Analysis of the origin area of the fracture of the water pump bearing

There are three areas where there are fractures in the water pump bearings. Today, let’s talk about the origin of the cracks.

   We observed the fracture of the water pump bearing with the naked eye and low magnification and found that there will be obvious traces of repeated friction in the source area of the crack, so we can conclude that this is the starting position of the fatigue crack. Radial streaks appear below this zone, as well as obvious tear marks, so this zone is the fatigue crack propagation zone.

   Through the observation and analysis of the fracture, it can be known that the fracture is a typical composite fatigue fracture of bending and torsion. At the beginning, the initiation and propagation of cracks are mainly based on bending stress. Once the cracks begin, the crack propagation speed will change from fast to slow, and then enter the stalemate stage of crack propagation, and finally the shear stress will lead to failure of the shaft fracture. .