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Extending recent work on Form Active Hybrid Structures of Active Bend and CNC knitted (Computer Numerical Control) tensile members we present a set of innovations in design and manufacturing, which together allow to build structural systems, that morph across multiple structural states. While state of the art tools and fabrications methods in textile hybrid structures provide architects and engineers with means to adopt the geometry of a chosen textile system to the requirements of a given site, constraints in design thinking, tools and manufacturing however still limit the ability to change the spatial and structural qualities and expressions within a textile object. The potentials of our developments to create new spatial expressions and atmospheres in textiles structures are demonstrated and evaluated through the large-scale installation Isoropia designed and built for the Danish Pavillion in the 2018 Venice Architectural Biennale.
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Proceedings of the TensiNet Symposium 2019
Softening the habitats | 3-5 June 2019, Politecnico di Milano, Milan, Italy
Alessandra Zanelli, Carol Monticelli, Marijke Mollaert, Bernd Stimpfle (Eds.)
Copyright © 2019 by BLINDED. Published by Maggioli SpA with License Creative Commons CC BY-NC-
ND 4.0 with permission.
Peer-review under responsibility of the TensiNet Association
Systems for transformative textile structures in CNC knitted fabrics
Extending recent work on Form Active Hybrid Structures of Active Bend and CNC knitted
tensile members we present a set of innovations in design and manufacturing, which together
allow to build structural systems, that morph across multiple structural states. While state of
the art tools and fabrications methods in textile hybrid structures provide architects and
engineers with means to adopt the geometry of a chosen textile system to the requirements of
a given site, constraints in design thinking, tools and manufacturing however still limit the
ability to change the spatial and structural qualities and expressions within a textile object.
The potentials of our developments to create new spatial expressions and atmospheres in
textiles structures are demonstrated and evaluated through the large-scale installation Isoropia
designed and built for the Danish Pavillion in the 2018 Venice Architectural Biennale.
Keywords: Architecture, Digital Design, Bending Active Textile Membrane Hybrids, Digital Chain - Integration
of Design, Simulation and Fabrication, CNC Knit
1. Introduction
Tensile membrane structures are per se customized, as the shape of the membrane can only be
determined through the process of form finding. In here the final membrane shape emerges as
equilibrium of forces. As result tensile membrane structures are usually one-offs, designed
and engineered specifically to the context, they are situated in, and fabricated to project
specific specifications of predominately non-standard elements.
In architectural fields outside of membrane structures new spatial experiences and expressions
have in the last decade been enabled through the use of non-standard design and fabrication
Proceedings of the TensiNet Symposium 2019
Softening the habitats. Sustainable Innovation in Minimal Mass Structures and Lightweight Architectures
methods. The success of these designs is based on the implementation of computational
techniques in design and analysis and an integration of digital design and digital fabrication
(Tamke & Thomsen, 2009).
These digital design methods and workflows have enabled new spatial and tectonic solutions
across all scales (Fig. 1-5) in which elements change and morph in order to change the
atmosphere and expression for the humans within. As shown in the 2009 CITA exhibition
design for “It’s a small World” a non-standard design approach allows structures to adapt
seamlessly to different scales and environments and act as a physical mediator between spatial
requirements. Furthermore the underlying computational approaches provide the base for
future highly material efficient structures, which rely on the total integration of design and
robotic manufacturing (Nicholas, Zwierzycki, Nørgaard Clausen, Hutchinson, & Thomsen,
2017; Solly, Frueh, Saffarian, Prado, & Menges, 2018)
Fig. 1-5 Interior Panels in Oslo Opera Hall (Olafur Eliasson), It´s A small World (CITA), Arch Union
Architects), Dongdaemun Design Plaza (Aaha Hadid architects), Aqua Tower (Studio Gang) - all photos CC
In the field of tensile architectures the use of non-standard approaches has been tested early
on in small scale academic prototypes, such as the 2007 AA Component Membrane
installation and related work (Hensel & Menges, 2008). However similar site and human scale
specific installations, that are based on the morph of the size and shape of membranes across
the structure, have until now not seen a wide implementation in the field. Instead discrete and
varying membrane fabric elements of same size are repeated, as in the case of the King Fahad
National Library (2014) (Dupont, 2014), or an intended morphing expression is created
through a combination of a customised steel structure and standard membrane elements, as in
the Nizhny Novgorod Stadium (2018) (Bernert, 2018).
While the authors of the latter structure do not reveal the reason, why their design shifted
from a non-standard approach towards the pattern cut of the membrane elements to standard
ones, accounts from small scale structures with non-standard approaches to geometry and
detailing (Hensel & Menges, 2008), point at the labor intensity in design, simulation,
fabrication and assembly as a challenge. Moreover the inherent stiffness of traditional
laminated membranes limits the scales by which it can be applied, as the need for seams to
Proceedings of the TensiNet Symposium 2019
Softening the habitats. Sustainable Innovation in Minimal Mass Structures and Lightweight Architectures
assemble patches to achieve double curvature and integrate detailing further limits the scales
by which the membranes can be used.
