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Aeolus Blades
2004-2005
Mechanical Engineering
Senior Design Project
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Build Proposal
Please click
here
 to download our Final Build
Proposal, submitted January 14, 2005.To access our Fall Build Proposal, click here. Blade ConstructionFor ease of manufacture, the blade will be fabricated in two halves, as illustrated in general in the figure below. The router will handle more easily a work piece with a flat bottom. Additionally, a sectioned blade is required to remove material in creating the internal hollowed section. Installation of the cable for lightening protection is also facilitated.
The blades will be shaped from billets of engineered wood using a CNC router. A CNC machine with a 26-ft long table is available for this work in the Burnside Industrial Park. The machine is an AXYZ Automation router owned by Mattatall Signs Ltd. MasterCAM is a software package that creates the numerical control file (known as g-code) that drives the AXYZ Automation router. The final 3D model will be used to generate the g-code using MasterCAM software with the assistance of the Advanced Manufacturing Group at Dalhousie. The billets of engineered wood will be custom made from strips of Microllam. The main drawback of using typical LVL is its tendency to fail due to shear at the inter-laminar glue layers when subjected to cyclic, flat-wise bending. This is a significant concern since it is the direction of loading of a wind turbine blade. To avoid this problem, billets from the testing material have been cut into strips, turned at 90°, and then laminated back together. The before-and-after veneer-orientation is shown in the following figure.
This process creates a billet with the inter-laminar glue layers in a plane perpendicular to the shear planes induced by bending. This alternative will increase labour costs associated with manufacturing the blades; however, it may reduce costs in other ways. The re-laminated billets would be arranged to more closely resemble the final blade shape and thus reduce the amount of wasted material. This will also reduce the amount of CNC time required for shaping the blades.
Bill of MaterialsNote: Quantities are given per blade.
Manufacturing Process
1)
The upper blade section will be machined from a
single custom-made billet of EWP. The process is described
below. 2) The lower blade section will be machined in the same fashion as the upper blade section. 3) Seal the inner surfaces of the two halves with an epoxy resin. 4) Install the grounding cable on the inside surface of the bottom half of the blade. The hollow space within the blade will house the cable. A hole will be drilled into the blade’s root and tip through which the cable will be fed. 5) Bond the two halves of the blade together. 6) Sand the exterior surface of the assembled blade. 7) Install carbon fiber strips with epoxy resin. 8) Cover the exterior of blade with protective fiberglass and epoxy coating. 9) Sand and finish the blade with exterior grade paint. The fabricated blades will have the same exterior profile and dimensions as the sample fiberglass and carbon fiber blades provided by the client, as measured using the portable CMM. Overall dimensions are listed below. (See Engineering Drawings and Manufacturing Model)
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