Effects of root gap on anti-fatigue properties of fillet welds for a tie rod seat of locomotive bogie

Root gap of fillet welds can not be fully controlled in a real welding scenario, while engineers in the industry must provide reasonable maintenance solutions for gaps with different size. Following standard working loads of the International Union of Railways, influences of the dimensions of root gap on the maximum stress amplitude (AMAX) in fillet weld were analyzed. It is found that: 1) The position of the maximum AMAX value calculated based on the standard working conditions coincides with the position of actual fatigue crack; 2) Fillet welds with root gaps of typical size have more than double the AMAX values of fillet welds without root gaps; 3) By using Goodman fatigue limit diagram, the specific disposal scheme of root gap with varying dimensions was determined. These results have a general guiding significance for improving the fatigue properties of structures containing fillet welds.