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Photomechanical Bending of Azobenzene-Based Photochromic Molecular Fibers  [PDF]
Hideyuki Nakano,Ryoji Ichikawa,Riku Matsui
Micromachines , 2013, DOI: 10.3390/mi4020128
Abstract: Microfibers composed of azobenzene-based photochromic amorphous molecular materials, namely low molecular-mass photochromic materials with a glass-forming property, could be fabricated. These fibers were found to exhibit mechanical bending motion upon irradiation with a laser beam. In addition, the bending direction could be controlled by altering the polarization direction of the irradiated light without changing the position of the light source or the wavelength of the light. In-situ fluorescence observation of mass transport induced at the surface of the fiber doped with CdSe quantum dots suggested that the bending motions were related with the photoinduced mass transport taking place near the irradiated surface of the fiber.
An optically activated cantilever using photomechanical effects in dye-doped polymer fibers  [PDF]
Shaoping Bian,Dirk Robinson,Mark G. Kuzyk
Physics , 2005, DOI: 10.1364/JOSAB.23.000697
Abstract: We report on what we believe is the first demonstration of an optically activated cantilever due to photomechanical effects in a dye-doped polymer optical fiber. The fiber is observed to bend when light is launched off-axis. The displacement angle monotonically increases as a function of the distance between the illumination point and the fiber axis, and is consistent with differential light-induced length changes. The photothermal and photo-reorientation mechanisms, each with its own distinct response time, are proposed to explain the observed time dependence. The measured degree of bending is consistent with a model that we have proposed which includes coupling between photoisomerization and heating. Most importantly, we have discovered that at high light intensity, a cooperative release of stress results in cis-to-trans isomerization that yields a large and abrupt length change.
Photomechanical Response of Composite Structures Built from Azobenzene Liquid Crystal Polymer Networks  [PDF]
Kyung Min Lee,Timothy J. White
Polymers , 2011, DOI: 10.3390/polym3031447
Abstract: Optically directed shape adaptive responses have been sought after for many decades in photoresponsive polymeric materials. A number of recent examinations have elucidated elucidated the unique opportunities of photomechanical responses realized in azobenzene-functionalized liquid crystalline polymer networks (both elastomers and glasses). This work summarizes and contrasts the photomechanical response of glassy polydomain, monodomain, and twisted nematic azo-LCN materials to blue-green irradiation. Building from this summary, the combinatorial photomechanical response observed upon irradiation of composite cantilevers is examined. Large scale shape adaptations are realized, with novel responses that may be of potential use in future employment of these materials in actuation.
Singular fibers of the bending flows on the moduli space of 3D polygons  [PDF]
Damien Bouloc
Mathematics , 2015,
Abstract: In this paper, we prove that in the system of bending flows on the moduli space of polygons with fixed side lengths introduced by Kapovich and Millson, the singular fibers are isotropic homogeneous submanifolds. The proof covers the case where the system is defined by any maximal family of disjoint diagonals. We also take in account the case where the fixed side lengths are not generic. In this case, the phase space is an orbispace, and our result holds in the sense that singular fibers are isotropic orbispaces.
Influence of Synthetic Fibers Angle Orientation on Bending Properties of Composite Plywood  [PDF]
Mladen Brezovi?,Jaroslav Kljak,Stjepan Pervan,Alan Antonovi?
Drvna Industrija , 2010,
Abstract: This paper presents the results of research on carbon fiber angle orientation and quantity of carbon fi bers in yarn on bending properties of plywood. For that purpose the specimens have been defined as multilayer composites made from carbon fibers and veneer. Carbon fibers were inserted in the second and third glue line of the composite with angle variation of 15°. Stresses and strain were analyzed in significant layers together with displacement of the whole composite plate. The influence of carbon fiber angle orientation on properties of the composite (amount of stresses and related strains) was significant. The best results have been achieved with carbon fiber angle of 0°, and bidirectional carbon fiber type (BCF) with the orientation angle of 90°. The lowest values have been achieved with carbon fiber angle of 65° (unidirectional carbon fibers-UCF), and bidirectional carbon fiber type (BCF) with the orientation angle of 45°. Greater quantity of carbon fibers per one yarn has positive influence on decrease of stresses and strains in veneer layers and provides better stiffness of plywood.
