2025
Conference article
Open Access
Inventory-constrained optimization of grid shells driven by reuse
Laccone F., Cignoni P., Malomo L., Giorgi D., Favilli A.
This work presents a novel design approach to enhance grid shell structures using steel beams from dismantled buildings. The objective is to improve grid shell performance with minimal aesthetic changes by minimizing the cut-off waste from reused elements. Given an input grid shell, the optimization combines Integer Linear Programming (ILP), differentiable optimization and graph neural networks to address two key objectives. First, it promotes the use of recycled components from a donor inventory, maximizing the reuse of beams over new elements and minimizing cutting processes. Practically, the target is trying to reuse the beams as-is. Second, it updates the nodal coordinates of the grid shell to reduce a loss function based on strain-energy, improving structural efficiency. Results show topology-preserving shape modifications and global form changes that enhance structural response. Life Cycle Assessment (LCA) confirms the method’s viability as a sustainable development strategy.DOI: 10.1201/9781003658641
Metrics:
Laccone F., Cignoni P., Malomo L., Giorgi D., Favilli A.
This work presents a novel design approach to enhance grid shell structures using steel beams from dismantled buildings. The objective is to improve grid shell performance with minimal aesthetic changes by minimizing the cut-off waste from reused elements. Given an input grid shell, the optimization combines Integer Linear Programming (ILP), differentiable optimization and graph neural networks to address two key objectives. First, it promotes the use of recycled components from a donor inventory, maximizing the reuse of beams over new elements and minimizing cutting processes. Practically, the target is trying to reuse the beams as-is. Second, it updates the nodal coordinates of the grid shell to reduce a loss function based on strain-energy, improving structural efficiency. Results show topology-preserving shape modifications and global form changes that enhance structural response. Life Cycle Assessment (LCA) confirms the method’s viability as a sustainable development strategy.DOI: 10.1201/9781003658641
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CNR IRIS 
| www.taylorfrancis.com | CNR IRIS 
2025
Journal article
Open Access
Optimizing free‐form grid shells with reclaimed elements under inventory constraints
Favilli A., Laccone F., Cignoni P., Malomo L., Giorgi D.
We propose a method for designing 3D architectural free-form surfaces, represented as grid shells with beams sourced from inventories of reclaimed elements from dismantled buildings. In inventory-constrained design, the reused elements must be paired with elements in the target design. Traditional solutions to this assignment problem often result in cuts and material waste or geometric distortions that affect the surface aesthetics and buildability. Our method for inventory-constrained assisted design blends the traditional assignment problem with differentiable geometry optimization to reduce cut-off waste while preserving the design intent. Additionally, we extend our approach to incorporate strain energy minimization for structural efficiency. We design differentiable losses that account for inventory, geometry, and structural constraints, and streamline them into a complete pipeline, demonstrated through several case studies. Our approach enables the reuse of existing elements for new designs, reducing the need for sourcing new materials and disposing of waste. Consequently, it can serve as an initial step towards mitigating the significant environmental impact of the construction sector.Source: COMPUTER GRAPHICS FORUM
DOI: 10.1111/cgf.70047
Project(s): Future Artificial Intelligence Research
Metrics:
Favilli A., Laccone F., Cignoni P., Malomo L., Giorgi D.
We propose a method for designing 3D architectural free-form surfaces, represented as grid shells with beams sourced from inventories of reclaimed elements from dismantled buildings. In inventory-constrained design, the reused elements must be paired with elements in the target design. Traditional solutions to this assignment problem often result in cuts and material waste or geometric distortions that affect the surface aesthetics and buildability. Our method for inventory-constrained assisted design blends the traditional assignment problem with differentiable geometry optimization to reduce cut-off waste while preserving the design intent. Additionally, we extend our approach to incorporate strain energy minimization for structural efficiency. We design differentiable losses that account for inventory, geometry, and structural constraints, and streamline them into a complete pipeline, demonstrated through several case studies. Our approach enables the reuse of existing elements for new designs, reducing the need for sourcing new materials and disposing of waste. Consequently, it can serve as an initial step towards mitigating the significant environmental impact of the construction sector.Source: COMPUTER GRAPHICS FORUM
DOI: 10.1111/cgf.70047
Project(s): Future Artificial Intelligence Research
Metrics:
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CNR IRIS | onlinelibrary.wiley.com | CNR IRIS
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, vol. 168
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, vol. 168
DOI: 10.1016/j.cad.2023.103670
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CNR IRIS | CNR IRIS | CNR IRIS | www.sciencedirect.com
2024
Journal article
Open Access
Procedural generation of geometric patterns for thin shell fabrication
Scandurra E., Laccone F., Malomo L., Callieri M., Cignoni P., Giorgi D.
