Motivated by the demand for sustainable thermoset matrix systems, this study proposes several approaches; the most effective combines flax fibers, furan resin, and biochar filler into a low-impact material system. Eco-mechanical performance was experimentally assessed at the material level via four-point bending and at the structural level via axial compression tests, using global warming potential as the sustainability metric considering LCA module A1, with estimates extended to cradle-to-gate (A1-A3). Incorporating 19.1 wt% biochar achieved A1 carbon neutrality, with 15.1% and 16.3% reductions in mass-specific flexural modulus and strength, respectively. Up to 27.6 wt% biochar was implemented in (hybrid) coreless filament-wound structures, while maintaining processability and adequate mechanical performance. In flax-epoxy systems, biochar addition improved eco-mechanical performance but could not achieve A1 carbon neutrality. The proposed flax-furan-biochar system offers a fully renewable, carbon-neutral/carbon-negative, mechanically viable solution for fiber-composite lightweight structural applications.

Fiber-reinforced plastics enable lightweight building systems through digitizable and automatable additive manufacturing techniques such as coreless filament winding (CFW). Replacing carbon fibers with low-CO2-impact natural fibers offers opportunities for sustainable structures. A prior CFW study using four-point bending demonstrated the eco-mechanical potential of Linum usitatissimum fibers but was confined to simple sample geometries, emphasizing material over structural performance. This study addresses this limitation by introducing a new structural sample fabricated with a 3D-printed winding fixture and hybrid CFW. Samples from Phormium tenax fibers were experimentally benchmarked against carbon and L. usitatissimum fiber samples. Carbon samples exhibited 2.15x the mass/CO2-specific stiffness and failure load of the natural fiber samples. L. usitatissimum slightly outperformed P. tenax due to greater raw material optimization. Projections suggest increasing fiber volume ratios, coupled with advances in fabrication, could close performance gaps while balancing lightweight and sustainability goals.

Bamboo has evolved a highly optimized structural system in its culms, which this study transfers into lightweight fiber composite trusses fabricated by coreless filament winding. Focusing on the structural segmentation involving diaphragms of the biological role model, this design principle was integrated into the additive manufacturing process using a multi-stage winding, a tiling approach, and a water-soluble winding fixture. Through a FE-assisted analytical abstraction procedure, the transition to a carbon fiber material system was considered by determining a geometrical configuration optimized for structural mass, bending deflection, and radial buckling. Samples were fabricated from CFRP and experimentally tested in four-point bending. In mass-specific terms, integrating diaphragms into wound fiber composite samples improved failure load by 36%, ultimate load by 62%, and energy absorption by a factor of 7, at a reduction of only 14% in stiffness. Benchmarking against steel and PVC demonstrated superior mass-specific performance, although mōsō bamboo still outperformed all technical solutions, except in energy absorption.

This study investigates the potential of regionally sourced natural fibers (NF) as sustainable feedstocks for coreless filament winding (CFW), an innovative and resource-efficient composite fabrication method for construction. As the sector moves towards bio-based materials, flax has emerged as a benchmark due to its compatibility with CFW and favorable mechanical properties. However, supply chain vulnerabilities and price volatility highlight the need for regional alternatives to flax fibers. By assessing hemp, miscanthus, lavender, nettle and wheat straw cultivated in Baden-Württemberg (BW), this paper links crop sustainability and fiber suitability with the broader aim of strengthening local biomass utilization within the bioeconomy. A multi-stage evaluation framework compares environmental, economic, social, and technical indicators against flax, focusing on biomass availability, input intensity, ecosystem services, land-use competition, and fiber properties. The results identify hemp as the most promising alternative due to its high fiber output, low cultivation inputs, beneficial ecosystem services and mechanical performance. Nettle offers strong mechanical performance but faces agronomic limitations, while lavender presents niche potential under integrated production systems. Miscanthus and wheat straw, while unsuitable for direct CFW due to fiber morphology, may serve as supplementary feedstocks through modified processing. These findings underscore the role of local biomass streams in creating robust regional value chains, contributing to the resilience and sustainability of the bioeconomy. While the focus of this study is on BW, the framework can be transferred to other regions and may serve as a practical tool for policy, industry, and research seeking to advance circular approaches in bio-based construction.

Fiber-reinforced composites offer innovative solutions for architectural applications with high strength and low weight. Coreless filament winding extends industrial processes, reduces formwork, and allows for tailoring of fiber layups to specific requirements. A previously developed computational co-design framework for coreless filament winding is extended toward the integration of reciprocal design feedback to maximize design flexibility and inform design decisions throughout the process. A multi-scalar design representation is introduced, representing fiber structures at different levels of detail to generate feedback between computational design, engineering, and fabrication. Design methods for global, component, and material systems are outlined and feedback generation is explained. Structural and fabrication feedback are classified, and their integration is described in detail. This paper demonstrates how reciprocal feedback allows for co-evolution of domains of expertise and extends the existing co-design framework toward design problems. The developed methods are shown in two case studies at a global and component scale. Graphical Abstract

