# US 2014/0154090 A1 · Wind blades with mechanical elements for pretensioning in tension fabrics > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0154090 A1 - Document ID: US20140154090A1 - Status: Published application - Kind: A1 - Application number: 14/065,779 - Filed: 2013-10-29 - Published: 2014-06-05 - Earliest claimed: 2012-12-04 - Assignees: General Electric Company - Applicants: General Electric Company - Inventors: Vidyashankar Ramasastry BURAVALLA; Sriram KRISHNAMURTHY - Web page: https://patentgrep.com/patent/US20140154090A1 ## CPC - F03D 1/0675: {of the blades} - F03D 7/0236: {by changing the active surface of the wind engaging parts, e.g. reefing or furling} - F03D 13/10: Assembly of wind motors; Arrangements for erecting wind motors - F05B 2260/502: involving springs - Y02E 10/72: Wind turbines with rotation axis in wind direction - Y10T 29/49337: Composite blade - F03D: WIND MOTORS - F05B: INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A wind blade is provided. The wind blade includes a self-supporting structural framework, having multiple chord-wise members and one or more span-wise members. Each of the multiple chord-wise members and the one or more span-wise members have an aerodynamic contour. The wind blade also comprises a fabric skin located over the self-supporting structural framework. Further, the wind blade includes a tensioning mechanism configured for providing pretensioning in the fabric skin. The tensioning mechanism includes multiple mechanical force elements coupled with the fabric skin for providing a predetermined force for maintaining an aerodynamic surface of the fabric skin during operation of the wind blade. ## Claims ### Claim 1 A wind blade comprising: a self-supporting structural framework, having a plurality of chord-wise members and one or more span-wise members, wherein each of the plurality of the chord-wise members and the one or more span-wise members have an aerodynamic contour; a fabric skin located over the self-supporting structural framework; and a tensioning mechanism configured for providing pretensioning in the fabric skin, wherein the tensioning mechanism comprises a plurality of mechanical force elements coupled with the fabric skin for providing a predetermined force for maintaining an aerodynamic surface of the fabric skin during operation of the wind blade. ### Claim 2 (depends on 1) The wind blade of claim 1, wherein the plurality of mechanical force elements comprises torsion springs, extension springs, turnbuckles, sail-mast apparatus, tension rods, spring cables, superelastic elements and ratchet straps. ### Claim 3 (depends on 1) The wind blade of claim 1, wherein the superelastic elements comprises nickel-titanium alloy in a wire form or a spring form. ### Claim 4 (depends on 1) The wind blade of claim 1, wherein the plurality of mechanical force elements are coupled with the fabric skin via a plurality of support members. ### Claim 5 (depends on 4) The wind blade of claim 4, wherein the plurality of support members comprises brackets, fabric strips with glued patches, fabric strips with stitched patches, fabric strip extentions with metal rings, and spindles. ### Claim 6 (depends on 1) The wind blade of claim 1, wherein the tensioning mechanism comprises a plurality of torsion springs or extension springs with hooked ends attached with a plurality of fabric strips that are glued or stiched with the fabric skin, ### Claim 7 (depends on 6) The wind blade of claim 6, wherein the plurality of torsion springs or extension springs are coupled with the plurality of fabric strips at one first hooked end and coupled with the chord-wise members or the one or more span-wise members at one second hooked end. ### Claim 8 (depends on 6) The wind blade of claim 6, wherein the plurality of torsion springs or extension springs are coupled with the chord-wise members or the one or more span-wise members at one first hooked end and coupled with the plurality of fabric strips at one second hooked end via a metal ring. ### Claim 9 (depends on 1) The wind blade of claim 1, wherein the tensioning mechanism comprises a plurality tension rods, extension springs and umbrella-like wire stiffners coupled together with the fabric skin for providing pretension in the fabric skin. ### Claim 10 (depends on 1) The wind blade of claim 1, wherein the tensioning mechanism comprises a plurality of turnbuckles attached to a plurality of fabric sections in a span-wise and chord-wise directions for pretensioning the fabric skin in the wind blade. ### Claim 11 (depends on 1) The wind blade of claim 1, wherein the tensioning mechanism comprises a combination of a plurality of first springs and cables attached to a plurality of regions of the fabric skin at one end and to a plurality of ring structures at the other end for providing pretensioning of the fabric skin. ### Claim 12 (depends on 11) The wind blade of claim 11, wherein the plurality of ring structures are arranged in a length-wise direction of the wind blade and configured to be attached to a root section of the wind blade via a combination of a plurality of second springs and cables. ### Claim 13 (depends on 1) The wind blade of claim 1, wherein the tensioning mechanism comprises a plurlaity of extension springs with hooked ends coupled with a plurality of stiffners with attached fabric skin strips at one end and coupled with a pluralty of brackets at the other end. ### Claim 14 (depends on 1) The wind blade of claim 1, wherein the tensioning mechanism comprises a plurality of torsion springs with spindles arranged with a bracket for pretensioning a plurality of fabric sections. ### Claim 15 (depends on 1) The wind blade of claim 1, wherein the tensioning mechanism comprises a plurality of ratchet straps attached with the fabric skin and a gear system for locking the ratchet straps tightly for imparting tension in the fabric skin. ### Claim 16 A method of tensioning a fabric skin of a wind blade, the method comprising: assembling a fabric skin having a plurality of fabric strips over a self-supporting structural framework having a plurality of chord-wise members and one or more span-wise members, wherein each of the plurality of the chord-wise members and the one or more span-wise members have an aerodynamic contour; and providing a tensioning mechanism for pretensioning the fabric skin, wherein the tensionsing mechanism is configured to couple a plurality of mechanical force elements with the fabric skin for providing a predetermined force for maintaining an aerodynamic surface of the fabric skin during operation of the wind blade. ### Claim 17 (depends on 13) The method of claim 13, wherein the plurality of mechanical force elements comprises torsion springs, extension springs, turnbuckles, sail-mast apparatus, tension rods, superelastic elements and ratchet straps. ### Claim 18 (depends on 13) The method of claim 13, comprising coupling the plurality of mechanical force elements with the fabric skin via a plurality of support members. ### Claim 19 (depends on 15) The method of claim 15, wherein the plurality of support members comprises stiffeners, fabric strips with glued patches, fabric strips with stitched patches, fabric strip extensions with metal rings, spring cables, and spindles. ### Claim 20 A wind turbine comprising: a plurality of wind blades, wherein each of the blade comprises: a self-supporting structural framework, having a plurality of chord-wise members and one or more span-wise members, wherein each of the plurality of the chord-wise members and the one or more span-wise members have an aerodynamic contour; a fabric skin located over the self-supporting structural framework; a tensioning mechanism configured for providing pretensioning in the fabric skin, wherein the tensionsing mechanism comprises a plurality of mechanical force elements coupled with the fabric skin for providing a predetermined force for maintaining an aerodynamic surface of the fabric skin during operation of the wind blade.