Mathematical simulation of mechanical stresses arising at uneven heating of the traction electric motor nb-514 and improvement of its design

The purpose of this work is to determine the causes of cracks in the frame of traction motors of electric locomotives. An analysis of the statistics of detecting cracks in the frame of NB-514 traction motors at the Eastern testing area is presented, showing that every third frame in operation has cracks. The method of mathematical modeling on a computer with the use of FEM was used. It is noted that carrying out measurements in the crack initiation zone by the tensometric method is practically impossible due to the geometry of the frame. The results of mathematical modeling of mechanical stresses arising in the frame of the NB-514 traction motor during its uneven heating to temperatures characteristic of the hourly mode of operation of the traction motor are considered. It is shown that mechanical stresses arising only due to the temperature difference between the ambient air and the windings of the main and additional poles of the traction motor can reach 100 MPa. Variants of changing the design of the ventilation windows of the frame are proposed to reduce the magnitude of temperature stresses with a constant area of the ventilation openings. When correcting the shape of the ventilation windows of the traction motor frame, these voltages can be reduced to 76 MPa. It was concluded that one of the main reasons for the formation of cracks in the frame of traction motors are cyclically repeating temperature stresses, which is especially important for electric locomotives operating on mountain pass sections in the pushing mode. It is noted that the appearance of mechanical stresses in the backbone of the traction motor also depends on vibrations arising from the path and operation of the gear train, as well as on the variable part of the magnetic field of the motor, which are not currently studied in detail.