Zechmeister, C., Gil Pérez, M., Knippers, J., & Menges, A. (2023). Concurrent, computational design and modelling of structural, coreless-wound building components.
Automation in Construction,
151, 104889.
https://doi.org/10.1016/j.autcon.2023.104889 Abstract
Coreless filament winding extends established industrial processes, enabling the fabrication of building parts with minimal formwork. Since the part's final geometry is unknown until completed, it creates uncertainties for design and engineering. Existing architectural design workflows are insufficient, and industrial software packages cannot capture the complexity of self-deforming fibres to model complex fibre layups. This research introduces a feedback-based computational method conceived as four development cycles to design and evaluate fibre layups of large-scale architectural building components, and a multi-scalar digital-physical design and evaluation toolset to model and evaluate them at multiple resolutions. The universal applicability of the developed methods is showcased by two different architectural fibre structures. The results show how the systematization of methods and toolset allow for increased design flexibility and deeper integration of interdisciplinary collaborators. They constitute an important step towards a consolidated co-design methodology and demonstrate the potential to simultaneously co-evolve design and evaluation methods. Gil Pérez, M. (2023). Integrative Structural Design of Non-Standard Building Systems: Coreless Filament-Wound Structures as a Case Study. [Dissertation]. In Forschungsberichte aus dem Institut für Tragkonstruktionen und Konstruktives Entwerfen, Universität Stuttgart (Vol. 49, p. 75). Institut für Tragkonstruktionen und Konstruktives Entwerfen, Universität Stuttgart.
Abstract
Our society is experiencing the emergence of novel nonstandard building systems unlocked by digital technologies in the building sector. The utilisation of computational design processes and digital fabrication, coupled with the exploration of new materiality, bring the potential to break with conventional ways of building. However, they also demand new ways of designing and proving the structure's safety.
This dissertation aims to develop an integrative structural design methodology and workflow to design, optimise and validate non-standard building systems. Therefore, a multiscale, digital-physical approach is proposed, which combines structural simulation with small-scale models and material testing, allowing the structure's optimisation and proof of safety.
The first two chapters explain the research motivation, objectives and ontextualisation. Historical remarks are given to understand the evolution of structural design and the key aspects that created innovation and non-standard systems in the past. Coreless filament winding (CFW) is also introduced here as a representative example of non-standard building systems.
Chapter three contains the publications that describe the development of the integrative structural design methodologies through coreless filament wound structures as a case study. All the publications are supported by CFW specimens
or full-scale built demonstrators, including BUGA Fibre Pavilion, Maison Fibre and LivMatS Pavilion.
Chapters four and five summarise the results, generalising the workflow from CFW structures to non-standard building systems into four sub-methods: multi-level modelling and evaluation; structural characterisation; integrative design; and optimisation and safety verification. The discussion locates the integrative structural design in the historical context and analyses the strategies to prove the safety of
other non-standard systems. The conclusion emphasises the potential of this methodology to shorten the gap between research and industry, facilitating the realisation of innovative structures.Abstract
Structural members made of fiber-reinforced polymers (FRP) attract increasing attention in the development of novel architectural systems that challenge the standard design methodologies. Cylindrical surfaces constitute one of the typical geometric sets obtained with the FRP component fabrication. This paper explores the influences of two geometric parameters on the buckling performance of elliptical cylinders: inverse slenderness (ratio of minimum diameter to height) and eccentricity (ratio of radii along semi-axes). The overall stiffness properties are defined using lamination parameters. This analysis method eliminates the dependency of optimal solutions on the initial assumptions regarding the laminate configuration, which needs to be explicitly described in multi-layer modeling. Finite element analyses are utilized to compute buckling loads of the cylinders under axial compression force and bi-axial bending moments. The optimal lamination parameters and buckling stresses are determined for various parameters, and the lamination parameters corresponding to the optimal and simple ±45° angle-ply design points are presented in the lamination parameter plane via Miki's diagram. The results reveal the level of performance that can be achieved by a specific geometry and provide guidelines for the optimal design of elliptical laminated cylinders against buckling. Mindermann, P., Gil Pérez, M., Knippers, J., & Gresser, G. T. (2022). Investigation of the Fabrication Suitability, Structural Performance, and Sustainability of Natural Fibers in Coreless Filament Winding.
