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A laminate material for damping a vibrational mode of a structure is provided, the laminate material comprising a viscoelastic layer and a stiff constrained layer adhered to the viscoelastic layer, wherein the viscoelastic layer is elastomer based and the constrained layer is made of steel, galvaniz

A laminate material for damping a vibrational mode of a structure is provided, the laminate material comprising a viscoelastic layer and a stiff constrained layer adhered to the viscoelastic layer, wherein the viscoelastic layer is elastomer based and the constrained layer is made of steel, galvanized steel or aluminum. Furthermore, a damping arrangement for damping at least one vibrational mode of a structure is provided, comprising a laminate material having a soft viscoelastic layer and a stiff constrained layer, wherein the laminate material is provided in the form of at least two longish stripes, the soft viscoelastic layer of the at least two stripes being adhered to a surface of the structure, and the at least two stripes being oriented at an angle of 0째 to 180째, preferably 90째, with respect to each other.

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What is claimed is: 1. A laminate material for damping a vibrational mode of a structure, comprising a viscoelastic layer and a stiff constrained layer adhered to the viscoelastic layer, wherein the constrained layer is made of a metal, wherein the laminate material is provided in the form of at le

What is claimed is: 1. A laminate material for damping a vibrational mode of a structure, comprising a viscoelastic layer and a stiff constrained layer adhered to the viscoelastic layer, wherein the constrained layer is made of a metal, wherein the laminate material is provided in the form of at least two ribbons, wherein a viscoelastic layer of the at least two ribbons is adhered to a surface of the structure, wherein the structure comprises an almost rectangular surface and the at least two ribbons are arranged cross-like, wherein the at least two ribbons are angled with respect to the sides of the surface by about 45째. 2. The material according to claim 1, wherein the metal is steel, galvanized steel or aluminum. 3. The material according to claim 1, wherein the viscoelastic layer has a thickness between 2 mm and 8 mm. 4. The material according to any of claim 1, wherein the constrained layer has a thickness between 1 mm to 4 mm. 5. The material according to claim 1, wherein the viscoelastic layer has a thickness of 6 mm and the constrained layer is made of galvanized steel of 1.5 mm thickness. 6. The material according to claim 1, wherein the viscoelastic layer has a shear modulus in the range of 105 N/m2 to 106 N/m2. 7. The material according to claim 1, wherein the structure is a nacelle of a wind turbine. 8. A damping arrangement for damping at least one vibrational mode of a structure, comprising a damping material wherein the damping material is provided in the form of at least two ribbons, wherein a viscoelastic layer of the at least two ribbons is adhered to a surface of the structure, and the at least two ribbons are oriented at an angle of at least approximately 30째 with respect to each other. 9. The damping arrangement according to claim 8, wherein the at least two ribbons form overlapping crossovers at their intersections. 10. The damping arrangement according to claim 8, wherein the overlapping crossovers of the at least two ribbons are located at the antinodes of the at least one vibrational mode to be damped of the structure. 11. The damping arrangement according to claim 9, wherein a first ribbon crosses a second ribbon at the crossovers alternately above and beneath the second ribbon. 12. The damping arrangement according to claim 11, wherein a third ribbon crosses a fourth ribbon at the crossovers alternately above and beneath the fourth ribbon and wherein the third ribbon runs parallel to the first ribbon and the fourth ribbon runs parallel to the second ribbon, and wherein the third and fourth ribbons cross the first and second ribbons above the first and second ribbons. 13. The damping arrangement according to claim 12, wherein the third and fourth ribbons are spaced from the first and second ribbons, respectively, so that the crossovers of the third and fourth ribbons are adjacent to the crossovers of the first and second ribbons. 14. The damping arrangement according to claim 12, wherein the third and fourth ribbons are spaced from the first and second ribbons, respectively, so that the crossovers of the third and fourth ribbons are located approximately halfway between two successive crossovers of the first and second ribbons. 15. The damping arrangement according to claim 8, wherein the structure is tubular and each of the at least two ribbons is helical. 16. The damping arrangement according to claim 15, wherein the structure is a tower or rotor blade of a wind turbine. 