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Design of a curved-line bending mechanism inspired by skin wrinkles for elastic–kinetic structures in architecture
Abstract
The application of flexible materials for convertible structures in architecture and the use of bending deformation in these structures have been new topics in recent years. The importance of bending deformation is highlighted by reducing or removing the hinges or other movable joints which result in reducing the complexity of the structures and the maintenance costs. The lack of proper bending materials, the homogeneous deformation of the existing bendable surfaces and the need for folding to create some deformation mechanisms are the limitations of the work. This research provides solutions for these limitations by extracting deformation principles from skin wrinkles. The deformation principles of wrinkles are used to create specific patterns for a lattice hinge, which can compose a heterogeneous deformation in a bending-active surface. The patterns are enhanced by testing a number of physical models and computer-based simulations in different steps. Consequently, a particular type of a curved-line bending compliant mechanism is developed with the ability to reduce some of the deformation constraints, specifically the need to fold in an elastic–kinetic structure.
... 18,21 Kerfing studies are mostly based on digital design, geometry flattening and fabrication. Although some investigations also include the simulation of the material mechanical stress 5,6,15,[22][23][24][25] for necessary adjustments to the project, few studies have evaluated its geometry and accuracy after fabrication compared to the digital one. ...
... Current studies mostly approach some architectural applications of the kerfing technique, ranging from acoustic panels, 22 facade and roof systems, 23 furniture, 8,33,34 structural formwork, 9 decorative or structural panels, 10,11,15 integrated floor, wall and roof structures. 24 Some researchers explore the structure potential to change shapes 23,25 or to be converted into diverse configurations. 9,10,22,35 Major process factors affecting the kerfing material flexibility are: the properties of the material itself (particularly Young's modulus), the kerfing type (face of application), the cut pattern (cut design) and parameters (scale, density, etc.) as well as the cuts distribution on the surface. ...
... 6 The most influential movement is torsion of segments parallel to the bending axis, called beams. 22,23 Regarding the bending effort, the authors point out that it occurs in the segments perpendicular to the structure bending axis (bridges), but it does not have as much influence as the torsion of the other segments. Figure 1 illustrates the material mechanical efforts in kerfing. ...
In digital design, rigid flat materials commonly hinder the fabrication of complex-curved geometries. A fabrication approach based on the socalled bending cut patterns or “kerf-bending” can be used to improve the ability of a material to bend. This bending method relies on a complex mechanical behavior, requiring an accurate evaluation of the resultant surface. By mastering the geometric effects, some adjustments can be made to the project so that the result better approximates the designer’s intentions. This study focused on geometric accuracy of MDF kerfbending, including target-geometry design, cutting, bending, 3D scanning and analysis. It demonstrated that depending on the arc bending radius, the sample with a defined cut pattern may become excessively tensioned, protruding to the outside, or without enough stiffness to conform to an ideal shape. Experiments have validated this methodology and obtained a stable and precise half-cylinder by selecting the most adequate radius range for the material and parameters adopted.
... In many cases, such as Borhani and Kalantar [2], the technique aims to meet situations in which contradictory attributes are necessary, such as the simultaneous need for high elastic deformation and rigidity to support load. One of its advantages is that, by combining it into a single component, the number of parts, assembly time and maintenance costs are reduced [55], in addition to facilitating transport and storage in the flat format [49,50]. ...
... Kerfing is usually applied to wood, MDF, cardboard, polymers and metals [54], aiming largely at architectural purposes, such as acoustic panels [56], systems for facades and roofs [55], furniture [49,57,58], structural formworks [4], decorative or structural panels [1,50,52], integrated floor, wall and roof structures [11], among others. One of the disadvantages of this technique is that, due to the reduced stiffness and strength of the resultant material, it may not be suitable for situations that require significant structural performance [11,49,59], being more appropriate to applications that explore their aesthetic potential, as in Capone and Lanzara [49], Holterman [56], Jensen, Blindheim and Steinert [60], Mitov et al. [52] and Wei and Singh [61]. ...
... The main mechanical effort responsible for the apparent flexibility of the kerfing materials is the torsion of the segments parallel to the bending axis, when the set is bent [3,55,56]. A minor bending movement also occurs, but in the segments perpendicular to the rotation axis. ...
