2024
Journal article
Restricted
Bending-reinforced grid shells for free-form architectural surfaces
Laccone F., Pietroni N., Cignoni P., Malomo L.
We introduce a new method for designing reinforcement for grid shells and improving their resistance to out-of-plane forces inducing bending. The central concept is to support the base network of elements with an additional layer of beams placed at a certain distance from the base surface. We exploit two main techniques to design these structures: first, we derive the orientation of the beam network on a given initial surface forming the grid shell to be reinforced; then, we compute the height of the additional layer that maximizes its overall structural performance. Our method includes a new formulation to derive a smooth direction field that orients the quad remeshing and a novel algorithm that iteratively optimizes the height of the additional layer to minimize the structure's compliance. We couple our optimization strategy with a set of constraints to improve buildability of the network and, simultaneously, preserve the initial surface. We showcase our method on a significant dataset of shapes to demonstrate its applicability to cases where free-form grid shells do not exhibit adequate structural performance due to their geometry.Source: Computer Aided Design 168 (2024). doi:10.1016/j.cad.2023.103670
DOI: 10.1016/j.cad.2023.103670
Metrics:
Laccone F., Pietroni N., Cignoni P., Malomo L.
We introduce a new method for designing reinforcement for grid shells and improving their resistance to out-of-plane forces inducing bending. The central concept is to support the base network of elements with an additional layer of beams placed at a certain distance from the base surface. We exploit two main techniques to design these structures: first, we derive the orientation of the beam network on a given initial surface forming the grid shell to be reinforced; then, we compute the height of the additional layer that maximizes its overall structural performance. Our method includes a new formulation to derive a smooth direction field that orients the quad remeshing and a novel algorithm that iteratively optimizes the height of the additional layer to minimize the structure's compliance. We couple our optimization strategy with a set of constraints to improve buildability of the network and, simultaneously, preserve the initial surface. We showcase our method on a significant dataset of shapes to demonstrate its applicability to cases where free-form grid shells do not exhibit adequate structural performance due to their geometry.Source: Computer Aided Design 168 (2024). doi:10.1016/j.cad.2023.103670
DOI: 10.1016/j.cad.2023.103670
Metrics:
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| CNR ExploRA
2023
Conference article
Open Access
A geometry-preserving shape optimization tool based on deep learning
Favilli A., Laccone F., Cignoni P., Malomo L., Giorgi D.
In free-form architecture, computational design tools have made it easy to create geometric models. However, obtaining good structural performance is difficult and requires further steps, such as shape optimization, to enhance system efficiency and material savings. This paper provides a user interface for form-finding and shape optimization of triangular grid shells. Users can minimize structural compliance, while ensuring small changes in their original design. A graph neural network learns to update the nodal coordinates of the grid shell to reduce a loss function based on strain energy. The interface can manage complex shapes and irregular tessellations. A variety of examples prove the effectiveness of the tool.Source: IWSS 2023 - Italian Workshop on Shell and Spatial Structures, pp. 549–558, Torino, Italy, 26-28/06/2023
DOI: 10.1007/978-3-031-44328-2_57
Metrics:
Favilli A., Laccone F., Cignoni P., Malomo L., Giorgi D.
In free-form architecture, computational design tools have made it easy to create geometric models. However, obtaining good structural performance is difficult and requires further steps, such as shape optimization, to enhance system efficiency and material savings. This paper provides a user interface for form-finding and shape optimization of triangular grid shells. Users can minimize structural compliance, while ensuring small changes in their original design. A graph neural network learns to update the nodal coordinates of the grid shell to reduce a loss function based on strain energy. The interface can manage complex shapes and irregular tessellations. A variety of examples prove the effectiveness of the tool.Source: IWSS 2023 - Italian Workshop on Shell and Spatial Structures, pp. 549–558, Torino, Italy, 26-28/06/2023
DOI: 10.1007/978-3-031-44328-2_57
Metrics:
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| CNR ExploRA
2023
Conference article
Open Access
Static- and fabrication-aware segmented concrete shells made of post-tensioned precast flat tiles
Laccone F., Menicagli S., Cignoni P., Malomo L.
This paper introduces a novel structural concept for freeform shells, in which the shape is decomposed into flat tiles to be assembled sequentially with the help of falseworks. Once the structure is completed, the tiles are post-tensioned to minimize the tension forces and avoid detachment. The entire design process, from an input shape to fabrication, is managed by an automatic pipeline. The input shape is segmented into a field-aligned quad mesh, computed from the principal stress of the thin shell. The flat tiles are obtained by extruding each face along the normal of the best-fitting plane per face. The contact between adjacent tiles is ensured only at their edge midpoints so the forces can mainly flow along the cross directions. The best configuration of cable paths and pre-loads is found by solving a constrained optimization problem exploiting a reduced beam model of the shell. All tiles can be prefabricated in the shop with an adaptable and reusable molding system. Once the structure is completed, the top surface is finally completed with an in situ cast that fills the gaps and activates the entire shell behavior. In contrast, the bottom surface maintains its jagged aesthetics.Source: IWSS 2023 - Italian Workshop on Shell and Spatial Structures, pp. 1–10, Turin, Italy, 26-28/06/2023
DOI: 10.1007/978-3-031-44328-2_1
Metrics:
Laccone F., Menicagli S., Cignoni P., Malomo L.
