Structural Analysis Of Tubular Tower Foundation On Wind Turbine

Tower is an important load-bearing part of wind turbine, and the bottom of thetubular tower is the largest load-bearing position. In recent years, the analysis of thetower bottom structure is given serious attention because of the frequent tower collapseaccidents, which is a serious threat to the safety of the wind turbine operation. With thehigh-power development of wind turbine, it increases the load of the tower bottomstructure gradually, which has a very high demand on the safety of tower structure.Research on tower bottom structure is important for the structure optimization designand the safety of the wind turbine operation in the initial design stage.Consider the structural failure of the tubular tower bottom which leads to the towercollapse accidents, research and verification on structures and parts are conducted,according to the security verification requirements on the structures and parts by GLRules.Main researches covered in this paper are as follows:First, Calculated limit load of the tower bottom structure in all kinds of extremeconditions, and analyzed the static strength of the tower foundation structure, thestability of the tower bottom structure and the fatigue life of the tower foundationstructure in the design life. Considered the influence of a door opening in the bottom ofthe tower structure to the stability analysis, and determined the S Ncurve of thestructure and its influence factors when analyze the fatigue life of the tower foundationstructure.Second, used the hot spot stress method to analyze the fatigue life of the door frameweld. Considered the influence factors on the fatigue strength of the welded structuresand modified the S Ncurve. Obtained the structure hot spot stress by the surface linearextrapolation method by the finite element method.Third, analyzed ring flange connection structure load-bearing capacity. Accordingto three failure modes of the Petersen theory, analyzed flange geometry influence on theload-bearing capacity of the flange connection structure.Fourth, used three calculation models to calculate the relationship between theconnecting bolt stress and the structure load, and compared both the advantages anddisadvantages of the three calculation models, in which, M.Seidel curve modelconsidered the influence of eccentric blessing and loading of the flange connection structure to the bolt working stress, and calculated tensile stress and bending momentstress that caused connection bolt fatigue damage. Under certain conditions, M.Seidelcurve model can be used as the most reasonable model of the calculating therelationship between the connection bolt working stress and structural loading.Fifth, analyzed fatigue life of the connection bolt. Conducted a detailed analysis ofthe influencing factors on S Ncurve of the connecting bolts. The connecting boltfatigue life analysis not only verified the advantages and disadvantages of the threecomputational models, but also provided an effective and workable solution toconnecting bolt fatigue life.