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Design and construction principles in nature and architecture
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IOP PUBLISHING BIOINSPIRATION &BIOMIMETICS
Bioinspir. Biomim. 7 (2012) 015002 (10pp) doi:10.1088/1748-3182/7/1/015002
Design and construction principles in
nature and architecture
Jan Knippers
1,2,3,4,6
and Thomas Speck
2,3,5
1
Institute of Building Structures and Structural Design (ITKE), University of Stuttgart, Stuttgart,
Germany
2
Competence Network Biomimetics, Baden-W
¨
urttemberg, Germany
3
Bionics Competence Network (BIOKON eV), Germany
4
Knippers Helbig Advanced Engineering, Stuttgart, Germany
5
Plant Biomechanics Group Freiburg, Botanic Garden, Faculty of Biology, University of Freiburg,
Freiburg, Germany
E-mail: j.knippers@itke.uni-stuttgart.de
Received 19 July 2011
Accepted for publication 29 November 2011
Published 16 February 2012
Online at stacks.iop.org/BB/7/015002
Abstract
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.
(Some figures in this article are in colour only in the electronic version)
1. Introduction
Architects and master-builders have been using nature as a
source of inspiration long before the terms bioinspiration or
biomimetics were introduced. The eras in which architects
transferred the variety of natural shape and form directly into
their work alternated with those of strict geometrical order.
After a period of technological functionalism and subsequent
post-modern architecture, today’s aesthetic understanding is
focused once more towards movement and flowing spaces
which reflect forms found more or less directly in nature.
Which new findings can this young scientific discipline
biomimetics offer architecture? New options can only result
from an in-depth analysis and comparison of architecture and
nature, both from a broader and deeper perspective as well as
on a functional and methodological level. Not only architects
show a deep interest in this discussion, also biologists are
actively pursuing their interest in architectural design (Gould
and Lewontin 1979).
Architectural design and biological evolution are non-
deterministic processes. In biological evolution and
architectural design, evaluation criteria and development
targets are created and are part of a process subject to
6
Author to whom any correspondence should be addressed.
constant change and adaptation. In this respect, biology and
architecture differ from most engineering sciences, which
usually concentrate on the optimization of clearly defined
individual functions with fixed boundary conditions and target
functions. In architecture, a quantifiable optimum is, at its best,
only possible with some technical or economical parameters
(e.g. optimization of energy or material consumption), but
it does not allow for an integrated assessment of important
features such as aesthetic, spatial, urban or social qualities,
which are vital for successful and sustainable architecture.
During the course of evolution, biological organisms
adapted their character through selection and interaction
to meet constantly changing environmental conditions by
developing multifunctional solutions. The result is a
compromise satisfying partially conflicting requirements
(Rowe and Speck 2004, Speck and Rowe 2006). In this
context, it is worth mentioning that living beings carry
an ‘evolutionary burden’ because evolutionary innovations
always build on inherited structures (the ‘bauplan’) and their
respective functions. The ‘bauplan’ and the fact that living
beings have to ‘function’ successfully during all phases of
evolution confine the potential of natural selection as an
optimizing agent. A comparable situation can be found in
architecture, where a building plan based on static constraints
1748-3182/12/015002+10$33.00 1 © 2012 IOP Publishing Ltd Printed in the UK
Bioinspir. Biomim. 7 (2012) 015002 J Knippers and T Speck
Figure 1. Five different structural hierarchical levels of plant stems covering up to 12 orders of magnitude, shown as an example in a pine
stem and a tracheid. Adapted from Speck and Rowe (2006).
confines the degree of freedom of further architectural
embodiment. Therefore, similar to architectural design,
evolutionary adaption in nature is limited by ‘architectural’
constraints predetermined in the bauplan’ of the biological
organism (Gould and Lewontin 1979).
The requirements modern buildings have to fulfil today are
very complex, often contradictory, and during their life cycle
need to be adapted for utilization, economical and ecological
reasons. In the last decades, emerging ecological demands
have been a driving force in the development of highly
evolved building technologies including material development
and automation. Nonetheless, these technologies are still
handled as isolated components which are integrated into
otherwise traditional building concepts.
Holistic approaches for new structural, functional and
ecologically efficient buildings may be expected from a more
interdisciplinary approach. A very important aspect will be
an effective exchange of research between the disciplines,
not only on the level of scientific knowledge but also on a
methodological level. Biology is in this respect of particular
interest for architects and civil engineers, since it delivers
not only isolated phenomena but also new technical and
methodological strategies.
2. Design and construction in nature and
architecture
In addition to the initially drawn parallels, fundamental
differences between architecture and biology can also be
identified. Taking these differences into consideration can lead
to a change in perspective and to an expansion of possibilities
for architects and engineers.
If we restrict ourselves to considering structures in biology
and architecture, it becomes apparent that, in respect of
structural design, they have diametrically opposite principles.
Architecture and civil engineering define construction in two
categories: ‘material’ and ‘structure’. In today’s practice,
the design of a structure is a hierarchical process. It starts
with the choice of a load-bearing system. This is based on
a limited canon of options (e.g. beam, truss, wall, slab, arch,
etc) that are primarily classified through analysis as well as
construction methods. Such support systems are realized in
very similar forms but using different materials which are
selected during the second stage (e.g. steel, timber, masonry
or concrete, etc). Natural constructions, however, arise from
an almost infinite diversity through mutation, recombination
and selection. They show a hierarchical structure on usually
five to seven levels that may span up to twelve orders of
magnitude (Dunlop and Fratzl 2011, Fratzl and Weinkammer
2007,Milwichet al 2006, 2008, Speck and Rowe 2006).
