| In recent years, the wind power industry has got rapid progress, at the sametime the wind turbine technology continued to be improved. As a result, thesecurity of the wind turbine has been taken more and more attention. The windturbine tower is currently use L-flange to connect, tower and foundation is oftenused T-flange to connect. From many wind turbine collapse accidents, we canfind a very important factor that is the wind turbine connection failure. In manycases, even the whole flange may happen bending deformation. Stress research inChina and abroad based on the flange of the wind turbine is very little, so thispaper focuses on the stress analysis of wind turbine flange and foundationconnection system and it aims to give the calculation formula of the system. Byusing the commercial finite element software ABAQUS to do the simulationwork, the result of the simulation verifies the accuracy of the theoreticalcalculation; the stress research will play a positive role in the perfection of windpower industry. The main research content and the results of this paper are givenas follows:By analyzing and comparing the domestic and foreign codes about theflange calculation, we find that the Japanese codes are more accurate. In terms ofcalculating the stress of the flexible flange, the stress calculation error using theJapanese codes is much smaller. At the same time, we analyzed the stresscalculation formula, the check formula and the calculation formula of boltpre-tightening force when it is under the action of axial force and bendingmoment. By using our new formula, we got the bolt pre-tightening force, whichis23%smaller than the result by using normative method. The bolts can alsomeet the requirements on the mechanical properties, as a result, it can effectivelyprevent the gaskets been killed and bolt been twist off.The mechanics analysis model between wind turbine base T-flange andfoundation connected system has been built, and we deduce mechanics formulaof the system as well. It mainly includes T-flange compression side and tensionside stress formula and bolt pre-tightening force formula. With the help of finiteelement software, the maximum stress in the model is not beyond the yield limit, so the whole connected system is security. The maximum stress of grout is36.6MPa, it is far below the yield strength of grout. The maximum stress value bysimulating compares with the theoretical calculation (34.65MPa), the error isabout5.628%, so it confirms that theoretical calculation is really correct. Basedon the flange connected to the foundation dose not disengage, the grout materialmeets the requirements, then we can conclude that the system which the windturbine base T-flange connected to the base is safe.For the system connected by L-flange and foundation, we deduce themechanics formula of the connection system. Between flange and concrete, therehas been a very obviously release. The biggest stress of grout is much higherthan the yield strength of grout, the grout will be crushed in local compressionarea, so the strength of the grout does not meet the requirements. With theincrease of applying pre-tightening force of bolt, the release area graduallydecreases, but the bolt stress also will increase. Gradually bolts start to be yield,it also led to the grout broken area to be gradually increased. Based on the above,we can draw the conclusion that the L-flange should not be used to the windturbine and base connected system. |
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