This paper addresses the design of surface shells as assemblies of tileable, flat 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 that would produce disconnected or weak patterns. We devise a strategy for creating continuous variations on the geometry of individual patterns, in both aesthetics and behavior, to enrich the catalog of available designs. Finally, 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 catalog of patterns with varied aesthetics and predefined mechanical behavior, to use for the direct design of mechanical metamaterials. To assess the feasibility of our design-to-fabricate approach, we show fabricated 3D objects with different curvatures, and compare physical and simulated experiments.Source: COMPUTERS & GRAPHICS, vol. 122 (issue 103958)
DOI: 10.1016/j.cag.2024.103958
Project(s): NextGenerationEU programme under the funding schemes PNRR-PE-AI scheme (M4C2, investment 1.3, line on AI) FAIR (Future Artificial Intelligence Research), Social and hUman ceNtered XR
Metrics:
Scandurra E., Laccone F., Malomo L., Callieri M., Cignoni P., Giorgi D.
This paper addresses the design of surface shells as assemblies of tileable, flat 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 that would produce disconnected or weak patterns. We devise a strategy for creating continuous variations on the geometry of individual patterns, in both aesthetics and behavior, to enrich the catalog of available designs. Finally, 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 catalog of patterns with varied aesthetics and predefined mechanical behavior, to use for the direct design of mechanical metamaterials. To assess the feasibility of our design-to-fabricate approach, we show fabricated 3D objects with different curvatures, and compare physical and simulated experiments.Source: COMPUTERS & GRAPHICS, vol. 122 (issue 103958)
DOI: 10.1016/j.cag.2024.103958
Project(s): NextGenerationEU programme under the funding schemes PNRR-PE-AI scheme (M4C2, investment 1.3, line on AI) FAIR (Future Artificial Intelligence Research), Social and hUman ceNtered XR
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Computers & Graphics | IRIS Cnr | IRIS Cnr | CNR IRIS
2024
Conference article
Open Access
Single-instance, multi-target learning of 3D architectural gridshells for material reuse and circular economy
Favilli A., Laccone F., Cignoni P., Malomo L., Giorgi D.
We propose a learning-based method for the assisted design of 3D architectural free-form gridshells which reuse elements from dismantled, old buildings. Given a gridshell design as input, the output is a learned gridshell whose shape has been modified to reuse as many stock elements as possible, while preserving the design intent and optimizing for statics performance. The main idea is to perform multi-target shape optimization as a single-instance machine learning task, featuring differentiable losses that account for both structural and stock constraints. Since our approach enables the reuse of existing elements for new designs, it reduces the need for sourcing new materials and for disposing waste. Therefore, it contributes to switch to a circular economy and alleviate the environmental impact of the construction sector. © 2024 Copyright for this paper by its authors.Source: CEUR WORKSHOP PROCEEDINGS, vol. 3762, pp. 470-475. Naples, Italy, 29-30/05/2024
Project(s): NextGenerationEU programme under the funding schemes PNRR-PE-AI scheme (M4C2, investment 1.3, line on AI) FAIR (Future Artificial Intelligence Research)
Favilli A., Laccone F., Cignoni P., Malomo L., Giorgi D.
We propose a learning-based method for the assisted design of 3D architectural free-form gridshells which reuse elements from dismantled, old buildings. Given a gridshell design as input, the output is a learned gridshell whose shape has been modified to reuse as many stock elements as possible, while preserving the design intent and optimizing for statics performance. The main idea is to perform multi-target shape optimization as a single-instance machine learning task, featuring differentiable losses that account for both structural and stock constraints. Since our approach enables the reuse of existing elements for new designs, it reduces the need for sourcing new materials and for disposing waste. Therefore, it contributes to switch to a circular economy and alleviate the environmental impact of the construction sector. © 2024 Copyright for this paper by its authors.Source: CEUR WORKSHOP PROCEEDINGS, vol. 3762, pp. 470-475. Naples, Italy, 29-30/05/2024
Project(s): NextGenerationEU programme under the funding schemes PNRR-PE-AI scheme (M4C2, investment 1.3, line on AI) FAIR (Future Artificial Intelligence Research)
See at:
ceur-ws.org | CNR IRIS | CNR IRIS
2024
Conference article
Open Access
Constrained shape optimization of grid shells based on deep learning
Favilli A., Laccone F., Cignoni P., Malomo L., Giorgi D.
