Non-linear Ultimate Limit State Analysis of a Wind Turbine Blade

Masterarbeit aus dem Jahr 2013 im Fachbereich Ingenieurwissenschaften - Energietechnik, Note: -, - (Technical University of Denmark), Sprache: Deutsch, Abstract: A geometrically non-linear structural response of a 34 m wind turbine blade under flap-wise loading was compared with a linear analysis to show the need of non-linear analysis in wind turbine blade design. Non-linear effects revealed from a numerical finite element model were compared with an analytical plate model of the cap under compression load. The plate model was subjected to a transversal load due to the non-linear Brazier effect, and to in-plane loading to reveal the local cap displacement and the buckling resistance respectively. Focus was on the verification of the characteristic and design resistance in the ultimate strength and stability limit state. For the design resistance, an analysis due to the lowest GL requirements was used and compared with the results of a non-linear approach proposed by GL that required the application of an imperfection to the model. The way to apply an imperfection due to EUROCODE seemed more realistic compared with GL s approach. Numerous simulations revealed the requirement of non-linear analysis methods in design of wind turbine blades. A linear analysis due to the lowest GL requirements yielded less conservative results than a non-linear approach proposed by GL. That led to the fact, that the investigated blade designed after the lowest requirements would pass the certification, whereas the same blade design verified with the non-linear approach would not. The non-linear structural response was significantly dependent on the scaling of an applied imperfection.