A conifer stem shows (at least) five different structural
hierarchical levels (figure 1). On each of these hierarchical
levels, which cover up to twelve orders of magnitude,
the different functionally important properties of the
stem (including mechanical properties such as stiffness,
damping and prestressing; water and assimilated transport;
nutrient storage; adaptive growth by reaction wood, self-
repair; heat insulation, etc) may be varied (Speck and Burgert
2011). Mechanical properties for example can be influenced
on the biochemical level by the cellulose-to-lignin ratio, on
the ultrastructural level by the angle of cellulose microfibrils,
on the microscopic level by the cell wall thickness (mainly the
thickness of the S2-layer) and the distribution of pits, on the
macroscopic level by the ratio of early wood to late wood, and
on the integral level by the amount of secondary wood.
From the macroscopic organism down to the smallest
molecular components, each structural element consists
of smaller sub-structures made up of similar building
components. A separation into ‘material’ and ‘structure’
categories is therefore not possible (figure 1). The same
2
Bioinspir. Biomim. 7 (2012) 015002 J Knippers and T Speck
(a)(b)
Figure 2. (a) Geodesic Dome Montreal 1967, Buckminster Fuller (photo: Philip Hienstorfer). (b) Grid Shell Frankfurt MyZeil, Architect:
M Fuksas, Rome; Engineer: Knippers Helbig Advanced Engineering (Knippers and Helbig 2007, 2009; photo: Christian Sauter).
applies to the terms ‘structure’ and ‘form’, which are of great
importance in architecture. The various functions of a thermal
envelope, spatial separation, building services, load transfer,
etc are assigned to different components. Consequently, the
load-bearing ‘structure’ and the space-shaping ‘form’ of the
building are functionally separated. In an architecture that is
driven by formal aesthetics, the geometric ‘form’ is often not
even related to the geometry of the ‘structure’.
In natural structures, however, the basic building
components not only support the structure but also carry
substances that catalyze chemical reactions and recognize
molecular signals. The ‘form’ arises from functional
requirements that are met by a ‘structure’ which is often
composed of a single basic substance.
From an engineering perspective, the analysis of natural
structures demonstrates that they essentially consist of a small
number of mostly light elements (C, H, O, N, P, S, P, Ca,
etc) and only a few polymeric substance groups (proteins,
polysaccharides, lipids, nucleic acids, etc) exist (Dunlop
and Fratzl 2010, Fratzl and Weinkammer 2007, Jeronimidis
2000a, 2000b,Milwichet al 2006, Speck and Rowe 2006).
Individual cells form tissues that are combined to create
‘organs’ with different functions. Natural structures are
often not isotropic but consist of fibres such as cellulose or
collagen with direction-dependent properties. By combining
different trajectories and the packing density of fibres, a
number of finely tuned structural properties is achieved.
In addition, chemical and structural heterogeneities play an
important role in allowing local adjustments to be integrated.
The continuous external skeleton (exoskeleton) of insects,
for example, is made from chitin fibres (polysaccharides)
which are embedded in a protein matrix. The chemical,
structural and mechanical properties of such a composite
material may vary to a large extent and thereby allow for
local functional adaptations in different areas of the insect’s
body. Natural constructions, therefore, consist of only a
few basic components which are geometrically, physically
and chemically differentiated. In this respect, they are
fundamentally different to most architectural constructions.
These consist of highly differentiated material and functional
components (e.g. steel for the structure, glass for the envelope
and different plastics for the installations, etc), which, in
themselves, are geometrically simple and can be assembled by
being added to each other to build up the desired construction.
The question arising at this point is whether the
morphological form and function principles of nature which
have developed over 3.8 billion years of evolution can be used
for structural, functional and ecologically efficient building
structures.
2.1. Paradigm shift in building construction
The use of as many equal building parts as possible, arranged
and joined in the simplest possible manner was paradigm
until a few years ago. This has dramatically changed in
the last decade through the introduction of computer-aided
manufacturing processes.
The following example may illustrate this. The American
visionary inventor Buckminster Fuller worked intensively for
over 50 years on the geometrical laws of geodesic domes (cf
Hays and Miller 2008). One of his many aims was to develop
topologies for spherical shell structures that allowed the use
of as many identical beam and node elements as possible. He
accomplished this by dividing a sphere into twenty identically
large spherical triangles (icosahedron), which were subdivided
into a regular triangular mesh. At the corner points of the large
spherical triangles, special nodes joined by only five members,
an irregularity because all the other nodes are supported by six
members (figure 2(a)).
For modern computer-aided manufacturing CAM
techniques, such considerations are obsolete; it is not
important whether the milling geometry of a joint is changed
or not; it has no influence today on the production process.
In recent years, numerous lattice shells were constructed,
consisting of many thousands of different rods and nodes,
without significant additional expense. This provides greater
freedom in the design process: Buckminster Fuller and other
designers of his time were still limited to regular geometries
such as the dome or barrel. Today’s lattice shells, however, can
adapt to almost any geometry, driven by functional or aesthetic
requirements (figure 2(b)).
During the mid-1990s such lattice shells, composed of
steel rods and glass plates, took over an important model role
3
Bioinspir. Biomim. 7 (2012) 015002 J Knippers and T Speck
(a)(b)
Figure 3. (a)ICD/ITKE Research Pavilion 2010, University of Stuttgart (photo: Roland Halbe), (b) digital fabrication of plywood strips
(photo: University of Stuttgart).
in the steel construction industry in terms of developing a
digital design and production chain. Other building techniques
including concrete and timber construction are gradually
reaching similar innovative results.
A fitting example is the research pavilion built by the
members of the Institute of Computational Design (ICD,
Professor Achim Menges) and the Institute of Building
Structures and Structural Design (ITKE, Professor Jan
Knippers) of the Faculty of Architecture and Urban Planning
at the University of Stuttgart with the help of many students
in 2010 (Menges et al 2011, Lienhard et al 2011). The
structure is entirely based on the elastic bending behaviour of
6.5 cm thick birch plywood strips. The strips were robotically
manufactured as planar elements and subsequently connected
to coupled arch systems as shown in figure 3. A radial
arrangement and interconnection of the self-equilibrating arch
system lead to the final torus-shaped design of the pavilion.