Designing grid shells requires finding a happy medium between aesthetics and engineering quality: architects and structural engineers join efforts to define geometries and grid topologies that achieve structural efficiency. In sculptural architecture, the artistic intent prevails, and produces freeform shapes with possibly large openings to create spectacular effects. This calls for shape optimization methods to mitigate inefficiency caused by bending forces. However, if modifications are not bounded, optimization may either alter the surface aesthetics or violate design constraints. This paper implements a shape optimization method that improves the performance of triangular grid shells while ensuring small shape changes. A graph neural network learns to update the nodal coordinates of the grid shell and reduce both strain-energy, as a measure of structural efficiency, and the total weight of the structure, as a measure of sustainability. Our case studies include regular shapes among the baseline structures of the FreeGrid benchmark, as well as non-conventional geometries.Project(s): Future Artificial Intelligence Research
Favilli A., Laccone F., Cignoni P., Malomo L., Giorgi D.
Designing grid shells requires finding a happy medium between aesthetics and engineering quality: architects and structural engineers join efforts to define geometries and grid topologies that achieve structural efficiency. In sculptural architecture, the artistic intent prevails, and produces freeform shapes with possibly large openings to create spectacular effects. This calls for shape optimization methods to mitigate inefficiency caused by bending forces. However, if modifications are not bounded, optimization may either alter the surface aesthetics or violate design constraints. This paper implements a shape optimization method that improves the performance of triangular grid shells while ensuring small shape changes. A graph neural network learns to update the nodal coordinates of the grid shell and reduce both strain-energy, as a measure of structural efficiency, and the total weight of the structure, as a measure of sustainability. Our case studies include regular shapes among the baseline structures of the FreeGrid benchmark, as well as non-conventional geometries.Project(s): Future Artificial Intelligence Research
See at:
CNR IRIS | www.ingentaconnect.com | CNR IRIS
2024
Journal article
Open Access
Computational design of segmented concrete shells made of post-tensioned precast flat tiles
Laccone Francesco, Menicagli Sandro, Cignoni Paolo, Malomo Luigi
This paper introduces a novel structural concept for free-form shells, in which the shape is decomposed into flat concrete tiles to be assembled sequentially with the help of falseworks. All tiles can be prefabricated in the shop with an adaptable and reusable molding system. Once the assembly is completed, the tiles are post-tensioned through a network of cables to minimize tension and avoid detachment. The top surface can finally be completed with an in situ cast layer that fills the gaps and activates the entire shell behavior. In contrast, the bottom surface maintains a jagged aesthetics. The paper presents the automatic pipeline supporting the computational design of these shells, from an input shape to its fabrication. The segmentation of the input shape is guided by a field-aligned quad mesh derived from the principal stresses of the thin shell. The tiles are flattened individually and extruded along the normal of the best-fitting plane. In this configuration, only edge midpoints of adjacent tiles share a contact point. Thus, forces can mainly flow along the tiles’ cross directions. The best configuration of cable paths and pre-loads is found by solving a constrained optimization problem exploiting a reduced model of the shell as a network of beams. Six different input shapes are tested to demonstrate the applicability of the proposed design method. The working hypotheses are validated through a higher-resolution nonlinear Finite Element Analysis. The fabrication pipeline is assessed utilizing a reduced-scale 3D-printed replica.Source: STRUCTURES, vol. 62 (issue 106156)
DOI: 10.1016/j.istruc.2024.106156
Metrics:
Laccone Francesco, Menicagli Sandro, Cignoni Paolo, Malomo Luigi