Materials,
15(9), Article 9.
https://doi.org/10.3390%2Fma15093260 Abstract
Coreless filament winding is an emerging fabrication technology in the field of building construction with the potential to significantly decrease construction material consumption, while being fully automatable. Therefore, this technology could offer a solution to the increasing worldwide demand for building floor space in the next decades by optimizing and reducing the material usage. Current research focuses mainly on the design and engineering aspects while using carbon and glass fibers with epoxy resin; however, in order to move towards more sustainable structures, other fiber and resin material systems should also be assessed. This study integrates a selection of potential alternative fibers into the coreless filament winding process by adapting the fabrication equipment and process. A bio-based epoxy resin was introduced and compared to a conventional petroleum-based one. Generic coreless wound components were created for evaluating the fabrication suitability of selected alternative fibers. Four-point bending tests were performed for assessing the structural performance in relation to the sustainability of twelve alternative fibers and two resins. In this study, embodied energy and global warming potential from the literature were used as life-cycle assessment indexes to compare the material systems. Among the investigated fibers, flax showed the highest potential while bio-based resins are advisable at low fiber volume ratios. Gil Pérez, M., Guo, Y., & Knippers, J. (2022). Integrative material and structural design methods for natural fibres filament-wound composite structures: The LivMatS pavilion.
Material & Design,
217.
https://doi.org/10.1016/j.matdes.2022.110624 Abstract
Coreless filament winding (CFW) is a novel fabrication technique that utilises fibre-polymer composite materials to efficiently produce filament wound structures in architecture while reducing manufacturing waste. Previous projects have been successfully built with glass and carbon fibre, proving their potential for lightweight construction systems. However, in order to move towards more sustainable architecture, it is crucial to consider replacing carbon fibre’s high environmental impact with other material systems, such as natural fibre. This paper evaluates several fibres, resin systems, and their required CFW fabrication adjustments towards designing and fabricating a bio-composite structure: the LivMatS Pavilion. The methods integrate structural design loops with material evaluation and characterisation, including small-scale and large-scale structural testing at progressive stages. The results demonstrate the interactive decision-making process that combines material characterisation with structural simulation feedback, leveraged to evaluate and optimise the structural design. The built pavilion is proof of the first successful coreless filament wound sustainable natural fibres design, and the developed methods and findings open up further research directions for future applications. Gil Pérez, M., Früh, N., La Magna, R., & Knippers, J. (2022). Integrative structural design of a timber-fibre hybrid building system fabricated through coreless filament winding: Maison Fibre. Journal of Building Engineering, 49.
Abstract
Coreless filament winding is a robotic fabrication technique in which conventional filament winding is modified to reduce the core material to its minimum. This method was showcased and developed through a series of pavilions demonstrating its potential to create lightweight structures. The latest project, Maison Fibre, goes one step further and adapts the fabrication into a hybrid structure combining fibre-polymer composites (FPC) with laminated veneer lumber (LVL) to allow for walkability. The result is the first multi-storey building system fabricated with this novel technique. During the integrative design process of the slab system, the optimum fibre layup was negotiated between the timber support span, load induction, boundary conditions, and material amount required. A total of four iterations of the hybrid component were load tested and compared with the maximum enveloped forces resulting from the global structural simulation. The full-scale load tests were used to calibrate the refined structural simulation of the slab components. The experimental process allowed for material reduction and validated the structural system's capability to withstand the design forces. In addition, the fibre layup was tailored and load adapted for the non-tested wall and slab components of the installation using the test results and achieving further material optimization. This publication describes the integrative design process of the hybrid slab system from initial concepts to the iterative optimization of the structural system, demonstrating its potential for future applications. Gil Pérez, M., Zechmeister, C., Kannenberg, F., Mindermann, P., Balangé, L., Guo, Y., Hügle, S., Gienger, A., Forster, D., Bischoff, M., Tarín, C., Middendorf, P., Schwieger, V., Gresser, G. T., Menges, A., & Knippers, J. (2022). Computational co-design framework for coreless wound fibre–polymer composite structures.