Due to the reduced structural height, the connection points
locally weaken the coupled arch system. In order to prevent
these local points from reducing the structural capacity of the
entire pavilion, the locations of the weak connection points
between the strips had to be varied along the entire length of
the structure which resulted in 80 different strip patterns being
constructed from more than 500 geometrically unique parts.
A continuous computer-aided process for design, simulation
and manufacturing was implemented to realize this structure.
Although neither the design nor the construction of
this pavilion was inspired by biological role models, it
inevitably is reminiscent of natural structures, because the
seemingly innovative principles used here are frequently found
in nature. These principles are the homogeneous nature of the
construction using a single textured material, the parametric
differentiation of the plate geometry with a uniform basic
typology and the shaping of large elastic surface deformations.
This example shows that digital simulation, planning and
production processes open up new methods of approaching
natural role models. Today, the technical requirements
for a transfer of knowledge from nature into construction
engineering are much more prevalent than those even a few
years ago (Fratzl 2007, Masselter et al 2011, Masselter
and Speck 2011,Milwichet al 2006, 2008, Pohl et al
2010). Therefore, the study of biomimetics for architects and
engineers is even more relevant today than ever before.
2.2. Natural design principles in architecture
An important characteristic of natural systems is a multi-
layered, finely tuned and differentiated combination of basic
components which lead to structures that feature multiple
networked functions (Dunlop and Fratzl 2010, Fratzl 2007,
Fratzl and Weinkammer 2007, Jeronimidis 2000a, 2000b,
Masselter and Speck 2011, Milwich 2008). Such design
principles have so far virtually never been used architecturally;
if at all, only in a very basic form (Godfaurd et al 2005). They
can be classified as follows.
Heterogeneity: natural constructions are characterized
by a geometric differentiation of their elements. As
described above, the introduction of digital design
and manufacturing processes increases the possible
level of geometric differentiation in building structures
and facilitates the transfer of natural morphologies
into architecture. Additionally, natural structures are
characterized by local adaptations of their physical
or chemical properties. Material research is currently
concerned with gradient materials, such as the targeted
control of porosity in concrete, trying to match
the opposing properties of thermal conductivity (high
porosity) and mechanical load bearing (low porosity) to
meet local requirements. The introduction of gradient
materials in construction practice is still pending.
Anisotropy: many natural constructions consist of fibre-
reinforced composite materials. Similarly modern high-
performance materials are increasingly based on the
principle of anisotropic fibre reinforcements. Current
developments are concerned with the manufacturing
methods for producing a demanding arrangement
of stress-related fibres, especially around load
concentrations at branching points (cf Fischer et al 2010,
4
Bioinspir. Biomim. 7 (2012) 015002 J Knippers and T Speck
Figure 4. Folding Bridge Kiel 1998. Architect: von Gerkan Marg and Partner; Engineer: Schlaich Bergermann and Partner (photo: Klaus
Frahm).
Masselter and Speck 2011). Therefore, many valid
suggestions can be expected, resulting from the study of
natural role models.
Hierarchy: biological structures are characterized by
a multi-level hierarchical structure from nano- to
macro-scale, each level consisting of similar molecular
components, but giving rise to different and, to some
extent, independent functional properties and adaptions
(figure 1).
In contrast, building structures show a very different
understanding of hierarchy: they consist of a static
system (e.g. optimized for maximum efficiency) using
components (e.g. girders with an optimized cross section)
made of different materials (e.g. optimized for maximum
strength or processability).
The natural conception of hierarchy still remains
virtually unexplored in architecture and civil engineering
so far. Current approaches for highly loaded structures
are moving away from static systems with a few specific
structural elements, towards structures with increased
redundancy, but the advantages and possibilities offered
by implementing a multi-level hierarchical construction
as found in living beings are still not being taken into
consideration.
Multifunctionality: botany fibres simultaneously serve
mechanical and diverse physiological functions. Current
research is focusing on integrating monofunctional
components into multifunctional material systems, such
as the integration of sensors and actuators in adaptive
composite structures for aircraft, or elements for
generation, transmission and storage of energy in facade
elements. Systems which reflect natural structures in
terms of uniform texture with a variety of functions are
unknown in architecture and engineering so far.
This classification is, of course, not complete. It could be
widely increased by describing principles such as redundancy,
adaptability, etc.
3. Case study on convertible structures
Based on selected functionality, namely the movement of
structures, it will be analysed how biomimetics can be used in
specific design questions.
Questions regarding this issue came to light during the
first author’s many years of work on kinematic structures,
such as the three-field Bascule Bridge in Kiel Horn, Germany
(figure 4), where he was employed as a project manager
responsible for design for Schlaich Bergermann and Partner.
The bridge is moved through a complex cable system of
numerous ropes, winches and rollers, and simultaneously each
change to the construction’s position had to be stabilized
to counteract wind loads from all directions (Knippers and
Schlaich 2000). The architectural intent was to incorporate not
only the mechanics but also the aesthetics of the surrounding
harbour cranes and transfer it to the bridge construction. This
bridge, however, is a unique item; it was planned and built
without any reference projects or prototypes. This is also
the case for the majority of structures in architecture. It is a
major contrast to industrial machinery and, for example, the
surrounding cranes which are usually developed with extensive
test runs and prototypes of various scales. This approach often
leads to problems in practice which can only be solved by
tedious experimentation on the finished object.
The arising question is how one can reduce the
complexity of movable building structures. This leads
almost automatically to the study of natural role models.