This paper introduces a novel structural concept for freeform shells, in which the shape is decomposed into flat tiles to be assembled sequentially with the help of falseworks. Once the structure is completed, the tiles are post-tensioned to minimize the tension forces and avoid detachment. The entire design process, from an input shape to fabrication, is managed by an automatic pipeline. The input shape is segmented into a field-aligned quad mesh, computed from the principal stress of the thin shell. The flat tiles are obtained by extruding each face along the normal of the best-fitting plane per face. The contact between adjacent tiles is ensured only at their edge midpoints so the forces can mainly flow along the cross directions. The best configuration of cable paths and pre-loads is found by solving a constrained optimization problem exploiting a reduced beam model of the shell. All tiles can be prefabricated in the shop with an adaptable and reusable molding system. Once the structure is completed, the top surface is finally completed with an in situ cast that fills the gaps and activates the entire shell behavior. In contrast, the bottom surface maintains its jagged aesthetics.Source: IWSS 2023 - Italian Workshop on Shell and Spatial Structures, pp. 1–10, Turin, Italy, 26-28/06/2023
DOI: 10.1007/978-3-031-44328-2_1
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2023
Conference article
Open Access
Statics and stability of bending-optimized double-layer grid shell
Laccone F., Pietroni N., Froli M., Cignoni P., Malomo L.
Grid shell structures are optimal when considering their aesthetics and lightness, but their efficiency is highly reduced when their shape deviates from a pure membrane. Many contemporary architectures possess a freeform shape, conceived mostly on aesthetics and functional criteria. In these cases, finding an efficient grid shell often requires substantial shape modifications. This work addresses a new kind of doublelayer structure that aims to preserve the desired shape design. The structural system comprises a quad-meshed grid shell aligned to the target shape and enriched with an additional reinforcement layer that adds bending stiffness. This additional layer, going inward and outward of the main surface, presents variable height and discontinuous elements based on the required bending strength. The obtained structural system differs from both grid shells, as these latter may be very deformable in this setup, and from classic double-layer structures (space frames), which are heavier and redundant. In this paper, we show how the presented system compares with grid shell and double-layer competitors in terms of statics and stability. We highlight the pros and cons based on a systematic comparative analysis run on selected freeform shapes.Source: IWSS 2023 - Italian Workshop on Shell and Spatial Structures, pp. 569–578, Turin, Italy, 26-28/06/2023
DOI: 10.1007/978-3-031-44328-2_59
Metrics:
Laccone F., Pietroni N., Froli M., Cignoni P., Malomo L.
Grid shell structures are optimal when considering their aesthetics and lightness, but their efficiency is highly reduced when their shape deviates from a pure membrane. Many contemporary architectures possess a freeform shape, conceived mostly on aesthetics and functional criteria. In these cases, finding an efficient grid shell often requires substantial shape modifications. This work addresses a new kind of doublelayer structure that aims to preserve the desired shape design. The structural system comprises a quad-meshed grid shell aligned to the target shape and enriched with an additional reinforcement layer that adds bending stiffness. This additional layer, going inward and outward of the main surface, presents variable height and discontinuous elements based on the required bending strength. The obtained structural system differs from both grid shells, as these latter may be very deformable in this setup, and from classic double-layer structures (space frames), which are heavier and redundant. In this paper, we show how the presented system compares with grid shell and double-layer competitors in terms of statics and stability. We highlight the pros and cons based on a systematic comparative analysis run on selected freeform shapes.Source: IWSS 2023 - Italian Workshop on Shell and Spatial Structures, pp. 569–578, Turin, Italy, 26-28/06/2023
DOI: 10.1007/978-3-031-44328-2_59
Metrics:
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ISTI Repository | link.springer.com | CNR ExploRA
2023
Conference article
Open Access
Computational design of fabricable geometric patterns
Scandurra E., Laccone F., Malomo L., Callieri M., Cignoni P., Giorgi D.
This paper addresses the design of surfaces as assemblies of geometric patterns with predictable performance in response to mechanical stimuli. We design a family of tileable and fabricable patterns represented as triangle meshes, which can be assembled for creating surface tessellations. First, a regular recursive subdivision of the planar space generates different geometric configurations for candidate patterns, having interesting and varied aesthetic properties. Then, a refinement step addresses manufacturability by solving for non-manifold configurations and sharp angles which would produce disconnected or fragile patterns. We simulate our patterns to evaluate their mechanical response when loaded in different scenarios targeting out-of-plane bending. Through a simple browsing interface, we show that our patterns span a variety of different bending behaviors. The result is a library of patterns with varied aesthetics and predefined mechanical behavior, to use for the direct design of mechanical metamaterials. To assess the feasibility of our approach, we show a pair of fabricated 3D objects with different curvatures.Source: STAG 2023 - Smart Tools and Applications in Graphics 2023 - Eurographics Italian Chapter Conference, pp. 81–91, Matera, Italy, 16-17/11/2023
DOI: 10.2312/stag.20231297
Metrics:
Scandurra E., Laccone F., Malomo L., Callieri M., Cignoni P., Giorgi D.
This paper addresses the design of surfaces as assemblies of geometric patterns with predictable performance in response to mechanical stimuli. We design a family of tileable and fabricable patterns represented as triangle meshes, which can be assembled for creating surface tessellations. First, a regular recursive subdivision of the planar space generates different geometric configurations for candidate patterns, having interesting and varied aesthetic properties. Then, a refinement step addresses manufacturability by solving for non-manifold configurations and sharp angles which would produce disconnected or fragile patterns. We simulate our patterns to evaluate their mechanical response when loaded in different scenarios targeting out-of-plane bending. Through a simple browsing interface, we show that our patterns span a variety of different bending behaviors. The result is a library of patterns with varied aesthetics and predefined mechanical behavior, to use for the direct design of mechanical metamaterials. To assess the feasibility of our approach, we show a pair of fabricated 3D objects with different curvatures.Source: STAG 2023 - Smart Tools and Applications in Graphics 2023 - Eurographics Italian Chapter Conference, pp. 81–91, Matera, Italy, 16-17/11/2023
DOI: 10.2312/stag.20231297
Metrics:
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diglib.eg.org | ISTI Repository | CNR ExploRA
2023
Journal article
Open Access
Geometric deep learning for statics-aware grid shells
Favilli A., Laccone F., Cignoni P., Malomo L., Giorgi D.
