Papers by Author: Wen Dong Shao

Abstract: Measurement on fracture roughness values is investigated to the grade B cast steel for China railway rolling wagon bogie frames. Due to be limited by production bogie frame geometry, a ductile fracture roughness measuring method is employed for the present study. Experiments reveal that, when crack growth increments are very scattered, the code based measurement of 0.2 mm crack growth increment for gauge ductile fracture roughness may be not reasonable. And a measurement of 90 % maximum ductile fracture roughness should be suggested to be an appropriate measurement. The new suggested 90 % maximum fracture roughness measurement is verified to be effective for the fracture roughness values of the present material.

Abstract: Experimental study is performed on the probabilistic cyclic stress-strain responses of grade B cast steel, which is utilized in the manufacture of Chinese K6 type bogie. Fatigue test is carried out by an incremental strain-controlled method with 8 strain levels. Analysis of test data and observation on fatigue fracture surfaces of test specimens indicate that difference and evolution of local conditions are basic causes of the random fatigue damage behavior. So it is verified again that the random character of stress-strain responses is an intrinsic fatigue behavior of engineering materials. Taking the scattering regularity and the size of specimens into account, cyclic constitutive models of present test data with arbitrary probability and confidence are obtained. The analysis reveals that these models can reflect the random responses of material correctly.