New opportunities for spatial expression and tactile experiences emerge through the
integration of design, analysis and fabrication combined with the shift of the textile system
from weave to CNC-knit (Ahlquist & Menges, 2013; Popescu et al., 2018; Sabin, 2013;
Thomsen et al., 2015). The inherent flexibility of knit, the ability to integrate shaping and
detailing in the textile fabrication process opens especially opportunities for designing
membranes at the smaller scale of state of the art membrane architecture, as in Ron Herrons
Imagination Building (Lyall & Herron Associates, 1992). Current application of CNC knitting
in the field have focused on small scale prototypes, but didn’t engage in building scale or
devised knitted textiles a role as structural member, as needed in Form Active Hybrid
Structures of Active Bend and Tensile members (Thomsen et al., 2015).
2. Isoropia - Outset and framework
In this paper we ask how state of the art materials and structural systems, design and
fabrication workflows can create avenues for new spatial experiences in textile architecture
taking the 2018 Venice Biennale Installation Isoropia as example. Isoropia, which in Greek
means balance, equilibrium and stability, is a 35m long structure made from 41 custom CNC
knitted patches of up to 7m length. The textile membrane is set in structural equilibrium with
bend glass fibre rods of varying thickness and strength.
The structure creates a spatial and structural continuum through the Danish Pavilion, forming
differentiated outdoor canopy structures on the two outer sides and a vaulted space in the
interior in a reaction to the specific program and sites (Fig. 6):
Proceedings of the TensiNet Symposium 2019
Softening the habitats. Sustainable Innovation in Minimal Mass Structures and Lightweight Architectures
Fig 6. Architectural concept of Isoropia. 1) The southern exterior part (left) welcomes visitors to the Biennale
and creates a canopy like structure guiding visitors into the Danish Pavilion. 2) The interior passage (middle) is
the only entrance to the Danish Pavilion. The aim was to create a dense textile space, which creates curiosity on
side of the visitors, allows them to slow down, study movies and text about the installation and finally redirects
them into the further exhibition of the pavilion. 3) The northern exterior part (right) is directed towards the lively
cafe zone of the Biennale and creates an shading entrance canopy, which adapts to the rhythm of the colonade of
the existing Danish Pavilion.
Further forming requirements have been:
the status of the Danish Pavilion as quasi listed building, which prohibits irreversible
modifications to the construction
the need to connect the structure to “Danish ground” only, which prohibited any ties to
the directly surrounding “Italian” ground and the large amount of ca. 150.000 visitors,
which required a sturdy construction and detailing in compliance to structural and
historical conservation code, that had to be documented in a building permission to the
the pavilion had to work at day and night, which required the integration of artificial
Most important of all the time given from commissioning of the installation to its completion
was only 4,5 months.
3. Isoropia solutions
The conceptual answer to the total amount of ideas and demands, was to create a structure,
which can morph and adopt on relatively small scale yet high level and quality of textile
surfaces and detail. In order to overcome the above listed constraints we had to devise new
Proceedings of the TensiNet Symposium 2019
Softening the habitats. Sustainable Innovation in Minimal Mass Structures and Lightweight Architectures
solutions on several levels. These are highly interconnected in terms of the processes in
design, analysis and fabrication as well across scales.
3.1. Structural system - Bending Active Textile Hybrid
The building system employed for the canopy falls into the category of bending-active
membrane hybrids (Ahlquist, Lienhard, Knippers, & Menges, 2013). These are defined as
systems that achieve equilibrium through the combination of bending-active elements (the
GFRP rods) with purely tensile elements (the membrane patches and cables), hence the hybrid
nature of the structure. The bending-active elements provide the required mechanical supports
to prestress the tensile elements, which in turn lock the bent rods into position. In this way, a
subtle equilibrium solution is achieved in which the interdependency between the individual
components is necessary for the stability of the structural system. The shape of the canopy is
therefore the result of the interplay of internal forces conveyed by the individual structural
In order to morph, the Isoropia structural system shifts from a cablenet system on the
exteriors, which pre-stresses and stabilises the structure, to a tensegrity-like structure in the
interior in which compression elements pre-stress the knitted membrane (Fig. 6). Each
arrangement posed a specific challenge in terms of analysis and assessment of the structural
The outdoor areas derive their shape from the mutual force interaction between the bent rods,
tensile Dyneema® membrane and Dyneema® cables. The only support being the dedicated
steel fixtures on the building’s wall, the rods cantilevered outwards and were kept in position
by only prestressing the tensile elements (Fig. 6). In terms of form-finding and structural
analysis, this area presented particular challenges due to the high nonlinearities deriving from
the minimal amount of supports and mechanical constraints in the system.
The interior is made of bending-active elements, which alternate their direction and create a
crossing pattern visible in Fig. 6. Here the GFRP rods were connected to the building’s walls
and ceiling, creating a continuous support condition of the beams. Less demanding from a
computational point of view thanks to the forgiving boundary conditions, this area presented
particular challenges in terms of analysis due to the topological arrangement of the membrane
patches and the stretched sections where the compression rods were inserted.
