R.B. Bucinell Union College Mechanical Engineering Schenectady, NY, USA

30 January 2003Châlons en Champague

CompTest 2003

Investigation of the State of Strain at the Nodal Intersections of

Thermoplastic Isogrids using Speckle Image Photogrammetry

R.B. BucinellUnion College Mechanical Engineering

Schenectady, NY, USA

Session 10: Applications of Optical Techniques


CompTest 2003

Agenda

• Grids Isogrids • Advantages of Thermoplastics• Prototype Isogrid Project–Manufacturing– Experimental Evaluation

• Results and Conclusions


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Advantages of Grid Structures

• Highly Efficient• Damage Tolerant– Redistribution around damage

• Take Advantage of the Anisotropy of Composites

• Potential in Composites for Fabrication Automation


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Grid Types

• Quadri-Directional

• Tri-Directional

• Orthogrid

• Anglegrid


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History of Isogrids

• British Vickers Wellington Bomber

• McDonnell Douglas (1960)

• Payload Fairings, Edwards AFB (mid 80s)

• Aerospace Applications


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Thermoplastics Provide Significant Advantages

• In Situ Processing

• Effective Repair

• Recycling


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Prototype Study

• Manufacture Isogrid

• Test Analogs

• Optimization of Isogrid Configuration

• Manufacturing Automation


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Isogrid Mold


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Isogrid Lay-Up Pattern


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Experimental Evaluation

• Compare Composites to Aluminum and Steel

• Develop Understanding of Impact of Lay-Up Pattern

• Experimental Methods– 3 Point Bend


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Prototype Isogrid


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Speckle ImagePhotogrammetry


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Analog Results


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Performance SummaryGl/Ny

isogridAL

isogridST

isogridAl

solidSt

solid

Mass (g) 2000 2391 6712 4336 12078

Slope (MN/m) 5.013 5.538 13.43 7.589 24.59

Mass Ratio 1 1.196 3.356 2.168 6.039

Stiffness Multiplication 1 1.71 37.5 10.2 220

Flexural Rigidity D=Et3/[12(1-2)]


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Full Field Results


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Grid Comparisons


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Next Steps


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Summary

• Thermoplastic Isogrids have Unique capabilities

• Composite Isogrid Outperforms Al and Steel Isogrid

• Speckle Image Photogrammetry verifies effectiveness of node strategy

• Future Work Includes Analysis and Manufacturing Automation


CompTest 2003

Acknowledgements and QUESTIONS?

• Students– Rebecca Terry, Matt Bamford, Paula

Denemma, Jenny Moon, Matt Hilbert• Orgaizations

– National Science Foundation– Automated Dynamics Corp.– NASA

R.B. Bucinell Union College Mechanical Engineering Schenectady, NY, USA

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