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Forster, David

David Forster

M. Sc.

Scientific Staff
Institute for Structural Mechanics

Contact

+49 711 685 66126
Email

Pfaffenwaldring 7
70550 Stuttgart
Deutschland
Room: 1.122

Vita

1993: Born in Lauingen an der Donau
2012: Abitur at the Margarete-Steiff-Gymnasium, Giengen an der Brenz
2012–2014: Federal volunteer service at the Bavarian Red Cross, ambulance service
2014–2017: Bachelor’s programme civil engineering at the University of Stuttgart
2015–2016: Working student at DEKRA Automobil GmbH
2016–2017: Semester abroad at the University of Calgary, Canada
2017–2019: Master’s programme civil engineering at the University of Stuttgart
2017: Admission to the German Academic Scholarship Foundation
2017–2019: Working student at Werner Sobek Stuttgart
Since 2019: Scientific staff at the Institute for Structural Mechanics, University of Stuttgart
05/2023–08/2023: Visiting scholar at the University of Illinois Urbana-Champaign, SMARTI Lab, Prof. Ann Sychterz

Research

Publications

Articles in journals

Forster, D., Paul, S., Bischoff, M., & Sychterz, A. C. (2024). Structural Assessment of Architected Material Using the Redundancy Matrix and Experimental Testing. ASME Journal of Applied Mechanics, 91. https://doi.org/10.1115/1.4065840
- Abstract
- BibTeX
Abstract
This paper presents the integration of a numerical structural model based on the redundancy matrix and experimental results of Multi-Layered Randomized Architected Materials (MLRAM). It presents a combination of the relatively new field of architected materials with a load-independent performance indicator from theoretical structural mechanics. The redundancy matrix by itself provides a measure for structural assessment that is independent of a specific load case. Various layouts of the MLRAM samples and recorded testing allow the analysis of the redundancy distribution within the structure as it undergoes failure. An in-depth analysis of the tested MLRAM samples is provided, as they show a high degree of static indeterminacy and thus, multiple different load paths. A special focus lies on the change of the redundancy distribution as global progressive failure happens. Another focus is set on the investigation of the failure initiation, meaning that the redundancy distribution can help to identify critical elements. A simple introductory example shows the interdependence between the variation of the geometric location of nodes and the redundancy distribution. The study shows, that the distribution of static indeterminacy can be used as a measure to quantify vulnerability to failure and rank the individual element's importance. Furthermore, progressive collapse is identified as a series of local effects in the highly statically indeterminate MLRAM samples, underlining the fact that the spatial distribution of static indeterminacy is of central importance for the assessment of structural safety.
BibTeX
@article{forster2024structural, abstract = {This paper presents the integration of a numerical structural model based on the redundancy matrix and experimental results of Multi-Layered Randomized Architected Materials (MLRAM). It presents a combination of the relatively new field of architected materials with a load-independent performance indicator from theoretical structural mechanics. The redundancy matrix by itself provides a measure for structural assessment that is independent of a specific load case. Various layouts of the MLRAM samples and recorded testing allow the analysis of the redundancy distribution within the structure as it undergoes failure. An in-depth analysis of the tested MLRAM samples is provided, as they show a high degree of static indeterminacy and thus, multiple different load paths. A special focus lies on the change of the redundancy distribution as global progressive failure happens. Another focus is set on the investigation of the failure initiation, meaning that the redundancy distribution can help to identify critical elements. A simple introductory example shows the interdependence between the variation of the geometric location of nodes and the redundancy distribution. The study shows, that the distribution of static indeterminacy can be used as a measure to quantify vulnerability to failure and rank the individual element's importance. Furthermore, progressive collapse is identified as a series of local effects in the highly statically indeterminate MLRAM samples, underlining the fact that the spatial distribution of static indeterminacy is of central importance for the assessment of structural safety.}, author = {Forster, David and Paul, Sagnik and Bischoff, Manfred and Sychterz, Ann C.}, doi = {10.1115/1.4065840}, journal = {ASME Journal of Applied Mechanics}, title = {Structural Assessment of Architected Material Using the Redundancy Matrix and Experimental Testing}, volume = 91, year = 2024 }
Kannenberg, F., Zechmeister, C., Gil Pérez, M., Guo, Y., Yang, X., Forster, D., Hügle, S., Mindermann, P., Abdelaal, M., Balangé, L., Schwieger, V., Weiskopf, D., Gresser, G. T., Middendorf, P., Bischoff, M., Knippers, J., & Menges, A. (2024). Toward reciprocal feedback between computational design, engineering, and fabrication to co-design coreless filament-wound structures. Journal of Computational Design and Engineering, 11(3), 374--394. https://doi.org/10.1093/jcde/qwae048
- Abstract
- BibTeX
Abstract
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.
BibTeX