Journal of Computational Design and Engineering,
9(2), Article 2.
https://doi.org/10.1093/jcde/qwab081 Abstract
In coreless filament winding, resin-impregnated fibre filaments are wound around anchor points without an additional mould. The final geometry of the produced part results from the interaction of fibres in space and is initially undetermined. Therefore, the success of large-scale coreless wound fibre composite structures for architectural applications relies on the reciprocal collaboration of simulation, fabrication, quality evaluation, and data integration domains. The correlation of data from those domains enables the optimization of the design towards ideal performance and material efficiency. This paper elaborates on a computational co-design framework to enable new modes of collaboration for coreless wound fibre–polymer composite structures. It introduces the use of a shared object model acting as a central data repository that facilitates interdisciplinary data exchange and the investigation of correlations between domains. The application of the developed computational co-design framework is demonstrated in a case study in which the data are successfully mapped, linked, and analysed across the different fields of expertise. The results showcase the framework’s potential to gain a deeper understanding of large-scale coreless wound filament structures and their fabrication and geometrical implications for design optimization. Guo, Y., Gil Pérez, M., Serhat, G., & Knippers, J. (2022). A design methodology for fiber layup optimization of filament wound structural components.
Structures,
38, 1125–1136.
https://doi.org/10.1016/j.istruc.2022.02.048 Abstract
The applications of fiber-reinforced polymer (FRP) composites extend rapidly along with the development of new manufacturing techniques. However, due to the complexities introduced by the material and fabrication processes, the application of conventional structural design methods for construction members has been significantly challenging. This paper presents an alternative methodology to find optimum fiber layups for a given tube-shape geometry via a graphical optimization strategy based on structural performance requirements. The proposed technique employs simplified shell element models based on classical lamination theory (CLT) to avoid explicit fiber modeling in the FEA simulations. Lamination parameters are utilized to generate the reduced stiffness matrices for continuous multi-layer FRP lamination. The fiber layup of the component is retrieved from the optimal lamination parameters that maximize the structural performance. The case study results demonstrate that the developed method provides compact solutions, linking the structural design requirements with optimal fiber orientations and volumetric proportions. In addition, the determined solutions can be interpreted directly by the winding fabrication settings. Mindermann, P., Gil Pérez, M., Kamimura, N., Knippers, J., & Gresser, G. T. (2022). Implementation of Fiber-Optical Sensors into Coreless Filament-Wound Composite Structures.
Composite Structures,
290, 115558.
https://doi.org/10.1016/j.compstruct.2022.115558 Abstract
Fiber-reinforced composite structures manufactured by coreless filament winding (CFW) are adaptable to the individual load case and offer high, mass-specific mechanical performance. However, relatively high safety factors must be applied due to the large deviations in the structural parameters. An improved understanding of the structural behavior is needed to reduce those factors, which can be obtained by utilizing an integrated fiber-optical sensor. The described methods take advantage of the high spatial resolution of a sensor system operating by the Rayleigh backscatter principle. The entire strain fields of several generic CFW samples were measured in various load scenarios, visualized in their spatial contexts, and analyzed by FEM-assisted methods. The structural response was statistically described and compared with the ideal load distribution to iteratively derive the actual load introduction and prove the importance of the sensor integration. The paper describes methods for the sensor implementation, interpretation and the calibration of structural data. Gil Pérez, M., Rongen, B., Koslowski, V., & Knippers, J. (2021). Structural design assisted by testing for modular coreless filament-wound composites: The BUGA Fibre Pavilion.