Finally the listed building status of the Danish pavilion coupled with the bending-active
hybrid nature of the canopy, pushed for solutions that reduced to the bare minimum the
interventions on the surroundings and consequently the support areas that could be used to
secure the structure.
Proceedings of the TensiNet Symposium 2019
Softening the habitats. Sustainable Innovation in Minimal Mass Structures and Lightweight Architectures
3.2. Design system
For the purpose of the project these constraints were translated into a dedicated design system
(Gengnagel, La Magna, Ramsgaard Thomsen, & Tamke, 2018) that seamlessly connected the
digital design pipeline used for geometrical exploration, based on Projection Dynamics
(Bouaziz, Martin, Liu, Kavan, & Pauly, 2014), with an intermediate Isogeometric Analysis
tool (Längst, Bauer, La Magna, & Lienhard, 2018), which provided frequently feedback on
the structural performance of the canopy and finally a robust and detailed analysis using more
established tools for simulation (Julian Lienhard, Bergmann, La Magna, & Runberger, 2017).
In this way, the behaviour of the structure could be constantly monitored during the
development of the project, providing valuable information to all the parties involved
throughout the conceptual and development phases.
3.2.1. Digital Design Workflow
The developed continuous membrane system is based on a single principle structural unit,
consisting of a pair of bend GFRP rods (Beams), which carry a connecting membrane,
stressed by cablenets or compression sticks. Through variations, of parameters in this basic
units, such as the width between the supporting rods, their lengths and the interposition of the
fabrics in relation to the rods, a continuous yet adapting structure is possible.
Around this basic parameters a generative design pipeline using Kangaroo2 (Quinn et al.,
2016) was built (Fig 7). This setup allowed rapid design variations, through changes of only a
few parameters, such as the beam locations in space (A), the beam length (B) and Z-position.
Fig. 7: Steps of the workflow for the Digital Design Tool A) Positions for the beams are indicated on 2D ground
level, considering the maximum fabrication width of the membranes. At each position a vector perpendicular to
the existing building indicates the direction of the beams. B) Based on the vectors beams are generated in
determined length. C)Z-values are given for the target locations of beam start and end, as well as values for start
and end of fabric on beams. The discretisation of the beams (30cm) is used to generate a membrane outline as
quads. The type of membrane is indicated (double or single-sided with cablenet)
E) All quads get discretized in custom resolutions, as either single or double layer membranes. The amount of
coverage of the second layer is increasing gradually F)The cablenets and the amount of pulling points are
introduced. G)The interior membranes are generated and compression sticks are introduced and iteratively
Proceedings of the TensiNet Symposium 2019
Softening the habitats. Sustainable Innovation in Minimal Mass Structures and Lightweight Architectures
optimised in order to find an equilibrium position in the textile. H)External constraints for the relaxation are
introduced: anchors, external tension ropes, links to the ceiling in the interior and back tension ropes for the non-
cablenet units. I) Kangaroo Force values are applied to the goals of the digital design tool pipeline and the
overall shape is found.
3.2.2. Analysis Workflows
The digital design tool provided an agile platform for quick design explorations and
geometrical variations of the canopy throughout its conception and development. Though, the
high level of documentation requested by the authorities, a detailed analysis of the structure
was necessary in order to assess its performance under high wind loading and its effects on
the surroundings, especially the reaction forces exerted by the canopy on the support areas
fixed to the building. A dedicated workflow between the design and analysis was set up to
quickly provide feedback to the design process.
Kiwi3d, a new tool for Isogeometric Analysis, was used for intermediate quick analysis. In
particular, Kiwi3d incorporates modules for linear and nonlinear analysis, as well as form-
finding based on the URS (Updated Reference Strategy) method (Philipp, Breitenberger,
D’Auria, Wüchner, & Bletzinger, 2016). To speed up the transfer between the two platforms,
a geometry processing workflow was set up which took care of the discrepancies between the
geometric models. This meant converting discrete lines and surfaces into continuous spline
and NURBS patches through interpolation of the nodes. This geometry conversion was
robust and reliable and an analysis of the full building process of the canopy could be
simulated: the bending of the GFRP rods, the attachment and form-finding of the membrane
patches and linking the cables to the membrane and prestressing it. Besides this initial
assessment of the structural behaviour under wind loading (930 mm vertical deformation for
wind suction, 640 mm vertical deformation for wind pressure) and the corresponding reaction
forces took place in Kiwi3D.
The analysis of the canopy was completed by running a Finite Element simulation on the final
design (SOFiSTiK coupled with the dedicated Grasshopper plugin STiKbug) (J. Lienhard, La
Magna, & Knippers, 2014). This step was necessary to validate the intermediate results using
well-established tools which have been extensively tested both in research and in practice.
The Finite Element tools allow for a very detailed description and simulation of the structural
behaviour, giving the analyst the possibility to incorporate advanced aspects such as long-
term behaviour and plasticity. Specific to this case, compressive springs were added in the
final simulation model to take into account the contact between the bending-active rods and
the building’s walls, an aspect that needed to be verified due to the scrupulous requirements of
the organization.
