Drawing and Application of Goodman-Smith Diagram for the Design of Railway Vehicle Fatigue Reliability

Methods of drawing and applying the Goodman-Smith diagram are investigated for the railway vehicle fatigue reliability design.The fatigue strength at arbitrary given reliability level is evaluated by the probabilistic fatigue S—N curves covering the mid-and-short and long life regimes.The transition point coordinates of the diagram are determined on an entire probabilistic sense.The diagram is drawn by a structural fatigue life concept of driving mileage in terms of ten kilometers with a characteristic of vehicle wheel circling number equal to fatigue stress cycling number.In addition,for the production application of the diagram three modification factors are suggested and formulated to consider the differences of the numbers between fatigue stress cycling and the wheel circling,the differences of loading modes between the specimens and the production structures,and the differences of geometries,surface quality,and environments between the vehicle structures and the diagram established specimen.Feasibility of the present methods is indicated by the drawing of LZ50 carbon steel basic design diagram and the modification of the diagram for railway vehicle axle design.