Botany in particular provides the most radical answer which
stands in total contradiction to the technical solution as
shown in figure 4. Many plant organs move without
any specific mechanical elements but through the locally
adapted and adaptive flexibility of their components. One
can distinguish between autonomous and non-autonomous
movements. Active autonomous movements are characterized
by motor organs, e.g. pulvini driven by a change of
turgor pressure. Passive autonomous movements occur
by changing physical circumstances, e.g. bending through
desiccation. Non-autonomous movements are mostly
reversible deformations caused by the release of stored elastic
energy following an external trigger or by direct application
of mechanical forces (Burgert et al 2007, Burgert and Fratzl
2009a, 2009b,Dawsonet al 1997, Elbaum et al 2007, 2008,
Fratzl et al 2008, Lienhard et al 2009, 2010, 2011a, 2011b,
Martone et al 2010, Melzer et al 2010, Poppinga et al
2010a, 2010b, Schleicher et al 2010, 2011, Vincent et al 2011).
If and how such plant movements can be used technically
was investigated by developing the elastic kinematics for a
facade shading system (Lienhard et al 2009, 2010, 2011a,
5
Bioinspir. Biomim. 7 (2012) 015002 J Knippers and T Speck
(b)(a)
Figure 5. Process sequences in biomimetic research. (a) Bottom-up process of biomimetics (biology push). (a) Top-down process of
biomimetic research (technology pull).
(a)(b)(c)
Figure 6. Elastic deformation of the kinetic system in the Strelitzia reginae flower. When mechanical force is applied (as indicated by an
arrow), the sheath-like perch opens (adapted from Lienhard et al 2011b).
2011b). This exemplifies a top-down process of biomimetics
(figure 5). Screening various plants identified the movements
of the ‘bird of paradise’ flower (Strelitzia reginae) as a suitable
kinematic principle. The Strelitzias flower features two adnate
petals that form a perch for pollinating birds. When a bird sits
on this perch to sip the nectar, its weight causes the perch to
bend down. In a simultaneous movement, the petal lamina
exposes the anthers and the style that are otherwise hidden and
kept safe (figure 6). This bending actuates a lateral unfolding
of the wings (lamina) (Poppinga et al 2010a, 2010b).
From an engineering perspective, the arrangement of
fibre-reinforced ribs, lamina and wings, which the perch
consists of, initially appears to be quite a complex design.
A gradual abstraction, described in detail in Poppinga et al
(2010a, 2010b) and Lienhard et al (2010, 2011a, 2011b),
transforms the elastic kinematics into a simple mechanism
which consists of a thin shell element attached to a beam
(figure 7).
The equilibrium path of the shell element is a non-
symmetrical bending motion, triggered by torsional buckling
which is induced by uniaxial bending of the attached
beam. This torsional buckling phenomenon is well known
to engineers. However, in structural design, it is usually
considered as a failure, which needs to be prevented through
design countermeasures and static verification. Nature,
however, exploits this principle and uses it actively to mobilize
certain functions.
Based on the first physical models and numerical
simulations, a prototype facade shading system called
Flectofin
R
was developed (figure 8) and registered for a patent
(Lienhard et al 2010, 2011a, 2011b, patent application). The
Flectofin
R
lamellas consist entirely of fibreglass-reinforced
plastic, which offers high tensile strength combined with low
bending stiffness, allowing for large elastic deformations.
Because the system functions without a straight turning
axis but with a bent backbone, it can also be adapted to
facades with curved geometries. This represents a significant
expansion of possible future applications. Another important
advantage is the shading system not having any maintenance-
intensive parts such as sliding joints or hinges. This reduces
costs for maintenance and care. Presumably, this mode of
6
Bioinspir. Biomim. 7 (2012) 015002 J Knippers and T Speck
(a)(b)
Figure 7. Simple physical model as a first-level abstraction of the kinematic system in the Strelitzia flower (adapted from Poppinga et al
2010b). Courtesy of WIT Press from the book C A Brebbia (ed) 2010 Design and Nature V pp 403–10.
Figure 8. Prototype of the fa¸cade shading system based on the Flectofin
R
produced in collaboration with the industrial partner Clauss
Markisen (adapted from Lienhard et al 2011b).
function will also increase the durability of the biomimetic
facade shading system.
3.1. Biomimetics in the architectural design process—design
of the thematic Pavilion EXPO 2012
The opportunity of introducing such systems on a larger scale
in an architectural design will be presented at the Thematic
Pavilion at EXPO 2012 in Yeosu, Korea (figure 9). A
kinematic media facade with 108 individually controllable fins
is planned on the pavilion side facing the expo. The design
is the result of an open design competition which was won
by Soma architects (Vienna, Austria). The technical concept
of the kinematic fins comes from Knippers Helbig Advanced
Engineering, Stuttgart, New York. The facade can adapt to
light conditions and physical building conditions and allows
the artistic staging of special lighting effects. It has a total
length of 140 m and a height of between 3 and 14 m, and is
designed to withstand the very high wind speeds on the Korean
coast.
It was initially attempted to scale Flectofin
R
to the size of
this fa¸cade. However, this proved to be difficult in its original
configuration. On the one hand, it did not fulfil all aspects of
the architectural design; on the other hand, without additional
structural reinforcement, it does not offer enough stability to
withstand the high wind loads. Inspired by the research on
plant movements, another kinetic system has been developed
(figure 10). The facade is made of slightly curved plates which
are supported by two hinged corners at the top and the bottom.
In the other two corners, a small compressive force is applied
in the plane of the fin, which leads to a controlled buckling.