The techniques that permit the materialization of organic and curved geometries include those based on curving flat materials using cut patterns, which have been explored with the improvement of digital manufacturing tools. This study has analyzed kerfing, lamina emergent mechanisms, auxetic linkages and kirigami, seeking greater knowledge and differentiation between these techniques. The mechanical principles, objectives, materials and possible applications, types of cutting patterns, among other aspects, were investigated. It was noted that kerfing and lamina emergent mechanisms presented similar aspects with regards to aiming at folding or bending the material, the use of materials with considerable thickness, and the dependence of the torsion of segments for bending the set. Meanwhile, auxetic linkages and kirigami were also used for stretching the material and depended on buckling or bending of segments, being more suitable to thin or flexible materials. For kerfing, the focus was on architectural scale applications, while kirigami was used in small scale applications (such as electronics). No specific applications were identified for LEMs and auxetic linkages. The information collected and the understanding of each system sought to contribute to a greater knowledge and adoption of these techniques by designers.
Transformational advances in additive manufacturing combined with the unique functional behavior of shape memory alloys (SMAs) has propelled the field of 4D printing “smart” materials. In this study, we leverage multiple processing pathways with additive manufacturing to design and fabricate SMA components capable of precise, self-guided shape change that could actuate large-scale (up to 25 × 25 × 33 cm³) structures under external thermal stimuli. The dual benefits of minor alloy doping (<2 at%) and laser processing parameters (laser hatch spacing) were identified to be the most effective method to engineer SMA joints and hinges with locally tailored transformation temperatures over a 90 °C range. Custom-designed plywood-style NiTi hinges with self-regulating features enabled tight bend radii and compact packing sizes. Implementation of these novel SMAs hinges with large deployment structures, mimicking solar panel arrays, demonstrated a 75–90% reduction in cross-sectional area compared to the fully deployed structure. The fundamental understanding and demonstration of tailored and controlled complex shape-morphing kinematics, without the use of specialized and heavy external motors, lays the groundwork for future SMA-enabled deployable structures in remote environments.
This paper discusses the development of a bio-inspired compliant mechanism for architectural applications and explains the methodology of investigating movements found in nature. This includes the investigation of biological compliant mechanisms, abstraction, and technical applications using computational tools such as finite element analysis (FEA). To demonstrate the possibilities for building envelopes of complex geometries, procedures are presented to translate and alter the disclosed principles to be applicable to complex architectural geometries. The development of the kinetic façade shading device flectofold, based on the biological role-model Aldrovanda vesiculosa, is used to demonstrate the process. The following paper shows results of FEA simulations of kinetic curved-line folding mechanisms with pneumatic actuation and provides information about the relationship between varying geometric properties (e.g. curved-line fold radii) and multiple performance metrics, such as required actuation force and structural stability.
Active experimentation during intertranslations between digital and physical modelling allow designers to explore new geometrical possibilities. Particularly, while changing the strength of the material, cut operations augment bending performance of the planar surfaces. Keeping in mind the potentiality of bending behavior as a generative tool for computational process, this paper presents the findings of three phased experimentation: implication of cut patterns to 2D planar material, mapping 2D patterns onto 3D surfaces and exploring new 3D free-form surfaces.
Die Verformungsfähigkeiten der neuen Baumaterialien wie zum Beispiel Glas- oder kohlefaserverstärkter Kunststoffe zeigen neue Möglichkeiten für wandelbare Konstruktionen in der Architektur: Konstruktionen, die sich mit Hilfe von Biegsamkeit ihrer Komponenten verformen lassen. Diese Arbeit versucht zu zeigen, wie man diese biegsamen Konstruktionen entwickeln kann. In dieser Arbeit liegt der Schwerpunkt auf Verformungsmechanismen, Verformungsmöglichkeiten und Anwendungsmöglichkeiten dieser Art von wandelbaren Konstruktionen, die besonders aus biegsamen Stäben bestehen.