Proceedings of the TensiNet Symposium 2019
Softening the habitats. Sustainable Innovation in Minimal Mass Structures and Lightweight Architectures
3.3. Material Systems
In Isoropia we further develop the inter-scalar approach first suggested in the Hybrid Tower
projects (Holden Deleuran et al., 2015; Thomsen et al., 2015). Here, design takes place at
multiple scales from the overall structural system, to the single patch, the implemented knit
structure and down to fibre selection and fibre surface.
3.3.1. Knitted membrane: an inter-scale approach
In difference to Hybrid Tower, in which a single patch design is repeated to achieve the
rotational geometry, Isoropia works with mass customised patches. As the structure morphs
from canopy to vault and back again and as it twists through the Danish Pavilion building,
each patch is differentiated both in size and shape. This differentiation creates variances in the
patch design from a variation of protruding cones and slits (Fig.8).
Fig 8: Outline drawings of all patches produced for the three zones of Isoropia. The graph lines surrounding the
bounding boxes indicate the amount of elasticity in areas of the patches through combination of different knit
Isoropia also further develops the innovative membrane design from Hybrid Tower, where we
detailed the membrane through tubular jersey for double surface channels, interlocking for
reinforcement parts and holes for tying and pre-stressing (Tamke et al., 2016). Isoropia further
differentiates between various knit patterns within the patch surface (Fig 9). Initial tests using
only one base knit pattern (Piquet Lacoste) revealed to be too tight to achieve the strong three
dimensionality needed for the cones, which provides together with the cablenet structural
depth and capacity. To increase cone depth we defined a fourth stitch pattern, in which the
interlocking between needles is less, therefore allowing more flexibility of the yarn and better
Proceedings of the TensiNet Symposium 2019
Softening the habitats. Sustainable Innovation in Minimal Mass Structures and Lightweight Architectures
deformation. This fourth stitch pattern is introduced in star-shaped zones around the cones
grading the material locally for performance
Fig 9: The in Isoropia used knit patterns (from left: tubular, piquet lacoste, interlock, piquet)
The double patches are assembled using a knit logic (Fig. 10&11). By linking the two
surfaces together, in the way that garment patches are linked together, we employ a knit stitch
and use the same fibres as in the patches. In this we achieve similar performance of the
assembly stitch as in the overall patch allowing better pre-stressing of the membrane.
3.3.2. Fibre system - manufacturing bespoke knit
At fibre level the material, machine requirement and final textile structure had to be
considered in order to achieve a promising textile system, which could handle the variations
in pattern and mechanical stress that characterizes Isoropia. It was further important, to create
a welcoming and soft haptic experience for visitors who touch the fabric, unlike the plastic
nature of state of the art building membranes. From a limited range of available high
performance yarns, ultra high molecular weight polyethylene yarns Dyneema® SK65 was
selected due to its enhanced mechanical properties specifically 3,3-3,9 GPa of Tensile
Strength; 109-132 GPa of Tensile Modulus and 3-4% Elongation at Break (Fig. 12&13)
Fig 10-13: Linking using Dunkermotoren linker (BG83 14GG),Dyneema® SK75 220DTex
Proceedings of the TensiNet Symposium 2019
Softening the habitats. Sustainable Innovation in Minimal Mass Structures and Lightweight Architectures
3.4. Fabrication Systems
In Isoropia the development of design, knit specification and fabrication system ran in parallel
and each step of this rapid process was evaluated in 1:1 prototypes. This required to have
early on an automatic link between the digital design tool at BLINDED, and the CNC knitting
machines at the textile producer BLINDED.
3.4.1. Digital Fabrication Interface
The interface between design and production takes place through bitmap files (Thomsen et al.,
2016). These files are automatically generated from planarised meshes of the digital design
system (Fig. 14)
Fig. 14: Workflow for the Digital Fabrication Tool: A) A 2D mesh with identical mesh topology to the
formfound 3d mesh is generated. B) The protrusion of each cone is “relaxed” into a simplified 3d mesh, as the
cones are formed as the result of textile stretch only. The outer edge lengths are maintained. C) The internal and
external edges of the 3d mesh are measured and used as constraints for a K2 relaxation of the 2D mesh with a
0.01m tolerance for the output edge lengths. D) A best fitting bounding box is generated and tested against the
max width of the CNC knitting machine. E) The 2D mesh and the transposed cone centres serve as base for the
automated specification of the boundaries of areas with different knit structures (rods channels, details for the
lighting details, reinforcement edge and the expandable cone stars, large slits). Visual feedback is provided on
the relation between zones of different stretch (Piquet and Piquet Lacoste). F)Colours are assigned to the
different areas.the lines in linework was set a colour. H) In order to accommodate the non-square nature of knit
stitches, a non-uniform scaling is performed. I) Lineworks is processed with Squid (Grasshopper Plug-In,
developed at CITA by Mateusz Zwierzycki ), filled with predefined colours and exported as bmp.