This paper introduces a novel method for shape optimization and form-finding of free-form, triangular grid shells, based on geometric deep learning. We define an architecture which consumes a 3D mesh representing the initial design of a free-form grid shell, and outputs vertex displacements to get an optimized grid shell that minimizes structural compliance, while preserving design intent. The main ingredients of the architecture are layers that produce deep vertex embeddings from geometric input features, and a differentiable loss implementing structural analysis. We evaluate the method performance on a benchmark of eighteen free-form grid shell structures characterized by various size, geometry, and tessellation. Our results demonstrate that our approach can solve the shape optimization and form finding problem for a diverse range of structures, more effectively and efficiently than existing common tools.Source: Computers & structures 292 (2023). doi:10.1016/j.compstruc.2023.107238
DOI: 10.1016/j.compstruc.2023.107238
Metrics:
Favilli A., Laccone F., Cignoni P., Malomo L., Giorgi D.
This paper introduces a novel method for shape optimization and form-finding of free-form, triangular grid shells, based on geometric deep learning. We define an architecture which consumes a 3D mesh representing the initial design of a free-form grid shell, and outputs vertex displacements to get an optimized grid shell that minimizes structural compliance, while preserving design intent. The main ingredients of the architecture are layers that produce deep vertex embeddings from geometric input features, and a differentiable loss implementing structural analysis. We evaluate the method performance on a benchmark of eighteen free-form grid shell structures characterized by various size, geometry, and tessellation. Our results demonstrate that our approach can solve the shape optimization and form finding problem for a diverse range of structures, more effectively and efficiently than existing common tools.Source: Computers & structures 292 (2023). doi:10.1016/j.compstruc.2023.107238
DOI: 10.1016/j.compstruc.2023.107238
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2022
Conference article
Open Access
Exploratory study on a segmented shell made of recycled-HDPE plastic
Laccone F., Manolas I., Malomo L., Cignoni P.
Recycled HDPE plastic can be obtained from up to 100% waste material and can be produced in the shape of panels and rods. The aim of this work is to explore the possibility to employ this material for structural purposes. The proposed concept for segmented shells is based on the cassette system, namely a spatial waffle structure clamped by inner and outer plates, and a shaping strategy of the shell cross section targeted on bending. The concept is applied on translational surfaces, in which the transverse cross section serves as the shaping objective. A digital workflow is implemented to explore the possible solutions and to evaluate the shells' feasibility from both a fabrication and a structural point of view. A case study of 5.2 meters is further explored with nonlinear analysis.Source: IASS 2020/21 - Inspiring the Next Generation. The 7th International Conference on Spatial Structures and the Annual Symposium of the IASS, pp. 1859–1870, University of Surrey, UK, 23-27/08/2021
DOI: 10.15126/900337
Project(s): EVOCATION
Metrics:
Laccone F., Manolas I., Malomo L., Cignoni P.
Recycled HDPE plastic can be obtained from up to 100% waste material and can be produced in the shape of panels and rods. The aim of this work is to explore the possibility to employ this material for structural purposes. The proposed concept for segmented shells is based on the cassette system, namely a spatial waffle structure clamped by inner and outer plates, and a shaping strategy of the shell cross section targeted on bending. The concept is applied on translational surfaces, in which the transverse cross section serves as the shaping objective. A digital workflow is implemented to explore the possible solutions and to evaluate the shells' feasibility from both a fabrication and a structural point of view. A case study of 5.2 meters is further explored with nonlinear analysis.Source: IASS 2020/21 - Inspiring the Next Generation. The 7th International Conference on Spatial Structures and the Annual Symposium of the IASS, pp. 1859–1870, University of Surrey, UK, 23-27/08/2021
DOI: 10.15126/900337
Project(s): EVOCATION
Metrics:
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ISTI Repository | openresearch.surrey.ac.uk | CNR ExploRA
2022
Journal article
Open Access
Automated generation of flat tileable patterns and 3D reduced model simulation
Manolas I., Laccone F., Cherchi G., Malomo L., Cignoni P.
The computational fabrication community is developing an increasing interest in the use of patterned surfaces, which can be designed to show ornamental and unconventional aesthetics or to perform as a proper structural material with a wide range of features. Geometrically designing and controlling the deformation capabilities of these patterns in response to external stimuli is a complex task due to the large number of variables involved. This paper introduces a method for generating sets of tileable and exchangeable flat patterns as well as a model-reduction strategy that enables their mechanical simulation at interactive rates. This method is included in a design pipeline that aims to turn any general flat surface into a pattern tessellation, which is able to deform under a given loading scenario. To validate our approach, we apply it to different contexts, including real-scale 3D printed specimens, for which we compare our results with the ones provided by a ground-truth solver.Source: Computers & graphics 106 (2022): 141–151. doi:10.1016/j.cag.2022.05.020
DOI: 10.1016/j.cag.2022.05.020
Project(s): EVOCATION
Metrics:
Manolas I., Laccone F., Cherchi G., Malomo L., Cignoni P.
The computational fabrication community is developing an increasing interest in the use of patterned surfaces, which can be designed to show ornamental and unconventional aesthetics or to perform as a proper structural material with a wide range of features. Geometrically designing and controlling the deformation capabilities of these patterns in response to external stimuli is a complex task due to the large number of variables involved. This paper introduces a method for generating sets of tileable and exchangeable flat patterns as well as a model-reduction strategy that enables their mechanical simulation at interactive rates. This method is included in a design pipeline that aims to turn any general flat surface into a pattern tessellation, which is able to deform under a given loading scenario. To validate our approach, we apply it to different contexts, including real-scale 3D printed specimens, for which we compare our results with the ones provided by a ground-truth solver.Source: Computers & graphics 106 (2022): 141–151. doi:10.1016/j.cag.2022.05.020
DOI: 10.1016/j.cag.2022.05.020
Project(s): EVOCATION
Metrics:
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ISTI Repository | www.sciencedirect.com | CNR ExploRA
2022
Doctoral thesis
Restricted
Computational methods for improving manufacturing processes
Alderighi T.