Natürliche Prinzipien werden in der vorliegenden Arbeit als Vorbild geeigneter Mechanismen von biegsamen Konstruktionen betrachtet. Zuerst werden acht passende Vorbilder aus der Natur ausgewählt, die einen Körperteil oder den gesamten Körper eines Tieres oder einer Pflanze betreffen. Für die Übertragung ihrer Prinzipien auf die Architektur wird eine geometrische Methode angewandt. Acht Prinzipien, die von natürlichen Mechanismen hergeleitet sind, werden durch geometrische Modelle abstrahiert. Durch eine schrittweise Modifikation werden acht Grundmuster definiert. Jedes Muster beschreibt einen Mechanismus für die Verformung einer biegsamen Konstruktion in der Architektur.
Im nächsten Schritt werden die Grundmuster weiterentwickelt, um verschiedene Möglichkeiten der Verformung durch Anwendung dieser Mechanismen studieren zu können. Damit haben wir verschiedene Varianten der Grundmuster durch ihre Manipulationen, Kombinationen und Anordnungen dargestellt. Diese Varianten präsentieren unterschiedliche Entwurfskategorien für biegsame Konstruktionen, die von acht ursprünglichen Grundmustern abstammen.
Die Umsetzung entwickelter Grundmuster in der Architektur wird im letzten Schritt vorgestellt. In dieser Phase haben wir gezeigt, dass drei Gruppen der Anwendungszwecke für diese biegsamen Konstruktionen vorstellbar sind, die sich entweder erweitern können oder mit gleichen Elementen verschiedene Räume kreieren oder sich zur Anpassung an verschiedene Forderungen variieren können. Sie werden durch verschiedene Beispiele demonstriert.
Animals and plants can transform their body in response to their needs, adapting
to environmental changes and movement or locomotion. The mechanisms of
these transformations and deformations can be used for the creation of new
deployable structures in architecture. The possibilities of new synthetic materials
enable the architects to apply the natural principles in design much more easily
than before.
Today’s deployable structures are often made of soft or hard materials. New
synthetic and composite materials (e.g. glass-reinforced plastic) provide the
possibility of using elastic materials for new deployable structures. The
deformation of such structures can be made not only with hinges and rollers, but
also with the elasticity of materials.
Answering the question of how it is possible to translate these natural
mechanisms into architecture is the main focus of this paper. We use here the
\“abstract formal patterns” for representing the natural mechanisms. These
patterns show the transformation of an organ or a body and are represented by
wire-frame models as points, lines and colors. We want to present how these
models can be used in architecture after gradual modifications in different steps.
We have chosen the body deformation of an \“earthworm” as a case study in
order to explain this method. An earthworm moves by means of waves of
muscular contractions, which alternately shorten and lengthen the body. We
present an abstraction of this natural principle and development of new
deployable structures in architecture by using the abstract model.
Keywords: bionics, deployable structure, convertible structure, deformation,
geometric patterns, modification, architectural design, structural design.
Putting forward an innovative approach to solving current technological problems faced by human society, this book encompasses a holistic way of perceiving the potential of natural systems. Nature has developed several materials and processes which both maintain an optimal performance and are also totally biodegradable, properties which can be used in civil engineering.
Delivering the latest research findings to building industry professionals and other practitioners, as well as containing information useful to the public, ‘Biotechnologies and Biomimetics for Civil Engineering’ serves as an important tool to tackle the challenges of a more sustainable construction industry and the future of buildings.
his thesis aims to provide general insight into form-finding and structural analysis of bending-active structures. The work is based on a case study approach, in which findings from prototypes and commercial building structures become the basis for generalised theoretical investigations. Information is continuously fed back from these case study structures into theoretical research, which creates the basis for overall working methods. The behaviour of five investigated structures is found to be independent of clearly predictable load bearing categories. Their load bearing mechanisms are largely dependent on the boundless variety of topologies and geometrical expressions that may be generated. The work therefore understands active bending as an approach to generating new structural forms, in which common load bearing behaviour is found due to the structures inherently large elasticity and inner stress state.
