The Wind Turbine Gearbox Thermal-structure And Fatigue Damage Research

Compared to traditional fossil energy, wind energy is a new clean renewable energy, whichis mainly used in wind turbine. Since the first wind power station was built at Danish in1981,the wind turbine technology has developed fast. Furthermore,the wind energy is comparable tocoal energy if we take environmental cost into consideration. As well, a good prospect in windenergy has been developed in our country. China has promulgated a series of incentive policiesto make progress in wind energy field since the last nineteenth century. In2013, both of thecumulative installed capacity and newly installed capacity in china ranked first around the world.There are two main transmission modes which are horizontal axis and vertical axis in thewind turbine. With the advantage of higher wind energy conversion and shorter wheelbase,multi-level transmission structure is largely used by major international manufacturers. Ordinary,fan blades pushed by the wind in a low speed (approximately13rpm), while the generatorrequired spindle running in a higher rotation speed (about1200rpm), so the transmission ratio isabout100times in total. In this case, the wind turbine gearbox structure is too complex,unreliability and short-lived to meet the requirements of wind turbine gearbox, as mostinternational brand gearbox failure rate was about9.8%, the downtime caused by gearbox failureaccounts was about19.4%, all this indicating that the repair of faulted gearbox is difficulties.Moreover it will result in greater financial losses. Generally, wind turbine gearbox failureanalysis focused on structural mechanics drive-line, in fact, the megawatt-class wind turbinegearbox are heavy loaded transmission gearbox, there is a big temperature rising in gear surfaceat the time of gear teeth meshing processing due to friction heat, it must lead to elevatedtemperature and the corresponding thermal stress. The gear generates a lot of heat and cannotremove completely though there are lubricated gearbox cooling system, so the thermal stressinevitably will superimpose on the original structure stress, the gear thermal-structure couplingstress makes it more complex, then coupling stress will further reduce the gear reliability andfatigue life. So how to take various factors into account in researching wind turbine gearboxreliability and life is very significance for wind turbine, wind power machine business andgearbox manufacturers.In this paper, writer will analyze the wind turbine gearbox thermal＆structure coupling stress,PROE software will be used to establish a company’s existing2.5MW gearbox gearbox power-train model, then assembled it after addendum practice of a sun gear and planet gear; Themodel will be imported into the finite element software from PROE and ANSYS interface andtuning it. Then, it will be performed dynamics analysis and thermal-structural coupling dynamicsanalysis after meshing, contact set, solver set. The above results will be used for gear surfacedamage fatigue analysis. This thesis results showed that: under normal load conditions, puredynamics analysis stress is lower65.4MPa than thermal-structure coupling analysis stress inaverage. Our fatigue analysis based on the coupling analysis, when reliability is less than0.999the planetary gear system damage is less than1which it’s meet the design requirements.