Research On Fatigue Performance Of Steel Members Under Crane Load

With the development of industry and demand of production, the increase in tonnage and frequency of operation is an inevitable trend as to whether bridge crane or suspension crane, and fatigue problem will be the key point effecting safety and benefit of production. This paper took steel crane girder and steel tube-welded hollow spherical joint in suspension crane as research objects and established modals by ABAQUS to analyze the stress and fatigue performance of the two members and compared the applicability on fatigue life predicting by the hot spot stress method, effective notch stress method and local stress-strain method. The main research contents are as follows:(1)Force situation of steel crane girder were analyzed by ABAQUS, then fatigue life was predicted by hot spot stress method, effective notch stress and local stress-strain method and evaluated applicability of the three methods.(2)The hot spot stress concentration factor(SCF) of spherical and tube surface was calculated by ABAQUS, then analyzed the relation between these two kinds of SCF and each factor of joint, and fitted several functions of SCF about each factor; merits and demerits of function was evaluated by comparing with results of finite element analysis. Finite element modals were built according to data of constant amplitude fatigue test and hot spot stress was got; fatigue life predicted by S-N curve matching hot spot stress method were compared with test members' life to estimate application of this method.(3)Submodals were built based on the modal used for steel tube-welded hollow spherical joint analyzed by hot spot stress method, then notch stress concentration factor(Kt) was gotten by effective notch stress method and fitted functions of Kt about each factor; fatigue life predicted by this method using FAT225 curve suggested by IIW was compared with test data, and evaluated the application of effective notch stress method.(4)Local strain was obtained according to the results of effective notch stress method, and predicted fatigue life of steel tube-welded hollow spherical joint by local stress-strain method; the feasibility of local stress-strain method was accessed by contrast with test result.(5)According to comparing hot spot stress method, effective notch stress method and local stress-strain method with test results, application of each method forecasting fatigue life of steel tube-welded hollow spherical joint was appraised.