Based on engineering and historical background, methodological, mechanical and material fundamentals of active-bending are discussed in Chapter B and C. The case study structures introduced in Chapter D open a wide field of active-bending applications, in lightweight building structures. Whether the conclusions drawn from case studies, are generally viable for bending-active structures is then discussed in the core of the work presented in two chapters on Form-Finding (Chapter E) and Structural Behaviour (Chapter F). The chapter on form-finding introduces the working methods and modelling environments developed for the present work. The chapter on structural behaviour is concerned with the influence of residual bending stress on the stiffness, scaling and stability of bending-active structures. Based on these findings, generalised design rules for bendingactive structures are highlighted in a concluding chapter.
Bending-active structures are composed of curved beam or shell elements which base their geometry on the elastic deformation of an initially straight or planar configuration. In bending-active structures the moment of inertia has a direct influence on the residual stress and is therefore limited by a given minimal curvature in the system and the permissible bending stress capacities of the chosen material. These interdependencies may lead to a scaling issue that limit bending-active structures to a certain size range. This range may be widened if the system's reliance on elastic stiffness is compensated by other stiffening factors such as coupling of structural elements and stress stiffening effects.
This paper will analyse the scaling effects in bending-active structures. Some basic systems are studied by means of dimensional analysis and FEM parameter studies to clarify at which power each influencing factor effects scaling. Based on these findings some more complex structures are studied for their scalability. This will offer the basis for some more general conclusions.
Today's architectural foils and membranes amaze with their superior strength-to-weight ratio and are often implemented as lightweight building envelopes or shading devices. Most claddings, however, are optimized for high tensile strength, which reduces the design possibilities to pre-stressed inflexible shapes. Only a few projects are exploring the potential inherent in the membrane's low bending stiffness. Nowadays, new materials and manufacturing methods allow for customized pliability of semi-rigid thin-shell structures, which fully tap the potential of reversible elastic deformation. While this concept has hardly been used in architecture, convertible surfaces are rampant in nature. Therefore, the aim of this paper is to review in general how nature's soft, flexible, and force-adaptive structures may inspire the development of technical membrane structures and outline their architectural potential in particular. Focusing on bio-inspired pliable systems that show distinct curved-line folding principles will be the framework for a close collaboration among architects, engineers, and biologists. Examining the flower opening of Ipomoea alba will clarify the drawbacks and opportunities of elastic kinematics. Therefore, the first part of the study will introduce this nocturnal flower, whose environmentally responsive petals adapt their geometry in a circadian rhythm. Morphological and anatomical analyses will secondly lead to a better understanding of their primarily turgor-dependent cascade of multiple motion sequences. Examining the interaction of geometrically constraint surfaces and material-specific stress distribution in the flower's curved-line folding is thereby of particular interest. The plant's pattern will thirdly be abstracted and the interdependencies will be tested in digital models. Recording their packaging efficiency, mechanical simplicity, and structural characteristics will fourthly make the systems comparable. Finally, the project will deduce the physical principles by tracking the plant's kinematics and outline their use for architectural foils and membranes with similar adaptive behavior.
The purpose of investigating the areas common to architecture and biology is not to draw borders or make further distinctions, or even to declare architecture alive, but to clarify what is currently happening in the overlapping fields, and to investigate the emerging discipline of „biomimetics in architecture" [Architekturbionik].
An overview of the present state of research in the relatively young scientific field of biomimetics shows the potential of this approach. The new discipline aims at innovation by making use of the subtle systems and solutions in nature which have evolved over millions of years. Approaches taken to transfer nature's principles to architecture have provided successful developments.
The new approach presented in this book transfers the abstract concept of life onto the built environment. Strategic search for life's criteria in architecture delivers a new view of architectural achievements and makes visible the innovative potential, although that has not yet been exploited. A selection of case studies illustrates the diversity of possible starting points: from vernacular architecture to space exploration.
This paper will focus on how the emerging scientific discipline of biomimetics can bring new insights into the field of architecture. An analysis of both architectural and biological methodologies will show important aspects connecting these two. The foundation of this paper is a case study of convertible structures based on elastic plant movements.
