The Monitoring System Of The Weld Crack Germination Based On Theory Of EDDY Current Testing

At present, with the rapid development of railway construction, the train running speed and safety performance also had a higher request. In train running process, due to the line or the changes and changes in curvature, bogie has anisotropic displacement. Along with the train speed, bogie under dynamic load are increased. Train bogie connection form is welded, so a low fatigue strength, become the train bearing capacity of the weak links. This topic is supported by the National Natural Science Fund Project " train bogie weld joint surface Nan crystallization mechanism and fatigue performance study " in part, use of electric eddy current principle, developed a set of on-line monitoring system for monitoring, a large number of different specimen in fatigue test of crack germination time, for testing different welded frame fatigue life to provide technical support.(1) Design and manufacture of the eddy current probe. Probe using excitation and detection coils separated, double coil juxtaposed placed type probe structure, the coil are rectangular in shape. The simulation results and the standard test piece test two ways to probe structural parameters optimization.(2) Design a monitoring system scheme. Proposed the use of a plurality of probe sensing area, a single probe inspection monitoring programmers, the actual use of8probes, the probes were layout optimization, design the corresponding fixture. Test system based on Virtual Instrument Architecture, in make full use of existing laboratory kit foundation, design and build their own parts of the peripheral circuit, design of signal acquisition and processing software.(3) The design of signal detection of soft, hardware system. Select NI SCXI-1125eight channel processing module, using multiplex mode, by the data acquisition card a passageway to receive all the output of the sensor. The use of N channel N sampling form the acquired signal split into multiple signal analysis. Signal processing, using peak feature extraction, basically achieved the desired effect.Field test shows that, in this paper the design and production of the system can basically meet the predetermined monitoring requirements.