amount of the information of the vortex flow that is indicated with the meter of a flaw detecting device 6 without destruction. A test panel 7 which comprises, e.g. Al alloy material, and has the different thicknesses (t) is used. Two Al alloy plates having the thickness of e.g. 2mm are butted to the panel 7. Then a simulated defect (butted surface) 8 is formed. At this time, the butted surface is fixed with cellophane tape. Then the probe 1 is slowly scanned from A to B on the panel 7 under the constant flaw detecting conditions. The deflecting amount of the pointer of the meter of the device 6 when the probe crosses the defect 8 at the central part is recorded. Then, the panel 7 is changed, and the relationship between the plate thickness of (t) mm and the amount of the information of the vortex flow is plotted, and the curve of the relationship is drawn. thus, the effective detecting depth of the probe 1 is obtained.