This paper presents a novel biomimetic approach to the kinematics of deployable systems for architectural purposes. Elastic deformation of the entire structure replaces the need for local hinges. This change becomes possible by using fibre-reinforced polymers (FRP) such as glass fibre reinforced polymer (GFRP) that can combine high tensile strength with low bending stiffness, thus offering a large range of calibrated elastic deformations. The employment of elasticity within a structure facilitates not only the generation of complex geometries, but also takes the design space a step further by creating elastic kinetic structures, here referred to as pliable structures. In this paper, the authors give an insight into the abstraction strategies used to derive elastic kinetics from plants, which show a clear interrelation of form, actuation and kinematics. Thereby, the focus will be on form-finding and simulation methods which have been adopted to generate a biomimetic principle which is patented under the name Flectofin®. This bio inspired hingeless flapping device is inspired by the valvular pollination mechanism that was derived and abstracted from the kinematics found in the Bird-Of-Paradise flower (Strelitzia reginae, Strelitziaceae).
Elephants are possibly the most well-known members of the animal kingdom. The enormous size, unusual anatomy, and longevity of elephants have fascinated humans for millenia. Biology, Medicine, and Surgery of Elephants serves as a comprehensive text on elephant medicine and surgery. Based on the expertise of 36 scientists and clinical veterinarians, this volume covers biology, husbandry, veterinary medicine and surgery of the elephant as known today. Written by the foremost experts in the field. Comprehensively covers both Asian and African elephants. Complete with taxonomy, behavioral, geographical and systemic information. Well-illustrated and organized for easy reference.
This chapter provides a review of what are considered state-of-the-art of constitutive models used to describe and predict the biomechanics of skin. The focus is on the mathematical constitutive formulations which, ultimately, have also to be implemented into computational codes so that practical problems featuring complex geometries and boundary conditions can be solved via appropriate numerical techniques (e.g. the Finite Element Method (FEM)). Structurally-and phenomenologically-based constitutive modeling approaches, together with a combination of those two are presented. Models featuring elastic and inelastic responses (e.g. viscoelasticity, viscoplasticity) are reviewed. Mechanobiological models, going beyond the traditional realm of continuum mechanics by incorporating coupling between mechanics and biology are also discussed in the context of growth. For sake of completeness, a brief on non-linear continuum mechanics is also provided in this review. Finally, as an illustration, a practical application of the computational modeling of skin (wrinkles) is presented.
We expose it, cover it, paint it, tattoo it, scar it, and pierce it. Our intimate connection with the world, skin protects us while advertising our health, our identity, and our individuality. This dazzling synthetic overview is a complete guidebook to the pliable covering that makes us who we are. Skin: A Natural History celebrates the evolution of three unique attributes of human skin: its naked sweatiness, its distinctive sepia rainbow of colors, and its remarkable range of decorations. Jablonski places the rich cultural canvas of skin within its broader biological context for the first time, and the result is a tremendously engaging look at us.
Compliant mechanisms gain their motion from the deflection of flexible members rather than from traditional bearings and hinges. Advantages of compliant mechanisms include high precision, low cost, and ease of miniaturization. Compliant mechanisms should be designed to avoid fatigue failure and their design is often complicated by nonlinearities. One concept that makes compliant mechanism design possible is that it is possible for something to be both flexible and strong. The selection of material properties, geometry, and boundary conditions are key elements of compliant mechanism design.
The entire developmental process from the biological template to the marketable biomimetic product is characterized by close cooperation between biologists, engineers and other scientists involved in the research project, who may come from branches of mathematics, informatics, physics, chemistry, geology, hydrology or meteorology. The presented methodology of doing biomimetics has proven effective in many R&D projects. Two principally different approaches can be distinguished as 'bottom-up process' and 'top-down process'. Depending on the problem to be solved, numerous transitions exist between the two procedures.
The Karamba plug-in developed by Clemens Preisinger in collaboration with Bollinger + Grohmann Engineers has been developed to predict the behaviour of structures under external loads. Intended to be used by architects rather than being solely confined to an engineering setting, it enables a seamless flow of data between structural and geometric models. Preisinger here describes the program's evolution and application.
