Experimental Study Of Emission Source Detection Method On Bogie Frame

with the continuous improvement of the speed of the train, the bogie frame of train-set is the key component of train to ensure it run fast and smooth, higher performance for the bogie frame is be required. In the past, the test about bogie is done under static conditions, and which take much time and energy, and the defects in bogie are difficult to be monitored when the train is running. The acoustic emission testing technology as a new dynamic detection technology, it can use dislocation motion, force and deformation and cracks expand along with the elastic energy release about the metal material will emit acoustic emission signals. In this paper, experienced diagram analysis, association graph analysis, Fourier transform and wavelet transform were used to study the characteristics of acoustic emission signals in different stages(initiation, propagation and fracture), the experimental results show that results of tensile test and fatigue test can characterize the evolution stage of crack, and describe accurately the whole process of change about the crack,so these results can provide reliable reference for consecutive quantitative acoustic emission detection about the material. In this paper, the plane positioning method of acoustic emission instrument was used, and through certain conversion and adjustment, achieve the ability of positioning the acoustic emission source in the bogie frame, experimental results show that the method used in this paper has a certain positioning accuracy. The main work of this paper includes the following aspects:(1)In this paper, based on tensile test, bending test and fatigue test of the Q345 steel which is the main material of the bogie frame, analyze the acoustic emission phenomenon generated during the crack of Q345 steel in stretching, bending and fatigue stage in theses tests, and the experimental results and analysis verified the acoustic emission technique can be used effectively for the bogie frame of intercity train-set dynamic monitoring.(2) In order to predict the crack in which an unknown state, through experienced diagram analysis(through energy-time and count-time), associationgraph analysis(through energy-duration, rising time-duration, rising time-energy and count-duration), spectrum analysis(by Fourier transform) and time-frequency analysis(by wavelet transform) to summarizes the characteristic of acoustic emission signals in different stages(through the formation, expansion and rupture).(3)Due to under cyclic loading for a long time, the welding places of bogie frame prone to fatigue damage occur fatigue damage, so research on acoustic emission source location for the welded places between the side beam and the beam.Firstly arrange sensors on the scale for 1/10 of the bogie frame for welding place,and then through the lead-off signal acoustic emission source to research on acoustic emission source location, where the acoustic emission instrument positioning is to put the bogie frame beam into a plane, then project to the plane where the side beam in. The above approach will produce certain error,used in this paper the method of acoustic emission source location is combined with time difference positioning method and certain geometrical calculation method and put the plane positioning results calculate to the three-dimensional space plane, and compare the position of acoustic emission source location calculated with the experimental results, similar position demonstrated the method beam and side beam of the weld between positioning with certain accuracy.