This principle shows locally smaller strains than the Flectofin
R
7
Bioinspir. Biomim. 7 (2012) 015002 J Knippers and T Speck
Figure 9. Thematic Pavilion EXPO 2012, Yeosu, Korea; architect: Soma architects, Vienna; Engineer kinetic fa¸cade: Knippers Helbig;
Stuttgart, New York (visualisation: Soma
/isochrome).
Figure 10. Kinematic principle of the Yeosu fa¸cade (photo: Knippers Helbig).
but does not open completely. It perfectly matches the initial
design intentions of the architects and offers a favourable ratio
of structural stability and actuation energy (figure 9).
The elastically deformable fins are made of fibreglass-
reinforced plastic. They are up to 14 m high, 1.25 m wide and
only 9 mm thick with an additional stiffener on the side with
less-elastic deformation (the right edge in figure 10). When
open, the curved geometry, together with the residual stress
state, results in a very rigid system that deforms only a few
millimetres under high wind loads. In its closed state, the
adjacent plates are clamped together so that the facade can
withstand even the strongest storms without damage.
4. Conclusion
Both the Yeosu shading system and the Flectofin
R
movements
are made possible via elastic deformations that are associated
with correspondingly large strains. Both cases show nonlinear
deformation which, from a structural engineer’s perspective,
is considered to be a stability failure, and usually needs to
be prevented by sophisticated nonlinear analysis and bracings
or reinforcement. Even though the principle of the Yeosu
facade does not follow the abstraction of a plant movement
directly, the underlying idea was inspired and derived from
the observation and analysis of natural role models.
This encouraged the search for solutions outside the
traditional methods of design and construction and going
beyond preconceptions, such as avoiding disproportionately
growing deformations and stability failure modes.
The two examples show that a linear understanding of
biomimetics, as illustrated in figure 5, may only be sufficient
if the focus is on the abstraction of single functions as found in
technical products such as the shading system Flectofin
R
.In
architectural tasks, such as the design of the facade in Yeosu,
however, differing requirements between the aesthetics and
functionality have to be met in a given set of defined boundary
conditions. In addition, the biological role models very often
have to be scaled up to a large size, which leads to increasingly
difficult functional requirements.
In the context of architecture or building structures, a
linear abstraction process is therefore difficult to maintain.
Instead, an expanded definition of biomimetics is required:
the analysis of natural form and function principles have
the potential to stimulate architects and engineers to
8
Bioinspir. Biomim. 7 (2012) 015002 J Knippers and T Speck
fundamentally new strategies in architectural design and
technical implementation.
Acknowledgments
The work presented in this paper is supported by the funding
directive BIONA by the German Federal Ministry of Education
and Research. The authors were consulted by the Competence
Network Biomimetics. We want to thank Dipl.-Ing. Julian
Lienhard, Dipl.-Biol. Simon Poppinga, Dr Tom Masselter and
Simon Schleicher M.Arch. for the successful collaboration on
elastic architecture within the funding directive BIONA.
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Symp. of the Int. Association of Shell and Spatial Structures,
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hinge-less flapping mechanism Bioinspir. Biomim. 6 045001
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9
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underwater suction traps Proc. R. Soc. Batpress
(doi:10.1098/rspb.2010.2292)
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... This dicot species is a fast-growing tree with a tapered and regular cylindrical stem shape that can grow up to 30 meters high [2]. From the microscopic level of hierarchical structure (e.g., scaling from 0.1 mm to 1 µm [3,4]), balsa wood has a spongy texture (i.e., foam-like structure) due to large cells filled with water. Therefore, balsa wood is a lightweight biomaterial with a basic density (i.e.,a ratio of oven-dry weight to green volume) which depends on the tree's age and geographical location of growth [2]. ...
... Therefore, balsa wood is a lightweight biomaterial with a basic density (i.e.,a ratio of oven-dry weight to green volume) which depends on the tree's age and geographical location of growth [2]. Among its mechanical properties can be highlighted [1] an average MOE parallel to the fibers equals 3400 MPa, [2] an average Modulus of Rupture (MOR) parallel to the fibers equals to 14.9 MPa, and [3] an average MOR perpendicular to the fibers equals to 21.6 MPa. All previous values are given for an average basic density of 180 kg/m3 at 12% of moisture content [2]. ...
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The research of this paper aims at understanding, from an engineering perspective, the optimized mechanical efficiency of senile balsawood stem-tissues as concept generators for potential applications. Particularly, the objectives of this study are to determine, evaluate, and analyze the dynamic elastic properties and energy dissipation capacity of senile lightweight balsawood. To achieve these objectives, in accordance with the current American Society for Testing and Materials (ASTM) standards, a total of 40 specimens (i.e., 20 low-density and 20 high-density samples) were tested under static bending mechanical mode and technics of transversal vibration to determine static and dynamic Modulus of Elasticity (MOE), respectively. On the other hand, 8 samples (i.e., 4 low-density and 4 high-density samples) were subjected to Scanning Electron Microscope (SEM) process to compare the internal tissue of high and low density samples and their relationship with the dynamic and static MOEs. The dynamic MOE data were validated throughout 10 Finite Element Analyses (FEA) in LS-Dyna. The results show a high correlation between static and dynamic MOEs (R2 = 96.47%), which are directly proportional to density. Furthermore, SEM analysis reflects that the increase of double wall thickness affects the material energy dissipation capacity which consequently derives that low density balsa wood is the most suitable for energy dissipation applications.
... The vast diversity of biological structures all originate in this limited palette of fundamental materials, but their fibres' arrangement, directionality and density, as well as the chemical makeup of the matrix, is highly differentiated (Neville, 2011). Natures takes maximum advantage of the inherent anisotropy of fibrous systems by locally varying the layout, orientation and concentration of fibres in response to the required characteristics of the larger material structure, and thus fully utilizes the material effectiveness and local variability of fibrous systems (Knippers & Speck, 2012). ...