The last two decades have seen a rapid and wide growth of digital fabrication machinery and technologies. This led to a massive diffusion of such technologies both in the industrial setting and within the hobbyists' and makers' communities. While the applications to rapid prototyping and simple download-and-print use cases can be trivial, the design space offered by these numerically controlled technologies (i.e., 3D printing, CNC milling, laser cutting, etc.) is hard to exploit without the support of appropriate computational tools and algorithms. Within this thesis, we investigate how the potential of common rapid prototyping tools, combined with sound computational methods, can be used to provide novel and alternative fabrication methods and to enhance existing ones, making them available to non-expert users. In particular, the contributions presented in this thesis are four. The first is a novel technique for the automatic design of flexible molds to cast highly complex shapes. The algorithm is based on an innovative volumetric analysis of the mold volume that defines the layout of the internal cuts needed to open the mold. We show how the method can robustly generate valid molds for shapes with high topological and geometrical complexity for which previous existing methods could not provide any solution. The second contribution is a method for the automatic volumetric decomposition of objects in parts that can be cast using two-piece reusable rigid molds. Automating the design of this kind of molds can directly impact industrial applications, where the use of two-piece, reusable, rigid molds is a de-facto standard, for example, in plastic injection molding machinery. The third contribution is a pipeline for the fabrication of tangible media for the study of complex biological entities and their interactions. The method covers the whole pipeline from molecular surface preparation and editing to actual 3D model fab- rication. Moreover, we investigated the use of these tangible models as teaching aid in high school classrooms. Finally, the fourth contribution tackles another important problem related to the fabrication of parts using FDM 3D printing technologies. With this method, we present an automatic optimization algorithm for the decomposition of objects in parts that can be individually 3D printed and then assembled, with the goal of minimizing the visual impact of supports artifacts.
Alderighi T.
The last two decades have seen a rapid and wide growth of digital fabrication machinery and technologies. This led to a massive diffusion of such technologies both in the industrial setting and within the hobbyists' and makers' communities. While the applications to rapid prototyping and simple download-and-print use cases can be trivial, the design space offered by these numerically controlled technologies (i.e., 3D printing, CNC milling, laser cutting, etc.) is hard to exploit without the support of appropriate computational tools and algorithms. Within this thesis, we investigate how the potential of common rapid prototyping tools, combined with sound computational methods, can be used to provide novel and alternative fabrication methods and to enhance existing ones, making them available to non-expert users. In particular, the contributions presented in this thesis are four. The first is a novel technique for the automatic design of flexible molds to cast highly complex shapes. The algorithm is based on an innovative volumetric analysis of the mold volume that defines the layout of the internal cuts needed to open the mold. We show how the method can robustly generate valid molds for shapes with high topological and geometrical complexity for which previous existing methods could not provide any solution. The second contribution is a method for the automatic volumetric decomposition of objects in parts that can be cast using two-piece reusable rigid molds. Automating the design of this kind of molds can directly impact industrial applications, where the use of two-piece, reusable, rigid molds is a de-facto standard, for example, in plastic injection molding machinery. The third contribution is a pipeline for the fabrication of tangible media for the study of complex biological entities and their interactions. The method covers the whole pipeline from molecular surface preparation and editing to actual 3D model fab- rication. Moreover, we investigated the use of these tangible models as teaching aid in high school classrooms. Finally, the fourth contribution tackles another important problem related to the fabrication of parts using FDM 3D printing technologies. With this method, we present an automatic optimization algorithm for the decomposition of objects in parts that can be individually 3D printed and then assembled, with the goal of minimizing the visual impact of supports artifacts.
See at:
etd.adm.unipi.it | CNR ExploRA
2022
Journal article
Open Access
Design and construction of a bending-active plywood structure: the Flexmaps Pavilion
Laccone F., Malomo L., Callieri M., Alderighi T., Muntoni A., Ponchio F., Pietroni N., Cignoni P.
Mesostructured patterns are a modern and efficient concept based on designing the geometry of structural material at the meso-scale to achieve desired mechanical performances. In the context of bending-active structures, such a concept can be used to control the flexibility of the panels forming a surface without changing the constituting material. These panels undergo a formation process of deformation by bending, and application of internal restraints. This paper describes a new constructional system, FlexMaps, that has initiated the adoption of bending-active mesostructures at the architectural scale. Here, these modules are in the form of four-arms spirals made of CNC-milled plywood and are designed to reach the desired target shape once assembled. All phases from the conceptual design to the fabrication are seamlessly linked within an automated workflow. To illustrate the potential of the system, the paper discusses the results of a demonstrator project entitled FlexMaps Pavilion (3.90x3.96x3.25 meters) that has been exhibited at the IASS Symposium in 2019 and more recently at the 2021 17th International Architecture Exhibition, La Biennale di Venezia. The structural response is investigated through a detailed structural analysis, and the long-term behavior is assessed through a photogrammetric survey.Source: Journal of the International Association for Shell and Spatial Structures 63 (2022): 98–114. doi:10.20898/j.iass.2022.007
DOI: 10.20898/j.iass.2022.007
Metrics:
Laccone F., Malomo L., Callieri M., Alderighi T., Muntoni A., Ponchio F., Pietroni N., Cignoni P.
