FBG Displacement Sensor Application Research on Geology Security Monitoring of Substation

The great area crack can cause the landslide of the substation sliding. Dislocation is the significant factor to reflect the crack. Embedded the mast structure of FBG displacement sensor, the relative displacement of retaining wall in YanJin substation can be obtained. Placed 3 FBG displacement sensors on the southeast corner of the substation downstream integrated the real-time monitoring system for the dislocation crack of YanJin substation downstream. In the monitoring results of the 479 days, daily average displacement of 3# sensor located in substation downstream maximized to 1.58mm on January 27th 2011; and daily average displacement of 2# sensor located in substation downstream minimized to -1.94mm on September 18th 2011. The monthly rainfall maximized to 123.5mm, 70.7mm, 75.9mm in July, August, September 2011 and minimized to 26.8mm, 12.9mm, and 23.3mm in January 2011, November, December 2010. Considered local precipitation, cracks closely related to the local precipitation.

Research on Fatigue Test of LZ20Mn2 Axle Pipe Steel

The core of ultrasonic accelerate fatigue test is resonance, and specimens need resonating with the system. The ultrasonic fatigue test method was used to investigate the high cycle fatigue properties of LZ20Mn2 axle pipe steel. Tests were conducted on cylindrical dog-bone specimens, and all fatigue loadings were controlled by inputting vibration amplitude. The results showed that the S-N curve of LZ20Mn2 axle pipe steel presented a slow-decline shape and subsurface crack initiation. The fatigue fracture was observed by SEM. Two different crack initiation mechanisms were observed which were the mixed inclusions and dislocation. Crack closure effect played an important role at fatigue crack propagation area and the fracture mechanism was a typical plastic fracture.