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Fibrous architecture constitutes an alternative approach to conventional building systems and established construction methods. It shows the potential to converge architectural concerns such as spatial expression and structural elegance , with urgently required resource effectiveness and material efficiency, in a genuinely computational approach. Fundamental characteristics of fibre composite are shared with fibre structures in the natural world, enabling the transfer of design principles and providing a vast repertoire of inspiration. Robotic fabrication based on coreless filament winding, a technique to deposit resin impregnated fibre filaments with only minimal formwork, as well as integrative computational design methods are imperative to the development of complex fibrous building systems. Two projects, the BUGA Fibre Pavilion as an example for long-span structures, and Maison Fibre as an example of multi-storey architecture, showcase the application of those techniques in an architectural context and highlight areas of further research opportunities. The highly interrelated aesthetic, structural and fabrication characteristics of fibre nets are difficult to understand and go beyond a designer's comprehension and intuition. An AI powered, self-learning agent system aims to extend and thoroughly explore the design space of fibre structures to unlock the full design potential coreless filament winding offers. In order to ensure feedback between all relevant design and performance criteria and enable interdisciplinary convergence, these novel design methods are embedded in a larger co-design framework. It formalizes the interaction of involved interdisciplinary domains and allows for interactive collaboration based on a central data model, serving as a base for design optimisation and exploration. To further advance research on fibre composites in architecture, bio-based materials are considered, continuing the journey of discovery of fibrous architecture to fundamentally rethinking design and construction towards a novel, computational material culture in architecture.
... Material science is currently working with hierarchical controlled gradients and configurations at a different scale to create high-performance materials with unique emerging properties (e.g., micro-and nanostructured materials to create structural colors). Numerous studies have been carried out at nano-and microscale, however, the introduction of these structural materials on large scales, such as building construction, is still very challenging [26]. ...
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Biomimetics emerges as an effective approach to identify functional bio-inspired solutions for the development of original design applications. This approach does not necessarily result in sustainable products and processes, which are frequently made of petroleum-based materials fabricated with non-renewable and high-energy consuming technologies. Nevertheless, the inspiration from nature has a great potential in terms of sustainable innovation, taking into consideration not only analogies but also the differences between the natural and artificial world. In this regard, the present contribution aimed to highlight the differences between biological and human industrial systems in scale, complexity, and organization, encouraging new sustainable biologically inspired designs increasingly close to the construction law of organisms. The result of this comparison emphasized nature’s intelligence concerning balanced source consumption and regeneration of ecosystems as well as the effective adaptation of organisms to natural cycles in time and space. A biomimetic approach that combines the use of bio-based materials with a coherent use of bioinspiration is here identified as a future sustainable and effective strategy to design a new human world, which does not impose on nature but is inspired and integrated with it.
... In a similar way, design principles of biological composites, from cellulose-based plants to collagen-based living tissues, could be analogous to fibre composites [38]. Several characteristics were identified [39] to be of interest for future integration in the design of engineered architectural FRP. Such characteristics suggest that differently from the engineering problem-solving approach to biomimetics, the architectural one should aim for an adoption of principles and mechanisms at different scales of magnitude and with varying degrees of abstraction. ...
... While the mobility obtained in nature is often caused by the change in the state of the structural members in that natural specimen. [9] Using the field of mechanical bionics, many examples of these cases can be studied. Plants can be a reliable and promising source of inspiration. ...
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In architecture of moving structures, by using moving elements, the building will show suitable reactions to create favorable conditions in the spaces of buildings. These mechanical tools come in varieties of shapes and sizes. Such components can be achieved by attaching tough elements using hinges. These structures can be exciting in the practical and aesthetic parts. But increasing the demand for unique shapes is too costly for architectural purposes and will lead to major inefficiencies. Thus, the cost-effectiveness of such designs has been repeatedly criticized. Adaptation to unconventional geometries is only possible by acquiring complex and costly mechanical tools and structures. In the review category, this study seeks to find promising alternatives to achieve flexible surfaces instead of hardcover elements, using adaptable and flexible plant patterns, to find suitable solutions to solve this problem in architecture. Therefore, methods are shown that specify how to achieve techniques, modeling, and simulations based on the principles of plant motion and the integration of the underlying mechanism in their structure. Using case studies, the key principles of plant movement, bark, and distortion are presented. Eventually, we will know nature-inspired kinetic structures that can come up with the idea of using flexible surfaces as shades.
Article
Structural biological materials are multiphase composite materials in nature. Their mechanical properties are extraordinary despite their weak constituents. This review aims to decipher how these remarkable properties are achieved from the perspective of mechanics. The following three key codes can contribute to this: material properties derived from building blocks, geometrical information related to the size effects and dimensional characteristics, and their combination embedded in architectures. First, the prominent role of building blocks in structural biological materials and their mechanical characteristics are elucidated. Second, the importance of geometrical features extracted from structural biological materials in connecting the building blocks and architectures in biological systems is highlighted. The abovementioned principles and concepts underlying diverse architectures are demonstrated to interpret the structural-mechanical characteristics of hierarchical biological materials. This work seeks to enrich the understanding of structural biological materials from a mechanics perspective and trigger breakthroughs in the development of advanced bio-inspired materials.
Book
This book includes both theoretical conceptualization and practical applications in the fields of product design, architecture, engineering, and materials. The book aimed to inspire scholars and professionals to look at nature as a source of inspiration for developing new project solutions. Moreover, being one of the literature’s first direct associations of bionics with sustainability, the book can be used as a reference for those who seek to know more about the theory of bioinspired applications, as well as new technologies, methods, materials, and processes.