The development of the digital fabrication workflow did take place through iterative testing
and prototyping of samples in increasing size (Fig. 15). 1:1 prototyping of the system was
instrumental in order to understand and measure the interplay of all elements and materials
Proceedings of the TensiNet Symposium 2019
Softening the habitats. Sustainable Innovation in Minimal Mass Structures and Lightweight Architectures
across all scales, instead of working on assumptions gained from isolated tests. Each
prototype allowed the project to leap to a more reliable level and gain validated correction
values for the parameters in the design and fabrication workflow.
Fig. 15 1:1 Prototyping of the membrane units Fig.16: Evaluation through 3d scanning
3.4.2. Producing CNC Knit - Machines
The complexity of Isoropia on knit level required a high degree of freedom on side of
production machinery. For this a Shima Seiki M183514 14GG flat knitting machine and
APEX3 software was selected, due to their ability to interface on level of design and
programming code (Barfield, 2015). The process of converting the bitmap knit information
from the design level to CNC knitting code (Fig. 17 & 18) entailed that the single colour fills
of the bmps were assigned a smaller scale pixel pattern, which contains a particular
information for every single needle. This required the computationally powerful SHIMA
SEIKI computer units and novel processing steps and design planning for knitting procedures.
Some challenges were faced regarding the yarn flow, the structural detail of the textile area
itself and the pre-defined outer shape. Structural detail meaning the interfaces of the different
structures in the knit (Fig. 14). Techniques had to be developed in order to absorb or spread
tension between structures where needed and also allow a proper knitting flow whenever the
knit code changes between different structures. These three distinct textile architectures had to
be precisely programed and tested to resist mechanical solicitations without compromising
neighboring structural requirements. Though the project was based on previous collaborations
(Tamke et al., 2016) any new development posed challenges. The use of the inelastic and
hence demanding Dyneema® yarn required for instance an adjustment of the knitting machine
in order to be able to knit on a high speed without mistakes or damages to the machine. But as
well interdisciplinary challenges occurred, when new processes, as the linkage of two single
layer into a double membrane were introduced. In here the existing work procedures and the
lack of integrated markers on the fabric of the positions to link the fabric created a situation
Proceedings of the TensiNet Symposium 2019
Softening the habitats. Sustainable Innovation in Minimal Mass Structures and Lightweight Architectures
where the fabrics were linked wrong, which resulted in a non-matching assembly. Fortunately
the issue could be very easily solved by simply delinking the fabrics and linking them once
again in the right places.
Fig. 17 & 18: Processing of the CNC-knitting files for the membranes at BLINDED and final production
4. Conclusion and Potentials (1 page max with images)
The realisation of the bending-active membrane hybrid Isoropia was only possible, through
an integration of the Structural, Design, Material and Fabrication system. This
transdisciplinary and interscalar approach allowed us to design and build a morphing
structural membrane system in only 4,5 months, which delivers new spatial experiences and a
new level of detailing to the field of small scale membrane structures. Isoropia is until today
the largest structure made in preprogrammed CNC-knit, with every single membrane being
unique (Fig. 19-21).
The approach chosen in Isorpoia opens up opportunities for new design expressions in textile
architectures and an integrative approach towards other building elements. Isoropia morphs
between two very radically structural systems and spatial expressions: from a more normative
outer appearance to the radically textile space in the inner area. A unified impression is
created through the use of similar design features - the textile cones - in both systems and the
ability to specify gradual shifts in families of elements and materials.
The ability to morph provides the structure with modes to adapt and create highly local
interfaces to the existing buildings. This was beneficial for the design of structures in historic
context. A further factor, which contributed to the minimal invasive character of Isoropia was,
that we could avoid tension connections to the existing structures, as the prestressing of the
membranes was provided within the hybrid structure itself.
Proceedings of the TensiNet Symposium 2019
Softening the habitats. Sustainable Innovation in Minimal Mass Structures and Lightweight Architectures
Fig. 19 - 21: Interior view. Textile membrane ceiling together with integrated light created a special atmosphere
and invited guests to interact with the environment.
Despite being a first of its kind, the overall installation of Isoropia took only 8 days. Most of
the time was used to install the infrastructure, such as electrics and support, while the actual
assembly and tensioning of the hybrid structure only hours. This shows, how the integration
of functionality and performance in elements and materials, allows to minimise the overall
complexity and costs of building, which would else arise through on-site fabrication,
assembly and the handling of many parts.
During the exhibition we observed, that most of the more than 100.000 visitors touched the
textile surfaces of Isoropia with interest and pleasure. CNC knit is able to create surface
qualities on level with apparel, even when it is made from high performance yarns.
Finally Isoropia is giving rise to an environmental friendly architecture and smart production
strategy through CNC knit, which is able to address zero waste and low labor intensity
production, deliver elements with highly customised shapes, functions and behaviours and
new freedom in design of membrane architecture. In this aspect Isoropia is a stepping stone
and the exploration of designed movement of similar hybrid structures, the further integration
of lighting and the production of non-manifold surfaces are obvious next steps.
5. Acknowledgments
Blinded for this review
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... Tamke et al. (2016) have proposed a methodology of import of bitmap images with predefined shape and structure divided into zones depending on structural requirements in the knitting machine code. The projects of Hybrid Tower and Isotropia canopy (Thomsen et al., 2019) for Biennale 2018 use bespoke CNC-knitted textiles with complex structures. Working with bending-active systems, they perform as well the analysis of the textiles on macroscale within the rhino-grasshopper environment, using software like Kangaroo, Kiwi3D, SOFiSTiK ((La Magna et al., 2018)). ...