Cascading of Liquid Crystal Elastomer Photomechanical Optical Devices  [PDF]
Nathan J. Dawson,Mark G. Kuzyk,Jeremy Neal,Paul Luchette,Peter Palffy-Muhoray
Physics , 2010, DOI: 10.1016/j.optcom.2010.10.015
Abstract: Photomechanical actuation is demonstrated in two coupled liquid crystal elastomer photomechanical optical devices (PODs) acting in series. The response function of an individual POD is characterized and used to predict the temporal response of the coupled system. The predicted coupled-system response agrees with the experiment for several waveforms and frequencies, suggesting that large-scale integration of photomechanical devices is possible.
Photoresponsive Block Copolymers Containing Azobenzenes and Other Chromophores  [PDF]
Haifeng Yu,Takaomi Kobayashi
Molecules , 2010, DOI: 10.3390/molecules15010570
Abstract: Photoresponsive block copolymers (PRBCs) containing azobenzenes and other chromophores can be easily prepared by controlled polymerization. Their photoresponsive behaviors are generally based on photoisomerization, photocrosslinking, photoalignment and photoinduced cooperative motions. When the photoactive block forms mesogenic phases upon microphase separation of PRBCs, supramolecular cooperative motion in liquid-crystalline PRBCs enables them to self-organize into hierarchical structures with photoresponsive features. This offers novel opportunities to photocontrol microphase-separated nanostructures of well-defined PRBCs and extends their diverse applications in holograms, nanotemplates, photodeformed devices and microporous films.
Experimental Studies of the Mechanisms of Photomechanical Effects in a Nematic Liquid Crystal Elastomer in a Photomechanical Optical Device Geometry  [PDF]
Nathan J. Dawson,Mark G. Kuzyk,Jeremy Neal,Paul Luchette,Peter Palffy-Muhoray
Physics , 2011, DOI: 10.1364/JOSAB.28.001916
Abstract: Azo-dye-doped liquid crystal elastomers (LCEs) are known to show a strong photomechanical response. We report on experiments that suggest that photothermal heating is the underlying mechanism in surface-constrained geometry. In particular, we use optical interferometry to probe the length change of the material and direct temperature measurements to determine heating. LCEs with various dopants and optical density were used to study the individual mechanisms. In the high dye-doped limit, most of the light is absorbed near the entry surface, which causes a local strain from photothermal heating and a nonlocal strain from thermal diffusion. The results of our research on the microscopic mechanisms of the photomechanical response can be applied to designing photomechanical materials for actuating/sensing devices, the potential basis of smart structures.

LI Shirong,YU Wenshan,

力学与实践 , 2008,
Abstract: Based on Brinson's one-dimensional thermo-mechanical constitutive relations of shape memory alloys and the von K\'{a}rm\'{a}n theory of thin plates, the bending response of a uniform heated circular plate embedded with SMA fibers in the radial directions and subjected to a uniform distributed mechanical load is studied. The characteristic curves of the deflection at the center versus temperature rise of the circular plate with both clamped and simply supported boundary conditions are obtained. The numerical results show that, the recovery forces of the pre-strained SMA caused by the phase transformation from martensite to austenite can modify the bending deformation significantly. So, it is concluded that the bending deformation can be adjusted effectively and actively by embedment of the SMA fibers into the circular plates.
Ultra low bending loss equiangular spiral photonic crystal fibers in the terahertz regime
Arti Agrawal,N. Kejalakshmy,M. Uthman,B. M. A. Rahman
AIP Advances , 2012, DOI: 10.1063/1.4726055
Abstract: An Equiangular Spiral Photonic Crystal Fiber (ES-PCF) design in Topas for use in the Terahertz regime is presented. The design shows ultra low bending loss and very low confinement loss compared to conventional Hexagonal PCF (H-PCF). The ES-PCF has excellent modal confinement properties, together with several parameters to allow the optimization of the performance over a range of important characteristics. A full vector Finite Element simulation has been used to characterize the design which can be fabricated by a range of techniques including extrusion and drilling.
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