Construction and Building Materials,
301.
https://doi.org/10.1016/j.conbuildmat.2021.124303 Abstract
The BUGA Fibre Pavilion was built in 2019 in the Bundesgartenschau (National Gardening exhibition) at Heilbronn, Germany. The pavilion consists of modular fibre-polymer composite components made out of glass and carbon fibres with an epoxy resin matrix. The fabrication technique employed, called coreless filament winding (CFW), is a variant from conventional filament winding where the core is reduced to minimum frame support. The fibres are wound between these frames, freely spanning and creating the resulting geometry through fibre interaction. For the structural design of these components, conventional modelling and engineering methods were not sufficient as the system cannot be adequately characterized in the early stage. Therefore, a more experimental design approach is proposed for the BUGA Fibre Pavilion, where different levels of detailing and abstraction in the FE simulations are combined with prototyping and structural testing. This paper shows the procedure followed for the design and validation of the structural fibre components. In this process, the simulations are used as a design tool rather than a way to predict failure, while mechanical testing served for the verification and validation of the structural capacity. Koslowski, V., Knippers, J., Gil Pérez, M., & Rongen, B. (2020). Versuchsgestützte Bemessung des CFK-GFK-Tragwerks des BUGA-Faserpavillons 2019. In B. Oesterle, M. Bischoff, & M. von Scheven (Eds.), Baustatik - Baupraxis 14 (Vol. 14, pp. 207–214).
Bodea, S., Dambrosio, N., Zechmeister, C., Gil Pérez, M., Koslowski, V., Rongen, B., Dörstelmann, M., Kyjanek, O., Knippers, J., & Menges, A. (2020). BUGA Fibre Pavilion: Towards robotically-fabricated composite building structures. In J. Burry, J. Sabin, B. Sheil, & M. Skavara (Eds.), Fabricate 2020. (pp. 234–245). UCL Press.
Gil Pérez, M., Rongen, B., Koslowski, V., & Knippers, J. (2020). Structural design, optimization and detailing of the BUGA fibre pavilion.
International Journal of Space Structures,
35(4), Article 4.
https://doi.org/10.1177/0956059920961778 Abstract
The BUGA fibre pavilion built in April 2019 at the Bundesgartenschau in Heilbronn, Germany, is the most recent coreless fibre winding research pavilion developed from the collaboration between ICD/ITKE at the University of Stuttgart. The research goal is to create lightweight and high-performance lattice composite structures through robotic fabrication. The pavilion is composed of 60 carbon and glass fibre components, and is covered by a prestressed ethylene tetrafluoroethylene (ETFE) membrane. Each of the components is hollow in section and bone-like in shape. They are joined through steel connectors at the intersecting nodes where the membrane is also supported through steel poles. The components are fabricated by coreless filament winding (CFW), a technique where fibre filaments impregnated with resin are wound freely between two rotating scaffolds by a robotic arm. This novel structural system constitutes a challenge for the designer when proving and documenting the load-carrying capacity of the design. This paper outlines and elaborates on the core methods and workflows followed for the structural design, optimization and detailing of the BUGA fibre pavilion. Gil Pérez, M., Dambrosio, N., Rongen, B., Menges, A., & Knippers, J. (2019). Structural optimization of coreless filament wound components connection system through orientation of anchor points in the winding frames. In C. Lazaro, K.-U. Bletzinger, & E. Onate (Eds.), Proceedings of IASS Annual Symposia 2019: Form and Force (Vol. 2019, pp. 1381--1388). International Association for Shell and Spatial Structures (IASS).
Dambrosio, N., Zechmeister, C., Bodea, S., Koslowski, V., Gil Pérez, M., Rongen, B., Knippers, J., & Menges, A. (2019). Buga Fibre Pavilion: Towards an architectural application of novel fiber composite building systems. In K. Bieg, D. Briscoe, & C. Odom (Eds.), Acadia 2019: Ubiquity and Autonomy, proceedings of the 39th Annual Conference of the Association for Computer Aided Design in Architecture, Texas (pp. 140--149). Acadia Publishing Company.
Rongen, B., Koslowski, V., Gil Pérez, M., & Knippers, J. (2019). Structural optimisation and rationalisation of the BUGA fibre composite dome. In C. Lazaro, K. Bletzinger, & E. Onate (Eds.), Proceedings of IASS Annual Symposia: Form and Force (Vol. 2019, pp. 1859--1866). International Association for Shell and Spatial Structures (IASS).