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Eggs are nature's successful evolutionary design tricks, well designed to deliver multi-task biofunctional strategies for life's challenges. They appear in the vital scenario in the form of original and surprising bio-tech design solutions affected by the genetic and environmental constraints they are called to interact with. For these basic survival needs, the eggs must work very well: capturing the sperm of the male for a correct optimization of the fertilization processes, protection from physical and mechanical trauma, climatic mediation, and fine aeration of the internal larvae. These surprising embryo packagings are a sort of lifeboat laid down and often left alone by females in front of the intricate, complex, and highly wild food interweaving the planet's ecosystems. We found eggs in the reproductive cycles of many living species: fish, cephalopods, birds, and above all, individual insects. Butterfly eggs constitute a class of exciting and still little studied solutions, considered for possible bionic and biomimetic inspirations. Many Lepidoptera eggs generally have an external textured shell, the chorion, made up of waxed surface keratin, which maintains the correct humidity of the egg throughout the growth cycle. Keratin is a fibrous protein rich in sulfur amino acids, cysteine, and self-assemble into fiber bundles. It has the characteristic of a very tenacious mineralized fabric and is remarkably impermeable to water and atmospheric gases. Each egg is glued by the mother's butterfly to the support of branches or leaves of the nourishing plants by a gluey substance of chemical still largely unknown constitution, so adhesive that it is impossible to detach the eggs if not breaking them. In some butterfly species, like the Maniola and Lycaenidae family, the shell's structure has a spatial organization in the form of complex geodesic ribbed micro domes that resemble Buckminster Fuller's geodesic structures. Another exciting aspect of butterfly's eggs design concerns the micropyle and aeropyles layers system, which ensure the proper introduction of the male sperm, air, and oxygen needed to larva's growth. This study, conducted by the BionikonLab&FABNAT14 laboratory of Iglesias-SU Italy, considers the structural, morphological, and geometric aspects of some types of butterfly eggs that await internal ventilation. The purpose is to define a list of essential design problem-solving concepts that apply to creating food packaging, considering the crucial aspects of preserving freshness and commercial and nutritional qualities, reducing food waste, and the additional use of chemicals, antioxidants, and plastics packs.
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Bionics is fundamentally based on the development of projects for engineering, design, architecture, and others, which are inspired by the characteristics of a biological model organism. Essentially, bionics is based on a transdisciplinary approach, where teams are composed of researchers trained in a variety of disciplines, aiming to find and adapt characteristics from nature into innovative solutions. One of the key steps in a bioinspired project is the comprehensive study and analysis of biological samples, aiming at the correct understanding of the desired features prior to their application. Among the most sought natural elements for a project to be based on, plants represent a large source of inspiration for bionic designs of structures and products due to their natural efficiency and high mechanical performance at the microscopical level, which reflects into their functional morphology. Therefore, examining their microstructure is crucial to adapt them into bioinspired solutions. In recent years, several new technologies for materials characterization have been developed, such as X-ray Microtomography (µCT) and Finite Element Analysis (FEA), allowing newer possibilities to visualize the fine structure of plants. Combining these technologies also allows that the plant material could be virtually investigated, simulating environmental conditions of interest, and revealing intrinsic properties of their internal organization. Conversely to the expected flow of a conventional methodology in bionics—from nature-to-project —besides contributing to the development of innovative designs, these technologies also play an important role in investigations in the plant sciences field. This chapter addresses how investigations in plant samples using those technologies for bionic purposes are reflecting on new pieces of knowledge regarding the biological material itself. An overview of the use of µCT and FEA in recent bionic research is presented, as well as how they are impacting new discoveries for plant anatomy and morphology. The techniques are described, highlighting their potential for biology and bionic studies, and literature case studies are shown. Finally, we present future directions that the potential new technologies have on connecting the gap between project sciences and biodiversity in a way both fields can benefit from them.
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The remarkable growth of urban areas is a scenario faced by many cities due to the high rate of population that migrates to these zones, increasing the heat stored in the built environment creating insurmountable microclimatic conditions within the metropolitan area for pedestrians. Such microclimatic conditions might cause the unfeasibility of using natural ventilation for indoor passive cooling, increasing the air conditioners usage, and by overlapping to the previous heat stored the risk of overheating rises. Tropical regions have presented increased floods, extreme winds, earthquakes, and tropical-heat waves. To address such climate related challenges, a review on bio-inspired designs strategies at city scale, although not widely implemented in situ, is presented. On the other hand, developing countries in tropical regions recently started to develop energy regulations for the built environment, making it difficult to visualize a short-term implementation of any bio-inspired design at the city scale. As a result, most studies remain in a preliminary research project status. The evaluation and comparison of the sustainability of various tropical region cities through the Green City Index is presented. This evaluation led to assess in detail a Case study in Panama City considering the three critical aspects in the built environment: the conditioning of indoor spaces for cooling, transport, and lighting. Based on ecosystem services, a set of indicators are proposed and evaluated to measure regeneration at the city scale. Finally, to evaluate the proposed solutions, a SWOT analysis is presented. The use of a regenerative methodology in cities would mean a greater consideration of nature in planning goals and an improvement in urban ecosystem relations.
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At the interfaces of our mostly stationary architecture and surrounding nature we need to make constructions adaptable to ambient changes. Adaptability as a structural response to changing climate conditions, such as the intensity and direction of sun radiation, can be realised with deployable systems. These systems are often based on the combination of stiff compression members and soft tension members connected with hinges and rollers. Deployable systems in nature are often based on flexibility. This can be observed especially in plant movements. New construction materials such as fibre-reinforced polymers (FRP) can combine high tensile strength with low bending stiffness, allowing large elastic deformations. This may enable a completely new interpretation of convertible structures which work on reversible deformation, here referred to as elastic or pliable structures. In a current research project the kinematics for such systems are derived from certain applicable plant movements. This paper will focus on the biomimetic workflow used to develop elastic kinetic structures based on such movements. The abstraction and optimisation methods will be described from an engineering point of view, focusing on the technical approaches of converting the conceptual results of a first level abstraction into higher level abstractions and finally to physical design.