Integrating ceramic matrix systems into coreless filament winding (CFW) enables the creation of sustainable, heat- and fire-resistant fiber composite lightweight structures. This study introduces a chemically bonded ceramic matrix system based on metakaolin, tailored for space applications utilizing lunar resources. The system employs acidic activation for processing with basalt/mineral fibers and alkaline activation for carbon fibers composites. Initially, the constituents of the matrix system are outlined, alongside potential synthesis pathways from lunar resources. Various formulations, incorporating different additives, are proposed. Through coupon compression testing, the most performative formulations for each activation type are selected for further investigation. The addition of zirconium silicate resulted in a higher compressive strength without significantly affecting the compressive modulus. The study then proceeds to experimentally characterize the matrix system’s viscosity. Subsequently, the processability of the proposed matrix system with CFW is demonstrated through the fabrication of generic medium-size lattice samples. Finally, these samples undergo destructive structural testing in compression. While emphasizing material development aspects, the investigation concludes that the feasibility of the proposed concept is validated through the successful fabrication and testing of generic CFW samples, affirming its potential use in space-related structural applications.

Climate change necessitates exploring innovative geoengineering solutions to mitigate its effects-one such solution is deploying planetary sunshade satellites at Sun-Earth Lagrange point 1 to regulate solar radiation on Earth directly. However, such long-span space structures present unique technical challenges, particularly structural scalability, on-orbit manufacturing, and in-situ resource utilization. This paper proposes a structural concept for the sunshade's foil support system and derives from that a component-level modular system for long-span fiber composite lightweight trusses using coreless filament winding. Within a laboratory-scale case study, the component scalability, as well as the manufacturing and material impacts, were experimentally investigated by bending deflection testing. Based on these experimental results, FE models of the proposed structural concept were calibrated to estimate the maximum displacement and mass of the foil support structure, while comparing the influences of foil edge length, orbital load case, and material selection.

Despite all current efforts, climate change is the greatest challenge of the 21 st century. Since existing measures will fail to prevent critical tipping points from being reached, in addition to terrestrial geoengineering methods, efforts are underway to explore new ways to implement space-based geoengineering methods into the short-term construction of a buffer solution - the International Planetary Sunshade (IPSS). The IPSS system reduces solar irradiation mitigating the global mean temperature rise while offering a sustainable energy supply. The developement of the system poses multifaceted challenges only to be mastered by a collaboration of space agencies and private companies, while supported by society. Therefore, tackling the IPSS within international roadmaps is essential to exploit synergies, shorten development time, and promote international cooperation. An evolutionary concept achieves stepwise Earth independence by utilizing lunar resources. The feasibility of the IPSS also depends on the foil’s supporting structure. Therefore, a lightweight manufacturing technology that meets several criteria, such as scalability, adaptivity, material compatibility, full automation, on-orbit manufacturing, in-situ resource utilization, and digital design including function integration, must be adopted. Hence, coreless filament winding (CFW) may be a suitable technology for realizing the demanded mass savings. The prerequisite for the superiority of CFW structures is an application- and material-compliant component and fiber net design. Previous experience with CFW cannot be directly transferred to the IPSS system due to the changed requirements for space application. This paper will present a systematic design concept for the IPSS, initially exploring a CFW support structure by discussing segmentation and modularity, proposing a new connection system, and implementing function integration.

Coreless filament winding is a manufacturing process used for fiber-reinforced composites, resulting in high-performance lightweight lattice structures. Load transmission elements, which are assembled from commercially available standardized parts, often restrict the component design. A novel adaptive winding pin was developed, which is made by additive manufacturing and can therefore be adjusted to specific load conditions resulting from its position within the component. This allows to decouple the fiber arrangement from the winding pin orientation, which allows a fully volumetric framework design of components. A predictive model for the pin capacity was derived and experimentality validated. The hooking conditions, pin capacity, and occupancy were considered in the creation of a digital design tool.

Sparse composite frameworks can be produced integrally using coreless filament winding, resulting in components with high mass-specific performance that are mainly used in aerospace, automotive, and construction applications. The fiber orientation can be individually set to match the load direction, allowing high load capacities with minimized material usage. However, failure mainly occurs near the load transmission regions substantially before the load-carrying capacity of the actual straight fiber strand element is exhausted. This paper presents an experimental investigation on several concepts for arranging the fiber composite around the load transmitting pin in coreless filament winding. The samples' mechanical performances and failure behaviors in tension and compression were compared, based on force-displacement data, to improve the design of the transition element. The mechanical performance was improved by introducing secondary winding pins, additional wrapping of the fiber strand, or adding smoothening fiber guiding elements. Additionally, the impact of the consolidation on the coreless filament wound elements was quantified to negatively impact tensile load absorption.