Mesostructured patterns are a modern and efficient concept based on designing the geometry of structural material at the meso-scale to achieve desired mechanical performances. In the context of bending-active structures, such a concept can be used to control the flexibility of the panels forming a surface without changing the constituting material. These panels undergo a formation process of deformation by bending, and application of internal restraints. This paper describes a new constructional system, FlexMaps, that has initiated the adoption of bending-active mesostructures at the architectural scale. Here, these modules are in the form of four-arms spirals made of CNC-milled plywood and are designed to reach the desired target shape once assembled. All phases from the conceptual design to the fabrication are seamlessly linked within an automated workflow. To illustrate the potential of the system, the paper discusses the results of a demonstrator project entitled FlexMaps Pavilion (3.90x3.96x3.25 meters) that has been exhibited at the IASS Symposium in 2019 and more recently at the 2021 17th International Architecture Exhibition, La Biennale di Venezia. The structural response is investigated through a detailed structural analysis, and the long-term behavior is assessed through a photogrammetric survey.Source: Journal of the International Association for Shell and Spatial Structures 63 (2022): 98–114. doi:10.20898/j.iass.2022.007
DOI: 10.20898/j.iass.2022.007
Metrics:
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ISTI Repository | CNR ExploRA
2022
Report
Closed Access
Statics-aware 3D gridshells: a differential approach towards shape optimization
Favilli A., Giorgi D., Laccone F., Malomo L., Cignoni P.
In the context of architecture, gridshells are three-dimensional frame structures in which loads are entirely born by edges, or beams. Our contribution is to draw the way to a computational method that, given an input gridshell provided by a designer, slightly changes the input to ensure good static performance. The changing is induced by structure node repositioning. If the gridshell is represented as a surface mesh, the problem boils down to finding a proper vertex displacement. The vertex displacement should strike a happy medium between structure rigidity, with load deformation as low as possible, and structure resistance, preventing stress caused breaks. In this report, we introduce a shape optimization strategy based on automatic differentiation of a loss function, which embeds the static equilibrium problem of a girdshell.Source: ISTI Technical Report, ISTI-2022-TR/017, 2022
DOI: 10.32079/isti-tr-2022/017
Metrics:
Favilli A., Giorgi D., Laccone F., Malomo L., Cignoni P.
In the context of architecture, gridshells are three-dimensional frame structures in which loads are entirely born by edges, or beams. Our contribution is to draw the way to a computational method that, given an input gridshell provided by a designer, slightly changes the input to ensure good static performance. The changing is induced by structure node repositioning. If the gridshell is represented as a surface mesh, the problem boils down to finding a proper vertex displacement. The vertex displacement should strike a happy medium between structure rigidity, with load deformation as low as possible, and structure resistance, preventing stress caused breaks. In this report, we introduce a shape optimization strategy based on automatic differentiation of a loss function, which embeds the static equilibrium problem of a girdshell.Source: ISTI Technical Report, ISTI-2022-TR/017, 2022
DOI: 10.32079/isti-tr-2022/017
Metrics:
See at: CNR ExploRA
2022
Report
Closed Access
Geometric deep learning for statics-aware 3D gridshells
Favilli A., Giorgi D., Laccone F., Malomo L., Cignoni P.
In the context of architecture, gridshells are three-dimensional frame structures in which loads are entirely born by edges, or beams. Our contribution is to draw the way to a computational method that, given an input gridshell provided by a designer, slightly changes the input to ensure good static performance. The changing is induced by structure node repositioning. If the gridshell is represented as a surface mesh, the problem boils down to finding a proper vertex displacement. The vertex displacement should strike a happy medium between structure rigidity, with load deformation as low as possible, and structure resistance, preventing stress caused breaks. In this report, we inculde a solution to solve this mesh vertex displacement learning problem with a target goal of reducing a physically-based loss function, namely the mean strain energy of a gridshell, by means of a graph neural network. We adopt several geometric input features and discuss their effects on the results.Source: ISTI Technical Report, ISTI-2022-TR/016, 2022
DOI: 10.32079/isti-tr-2022/016
Metrics:
Favilli A., Giorgi D., Laccone F., Malomo L., Cignoni P.
In the context of architecture, gridshells are three-dimensional frame structures in which loads are entirely born by edges, or beams. Our contribution is to draw the way to a computational method that, given an input gridshell provided by a designer, slightly changes the input to ensure good static performance. The changing is induced by structure node repositioning. If the gridshell is represented as a surface mesh, the problem boils down to finding a proper vertex displacement. The vertex displacement should strike a happy medium between structure rigidity, with load deformation as low as possible, and structure resistance, preventing stress caused breaks. In this report, we inculde a solution to solve this mesh vertex displacement learning problem with a target goal of reducing a physically-based loss function, namely the mean strain energy of a gridshell, by means of a graph neural network. We adopt several geometric input features and discuss their effects on the results.Source: ISTI Technical Report, ISTI-2022-TR/016, 2022
DOI: 10.32079/isti-tr-2022/016
Metrics:
See at: CNR ExploRA
2022
Journal article
Open Access
State of the art in computational mould design
Alderighi T., Malomo L., Auzinger T., Bickel B., Cignoni P., Pietroni N.
Moulding refers to a set of manufacturing techniques in which a mould, usually a cavity or a solid frame, is used to shape a liquid or pliable material into an object of the desired shape. The popularity of moulding comes from its effectiveness, scalability and versatility in terms of employed materials. Its relevance as a fabrication process is demonstrated by the extensive literature covering different aspects related to mould design, from material flow simulation to the automation of mould geometry design. In this state-of-the-art report, we provide an extensive review of the automatic methods for the design of moulds, focusing on contributions from a geometric perspective. We classify existing mould design methods based on their computational approach and the nature of their target moulding process. We summarize the relationships between computational approaches and moulding techniques, highlighting their strengths and limitations. Finally, we discuss potential future research directions.Source: Computer graphics forum (Print) (2022). doi:10.1111/cgf.14581
DOI: 10.1111/cgf.14581
Metrics:
Alderighi T., Malomo L., Auzinger T., Bickel B., Cignoni P., Pietroni N.
