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Proceedings Paper

Bill Armstrong memorial session: elastic modulus and strain recovery testing of variable stiffness composites for structural reconfiguration
Author(s): Geoff McKnight; Robert Doty; Guillermo Herrera; Chris Henry
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Paper Abstract

Morphing structures have the potential to significantly improve vehicle performance over existing fixed component designs. In this paper, we examine new composite material design approaches to provide combined high stiffness and large reversible deformation. These composites employ shape memory polymers (SMP) matrices combined with segmented metallic reinforcement to create materials with variable stiffness properties and reversible accommodation of relatively large strains. By adjusting the temperature of the sample, the storage modulus can be varied up to 200x. We demonstrate the segmented composite concept in prototype materials made using thermoplastic polyurethane SMP reinforced with interlocking segmented steel platelets. Measured storage moduli varied from 5-12 GPa, below SMP Tg, and 0.1-0.5 GPa above SMP Tg. The samples demonstrated more than 95% recovery from induced axial strains of 5% at 80°C. Viscoelastic effects are dominant in this regime and we investigate the rate dependence of strain recovery.

Paper Details

Date Published: 17 April 2007
PDF: 11 pages
Proc. SPIE 6526, Behavior and Mechanics of Multifunctional and Composite Materials 2007, 652617 (17 April 2007); doi: 10.1117/12.717287
Show Author Affiliations
Geoff McKnight, HRL Labs., LLC (United States)
Robert Doty, HRL Labs., LLC (United States)
Guillermo Herrera, HRL Labs., LLC (United States)
Chris Henry, HRL Labs., LLC (United States)

Published in SPIE Proceedings Vol. 6526:
Behavior and Mechanics of Multifunctional and Composite Materials 2007
Marcelo J. Dapino, Editor(s)

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