Application and Analysis of Sandwich Elements in the Primary Structure of Large Wind Turbine Blades

Abstract

The present work studies the advantages of applying a sandwich construction as opposed to traditional single skin composites in the flanges of a load carrying spar in a future 180 m wind turbine rotor. A parametric finite element model is used to analyze two basic designs with single skin and sandwich flanges, respectively. Buckling is by far the governing criterion for the single skin design. Introducing a sandwich construction results in a globally more flexible structure making tower clearance the critical criterion. Significant weight reduction up to 22.3% and increased buckling capacity is obtained. Moreover, the study showed that proper choice of core material is important to prevent face wrinkling. Geometric nonlinear analysis showed sensitivity to imperfections. A consistent submodeling technique is presented for verifying the response from the global model in any section of interest.

Keywords

buckling sandwich FEA sensitivity analysis wind turbine blades.

Get full access to this article

View all access options for this article.

References

Abbott, I.H. and von Doenhoff, A.E. (1959). Theory of Wing Sections — Including A Summary of Airfoil Data, 2nd edn, Dover Publications, Inc., New York .

Berggreen, C. and Simonsen, B.C. (2005). Non-uniform Compressive Strength of Debonded Sandwich Panels - II. Fracture Mechanics Investigation , Journal of Sandwich Structures and Materials, 7(6): 483—517.

Brunelle, E.J. and Oyibo, G.A. (1983). Generic Buckling Curves for Specially Orthotropic Rectangular Plates, AIAA Journal , 21(8): 1150—1156.

Risø /DNV. (2002). Guidelines for Design of Wind Turbines, 2nd edn, Jydsk Centraltrykkeri, Denmark, p. 250.

Gal, E. , Levy, R. , Abramovich, H. and Pavsner, P. (2006). Buckling Analysis of Composite Panels, Composite Structures, 73: 179—185.

Geradin, M. and Rixen, D. (1997). Mechanical Vibritions, Theory and Application to Structural Dynamics, 2nd edn, Wiley & Sons, Chichester, UK.

Hansen, M.O.L. (2000). Aerodynamics of Wind Turbines, 1st edn, James and James, Copenhagen , Denmark.

Hoff, N.J. and Mautner, S.E. (1945). Buckling of Sandwich Type Panels, Journal of the Aeronautical Sciences, 12(3): 285—297.

Jones, R.M. (1999). Mechanics of Composite Materials, 2nd edn, p. 101, Taylor & Francis Ltd., 325 Chestnut Street, Philadelphia, PA.

10.

Jørgensen, E.R. , Borum, K.K. , McGugan, M. , Thomsen, C.L. , Jensen, F.M. , Debel, C.P. and Sørensen, B.F. (2004). Full Scale Testing of Wind Turbine Blade to Failure — Flapwise Loading, Risø-R-1392(EN) , Risø National Laboratory, Roskilde , Denmark.

11.

Leissa, A.W. (1985). Buckling of Laminated Composite Plates and Shell Panels, Technical Report, The Ohio State University, USA.

12.

Newmark, N.M. (1959). A Method of Computation for Structural Dynamics, Journal of the Engineering Mechanics Division, ASCE, 85(EM3): 6794.

13.

Nøkkentved, A. , Lundsgaard-Larsen , C. and Berggreen, C. (2005). Non-uniform Compressive Strength of Debonded Sandwich Panels - I. Experimental Investigation, Journal of Sandwich Structures and Materials , 7(6): 461—482.

14.

Ovesy, H.R. , GhannadPour, S.A.M. and Morada, G. (2005). Geometric Non-linear Analysis of Composite Laminated Plates with Initial Imperfection Under End Shortening, Using Two Versions of Finite Strip Method, Composite Structures, 71: 307—314.

15.

Reddy, J.N. (2004). Mechanics of Laminated Composite Plates and Shells , 2nd edn, p. 88, CRC Press, Boca Raton, FL.

16.

Riks, E. , Rankin, C.C. and Brogan, F.A. (1996). On the Solution of Mode Jumping Phenomena in Thin-walled Shell Structures, Computational Methods in Applied Mechanics and Engineering, 136: 59—92.

17.

Roberts, J.C. , Bao, G. and White, G.J. (1999). Experimental, Numerical and Analytical Results for Bending and Buckling of Rectangular Orthotropic Plates, Composite Structures, 43: 289—299.

18.

Schultz, J.P. and Jensen, J.F. (2005). Application of Load Carrying Sandwich Elements in Wind Turbind Blades, Master's Thesis, Technical University of Denmark, Department of Mechanical Engineering.

19.

Schweizerhof, K. , Vielsack, P. , Rottner, T. and Ewert, E. (2002). Stability and Sensitivity Investigations of Thin-walled Shell Structures Using Transient Finite Element Analyses, Proceedings of the Fifth World Congress on Computational Mechanics, Vienna.

20.

Sørensen, B.F. , Jørgensen, E. , Debel, C.P. , Jensen, F.M. , Jensen, H.M. , Jacobsen, T.K. and Halling, K.M. (2004). Improved Design of Large Wind Turbine Blade of Fibre Composites Based on Studies of Scale Sffects (Phase 1) — Summary Report, Risø-R-1390(EN), Risø National Laboratory, Roskilde, Denmark.