Hygroscopically actuated wood elements for weather responsive and self-forming building parts – Facilitating upscaling and complex shape changes

Wood, Dylan; Vailati, Chiara; Menges, Achim; Rüggeberg, Markus

doi:10.1016/j.conbuildmat.2017.12.134

Cited by 65 publications

(33 citation statements)

References 14 publications

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“…Wood, as a sustainable and natural-grown fiber composite material, has been used over many centuries as mankind’s research on wood and wood-based products has enabled countless applications. More recently, novel and innovative concepts for application as self-actuation-capable, humidity-responsive structures have arisen in applied research for biomimetic architecture [ 1 – 8 ]. Bi-layered wooden structures, capable of complex and extensive shape changes in function of a given geometrical setup and change in ambient climate have been envisaged for diverse uses including shading elements [ 7 ], climate-adaptive facades [ 9 ], or motor elements [ 1 ].…”

Section: Introductionmentioning

confidence: 99%

Modeling and design of thin bending wooden bilayers

2018

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In recent architectural research, thin wooden bilayer laminates capable of self-actuation in response to humidity changes have been proposed as sustainable, programmed, and fully autonomous elements for facades or roofs for shading and climate regulation. Switches, humidistats, or motor elements represent further promising applications. Proper wood-adapted prediction models for actuation, however, are still missing. Here, a simple model that can predict bending deformation as a function of moisture content change, wood material parameters, and geometry is presented. We consider material anisotropy and moisture-dependency of elastic mechanical parameters. The model is validated using experimental data collected on bilayers made out of European beech wood. Furthermore, we present essential design aspects in view of facilitated industrial applications. Layer thickness, thickness-ratio, and growth ring angle of the wood in single layers are assessed by their effect on curvature, stored elastic energy, and generated axial stress. A sensitivity analysis is conducted to identify primary curvature-impacting model input parameters.

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Section: Introductionmentioning

confidence: 99%

Modeling and design of thin bending wooden bilayers

2018

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“…Programmable self-shaping materials are widely studied, e.g. at small scale in fields such as soft (or hard) actuated matter [1][2][3][4][5][6][7][8][9], or at medium and large scale mostly for adaptive structures in construction applications [10][11][12][13][14][15][16][17]. A commonly known principle of obtaining self-shaping systems is the bilayer-laminate.…”

Section: Introductionmentioning

confidence: 99%

“…In addition, it is a common and low-cost construction material with unrivaled environmental virtues such as full renewability, low embodied energy and natural degradability. However, similar to the case of anisotropic shaping composites mentioned above, self-shaping bilayer plates made out of wood typically adopt a saddle-like configuration, and thus suffer from the above-mentioned restriction Δ K < 0 [ 14 , 29 ].…”

Section: Introductionmentioning

confidence: 99%

Computational analysis of hygromorphic self-shaping wood gridshell structures

et al. 2020

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Bi-layered composites capable of self-shaping are of increasing relevance to science and engineering. They can be made out of anisotropic materials that are responsive to changes in a state variable, e.g. wood, which swells and shrinks by changes in moisture. When extensive bending is desired, such bilayers are usually designed as cross-ply structures. However, the nature of cross-ply laminates tends to prevent changes of the Gaussian curvature so that a plate-like geometry of the composite will be partly restricted from shaping. Therefore, an effective approach for maximizing bending is to keep the composite in a narrow strip configuration so that Gaussian curvature can remain constant during shaping. This represents a fundamental limitation for many applications where self-shaped double-curved structures could be beneficial, e.g. in timber architecture. In this study, we propose to achieve double-curvature by gridshell configurations of narrow self-shaping wood bilayer strips. Using numerical mechanical simulations, we investigate a parametric phase-space of shaping. Our results show that double curvature can be achieved and that the change in Gaussian curvature is dependent on the system’s geometry. Furthermore, we discuss a novel architectural application potential in the form of self-erecting timber gridshells.

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“…Large shape changes can reciprocally be achieved by wood cross-ply laminates with layup (0°/90°), referred to as bilayers, when changing moisture content by either drying or wetting. Making use of the seeming inherent disadvantage of swelling and shrinkage of wood, thin wooden bilayers with fast dynamic responsiveness have recently been highlighted for diverse applications, predominantly as functional elements in biomimetic architecture (14)(15)(16)(17)(18)(19)(20)(21)(22)(23).…”

Section: Introductionmentioning

confidence: 99%

Analysis of hygroscopic self-shaping wood at large scale for curved mass timber structures

et al. 2019

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The growing timber manufacturing industry faces challenges due to increasing geometric complexity of architectural designs. Complex and structurally efficient curved geometries are nowadays easily designed but still involve intensive manufacturing and excessive machining. We propose an efficient form-giving mechanism for large-scale curved mass timber by using bilayered wood structures capable of self-shaping by moisture content changes. The challenge lies in the requirement of profound material knowledge for analysis and prediction of the deformation in function of setup and boundary conditions. Using time- and moisture-dependent mechanical simulations, we demonstrate the contributions of different wood-specific deformation mechanisms on the self-shaping of large-scale elements. Our results outline how to address problems such as shape prediction, sharp moisture gradients, and natural variability in material parameters in light of an efficient industrial manufacturing.

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Hygroscopically actuated wood elements for weather responsive and self-forming building parts – Facilitating upscaling and complex shape changes

Cited by 65 publications

References 14 publications

Modeling and design of thin bending wooden bilayers

Modeling and design of thin bending wooden bilayers

Computational analysis of hygromorphic self-shaping wood gridshell structures

Analysis of hygroscopic self-shaping wood at large scale for curved mass timber structures

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