Skin is a highly dynamic, autoregulated, living system that responds to mechanical stretch through a net gain in skin surface area. Tissue expansion uses the concept of controlled overstretch to grow extra skin for defect repair in situ. While the short-term mechanics of stretched skin have been studied intensely by testing explanted tissue samples ex vivo, we know very little about the long-term biomechanics and mechanobiology of living skin in vivo. Here we explore the long-term effects of mechanical stretch on the characteristics of living skin using a mathematical model for skin growth. We review the molecular mechanisms by which skin responds to mechanical loading and model their effects collectively in a single scalar-valued internal variable, the surface area growth. This allows us to adopt a continuum model for growing skin based on the multiplicative decomposition of the deformation gradient into a reversible elastic and an irreversible growth part. To demonstrate the inherent modularity of this approach, we implement growth as a user-defined constitutive subroutine into the general purpose implicit finite element program Abaqus/Standard. To illustrate the features of the model, we simulate the controlled area growth of skin in response to tissue expansion with multiple filling points in time. Our results demonstrate that the field theories of continuum mechanics can reliably predict the manipulation of thin biological membranes through mechanical overstretch. Our model could serve as a valuable tool to rationalize clinical process parameters such as expander geometry, expander size, filling volume, filling pressure, and inflation timing to minimize tissue necrosis and maximize patient comfort in plastic and reconstructive surgery. While initially developed for growing skin, our model can easily be generalized to arbitrary biological structures to explore the physiology and pathology of stretch-induced growth of other living systems such as hearts, arteries, bladders, intestines, ureters, muscles, and nerves.
StressThermal StressExertional StressElectrocution
Fourteen years have elapsed since publication of the second edition of this highly regarded book and in that time a vast new knowledge relating to the biology of skin has accumulated. Nevertheless, the third edition remains the same size as the second and covers the same basic subject matter, but here the similarity ends, for the book has been totally rewritten and the content only superficially resembles that of the earlier edition. The book presents a systematic discussion of the epidermis, dermis, and their modifications and constituents such as blood supply, cutaneous nerves, hair apparatus, nails, and glands. These topics are presented with discussions of gross, light microscopic, and electron microscopic morphology; embryology; function; cell kinetics and metabolism; and histochemistry. The picture of skin that evolves is that of a highly complex and dynamic organ for which the authors have a deep affection. The style is easily readable, and the
Skin microrelief alters progressively with age. Wrinkles do not result from these changes but are superimposed upon them. Wrinkles result from structural changes in the epidermis, dermis and hypodermis. Four types of wrinkles can be recognized.
Type 1 wrinkles are atrophic.
Type 2 wrinkles are elastotic.
Type 3 wrinkles are expressional.
Type 4 wrinkles are gravitational.
Each type of wrinkle is characterized by distinct microanatomical changes and each type of wrinkle develops in specific skin regions. Each is likely to respond differently to treatment. Skin microrelief and skin folds can be identified on histological examination. By contrast, only minimal dermal changes are found beneath permanent or reducible wrinkles compared with immediately adjacent skin. A series of objective and non-invasive methods is available to quantify the severity of wrinkling.
- Howell LL
Bio-inspired compliant mechanisms for architectural design: transferring bending and folding principles of plant leaves to flexible kinetic structure
- S Schleicher
Schleicher S. Bio-inspired compliant mechanisms for architectural design: transferring bending and folding principles
of plant leaves to flexible kinetic structure. PhD Dissertation,
ITKE, University of Stuttgart, Stuttgart, 2016.
Compliant mechanisms
- L L Howell
Howell LL. Compliant mechanisms. New York: John Wiley
& Sons, 2001.
Multisystem disorders
- M E Fowler
- Multisystem
Biotechnologies and biomimetics for civil engineering
- J Lienhard
- S Schleicher
- J Knippers
Lienhard J, Schleicher S and Knippers J. Bio-inspired, flexible structures and materials. In: Pacheco Torgal F, Labrincha
JA, Diamanti MV, et al. (eds) Biotechnologies and biomimetics for civil engineering. Heidelberg: Springer, 2014,
pp. 275-296.
- P Gruber
Gruber P. Biomimetics in architecture. Wien: Springer,
2011.
Bioengineering of the skin: skin imaging & analysis
- C El Gammal
- El Gammal
- S Kligman
El Gammal C, El Gammal S and Kligman AM. Anatomy
of the skin surface. In: Wilhelm KP, Elsner P, Berardesca
E, et al. (eds) Bioengineering of the skin: skin imaging &
analysis. New York: CRC Press, 2007, pp. 1-17.