This paper introduces a novel structural concept for free-form shells, in which the shape is decomposed into flat concrete tiles to be assembled sequentially with the help of falseworks. All tiles can be prefabricated in the shop with an adaptable and reusable molding system. Once the assembly is completed, the tiles are post-tensioned through a network of cables to minimize tension and avoid detachment. The top surface can finally be completed with an in situ cast layer that fills the gaps and activates the entire shell behavior. In contrast, the bottom surface maintains a jagged aesthetics. The paper presents the automatic pipeline supporting the computational design of these shells, from an input shape to its fabrication. The segmentation of the input shape is guided by a field-aligned quad mesh derived from the principal stresses of the thin shell. The tiles are flattened individually and extruded along the normal of the best-fitting plane. In this configuration, only edge midpoints of adjacent tiles share a contact point. Thus, forces can mainly flow along the tiles’ cross directions. The best configuration of cable paths and pre-loads is found by solving a constrained optimization problem exploiting a reduced model of the shell as a network of beams. Six different input shapes are tested to demonstrate the applicability of the proposed design method. The working hypotheses are validated through a higher-resolution nonlinear Finite Element Analysis. The fabrication pipeline is assessed utilizing a reduced-scale 3D-printed replica.Source: STRUCTURES, vol. 62 (issue 106156)
DOI: 10.1016/j.istruc.2024.106156
Metrics:
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IRIS Cnr | IRIS Cnr | IRIS Cnr | Structures | CNR IRIS | CNR IRIS
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: LECTURE NOTES IN CIVIL ENGINEERING, vol. 437, pp. 549-558. Torino, Italy, 26-28/06/2023
DOI: 10.1007/978-3-031-44328-2_57
Project(s): Future Artificial Intelligence Research
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: LECTURE NOTES IN CIVIL ENGINEERING, vol. 437, pp. 549-558. Torino, Italy, 26-28/06/2023
DOI: 10.1007/978-3-031-44328-2_57
Project(s): Future Artificial Intelligence Research
Metrics:
See at:
CNR IRIS | link.springer.com | CNR IRIS | CNR IRIS
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: LECTURE NOTES IN CIVIL ENGINEERING, vol. 437, 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: LECTURE NOTES IN CIVIL ENGINEERING, vol. 437, pp. 1-10. Turin, Italy, 26-28/06/2023
DOI: 10.1007/978-3-031-44328-2_1
Metrics:
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CNR IRIS | link.springer.com | ISTI Repository | CNR IRIS | CNR IRIS
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: LECTURE NOTES IN CIVIL ENGINEERING, 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: LECTURE NOTES IN CIVIL ENGINEERING, pp. 569-578. Turin, Italy, 26-28/06/2023
DOI: 10.1007/978-3-031-44328-2_59
Metrics:
See at:
CNR IRIS | link.springer.com | ISTI Repository | CNR IRIS | CNR IRIS
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.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.DOI: 10.2312/stag.20231297
Metrics:
See at:
diglib.eg.org | CNR IRIS | ISTI Repository | CNR IRIS
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, vol. 292
DOI: 10.1016/j.compstruc.2023.107238
Project(s): Future Artificial Intelligence Research, SUN
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, vol. 292
DOI: 10.1016/j.compstruc.2023.107238
Project(s): Future Artificial Intelligence Research, SUN
Metrics:
See at:
CNR IRIS | ISTI Repository | www.sciencedirect.com | CNR IRIS
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: PROCEEDINGS OF THE IASS ANNUAL SYMPOSIUM, 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: PROCEEDINGS OF THE IASS ANNUAL SYMPOSIUM, pp. 1859-1870. University of Surrey, UK, 23-27/08/2021
DOI: 10.15126/900337
Project(s): EVOCATION
Metrics:
See at:
CNR IRIS | ISTI Repository | openresearch.surrey.ac.uk | CNR IRIS
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, vol. 106, pp. 141-151
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, vol. 106, pp. 141-151
DOI: 10.1016/j.cag.2022.05.020
Project(s): EVOCATION
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CNR IRIS | ISTI Repository | www.sciencedirect.com | CNR IRIS
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, vol. 63 (issue 2), pp. 98-114
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, vol. 63 (issue 2), pp. 98-114
DOI: 10.20898/j.iass.2022.007
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2022
Other
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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.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.DOI: 10.32079/isti-tr-2022/017
Metrics:
2022
Other
Restricted
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.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.DOI: 10.32079/isti-tr-2022/016
Metrics:
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), vol. 41 (issue 6), pp. 435-452
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), vol. 41 (issue 6), pp. 435-452
DOI: 10.1111/cgf.14581
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2022
Journal article
Open Access
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), vol. 38 (issue 6), pp. 683-701
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), vol. 38 (issue 6), pp. 683-701
DOI: 10.1111/mice.12912
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CNR IRIS | onlinelibrary.wiley.com | CNR IRIS | CNR IRIS
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: 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: 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 | CNR IRIS | ISTI Repository | CNR IRIS