Moulding refers to a set of manufacturing techniques in which a mould, usually a cavity or a solid frame, is used to shape a liquid or pliable material into an object of the desired shape. The popularity of moulding comes from its effectiveness, scalability and versatility in terms of employed materials. Its relevance as a fabrication process is demonstrated by the extensive literature covering different aspects related to mould design, from material flow simulation to the automation of mould geometry design. In this state-of-the-art report, we provide an extensive review of the automatic methods for the design of moulds, focusing on contributions from a geometric perspective. We classify existing mould design methods based on their computational approach and the nature of their target moulding process. We summarize the relationships between computational approaches and moulding techniques, highlighting their strengths and limitations. Finally, we discuss potential future research directions.Source: Computer graphics forum (Print) (2022). doi:10.1111/cgf.14581
DOI: 10.1111/cgf.14581
Metrics:
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ISTI Repository | CNR ExploRA
2022
Journal article
Restricted
Vorogrid: a static-aware variable-density Voronoi mesh to design the tube structure tessellation of tall buildings
Laccone F., Gaudioso D., Malomo L., Cignoni P., Froli M.
In the context of tall building design, the tube concept represents one of the most performing systems. The diagrid is the widespread type of tube system and consists of a diagonal grid of beams that wraps the building, forming a diamond pattern. It performs as lateral bracing and is additionally able to sustain vertical loading through axial forces. Despite its efficiency, a growing interest is recently observed in alternative geometries to replace the diagrid pattern and improve the architectural impact conferred by the building skin aesthetics on the urban environment. The paper pursues the use of a Voronoimesh, in which the geometry of the cells is steered to known schemes for the structural design of a cantilever tube structure. The objective is to mimic a macroscopic structural behavior through a topology and sizemodification of the Voronoimesh that increases the density for creating resisting paths with higher stiffness. The paper proposes a novel method Vorogrid for designing a new class of tall buildings equipped with an organic-looking and mechanically sound tube structure, which makes them a valuable alternative to competitors (diagrid, hexagrid, random Voronoi). Diagrids and hexagrids still remain more efficient in terms of forces and displacements but are characterized by a more usual appearance, instead Vorogrid offers more design control and better performances on average with respect to random Voronoi structures. This method is streamed into a pipeline that includes grid initialization strategies, geometric and structural optimization to mitigate the effects of the grid randomness, and structural sizing.Source: Computer-aided civil and infrastructure engineering (Online) (2022): 1–19. doi:10.1111/mice.12912
DOI: 10.1111/mice.12912
Metrics:
Laccone F., Gaudioso D., Malomo L., Cignoni P., Froli M.
In the context of tall building design, the tube concept represents one of the most performing systems. The diagrid is the widespread type of tube system and consists of a diagonal grid of beams that wraps the building, forming a diamond pattern. It performs as lateral bracing and is additionally able to sustain vertical loading through axial forces. Despite its efficiency, a growing interest is recently observed in alternative geometries to replace the diagrid pattern and improve the architectural impact conferred by the building skin aesthetics on the urban environment. The paper pursues the use of a Voronoimesh, in which the geometry of the cells is steered to known schemes for the structural design of a cantilever tube structure. The objective is to mimic a macroscopic structural behavior through a topology and sizemodification of the Voronoimesh that increases the density for creating resisting paths with higher stiffness. The paper proposes a novel method Vorogrid for designing a new class of tall buildings equipped with an organic-looking and mechanically sound tube structure, which makes them a valuable alternative to competitors (diagrid, hexagrid, random Voronoi). Diagrids and hexagrids still remain more efficient in terms of forces and displacements but are characterized by a more usual appearance, instead Vorogrid offers more design control and better performances on average with respect to random Voronoi structures. This method is streamed into a pipeline that includes grid initialization strategies, geometric and structural optimization to mitigate the effects of the grid randomness, and structural sizing.Source: Computer-aided civil and infrastructure engineering (Online) (2022): 1–19. doi:10.1111/mice.12912
DOI: 10.1111/mice.12912
Metrics:
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onlinelibrary.wiley.com | CNR ExploRA
2022
Conference article
Open Access
A computational tool for the analysis of 3D bending-active structures based on the dynamic relaxation method
Manolas I., Laccone F., Cherchi G., Malomo L., Cignoni P.
The use of elastic deformation of straight or flat structural components for achieving complex 3D shapes has acquired attention from recent computational design works, particularly in architectural geometry. The so-called bending-active structures are built by deforming and restraining the components mutually to form a stable configuration. While the manufacturing of components from flat raw material and their assembly are simple and inexpensive, the complexity lies in the design phase, in which computational tools are required to predict the deformation and forces under a prescribed form-finding load or displacement. Currently, there is a scarcity of open and efficient tools that hinder the design of bending-active structures. This paper proposes and validates an open-source computational tool for predicting the static equilibrium of general bending-active structures in the form of a network of elements using the dynamic relaxation method. We apply our tool to various real-world examples and compare the results to a commercial FEM solver. The proposed tool shows accuracy and good time performance, making it a significant addition to the available open-source structural engineering toolkit.Source: Smart Tools and Applications in Graphics - Eurographics Italian Chapter Conference, Cagliari, Italy, 17-18/11/2022
DOI: 10.2312/stag.20221250
Project(s): EVOCATION
Metrics:
Manolas I., Laccone F., Cherchi G., Malomo L., Cignoni P.
The use of elastic deformation of straight or flat structural components for achieving complex 3D shapes has acquired attention from recent computational design works, particularly in architectural geometry. The so-called bending-active structures are built by deforming and restraining the components mutually to form a stable configuration. While the manufacturing of components from flat raw material and their assembly are simple and inexpensive, the complexity lies in the design phase, in which computational tools are required to predict the deformation and forces under a prescribed form-finding load or displacement. Currently, there is a scarcity of open and efficient tools that hinder the design of bending-active structures. This paper proposes and validates an open-source computational tool for predicting the static equilibrium of general bending-active structures in the form of a network of elements using the dynamic relaxation method. We apply our tool to various real-world examples and compare the results to a commercial FEM solver. The proposed tool shows accuracy and good time performance, making it a significant addition to the available open-source structural engineering toolkit.Source: Smart Tools and Applications in Graphics - Eurographics Italian Chapter Conference, Cagliari, Italy, 17-18/11/2022
DOI: 10.2312/stag.20221250
Project(s): EVOCATION
Metrics:
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diglib.eg.org | ISTI Repository | CNR ExploRA
2021
Journal article
Open Access
Computational design, fabrication and evaluation of rubber protein models
Alderighi T., Giorgi D., Malomo L., Cignoni P., Zoppè M.