17. The damping arrangement according to claim 8, wherein the structure comprises an almost rectangular surface and the at least two ribbons are arranged cross-like, wherein the at least two ribbons are angled with respect to the sides of the surface by about 45째. 18. The damping arrangement according to claim 17, wherein the structure is a nacelle of a wind turbine. 19. The damping arrangement according to claim 8, wherein the at least two ribbons have the same thickness and width. 20. The damping arrangement according to claim 8, wherein third and fourth ribbons have a smaller thickness and width than first and second ribbons. 21. The damping arrangement according to claim 20, wherein the damping material comprises a soft viscoelastic layer and a stiff constrained layer, and wherein the viscoelastic layer of the third ribbon is adhered to the stiff constrained layer of the first ribbon and the viscoelastic layer of the fourth ribbon is adhered to the stiff constrained layer of the second ribbon. 22. The damping arrangement according to claim 21, wherein the first ribbon and crosses the second ribbon at the crossovers alternately above and beneath the second ribbon and wherein the third ribbon and crosses the fourth ribbon at the crossovers alternately beneath and above the fourth ribbon. 23. The damping arrangement according to claim 8, wherein the damping material is an elastomeric material with a shear modulus of about 108 N/m2. 24. The damping arrangement according to claim 8, wherein the laminate material has a predetermined curved shape. 25. The damping arrangement according to claim 8, wherein the ribbons have a length of 1000 mm to 4000 mm and a width of 100 mm to 400 mm. 26. The damping arrangement of claim 8, wherein more than four ribbons overlap at a crossover. 27. The damping arrangement according to claim 8, wherein the at least two ribbons are oriented at an angle of 60째 to 120째 with respect to each other. 28. The damping arrangement according to claim 8, wherein the at least two ribbons are oriented at an angle of 90째 with respect to each other. 29. A method for designing a damping arrangement for a vibrating surface, comprising: (a) computing the modal response of a vibrating surface to a unit force; (b) computing the acoustic response of the vibrating surface to a given unit vibration velocity; (c) determining the acoustically radiating modes of the vibrating surface from the computed modal and acoustic responses; (d) determining the location of the antinodes of the acoustically radiating modes of the vibrating surface; and (e) determining the layout of at least two ribbons of a damping material, the at least two ribbons are oriented at an angle of 0째 to 180째 with respect to each other, wherein overlaps of the ribbons are located at antinodes of the acoustically radiating modes of the vibrating surface. 30. The method according to claim 29, further comprising before step (c) the step of computing the force excitation spectrum and, in step (c), considering also the force excitation spectrum for determining the antinodes of the acoustically radiating modes of the vibrating surface. 31. The method according to claim 29, further comprising (f) repeating the steps (a) to (e) while replacing the vibrating surface by the vibrating surface together with the layout determined in step (e). 32. The method according to claim 29, wherein in step (c) only between one and five most prominent acoustically radiating modes are selected. 33. The method according to claim 29, wherein the at least two ribbons are oriented at an angle of 60째 to 120째 with respect to each other. 34. The method according to claim 29, wherein the at least two ribbons are oriented at an angle of 90째 with respect to each other. 35. A wind turbine comprising a damping arrangement for damping at least one vibrational mode of a structure, comprising a damping material wherein the damping material is provided in the form of at least two ribbons, wherein a viscoelastic layer of the at least two ribbons is adhered to a surface of the structure, and the at least two ribbons are oriented at an angle of 0째 to 180째 with respect to each other. 36. The wind turbine according to claim 35, wherein the damping arrangement is disposed in one or more of the tower, the nacelle, and at least one of the rotor blades. 37. A wind turbine designed according to a method, comprising: (a) computing the modal response of a vibrating surface to a unit force; (b) computing the acoustic response of the vibrating surface to a given unit vibration velocity; (c) determining the acoustically radiating modes of the vibrating surface from the computed modal and acoustic responses; (d) determining the location of the antinodes of the acoustically radiating modes of the vibrating surface; and (e) determining the layout of at least two ribbons of a damping material, the at least two ribbons are oriented at an angle of 0째 to 180째 with respect to each other, wherein overlaps of the ribbons are located at antinodes of the acoustically radiating modes of the vibrating surface.