Abstract
In previous studies, it was demonstrated that the geometry of regular anticlastic membrane structures attached to edge beams on all four sides of the membrane is one of the most influential factors for the performance of the structure. However, regular anticlastic membranes are not easy to apply at specific design sites. For this reason, a greater degree of irregularity is introduced in this study to create a wider range of design possibilities. From the regular-shaped fabric panels that are symmetric about the two axes, one of the symmetries is removed. In this way, two new parameters are introduced: asymmetry about the transverse axis creating trapezoid-shaped panels, and asymmetry about the longitudinal axis creating inclined panels. These two types of panel parametric studies are the scope of this work. From findings of case studies of irregular anticlastic membrane structures with asymmetry about one or both axes, design aid charts and design equations for trapezoid-shaped and inclined panels are proposed that would be needed at the preliminary design phase. Gil Pérez, M., Kim, S. D., & Kang, T. H.-K. (2017). Development of design aid for barrel vault shaped membrane fabric structures.
Journal of Structural Integrity and Maintenance,
2(1), Article 1.
https://doi.org/10.1080/24705314.2017.1280592 Abstract
This study introduces the development of membrane fabric structures as well as the procedure for their design and analysis along with an explanation of the finite element modeling and conditions considered. In addition, a parametric study on regular barrel vault shaped membranes supported between arches is conducted. The following three parameters determine the geometry of this type of membranes: the arch curvature, the width of the panel, and the scale of the arch. Considering these three parameters and the different combinations among them, regular membrane panels are analyzed leading to the development of a design aid for this type of membranes. Gil Pérez, M., Kang, T. H.-K., Sin, I., & Kim, S. D. (2016). Nonlinear Analysis and Design of Membrane Fabric Structures: Modeling Procedure and Case Studies.
Journal of Structural Engineering,
142(11), Article 11.
https://doi.org/10.1061/(ASCE)ST.1943-541X.0001557 Abstract
Membrane fabric structures are spatial structures that allow for long span and lightweight roofs. In many cases, membrane roofs are supported with trusses or masts and prestressed together with cables to obtain a resistant shape for a given loading condition. For the design of membrane structures, geometrically nonlinear analysis is required. Additionally, modeling of each membrane element and formfinding of the shape are of great importance in the design process. First, an equilibrium-finding analysis is conducted for the purpose of obtaining the optimal shape of the membrane structure, during which the initial stresses of the membrane and cables must be balanced. Next, the stress-deformation analysis is performed for the required loading condition. This analysis allows understanding of the behavior of the structure and confirms that the design of the membrane satisfies the required safety factor for the construction. The analyses of the Southwestern Baseball Dome in Seoul and the Jeju Stadium Dome in Jeju Island, both in Korea, are presented, with an emphasis on details in all aspects of the analysis process. It is found that the selection of analysis and design techniques and appropriate construction materials would be most critical. The analysis results also show that the form-finding step has a significant effect on increasing the stiffness of the structure and a more regular geometry promotes a more stable response under various loading conditions. Gil Pérez, M., Sin, I., Kim, S., & Kang, T. (2015, May). Nonlinear Analysis of the Seoul Southwestern Baseball Dome. Proceedings, 11th Asian Pacific Conference on Shell and Spatial Structures (APCS 2015).
Gil Pérez, M., Sin, I., Kim, S., & Kang, T. (2014, June). Nonlinear Analysis and Modeling of Membrane Structures. Proceedings, The 2014 International Conference on Computational & Experimental Engineering and Sciences (ICCES 2014).
Gil Pérez, M., Lee, J., Kim, S., & Kang, T. (2014). Enviromentally Compatible Spatial Structures. International Proceedings If Chemical, Biological and Environmental Engineering, 62, 90–94.
Gil Pérez, M., Sin, I., Kim, S., & Kang, T. (2014). A study on fabric design of the Seoul Southwestern Baseball Dome. Proceedings of IASS Annual Symposia, 2014(8), Article 8.
Sin, I., Kim, N., Gil Pérez, M., Kang, T., & Kim, S. (2014). A study on instability behavior of the Seoul Southwestern Baseball Dome. Proceedings of IASS Annual Symposia, 2014(8), Article 8.