Tangible 3D molecular models conceptualize complex phenomena in a stimulating and engaging format. This is especially true for learning environments, where additive manufacturing is increasingly used to produce teaching aids for chemical education. However, the 3D models presented previously are limited in the type of molecules they can represent and the amount of information they carry. In addition, they have little role in representing complex biological entities such as proteins. We present the first complete workflow for the fabrication of soft models of complex proteins of any size. We leverage on molding technologies to generate accurate, soft models which incorporate both spatial and functional aspects of large molecules. Our method covers the whole pipeline from molecular surface preparation and editing to actual 3D model fabrication. The models fabricated with our strategy can be used as aids to illustrate biological functional behavior, such as assembly in quaternary structure and docking mechanisms, which are difficult to convey with traditional visualization methods. We applied the proposed framework to fabricate a set of 3D protein models, and we validated the appeal of our approach in a classroom setting.Source: Computers & graphics 98 (2021): 177–187. doi:10.1016/j.cag.2021.05.010
DOI: 10.1016/j.cag.2021.05.010
Metrics:
Alderighi T., Giorgi D., Malomo L., Cignoni P., Zoppè M.
Tangible 3D molecular models conceptualize complex phenomena in a stimulating and engaging format. This is especially true for learning environments, where additive manufacturing is increasingly used to produce teaching aids for chemical education. However, the 3D models presented previously are limited in the type of molecules they can represent and the amount of information they carry. In addition, they have little role in representing complex biological entities such as proteins. We present the first complete workflow for the fabrication of soft models of complex proteins of any size. We leverage on molding technologies to generate accurate, soft models which incorporate both spatial and functional aspects of large molecules. Our method covers the whole pipeline from molecular surface preparation and editing to actual 3D model fabrication. The models fabricated with our strategy can be used as aids to illustrate biological functional behavior, such as assembly in quaternary structure and docking mechanisms, which are difficult to convey with traditional visualization methods. We applied the proposed framework to fabricate a set of 3D protein models, and we validated the appeal of our approach in a classroom setting.Source: Computers & graphics 98 (2021): 177–187. doi:10.1016/j.cag.2021.05.010
DOI: 10.1016/j.cag.2021.05.010
Metrics:
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ISTI Repository | Computers & Graphics | Computers & Graphics | www.sciencedirect.com | CNR ExploRA
2021
Journal article
Open Access
Integrated computational framework for the design and fabrication of bending-active structures made from flat sheet material
Laccone F., Malomo L., Pietroni N., Cignoni P., Schork T.
This paper introduces an integrated computational design framework for the design and realization of arbitrarily-curved bending-active architectural structures. The developed framework consists of a series of methods that enable the production of a complex 3D structures composed of a set of flat 2D panels whose mechanical properties are locally tuned by varying the shape of embedded spiraling patterns. The resulting panels perform as variable stiffness elements, and they are optimized to match a desired target shape once assembled together. The presented framework includes all the steps for the physical delivery of architectural objects, including conception, static assessment, and digital fabrication. The developed framework has been applied to an architectural scale prototype, which demonstrates the potential of integrating architectural design, computational simulation, structural engineering, and digital fabrication, opening up several possible novel applications in the building sector.Source: Structures (Oxford) 34 (2021): 979–994. doi:10.1016/j.istruc.2021.08.004
DOI: 10.1016/j.istruc.2021.08.004
Metrics:
Laccone F., Malomo L., Pietroni N., Cignoni P., Schork T.
This paper introduces an integrated computational design framework for the design and realization of arbitrarily-curved bending-active architectural structures. The developed framework consists of a series of methods that enable the production of a complex 3D structures composed of a set of flat 2D panels whose mechanical properties are locally tuned by varying the shape of embedded spiraling patterns. The resulting panels perform as variable stiffness elements, and they are optimized to match a desired target shape once assembled together. The presented framework includes all the steps for the physical delivery of architectural objects, including conception, static assessment, and digital fabrication. The developed framework has been applied to an architectural scale prototype, which demonstrates the potential of integrating architectural design, computational simulation, structural engineering, and digital fabrication, opening up several possible novel applications in the building sector.Source: Structures (Oxford) 34 (2021): 979–994. doi:10.1016/j.istruc.2021.08.004
DOI: 10.1016/j.istruc.2021.08.004
Metrics:
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ISTI Repository | ISTI Repository | www.sciencedirect.com | CNR ExploRA
2021
Journal article
Open Access
Volume decomposition for two-piece rigid casting
Alderighi T., Malomo L., Bickel B., Cignoni P., Pietroni N.
We introduce a novel technique to automatically decompose an input object's volume into a set of parts that can be represented by two opposite height fields. Such decomposition enables the manufacturing of individual parts using two-piece reusable rigid molds. Our decomposition strategy relies on a new energy formulation that utilizes a pre-computed signal on the mesh volume representing the accessibility for a predefined set of extraction directions. Thanks to this novel formulation, our method allows for efficient optimization of a fabrication-aware partitioning of volumes in a completely automatic way. We demonstrate the efficacy of our approach by generating valid volume partitionings for a wide range of complex objects and physically reproducing several of them.Source: ACM transactions on graphics 40 (2021). doi:10.1145/3478513.3480555
DOI: 10.1145/3478513.3480555
Project(s): MATERIALIZABLE
Metrics:
Alderighi T., Malomo L., Bickel B., Cignoni P., Pietroni N.