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Modern CNC weft knitting machines are capable to produce textiles with complex non-uniform structures and shapes in a single operation with minimum human intervention. The type of knit structure and the settings of the knitting machine significantly influence the fabric characteristics and its role in architectural comfort. However, there is still no open-access tool for fast and efficient analysis of textiles with consideration of their knit structure, especially if they are knitted non-uniformly. Moreover, the existing methodologies of digital modeling of the knit structure are not linked to the actual production of textiles on flat-bed knitting machines. This paper presents a tool that reads'' a bitmap image that can be as well imported into a knitting machine software and generates a yarn-level geometry of the knitted textiles, that can be further integrated into the behavior analysis software within the rhino-grasshopper environment. This methodology helps to preview and analyze knitted textiles before production and can help to optimize the programming of bespoke knitted textiles for large-scale architectural applications.
... KnitVault takes a point of departure in the research project Isoropia [16]. Developed for the 2018 Venice Biennale, it represents a CNC knitted membrane architecture based on a system of arches pulled into tension by a cable-net system. ...
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This paper examines the use of machine learning in creating digitally integrated design-to-fabrication workflows. As computational design allows for new methods of material specification and fabrication, it enables direct functional grading of material at high detail thereby tuning the design performance in response to performance criteria. However, the generation of fabrication data is often cumbersome and relies on in-depth knowledge of the fabrication processes. Parametric models that set up for automatic detailing of incremental changes, unfortunately, do not accommodate the larger topological changes to the material set up. The paper presents the speculative case study KnitVault . Based on earlier research projects Isoropia and Ombre , the study examines the use of machine learning to train models for fabrication data generation in response to desired performance criteria. KnitVault demonstrates and validates methods for shortcutting parametric interfacing and explores how the trained model can be employed in design cases that exceed the topology of the training examples.
The development of a thermal form-active composite, based on Oak-Paulownia-Flax materials is presented, including new knowledge and methods for material-driven responsive envelopes in an architectural scale. The study investigates, examines, and propose an experimental wood-textile structure that directly address questions on reducing embodied and operational energy in the built environment by a novel use of CO2 absorbing regenerative materials. Thermal-active wood bi-layers are combined with organic textiles to create a responsive and modular envelope element. This element is nested into a new lightweight load bearing BoxBeam-Zollinger structure, with flax textile surface connections. Both form active composite and load bearing structure is inspired by skin-on-frame material-structural concepts observed in vernacular boat cultures. The structure alone is measured to 1 kg/m2, with a combined weight of the entire responsive envelope of 4.3 kg/m2. The studies are based on experimental prototypes and computational simulation studies before a full-scale demonstrator project is constructed to test and disseminate the knowledge and methods for designing material efficient, thermally active architectural envelopes.
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Knitted composites are textile composite materials that consist of knitted textile reinforcement and polymer matrix. Knitted composites exhibit great design flexibility by allowing the customization of shapes, textures, and material properties. These features facilitate the optimization of buildings’ material systems and the creation of buildings with light weight and high material efficiency. To achieve such a lightweight, material-efficient building structure with knitted composites, this research investigates the material properties of knitted composites and proposes a design process for building-scale knitted composite systems. In the material study, this research examines certain mechanical properties of the material and the effects of additional design elements. In the design exploration, this research explores the design workflow of the structural form, element arrangement, and knit distribution of the material system at the macro-, meso-, and microscales. The project of MeiTing serves as proof of the concept and the design workflow.
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This study explores the design possibilities with knitted architectural textiles subjected to wind. The purpose is to investigate how such textiles could be applied to alter the usual static expression of exterior architectural and urban elements, such as facades and windbreaks. The design investigations were made on a manual knitting machine and on a CNC (computer numerically controlled) flat knitting machine. Four knitting techniques - tuck stitch, hanging stitches, false lace, and drop stitch - were explored based on their ability to create a three-dimensional effect on the surface level as well as on an architectural scale. Physical textile samples produced using those four techniques were subjected to controlled action of airflow. Digital experiments were also conducted, to probe the possibilities of digitally simulating textile behaviours in wind. The results indicate that especially the drop stitch technique exhibits interesting potentials. The variations in the drop stitch pattern generate both an aesthetic effect of volumetric expression of the textile architectural surface and seem beneficial in terms of wind speed reduction. Thus, these types of knitted textiles could be applied to design architecture that are efficient in terms of improving the aesthetic user experience and comfort in windy urban areas.
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This open access book is a compilation of selected papers from 2020 DigitalFUTURES—The 2nd International Conference on Computational Design and Robotic Fabrication (CDRF 2020). The book focuses on novel techniques for computational design and robotic fabrication. The contents make valuable contributions to academic researchers, designers, and engineers in the industry. As well, readers will encounter new ideas about understanding intelligence in architecture.
