Screening Tests of Composites for Use in Tidal Energy Devices

1. Screening Tests of Composites for Use in Tidal Energy Devices Anderson Ogg Master Thesis Committee Members: Mark Tuttle - Chair Brian Fabian Brian Polagye

2. Tidal Energy In this context, tidal energy refers to the use of hydrokinetic devices, such as turbines, to extract energy from the water flow created by the changing of the tides. Some Advantages: • Sustainable • Predictable - Base Load Power

4. Overall Goal To provide device developers with useful information that enables them to make more informed design tradeoff decisions.

5. Why Composites? • Large rotational surfaces – Weight will be important • Lack of information in the public domain • Potential maintenance advantages • May not need to preserve (paint) • May be less susceptible to biofouling

6. Pre-Preg GFRE GFRV CFRE

7. Materials Chosen • Glass Fiber Reinforced Epoxy – GFRE • Carbon Fiber Reinforced Epoxy – CFRE • Pre-Impregnated Carbon Fiber – Pre-Preg • Glass Fiber Reinforced Vinylester – GFRV

8. A Quick Review • Stress is force divided by area (F/A) • A shear force acts tangent to a surface • Shear Stress is the shear force divided by area (V/A) • Strain is the change in length divided by the original length • Shear Strain is the change in angle

9. From Professor Tuttle’s ME 556 Review of Concepts Presentation

10. From Professor Tuttle’s ME 556 Review of Concepts Presentation

11. Why Shear Modulus? • Just a screening test • Changes in strength and stiffness properties were expected to be primarily caused by changes in the matrix • The shear modulus is a matrix dominated property • After determining the longitudinal and transverse strain, you can calculate the shear strain and shear modulus • ASTM standard D3518 “Standard Test Method for In-Plane Shear Response of Polymer Matrix Composite Materials by Tensile Test of a ±45° Laminate.”

13. Experiment Plan • As-produced • In situ exposure • Accelerated exposure • Weight monitoring • Changes in shear modulus • Optical microscopy

14. In Situ Experimental Setup • One panel of each system kept at the UW in a as-produced condition • Two panels of each system placed on NNMREC’s Sea Spider • One panel of each system removed after 9 months • One panel of each system is still on the Sea Spider and should be removed after 18 months (November 2011)

16. SS Location at Admiralty Inlet

17. Accelerated Experimental Setup • Chose to only use the GFRV system • 3 panels, each subjected to one month exposure in heated artificial seawater at 30, 40 and 50˚C • Similar techniques used throughout the literature. • Continuous weight monitoring

19. Specimen Construction

20. Testing Procedures

21. Data Collection Example

22. Results • Shear Modulus • Weight Gain • Microscopy • Biofouling

23. Shear Modulus Results

29. Weight Gain of In Situ Panels

31. Weight Gain of Accelerated Panels

32. Microscopy

33. GFRE Panels D and B

34. CFRE Panels G and E

35. Biofouling

37. Barnacle Removal

38. Flake Off at About 2% Shear Strain

40. Conclusions • The GFRV system was the least expensive and had the second best performance • From the literature, it was expected that the GFRV would absorb less moisture but that the epoxy based systems would perform better; these were not the results obtained in the experiment • Depending on weight tradeoffs, the GFRV system may be perfectly acceptable for use in tidal energy devices. • Biofouling had little effect • Accelerated testing results need to be used with caution

41. Differences in B and D Voids

43. Future Work • Further examination into the mechanism that caused such a change in the GFRE system • Remove the 18 month panels in November and test them • When does the loss of shear modulus level out?

44. Acknowledgements • Mariette • Bill and Tuesday Kuykendall • My Committee and Professors • Fellow Graduate Students • U.S. Coast Guard

45. Questions?

46. Extra Material