An autonomous shading system based on coupled wood bilayer elements

Vailati, Chiara; Bachtiar, Erik Valentine; Haß, Philipp; Burgert, Ingo; Rüggeberg, Markus

doi:10.1016/j.enbuild.2017.10.042

Cited by 56 publications

(35 citation statements)

References 23 publications

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“…Similarly to wood bilayer types, hygromorph biocomposite actuators could also be used in evapotranspiration cladding or membranes [11][12] [23], shading [50], soft robotics systems [51] or more generally for morphing structures. For those applications, the reversibility of the actuation during the sorption/desorption cycles is a key factor to their efficiency.…”

Section: Characterization Of the Actuationmentioning

confidence: 99%

Humidity responsive actuation of bioinspired hygromorph biocomposites (HBC) for adaptive structures

Duigou

Kéryvin

Beaugrand

et al. 2019

Composites Part A: Applied Science and Manufacturing

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Hygromorph biocomposites (HBC) possess moisture-induced actuation from bioinspired designs. The present work describes a large experimental and comprehensive database of the hygro-mechanical and bending actuation properties of flax/maleic anhydride grafted polypropylene (MAPP) HBC composites over a large range of moisture variation (10-90% RH) and water immersion. HBCs exhibit a promising responsiveness and reactivity over the whole relative humidity range (10-90% RH), with acceleration and increase of the actuation observed as soon as a 30% RH value is reached. The experimental data are compared to analogous results from an analytical model based on a modified Timoshenko theory, and a finite element model based on the use of classical laminate theory (CLT). We discuss the effects of the hygroscopic properties (β coefficient) and the design parameters (length/width and thickness ratios) of the composites on the actuation performance.

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Section: Characterization Of the Actuationmentioning

confidence: 99%

Humidity responsive actuation of bioinspired hygromorph biocomposites (HBC) for adaptive structures

Duigou

Kéryvin

Beaugrand

et al. 2019

Composites Part A: Applied Science and Manufacturing

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“…In architectural applications, a bilayered technique has been used to fabricate shape-changing materials with thermo-bimetals 8,9 and wood. 10,11 The second strategy, 3D printing, also entails constructing bilayers, but this time by 3D printing the layers. More complex material transformations can be obtained by embedding anisotropy through changing the 3D printing parameters (i.e.…”

Section: Literature Reviewmentioning

confidence: 99%

Formalizing shape-change: Three-dimensional printed shapes and hygroscopic material transformations

Vazquez

Gürsoy

Duarte³

2019

International Journal of Architectural Computing

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Shape-changing materials have become increasingly popular among architects in designing responsive systems. One of the greatest challenges of designing with these materials is their dynamic nature, which requires architects to design with the fourth dimension, time. This article presents a study that formalizes the shape-changing behavior of three-dimensional printed wood-based composite materials and the rules that serve to compute their shape-change in response to variations in relative humidity. In this research, we first developed custom three-dimensional printing protocols and analyzed the effects of three-dimensional printing parameters on shape-change. We thereafter three-dimensional printed kirigami geometries to amplify hygroscopic material transformation of wood-based composites.

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“…Therefore, smart building skins play an important role in the required global reduction of energy consumption, since autonomous, humidity-driven wood bilayers can serve as an energy-efficient alternative to motor-driven façade shading elements [26]. To assess the performance of the systems, especially the long-term stability as well as the repeatability of the humidity-driven movements, instrumented test setups, which simulate outdoor weathering conditions have been developed using environmental chambers and materials' reactions have been characterized, e.g.…”

Section: Bioinspired Stimuli-responsive Materials For Bioarchitecturmentioning

confidence: 99%

Impact of Solar Radiation on Chemical Structure and Micromechanical Properties of Cellulose-Based Humidity-Sensing Material Cottonid

Scholz

Langhansl

Hemmerich

et al. 2020

Preprint

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Renewable and environmentally responsive materials are an energy- and resource-efficient approach in terms of civil engineering applications, e.g. as so-called smart building skins. To evaluate the influence of different environmental stimuli, like humidity or solar radiation, on the long-term actuation behavior and mechanical robustness of these materials, it is necessary to precisely characterize the magnitude and range of stimuli that trigger reactions and the resulting kinetics of a material, respectively, with suitable testing equipment and techniques. The overall aim is to correlate actuation potential and mechanical properties with process- or application-oriented parameters in terms of demand-oriented stimuli-responsive element production. In this study, the impact of solar radiation as environmental trigger on the cellulose-based humidity-sensing material Cottonid, which is a promising candidate for adaptive and autonomously moving elements, was investigated. For simulating solar radiation in the lab, specimens were exposed to short-wavelength blue light as well as a standardized artificial solar irradiation (CIE Solar ID65) in long-term aging experiments. Photodegradation behavior was analyzed by Fourier-transform infrared as well as electron paramagnetic resonance spectroscopy measurements to assess changes in Cottonid’s chemical composition. Subsequently, changes in micromechanical properties on the respective specimens’ surface were investigated with roughness measurements and ultra-micro-hardness tests to characterize variations in stiffness distribution in comparison to the initial condition. Also, thermal effects during long-term aging were considered and contrasted to pure radiative effects. In addition, to investigate the influence of process-related parameters on Cottonid’s humidity-driven deformation behavior, actuation tests were performed in an alternating climate chamber using a customized specimen holder, instrumented with digital image correlation (DIC). DIC was used for precise actuation strain measurements to comparatively evaluate different influences on the material’s sorption behavior. The infrared absorbance spectra of different aging states of irradiated Cottonid show decreased absorption at 2,900 cm-1, i.e. the spectral region of C - H stretching vibrations, and increased absorption at 1,800-1,700 cm-1, i.e. the spectral region of C = O stretching vibrations, with respect to unaged samples and therefore indicate oxidative stress on the surface. These findings differ under pure thermal loads. EPR spectra could corroborate these findings as radicals were detected, which were attributed to oxidation processes. Instrumented actuation experiments revealed the influence of processing-related parameters on the sorption behavior of the tested and structurally optimized Cottonid variant. Experimental data supports the definition of an optimal process window for stimuli-responsive element production. Based on these results, tailor-made functional materials shall be generated in the future where stimuli-responsiveness can be adjusted through the manufacturing process.

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An autonomous shading system based on coupled wood bilayer elements

Cited by 56 publications

References 23 publications

Humidity responsive actuation of bioinspired hygromorph biocomposites (HBC) for adaptive structures

Humidity responsive actuation of bioinspired hygromorph biocomposites (HBC) for adaptive structures

Formalizing shape-change: Three-dimensional printed shapes and hygroscopic material transformations

Impact of Solar Radiation on Chemical Structure and Micromechanical Properties of Cellulose-Based Humidity-Sensing Material Cottonid

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