Introduction to scaling issues of damage and fracture in wind turbine blades

Transcription

1 Introduction to scaling issues of damage and fracture in wind turbine blades Bent F. Sørensen Composites and Materials Mechanics Section Department of Wind Energy Technical University of Denmark Risø Campus, 4000 Roskilde Denmark Wind Energy Denmark, October , Herning, Denmark

2 [Bent F. Sørensen] DTU Wind Turbine Test Center, Østerlid, Denmark Wind turbines - big structures... composite blades Note the turbine size relative to the car... Blades are designed against deflection and fatigue Composites are damage tolerant materials DTU Wind Energy, Technical University of Denmark

3 Main blade structures - manufacturing of wind turbine rotor blades Shear webs Main laminate DTU Wind Energy, Technical University of Denmark

4 Joining of blade structures - assemblage and joining Adhesive bond (leading edge) Bondlines (webs) DTU Wind Energy, Technical University of Denmark Adhesive bond (trailing edge)

5 Blade design - common blade designs Web type Box type

6 Failure modes - failure of a wind turbine rotor blade tested to failure 5 m wind turbine blade (Vestas V5) [Risø-R-1390(EN), 004, "Improved design of large wind turbine blade of fibre composites based on studies of scale effects (Phase 1) - Summary Report"]

7 Failure modes - a wind turbine blade [Risø-R-1390(EN), 004] Progressive failure: - multiple damage types - most are weak interfaces

8 Case 1: Cracks in gel-coat Channelling cracking in elastic layer: G ch I f ( D, D h ) E DTU Wind Energy, Technical University of Denmark 1 1 [Beuth, J. L., Int. J. Solid Structures, 199; 9, ]

9 Case 1: Cracks in gel-coat Model application: Find maximum gel-coat thickness, h 1 for c = 0.3% G Ic =100 J/m E 1 =4 GPa, E = 40 GPa D = Channelling cracking in elastic layer: f(d,d ) 1.5 h ch 1 GI f ( D, D ) h E 1 = m = mm DTU Wind Energy, Technical University of Denmark [Beuth, J. L., Int. J. Solid Structures, 199; 9, ]

10 Thick laminate (root section) Case : Delamination from a ply-drop delamination (crack parallel to fibres) Thin laminate (tip section) Siemens Wind Power A/S J ext E1h1 h (E h E h ) E 1 1

11 Thick laminate (root section) Model application: Find maximum plythickness, h 1 for c = 0.3% Data: [Sørensen and Jacobsen, 009] J 0 ( =45 )= 300 J/m E 1 = 40 GPa = 10 MPa Say: h Thin laminate = 50 mm (tip h 1 section) = 1.7 mm Siemens Wind Power A/S Case : Delamination from a ply-drop J ext delamination (crack parallel to fibres) E1h1 h (E h E h ) E 1 1

12 Thick laminate (root section) Model application: Find maximum plythickness, h 1 for c = 0.3% Say: h Thin laminate = 50 mm (tip h 1 section) = 1.7 mm Case : Delamination from a ply-drop J ext delamination (crack parallel to fibres) Data: [Sørensen and Jacobsen, 009] Accounting for fibre bridging: J 0 ( =45 )= 300 J/m E 1 = 40 GPa = 10 MPaData: [Sørensen and Jacobsen, 009] J ss 000 J/m h 1 0 mm Siemens Wind Power A/S E1h1 h (E h E h ) E 1 1

13 Case 3: Cracks in bondlines Generic bondlines: DTU Wind Energy, Technical University of Denmark

14 Case 3. Cracks in bondlines surface treatments Untreated adhesive/glass fibre laminate interface 50 BMA05_all.opj nom = 0 o Fracture Resistance, J R (J/m ) Onset of cracking No crack growth Cracking propagation End-Opening, * (m) BMA05-01 BMA05-0 BMA05-03 BMA05-04 BMA05-05 BMA05-06 [Kusano, Sørensen, Andersen, Toftegaard, Leipold, Salewski, Sun, Zhu, Li & Alden, 013, "Water-cooled non-thermal gliding arc for adhesion improvement of glass-fibre-reinforced polyester", Journal of Physics D: Applied Physics, Vol. 46, 13503]

15 Case 3. Cracks in bondlines plasma treatment of surface to be bonded Gliding arc set-up [Kusano, Sørensen, Andersen, Toftegaard, Leipold, Salewski, Sun, Zhu, Li & Alden, 013, "Water-cooled non-thermal gliding arc for adhesion improvement of glass-fibre-reinforced polyester", Journal of Physics D: Applied Physics, Vol. 46, 13503]

16 Case 3. Cracks in bondlines plasma treatment of surface to be bonded Gliding arc set-up Resulting fracture mechancis properties: A significant increasing fracture resistance due to crack bridging in laminate BMA0-01 BMA BMA0-03 BMA0-04 BMA0-05 BMA [Kusano, Sørensen, Andersen, Toftegaard, Leipold, Salewski, Sun, Zhu, Li & Alden, 013, "Water-cooled non-thermal gliding arc for adhesion improvement of glass-fibre-reinforced polyester", Journal of Physics D: Applied Physics, Vol. 46, 13503] Fracture Resistance, JR (J/m ) BMA0_all.opj End-Opening, * (m) nom = 0 o

17 Scaling issues... - consequences of manufacturing of large blades Future design rules should incorporate design rules for various damage modes and account for scaling issues Materials research can provide improvements in material properties (more damage tolerant materials) DTU Wind Energy, Technical University of Denmark

18 Thanks for your attention! Supported by the Danish Centre for Composite Structures and Materials for Wind Turbines (DCCSM), grant no , the Danish Strategic Research Council Any questions?