@article{noauthororeditor2024toward, abstract = {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.}, author = {Kannenberg, Fabian and Zechmeister, Christoph and Gil Pérez, Marta and Guo, Yanan and Yang, Xiliu and Forster, David and Hügle, Sebastian and Mindermann, Pascal and Abdelaal, Moataz and Balangé, Laura and Schwieger, Volker and Weiskopf, Daniel and Gresser, Götz T. and Middendorf, Peter and Bischoff, Manfred and Knippers, Jan and Menges, Achim}, doi = {10.1093/jcde/qwae048}, journal = {Journal of Computational Design and Engineering}, number = 3, pages = {374--394}, title = {Toward reciprocal feedback between computational design, engineering, and fabrication to co-design coreless filament-wound structures}, volume = 11, year = 2024 }
Gil Pérez, M., Mindermann, P., Zechmeister, C., Forster, D., Guo, Y., Hügle, S., Kannenberg, F., Balangé, L., Schwieger, V., Middendorf, P., Bischoff, M., Menges, A., Gresser, G. T., & Knippers, J. (2023). Data processing, analysis, and evaluation methods for co-design of coreless filament-wound building systems. Journal of Computational Design and Engineering, 10(4), 1460–1478. https://doi.org/10.1093/jcde/qwad064
- Abstract
- BibTeX
Abstract
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 analyze 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.
BibTeX
@article{gilperez2023processing, abstract = {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 analyze 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.}, author = {Gil Pérez, Marta and Mindermann, Pascal and Zechmeister, Christoph and Forster, David and Guo, Yanan and Hügle, Sebastian and Kannenberg, Fabian and Balangé, Laura and Schwieger, Volker and Middendorf, Peter and Bischoff, Manfred and Menges, Achim and Gresser, Götz T and Knippers, Jan}, doi = {10.1093/jcde/qwad064}, journal = {Journal of Computational Design and Engineering}, number = 4, pages = {1460–1478}, title = {Data processing, analysis, and evaluation methods for co-design of coreless filament-wound building systems}, volume = 10, year = 2023 }
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), 310--329. https://doi.org/10.1093/jcde/qwab081
- Abstract
- BibTeX
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.
BibTeX
@article{gilperez2022computational, 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.}, author = {Gil Pérez, Marta and Zechmeister, Christoph and Kannenberg, Fabian and Mindermann, P. and Balangé, L. and Guo, Yanan and Hügle, S. and Gienger, Andreas and Forster, David and Bischoff, Manfred and Tarín, C. and Middendorf, Peter and Schwieger, Volker and Gresser, Götz T. and Menges, Achim and Knippers, Jan}, doi = {10.1093/jcde/qwab081}, journal = {Journal of Computational Design and Engineering}, language = {eng}, month = {04}, number = 2, pages = {310--329}, title = {Computational co-design framework for coreless wound fibre–polymer composite structures}, volume = 9, year = 2022 }
Oesterle, B., Geiger, F., Forster, D., Fröhlich, M., & Bischoff, M. (2022). A study on the approximation power of NURBS and the significance of exact geometry in isogeometric pre-buckling analyses of shells. Computer Methods in Applied Mechanics and Engineering, 397(115144), Article 115144. https://doi.org/10.1016/j.cma.2022.115144
- Abstract
- BibTeX
Abstract
We present a comprehensive study on the approximation power of NURBS and the significance of exact geometry in stability analyses of shells. Pre-buckling analyses are carried out to estimate the critical load levels and the initial buckling patterns. Various finite element solutions obtained with the commercial code ANSYS are compared with solutions from the isogeometric version of the finite element method, using our in-house code NumPro. In some problem setups, the isogeometric shell elements provide superior accuracy compared to standard (as opposed to isogeometric) shell finite elements, requiring only a fractional amount of degrees of freedom for the same level of accuracy. The present study systematically investigates the sources of this superior accuracy of the isogeometric approach. In particular, hypotheses are tested concerning the influence of exact geometry and smoothness of splines.
BibTeX
@article{oesterle2022study, abstract = {We present a comprehensive study on the approximation power of NURBS and the significance of exact geometry in stability analyses of shells. Pre-buckling analyses are carried out to estimate the critical load levels and the initial buckling patterns. Various finite element solutions obtained with the commercial code ANSYS are compared with solutions from the isogeometric version of the finite element method, using our in-house code NumPro. In some problem setups, the isogeometric shell elements provide superior accuracy compared to standard (as opposed to isogeometric) shell finite elements, requiring only a fractional amount of degrees of freedom for the same level of accuracy. The present study systematically investigates the sources of this superior accuracy of the isogeometric approach. In particular, hypotheses are tested concerning the influence of exact geometry and smoothness of splines.}, author = {Oesterle, Bastian and Geiger, Florian and Forster, David and Fröhlich, Manuel and Bischoff, Manfred}, doi = {10.1016/j.cma.2022.115144}, journal = {Computer Methods in Applied Mechanics and Engineering}, number = 115144, title = {A study on the approximation power of NURBS and the significance of exact geometry in isogeometric pre-buckling analyses of shells}, volume = 397, year = 2022 }