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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.
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Many biological tissues, such as wood and bone, are fiber composites with a hierarchical structure. Their exceptional mechanical properties are believed to be due to a functional adaptation of the structure at all levels of hierarchy. This article reviews the basic principles involved in designing hierarchical biological materials, such as cellular and composite architectures, adapative growth and as well as remodeling. Some examples that are found to utilize these strategies include wood, bone, tendon, and glass sponges – all of which are discussed.
Article
An adaptationist programme has dominated evolutionary thought in England and the United States during the past 40 years. It is based on faith in the power of natural selection as an optimizing agent. It proceeds by breaking an oragnism into unitary 'traits' and proposing an adaptive story for each considered separately. Trade-offs among competing selective demands exert the only brake upon perfection; non-optimality is thereby rendered as a result of adaptation as well. We criticize this approach and attempt to reassert a competing notion (long popular in continental Europe) that organisms must be analysed as integrated wholes, with Baupläne so constrained by phyletic heritage, pathways of development and general architecture that the constraints themselves become more interesting and more important in delimiting pathways of change than the selective force that may mediate change when it occurs. We fault the adaptationist programme for its failure to distinguish current utility from reasons for origin (male tyrannosaurs may have used their diminutive front legs to titillate female partners, but this will not explain why they got so small); for its unwillingness to consider alternatives to adaptive stories; for its reliance upon plausibility alone as a criterion for accepting speculative tales; and for its failure to consider adequately such competing themes as random fixation of alleles, production of non-adaptive structures by developmental correlation with selected features (allometry, pleiotropy, material compensation, mechanically forced correlation), the separability of adaptation and selection, multiple adaptive peaks, and current utility as an epiphenomenon of non-adaptive structures. We support Darwin's own pluralistic approach to identifying the agents of evolutionary change.
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The significance of inspiration from nature for technical textiles and fibrous composite materials is demonstrated by examples of technical solutions that either parallel biology or are inspired by biological models. Two different types of biomimetic approach are briefly presented and discussed for the 'technical plant stem', a biomimetic product inspired by a variety of structural and functional properties found in different plants. The most important botanical role models are the stems of the giant reed (. Arundo donax, Poaceae) and of the Dutch rush (. Equisetum hyemale, Equisetaceae). After analysis of the structural and mechanical properties of these plants, the physical principles were deduced and abstracted and finally transferred to technical applications. Modern computer-controlled methods for producing technical textiles and for structuring the embedding matrix of compound materials render unique possibilities for transferring the complex structures found in plants into technical applications. This process is detailed for the 'technical plant stem,' a biomimetic, lightweight, fibrous composite material based on technical textiles with optimized mechanical properties and a gradient structure.
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Biomimetics plays an impending role in today's needs for products that cope with the demands of effectiveness in terms of energy consumption and material use. Especially in the field of architectural textiles, substantial progress is being made. The concerted systematic research in biology, engineering, architecture and other professional disciplines is leading to surprising detections of functional principles in biology, whose implementation in innovative technical solutions could not have been made without the help of nature. A multitude of new materials and constructions is under development, featuring outstanding properties concerning, for example, weight, stability and durability.
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Plants, apparently not capable of complex movements, have always fascinated scientists when proving the contrary. A multitude of movements in plants have been revealed, showing a broad spectrum of motion sequences and underlying principles. Interestingly, many of these movements show high elasticity and flexibility of the respective structures and allow reversible deformations. With the investigation of suitable biological role models and the use of new construction materials like fibre-reinforced polymers (FRP) the authors are developing deployable technical structures without local hinges. In this presentation the first steps of the applied biomimetic working process are described: selection of role models, investigation and basic abstraction of plant movements. An overall screening through the plant kingdom has led to a wide-ranged matrix comprising many different types of plant movements, which constitutes the basis for our investigations. We distinguish between autonomous and non-autonomous movements. Active autonomous movements are characterized by motor organs, e.g. pulvini driven by a change of turgor pressure. Passive autonomous movements occur due to changing physical circumstances, e.g. bending through desiccation. Non-autonomous movements are mostly reversible deformations caused by a release of stored elastic energy after an external trigger or by direct application of mechanical forces. In a case study we applied morphological and anatomical investigations on the valvular pollination 404 Design and Nature V mechanism of the Bird-Of-Paradise flower. A physical model as a first level abstraction step of the system is presented. In close collaboration between biologists and construction engineers this kinetic system is verified with the help of computer simulations and additional abstraction steps which finally led to the construction of a bio-inspired demonstrator for technical applications.
Article
Plant stems are one of nature's most impressive mechanical constructs. Their sophisticated hierarchical structure and multifunctionality allow trees to grow more than 100 m tall. This review highlights the advanced mechanical design of plant stems from the integral level of stem structures down to the fiber-reinforced-composite character of the cell walls. Thereby we intend not only to provide insight into structure-function relationships at the individual levels of hierarchy but to further discuss how growth forms and habits of plant stems are closely interrelated with the peculiarities of their tissue and cell structure and mechanics. This concept is extended to a further key feature of plants, namely, adaptive growth as a reaction to mechanical perturbation and/or changing environmental conditions. These mechanical design principles of plant stems can serve as concept generators for advanced biomimetic materials and may inspire materials and engineering sciences research.
Article
A fjord of the Baltic Sea divides the centre of the City of Kiel. To provide a pedestrian crossing that allows passage of ships, a folding cable-stayed bridge was built. Its unusual folding mechanism was proposed not only to ensure a safe and robust operation, but also to provide a visual and technical attraction. The deck folds at three hinges by the continuous rotation of a pair of single-speed winches, to which all cable drums are connected.