Multiaxial Fatigue Analysis Of Tower Door-weld On Wind Turbine Based On MWCM

The loads of weld of the wind turbine was more complex, mostly non-proportionalloads, the multiaxial fatigue damage was main failure mode, based on multiaxial fatiguefailure mechanism, the maximum shear stress and the normal stress as controlparameters of fatigue damage, the MWCM combination with the hot spot stressmethod, equivalent hot spot stress method and critical distance method was used tomultiaxial fatigue analysis for the tower door-weld, and compared with the analysisresult of the maximum principal stress method and the von Mises method. Thesisresearch provide technical support for the independent development of the wind turbinetower, the design and analysis of the wind turbine tower has theoretical and practicalvalueIn the thesis, the major work are summarized as follows:①A brief introduction of unit model of the hot spot stress method and the zeroposition of the equivalent hot spot stress method, the grid sensitivity of the hot spotstress method、equivalent hot spot stress method and critical distance method wasanalysis and compared. provide the basis for meshing of the the tower door-weldmultiaxial fatigue analysis.The fatigue analysis model of the tower flange wasestablished according to the fatigue cumulative damage theory. And the fatigue stressesof the top tower flange were calculated by using the Finite Element Method. Then thefatigue load spectrum was simulated by using rainflow counting method and thematerial S-N curve was revised thereby calculating the fatigue damage of top flange inthe design life.②The fatigue assessment for weld under uniaxial tension、pure bending、proportional load and round non-proportional load which applicate hot spot stressmethod, the equivalent hot spot stress method, the critical distance method wascompared.③The MWCM method was applied for multiaxial fatigue analysising of the windturbine tower door-weld combined with the hot spot stress method, equivalent hot spotstress method and critical distance method. Import finite element model to ansys tocalculate and extract the fatigue reference point stress, seted S-N curve based onMWCM method and compared the fatigue result of three methods.④For two methods-maximum principal stress method and von Mises method based on static strength criteria which mostly used to multiaxial fatigue analysis of weldin the wind power industry.this paper used two methods to multiaxial fatigue analysisfor tower door-weld and compared with multiaxial fatigue analysis result of towerdoor-weld based on MWCM method at the same time.