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CITA Complex Modelling investigates the infrastructures of architectural design models. By questioning the tools for integrating information across the expanded digital design chain, the book asks how to support feedback between different scales of design engagement moving from material design, across design, simulation and analysis to specification and fabrication. The book conveys the findings of the Complex Modelling research project a five-year framing project supported by the Independent Research Fund Denmark. Undertaken at CITA, the Centre for Information Technology and Architecture, The Royal Danish Academy of Fine Arts, School of Architecture, Complex Modelling asks how new interdisciplinary methods for adaptive parametrisation, advanced simulation, machine learning and robotic fabrication can be orchestrated within novel workflows that expand the agency of architecture. CITA Complex Modelling privileges the ‘how to’ of research and the maker-based inquisitiveness of design creation and gives insight into the nature and depth of considerations incorporated into the bespoke workflows developed in each project. By foregrounding deeper design-based explanations of the underlying computational and material methods, the book reveals the complex network of processes that merge design agency with analysis, simulation with prediction, parametrisation with open topological modelling and the practices of physical prototyping, fabrication testing and troubleshooting that form the projects.
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In this paper, we are presenting a design to fabrication system, which allows to produce efficiently and highly automated customised knitted textile elements for architectural application on industrial computer-controlled knitting machines (Computer Numerical Control (CNC) knitting machines). These textile elements can, in this way, be individual in both geometry, detailing and material behaviour. This work extends recent work on CNC knitted tensile members and presents a set of innovations in design and manufacturing, which together allow to build structural systems, in which highly individualised membrane members allow a structure to take on multiple structural states. Underlying these innovations is a shift from the focus on geometry and homogeneity in material and behaviour, expressed in current state-of-the-art membrane structures and materials. Instead our research lays the foundation for a new class of membrane materials with varying bespoke local material properties. In this paper we present the underlying digital tools and processes for design, analysis and manufacturing of these hyper specified textile membranes. We showcase and evaluate the potentials of Computational Knit for novel structural membrane systems through the large-scale installation Isoropia designed and built for the Danish Pavilion in the 2018 Venice Architectural Biennale.
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This paper discusses the design, simulation and construction of a bending-active textile hybrid structure commissioned to the authors as part of the 2018 Venice Biennale. The hybrid structure combines the flexibility and elastic properties of GFRP rods together with bespoke CNC knitted fabric, creating a subtle equilibrium of forces along the unfolding of the installation. Building on the knowledge developed by the authors on previous bending-active hybrid prototypes, the structure represents the latest effort in terms of integration of design analysis tools within a holistic and comprehensive workflow. This enables designers to step fluently from initial concept development and definition of overall shape to the final specification of the knitted membrane structure on loop level for digital fabrication. With particular emphasis on the simulation tools employed, the paper will focus on the most up-to-date computational technologies and numerical approaches that are currently being developed for the design and analysis of bending-active and textile hybrid structures. Specifically, three distinct environments were used to form-find and analyse the structural behaviour of the installation, these environments being Kangaroo (vector-based approach), Kiwi3d (Isogeometric Analysis) and SOFiSTiK (Finite Element Analysis). This all-encompassing approach provided the perfect platform to cross-benchmark the three different methods, highlighting the qualities of each one and providing valuable information on the most appropriate software within a certain stage of design.
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This paper presents the potentials of applied isogeometric finite element analysis by discussing a variety of case studies in the context of lightweight design. Isogeometric Analysis (IGA) is a modern, non-standard discretization approach for finite element analysis, which uses Non-Uniform Rational B-Splines (NURBS) to describe the geometry (CAD) as well as the physics (CAE) of the system within the same modelling environment. Consequently, the gap between design and analysis is greatly reduced, as one consistent mathematical model description is used throughout the entire design process. Hence, IGA allows to unveil new potentials in computer-aided structural engineering, as it enables a tighter link between the digital design environments of architecture and engineering. This potential is highlighted in the paper through a series of case studies which were developed using the Rhino/Grasshopper plugin Kiwi3d. The case studies shown include form finding, complex non-linear analysis, as well as the simulation of building and assembly processes.
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This paper describes the design and fabrication of the ICD/ITKE Research Pavilion 2016/2017, the most recent in the series of experimental installations developed as an outcome of the design-and-build studio of the ITECH Masters Programme. The completed structure is a 12m long cantilevering lattice-composite shell that was wound in one piece by a multi-machine fabrication system using coreless filament winding. To realise such a structure through this fabrication process involved a negotiation between architectural design, structural requirements and fabrication constraints, details of which are found in this paper. Technical details of the multi-machine fabrication system were previously described in Felbrich et al. [1].
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Form-active hybrid structures (FAHS) couple two or more different structural elements of low self weight and low or negligible bending flexural stiffness (such as slender beams, cables and membranes) into one structural assembly of high global stiffness. They offer high load-bearing capacity at a fraction of the weight of traditional building elements and do so with a clear aesthetic expression of force flow and equilibrium. The design of FAHS is limited by one significant restriction: the geometry definition, form-finding and structural analysis are typically performed in separate and bespoke software packages which introduce interruptions and data exchange issues in the modelling pipeline. The mechanical precision, stability and open software architecture of Kangaroo has facilitated the development of proof-of-concept modelling pipelines which tackle this challenge and enable powerful materially-informed sketching. Making use of a projection-based dynamic relaxation solver for structural analysis, explorative design has proven to be highly effective.