The linear design workflow for structural systems, involving a multitude of iterative loops and specialists, obstructs disruptive innovations. During design iterations, vast amounts of data in different reference systems, origins, and significance are generated. This data is often not directly comparable or is not collected at all, which implies a great unused potential for advancements in the process. In this paper, a novel workflow to process and analyse the data sets in a unified reference frame is proposed. From this, differently sophisticated iteration loops can be derived. The developed methods are presented within a case study using coreless filament winding as an exemplary fabrication process within an architectural context. This additive manufacturing process, using fiber-reinforced plastics, exhibits great potential for efficient structures when its intrinsic parameter variations can be minimized. The presented method aims to make data sets comparable by identifying the steps each data set needs to undergo (acquisition, pre-processing, mapping, post-processing, analysis, and evaluation). These processes are imperative to provide the means to find domain interrelations, which in the future can provide quantitative results that will help to inform the design process, making it more reliable, and allowing for the reduction of safety factors. The results of the case study demonstrate the data set processes, proving the necessity of these methods for the comprehensive inter-domain data comparison.

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.

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.

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.

Bar frameworks integrally manufactured by coreless filament winding are often the superior design solution for voluminous component shapes with distinctive load cases. Numerical simulation results must be validated by full-scale tests due to uncertainties in the mesoscale fiber structure. Pultrusion-winding allows to reduce the geometrical uncertainty of the composite without the limiting use of molds. This is achieved by the combination of intermittent ultraviolet pultrusion, coreless filament winding, and a novel tool trajectory creating method. Straight fiber strand segments are directly cured during winding. This defines their cross-sectional shape and decreases surface irregularities. Around winding points, the curing is temporarily discontinued and the fiber strand remains flexible for hooking. The new fabrication method could be validated on a laboratory scale showing improved mechanical performance and reduced fluctuations in fiber volume ratio in comparison to coreless filament winding.

Additive manufacturing processes, such as coreless filament winding with fiber composites or laser powder bed fusion with metals, can produce lightweight structures while exhibiting process-specific characteristics. Those features must be accounted for to successfully combine multiple processes and materials. This hybrid approach can merge the different benefits to realize mass savings in load-bearing structures with high mass-specific stiffnesses, strict geometrical tolerances, and machinability. In this study, a digital tool for coreless filament winding was developed to support all project phases by natively capturing the process-specific characteristics. As a demonstration, an aluminum base plate was stiffened by a coreless wound fiber-composite structure, which was attached by additively manufactured metallic winding pins. The geometrical deviations and surface roughness of the pins were investigated to describe the interface. The concept of multi-stage winding was introduced to reduce fiber–fiber interaction. The demonstration example exhibited an increase in mass-specific component stiffness by a factor of 2.5 with only 1/5 of the mass of a state-of-the-art reference. The hybrid design approach holds great potential to increase performance if process-specific features, interfaces, material interaction, and processes interdependencies are aligned during the digitized design phase.

A hemispherical research demonstration pavilion was presented to the public from April to October 2019. It was the first large-scale lightweight dome with a supporting roof structure primarily made of carbon- and glass-fiber-reinforced composites, fabricated by robotic coreless filament winding. We conducted monitoring to ascertain the sturdiness of the fiber composite material of the supporting structure over the course of 130 days. This paper presents the methods and results of on-site monitoring as well as laboratory inspections. The thermal behavior of the pavilion was characterized, the color change of the matrix was quantified, and the inner composition of the coreless wound structures was investigated. This validated the structural design and revealed that the surface temperatures of the carbon fibers do not exceed the guideline values of flat, black façades and that UV absorbers need to be improved for such applications.

Digitization and automation are essential tools to increase productivity and close significant added-value deficits in the building industry. Additive manufacturing (AM) is a process that promises to impact all aspects of building construction profoundly. Of special interest in AM is an in-depth understanding of material systems based on their isotropic or anisotropic properties. The presented research focuses on fiber-reinforced polymers, with anisotropic mechanical properties ideally suited for AM applications that include tailored structural reinforcement. This article presents a cyber-physical manufacturing process that enhances existing robotic coreless Filament Winding (FW) methods for glass and carbon fiber-reinforced polymers. Our main contribution is the complete characterization of a feedback-based, sensor-informed application for process monitoring and fabrication data acquisition and analysis. The proposed AM method is verified through the fabrication of a large-scale demonstrator. The main finding is that implementing AM in construction through cyber-physical robotic coreless FW leads to more autonomous prefabrication processes and unlocks upscaling potential. Overall, we conclude that material-system-aware communication and control are essential for the efficient automation and design of fiber-reinforced polymers in future construction.

The manufacturing process of robotic coreless filament winding has great potential for efficient material usage and automation for long-span lightweight construction applications. Design methods and quality control rely on an adequate digital representation of the fabrication parameters. The most influencing parameters are related to the resin impregnation of the fibers and the applied fiber tension during winding. The end-effector developed in this study allows efficient resin impregnation, which is controlled online by monitoring the induced fiber tension. The textile equipment was fully integrated into an upscaled nine-axis robotic winding setup. The cyber-physical fabrication method was verified with an application-oriented large-scale proof-of-concept demonstrator. From the subsequent analysis of the obtained datasets, a characteristic pattern in the winding process parameters was identified.