Laminated electroformed shape memory composite for deployable lightweight optics

Abstract

Abstract-Advances in earth and space instrumentation will come from future optical systems that can provide large, collecting areas of low areal mass density (< 10 kg/sq meter) at a cost much lower than current practice. Launch cost and volume constraints require mass and volume both be reduced to permit affordable systems using large apertures. Composite optics show promise for light-weight, stiff optical substrates, but surface finish has not been adequate for many applications. Electroplated, replicated optical surfaces of nickel have been used for producing smooth, accurate optical surfaces primarily for X-ray optics, but require high mass to be self-supporting. Combining a light-weight and stiff composite substrate with a high quality replicated metal optical surface combines the best properties of these disparate materials. Recent developments in polymer chemistry have led to development of resins that can be formed into structures with shape memory properties. The unique properties of shape memory resins in the composite provide a larger range of design parameters for production of usable optics, allowing repeated deployability and accurate recovery to replicated shapes, selective shaping of optical surfaces, and management of interface stresses. Results are presented from optical and structural tests of various mirror constructions that show progress towards a laminated, deployable optic. Key issues for successful space applications are interface stress control of the disparate materials, strain recovery of the resins for accurate deployment, and stability over the operating conditions of temperature and moisture loss. Initial requirements analysis and material properties measurements for both system and individual material target performance are presented with current status and goals for future development.

A review of applications of deployable structure

“…However, structures that have made progress and breakthroughs in the current research field, such as coiled boom and telescopic hangers, have yet to successfully cope with the more demanding working environment in the aerospace field. While shape memory composites with a thin coating of reflective material for astrophysical applications have only been shown for tiny apertures (1m diameter) [15], the technology has previously been employed in principle for large deployable antennas since they do not need strict surface accuracies. As a result, a bigger size would present difficult issues.…”

Shape memory polymer S-shaped mandrel for composite air duct manufacturing

“…The advantages of SMPs are their ability to undergo large-deformations and their shape memory effect. However, the low mechanical properties (stiffness and strength) are in general not sufficient for structural applications, and therefore several types of reinforcements are added into the SMP matrix to produce composites with improved mechanical properties [8][9][10], Nowadays, SMPs and especially shape memory polymer composites (SMPCs) have been widely used in several engineering applications ranging from deployable space structures [11][12][13], morphing airframes [11,14] and adaptive optical [15,16], and biomedical devices [11,17]. Other applications in which SMPCs have been used include smart textiles and fabrics [11,18], smart dry adhesives [19], self-healing systems [11,20] and mandrel fabrication technologies involving recycling [21,22].…”

Epoxy‐cyanate ester shape memory thermoset: some aspects of phase transition, viscoelasticity and shape memory characteristics

“…Recently, certain patents and one report from our group have investigated it for use as a SMP. [31][32][33][34] In our previous work, bisphenol A-based epoxy and CE (BACY) resins were co-reacted with a reversible semi-crystalline polymer for realizing a shape memory thermoset. [31] An important technique to confer shape memory properties to thermoset matrix is to incorporate crystallizable polymer segments in the matrix.…”