Multi-layer adaptive thin shells for future space telescopes

Autor: Peter Hagedorn, Renaud Bastaits, Gonçalo Rodrigues, P. Jetteur, André Preumont
Rok vydání: 2012
Předmět:
Zdroj: Smart Materials and Structures. 21:064004
ISSN: 1361-665X
0964-1726
DOI: 10.1088/0964-1726/21/6/064004
Popis: This paper examines the morphing capability of doubly curved elastic shells with various layers of active materials with strain actuation capability. The equivalent piezoelectric loads of an orthotropic multi-layer shell is established and it is demonstrated that a set of four active layers offer independent control of the in-plane forces and bending moments, which guarantees optimum morphing with arbitrary profile. This is illustrated by a numerical example which compares a unimorph configuration (single layer of active material) with a twin-bimorph (two pairs of symmetrical layers of active material with orthotropic properties). Numerical simulations indicate that the optical (Zernike) modes with shapes where the curvatures in orthogonal directions have opposite signs (e.g. astigmatism, trefoil, tetrafoil) are fairly easy to control with both configurations and that substantial amplitudes may be achieved. However, the optical modes with shapes where the curvatures in orthogonal directions have the same sign (e.g. defocus, coma, spherical aberration) are difficult to control with the unimorph configuration, and they lead to the appearance of slope discontinuities at the interface between the independent electrodes. As expected, a much better morphing is achieved with a twin-bimorph configuration.
Databáze: OpenAIRE
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