We introduce a novel technique to automatically decompose an input object's volume into a set of parts that can be represented by two opposite height fields. Such decomposition enables the manufacturing of individual parts using two-piece reusable rigid molds. Our decomposition strategy relies on a new energy formulation that utilizes a pre-computed signal on the mesh volume representing the accessibility for a predefined set of extraction directions. Thanks to this novel formulation, our method allows for efficient optimization of a fabrication-aware partitioning of volumes in a completely automatic way. We demonstrate the efficacy of our approach by generating valid volume partitionings for a wide range of complex objects and physically reproducing several of them.Source: ACM transactions on graphics 40 (2021). doi:10.1145/3478513.3480555
DOI: 10.1145/3478513.3480555
Project(s): MATERIALIZABLE
Metrics:
See at:
ISTI Repository | dl.acm.org | CNR ExploRA
2021
Conference article
Open Access
A high quality 3D controller for mobile and desktop web applications
Fornari D., Malomo L., Cignoni P.
The interaction between a 2D input device (like a mouse or a touchscreen) and a 3D object on the screen with the purpose of examining it in detail is a well-studied interaction problem. The inherent difference in degrees of freedom between input devices and possible 3D transformations makes it difficult to intuitively map inputs to operations to be performed on 3D objects. Although, over the years, studies led to a wide variety of solutions to overcome this problem, most of them are not actually available in real-world applications. In particular, for 3D web applications, only basic solutions are often implemented, and even the most used web framework for 3D still lacks state of the art implementations. We will face the problem of 3D interaction through touch and mouse input, and we propose our implementation of a 3D view manipulator for web applications, which offers a natural control, advanced functionalities, and provides an easy-to-use interface for both desktop and mobile environments.Source: STAG 2021 - Smart Tools and Apps for Graphics - Eurographics Italian Chapter Conference, pp. 103–107, Online Conference, 26-29/10/2021
DOI: 10.2312/stag.20211480
Metrics:
Fornari D., Malomo L., Cignoni P.
The interaction between a 2D input device (like a mouse or a touchscreen) and a 3D object on the screen with the purpose of examining it in detail is a well-studied interaction problem. The inherent difference in degrees of freedom between input devices and possible 3D transformations makes it difficult to intuitively map inputs to operations to be performed on 3D objects. Although, over the years, studies led to a wide variety of solutions to overcome this problem, most of them are not actually available in real-world applications. In particular, for 3D web applications, only basic solutions are often implemented, and even the most used web framework for 3D still lacks state of the art implementations. We will face the problem of 3D interaction through touch and mouse input, and we propose our implementation of a 3D view manipulator for web applications, which offers a natural control, advanced functionalities, and provides an easy-to-use interface for both desktop and mobile environments.Source: STAG 2021 - Smart Tools and Apps for Graphics - Eurographics Italian Chapter Conference, pp. 103–107, Online Conference, 26-29/10/2021
DOI: 10.2312/stag.20211480
Metrics:
See at:
diglib.eg.org | ISTI Repository | CNR ExploRA
2020
Journal article
Open Access
A bending-active twisted-arch plywood structure: computational design and fabrication of the FlexMaps Pavilion
Laccone F., Malomo L., Pérez J., Pietroni N., Ponchio F., Bickel B., Cignoni P.
Bending-active structures are able to efficiently produce complex curved shapes from flat panels. The desired deformation of the panels derives from the proper selection of their elastic properties. Optimized panels, called FlexMaps, are designed such that, once they are bent and assembled, the resulting static equilibrium configuration matches a desired input 3D shape. The FlexMaps elastic properties are controlled by locally varying spiraling geometric mesostructures, which are optimized in size and shape to match specific bending requests, namely the global curvature of the target shape. The design pipeline starts from a quad mesh representing the input 3D shape, which defines the edge size and the total amount of spirals: every quad will embed one spiral. Then, an optimization algorithm tunes the geometry of the spirals by using a simplified pre-computed rod model. This rod model is derived from a non-linear regression algorithm which approximates the non-linear behavior of solid FEM spiral models subject to hundreds of load combinations. This innovative pipeline has been applied to the project of a lightweight plywood pavilion named FlexMaps Pavilion, which is a single-layer piecewise twisted arch that fits a bounding box of 3.90x3.96x3.25 meters. This case study serves to test the applicability of this methodology at the architectural scale. The structure is validated via FE analyses and the fabrication of the full scale prototype.Source: SN Applied Sciences 2 (2020). doi:10.1007/s42452-020-03305-w
DOI: 10.1007/s42452-020-03305-w
Project(s): EVOCATION
Metrics:
Laccone F., Malomo L., Pérez J., Pietroni N., Ponchio F., Bickel B., Cignoni P.
Bending-active structures are able to efficiently produce complex curved shapes from flat panels. The desired deformation of the panels derives from the proper selection of their elastic properties. Optimized panels, called FlexMaps, are designed such that, once they are bent and assembled, the resulting static equilibrium configuration matches a desired input 3D shape. The FlexMaps elastic properties are controlled by locally varying spiraling geometric mesostructures, which are optimized in size and shape to match specific bending requests, namely the global curvature of the target shape. The design pipeline starts from a quad mesh representing the input 3D shape, which defines the edge size and the total amount of spirals: every quad will embed one spiral. Then, an optimization algorithm tunes the geometry of the spirals by using a simplified pre-computed rod model. This rod model is derived from a non-linear regression algorithm which approximates the non-linear behavior of solid FEM spiral models subject to hundreds of load combinations. This innovative pipeline has been applied to the project of a lightweight plywood pavilion named FlexMaps Pavilion, which is a single-layer piecewise twisted arch that fits a bounding box of 3.90x3.96x3.25 meters. This case study serves to test the applicability of this methodology at the architectural scale. The structure is validated via FE analyses and the fabrication of the full scale prototype.Source: SN Applied Sciences 2 (2020). doi:10.1007/s42452-020-03305-w
DOI: 10.1007/s42452-020-03305-w
Project(s): EVOCATION
Metrics:
See at:
SN Applied Sciences | link.springer.com | SN Applied Sciences | ISTI Repository | CNR ExploRA