Methods of making wind turbine rotor blades

A method of manufacturing a root portion of a wind turbine blade, the wind turbine blade including a root portion, a main portion, and a tip portion, said method comprising:

• providing an inner layer of reinforcing fibers comprising at least two woven mats of reinforcing fibers, the inner layer having an inner surface and an outer surface;
• positioning a first band of reinforcing fibers adjacent the outer surface of the inner layer, the first band having an inner surface and an outer surface, and comprising at least two woven mats of reinforcing fibers;
• positioning a first mat of randomly arranged reinforcing fibers adjacent the outer surface of the first band of reinforcing fibers, the first mat having an inner surface and an outer surface;
• positioning a second band of reinforcing fibers adjacent the outer surface of the first mat, the second band having an inner surface and an outer surface, and comprising at least two woven mats of reinforcing fibers;
• positioning an outer layer of reinforcing fibers comprising at least two woven mats of reinforcing fibers adjacent the second band, the outer layer having an inner surface and an outer surface;
• introducing a polymeric resin into the root potion of the wind turbine blade;
• infusing the resin through the outer layer, the inner layer, each band of reinforcing fibers, and each mat of random reinforcing fibers;
• and
• curing the resin to form the root portion of the wind turbine blade.

A wind turbine blade comprising a root portion, a main portion and a tip portion wherein said main portion is located between said root portion and said tip portion, said root portion comprising:

• an outer layer of reinforcing fibers comprising at least two woven mats of reinforcing fibers;
• an inner layer of reinforcing fibers having an inner surface and an outer surface and comprising at least two woven mats of reinforcing fibers;
• at least two bands of reinforcing fibers positioned between said inner layer and said outer layer, each said band of reinforcing fibers comprising at least two woven mats of reinforcing fibers;
• a mat of randomly arranged reinforcing fibers positioned between each pair of adjacent bands of reinforcing fibers;
• and
• a polymeric resin infused through said outer layer, said inner layer, each said band of reinforcing fibers, and each said mat of random reinforcing fibers.