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Membrane architecture uses currently off the shelf materials and produces the shapes and details through cutting and laborsome joining of textile patterns. This paper discusses investigations into an alternative material practice - knit - which engages bespoke membrane materials. A practice which allows for customised and graded material properties, the direct fabrication of shaped patterns and the integration of detailing directly into the membrane material. Based on two demonstrators built as hybrids of bespoke CNC knit and bending active GFRP rods this paper discusses the affordances and procedures, which this new practice of digital fabrication of membrane material requires. The central focus is set on the interaction between the involved disciplines and the emerging iterative process of design, material specification, prototyping, evaluation, (re-)design and (re-)specification. We discuss how design and engineering practices change, when material properties move from given and constant into the area of design and gradient.
Form-finding processes are an integral part of structural design. Because of their limitations, the classic approaches to finding a form – such as hanging models and the soap-film analogy – play only a minor role. The various possibilities of digital experimentation in the context of structural optimisation create new options for the designer generating forms, while enabling control over a wide variety of parameters. A complete mapping of the mechanical properties of a structure in a continuum mechanics model is possible but so are simplified modelling strategies which take into account only the most important properties of the structure, such as iteratively approximating to a solution via representations of kinematic states. Form finding is thus an extremely complex process, determined both by the freely selected parameters and by design decisions.
A novel formwork system is presented as a material saving, labour reducing and cost-effective solution for the casting of bespoke doubly curved concrete geometries. The approach uses a custom knit technical textile as a lightweight stay-in-place formwork with integrated solutions for the insertion of additional elements, and is fabricated as a nearly seamless fabric. Using weft knitting as the textile formation technique minimises the need for cutting patterns, sewing, welding or gluing, when compared to conventional weaving and gives the possibility to integrate channels, openings, have varying widths and directional material properties, thus broadening the geometric design space. The system has been tested through a small-scale concrete footbridge prototype, built using a pre-stressed hybrid knitted textile and a bending-active structure that acted as a waste-free, stay-in-place, self-supporting formwork. Through the gradual buildup of strength in thin layers of concrete, formwork deformations during casting were minimised. This allowed for low tensioning of the fabric and the possibility to use more pressure (e.g. during shotcreting) in applying the subsequent concrete without intermediate support from below. The computational design and fabrication of the knitted textile formwork included integrated channels for the insertion of bending-active rods, tensioning ribbons and features for controlling the concrete casting. The analysis and process of increasing the stiffness of the lightweight and flexible formwork is presented. The hybrid approach results in an ultra-lightweight formwork that is easily transportable and significantly reduces the need for falsework support and scaffolding, which has many advantages on the construction site.
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The exhibition design for It’s a SMALL World explores how non-standardised design practices can make new use of old materials. Developing bespoke interfaces for digital design and fabrication the exhibition design investigates how these techniques allow us to rethink the traditional boundaries between architect and builder, designer and craftsman (Kolarevic 2008). Non- Standard-Practice and the new understanding of craftsmanship in design and architecture are the driving questions within the travelling exhibition It’s a SMALL world that has its first show from 27. August 2009 to the 1. February 2010 in the Danish Design Centre in Copenhagen. The exhibition presents 18 designers, architects and people from the crafts that have an innovative take on the future questions of sustainability, new materials and technology. Their products challenge traditional Danish Design and are yet interconnected in the countries traits and the way they design. Curated by the Danish Design Centre, The Danish Architectural Centre and the Danish Crafts Organisation groups of three from the different disciplines were identified in 6 scenarios with distinct expression.
We present a new method for implicit time integration of physical systems. Our approach builds a bridge between nodal Finite Element methods and Position Based Dynamics, leading to a simple, efficient, robust, yet accurate solver that supports many different types of constraints. We propose specially designed energy potentials that can be solved efficiently using an alternating optimization approach. Inspired by continuum mechanics, we derive a set of continuum-based potentials that can be efficiently incorporated within our solver. We demonstrate the generality and robustness of our approach in many different applications ranging from the simulation of solids, cloths, and shells, to example-based simulation. Comparisons to Newton-based and Position Based Dynamics solvers highlight the benefits of our formulation.
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This paper presents an enquiry into how to inform material systems that allow for a high degree of variation and gradation of their material composition. Presenting knit as a particular system of material fabrication, we discuss how new practices that integrate material design into the architectural design chain presents new opportunities and challenges to how we understand and create cycles of design, analysis, specification and fabrication. By tracing current interdisciplinary efforts in establishing simulation methods for knitted textiles, our aim is to question how these efforts can be understood and extended in the context of knitted architectural textiles. The paper draws on a number of projects that prototype methods for using simulation and sensing as grounds for informing the design of complex, heterogeneous and performative materials. It asks how these methods can allow feedback in the design chain and be interfaced with highly craft based methods of fabrication.