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The rapid growth in wind energy technology has led to an increase in the amount of thermosetting FRP composite materials used in wind turbine blades that will need to be recycled or disposed of in the near future. Calculations show that 4.2 million tons of waste from wind blades will need to be managed globally by 2035, increasing to 16.3 million tons by 2055. Three waste management route are possible: disposal, recycling or reusing. Currently, most FRP composites taken out of service are disposal of in landfills or are incinerated. Recycling options consist of reclamation of the constituent fibers or the resins by thermo–chemical methods or recycling of small pieces of granular FRP material as filler material by cutting, shredding or grinding. Reuse options consist of reusing the entire FRP blade or large parts of the blade in new structural applications. This paper reports on the potential for reusing parts of wind turbine blades in new or retrofitted architectural and civil infrastructure projects. The paper introduces the geometry, materials, and laminates typically used in wind blades and provides a snapshot of the sizes of wind blades likely to be available from the inventory of active turbines. Because the materials and manufacturing of commercial wind blades are proprietary, generic blade geometries and materials are discussed. These come from the Sandia National Laboratory and National Renewable Energy Laboratory, in the United States, and from OPTIMAT in the European Union. The paper presents a method for generating the geometry and material properties of structural elements cut from wind blades, using the Numerical Manufacturing and Design Tool (NUMAD), published by the Sandia National Laboratory.
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Y-Shaped Cutting for the Systematic Characterization of Cutting and Tearing
Though they share the similarity of inducing material failure at a crack tip, the cutting and tearing energies of soft materials cannot be quantitatively related to one another. One of the reasons for this lack of understanding comes from additional complications that arise during standard cutting techniques. Decades ago, Lake and Yeoh [Int. J. of Fracture, 1978] described a natural rubber cutting method that uses a `Y-shaped' sample geometry to mitigate several of these challenges, including minimizing friction and controlling the strain energy available to drive fracture. The latter, understood via a fracture mechanics framework, enables relative tuning between a tearing contribution to the cutting energy and a cutting contribution. In this manuscript, we extend Lake and Yeoh's largely unreplicated results to softer, more highly deformable polydimethylsiloxane (PDMS) materials. The range of applicability of this technique to variations in material response, sample geometry, boundary conditions, and cutting rate is large. We utilize this flexibility to describe factors leading to the onset of a material-dependent, stick-slip cutting response, which occurs at low cutting rates and high tearing contributions. Furthermore, variation in cutting blade radius reveals a minimum cutting energy threshold even for blades with radii on the order of a few tens of nanometers. For blunter blades, cutting energy reflects the effects of material strain-stiffening. These results establish the Y-shaped cutting geometry as a useful tool in the study of soft fracture.
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- Award ID(s):
- 1562766
- PAR ID:
- 10086739
- Date Published:
- Journal Name:
- Experimental mechanics
- ISSN:
- 0014-4851
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1007/s11340-019-00476-5