Articles in proceedings

Forster, D., Baker, W. F., & Bischoff, M. (2024). Structural Analysis Using the Redundancy Matrix and Graph Theory. In P. Block, G. Boller, C. DeWolf, J. Pauli, & W. Kaufmann (Eds.), Proceedings of the IASS 2024 Symposium Redefining the Art of Structural Design.
- Abstract
- BibTeX
Abstract
Structural engineers often want to have a redundant structure where the loss of a member would not lead to structural collapse. For a truss, adding a bar beyond that required for static determinacy renders the structure redundant, but what is the spatial distribution of the static indeterminacy within the individual elements of a framework? Can an additional bar be redundant with several existing bars? Are there truss topologies and geometries that enhance redundancy? The assessment of structures based on such load-independent quantitative measures can be useful in early design stages to achieve an integrative planning process for designers and engineers. The degree of static indeterminacy and in particular its spatial distribution, quantified with the redundancy matrix can be used for assessing structural integrity of a framework. Focusing on structural properties independent of the individual member stiffness, such as geometry and topology, graph theory offers yet another tool to assess structural performance. This paper explores the integration of the Maxwell-Calladine count with the redundancy matrix from theoretical structural mechanics and with contributions of graph theory to explore a deeper understanding of structural redundancy.
BibTeX
@inproceedings{forster2024structural, abstract = {Structural engineers often want to have a redundant structure where the loss of a member would not lead to structural collapse. For a truss, adding a bar beyond that required for static determinacy renders the structure redundant, but what is the spatial distribution of the static indeterminacy within the individual elements of a framework? Can an additional bar be redundant with several existing bars? Are there truss topologies and geometries that enhance redundancy? The assessment of structures based on such load-independent quantitative measures can be useful in early design stages to achieve an integrative planning process for designers and engineers. The degree of static indeterminacy and in particular its spatial distribution, quantified with the redundancy matrix can be used for assessing structural integrity of a framework. Focusing on structural properties independent of the individual member stiffness, such as geometry and topology, graph theory offers yet another tool to assess structural performance. This paper explores the integration of the Maxwell-Calladine count with the redundancy matrix from theoretical structural mechanics and with contributions of graph theory to explore a deeper understanding of structural redundancy.}, author = {Forster, David and Baker, William F. and Bischoff, Manfred}, booktitle = {Proceedings of the IASS 2024 Symposium Redefining the Art of Structural Design}, editor = {Block, Philippe and Boller, Giulia and DeWolf, Catherine and Pauli, Jacqueline and Kaufmann, Walter}, title = {Structural Analysis Using the Redundancy Matrix and Graph Theory}, year = 2024 }
Forster, D., von Scheven, M., & Bischoff, M. (2024). Alternative Beurteilung von Tragwerken mit Hilfe der Redundanzmatrix. In B. Oesterle, A. Bögle, W. Weber, & L. Striefler (Eds.), Berichte der Fachtagung Baustatik – Baupraxis 15, 04. und 05. März 2024, Hamburg (pp. 67--74). https://doi.org/10.15480/882.9247
- Abstract
- BibTeX
Abstract
Zur Analyse von Tragwerken ist es in frühen Entwurfsphasen häufig ausreichend, Schnitt- und Verschiebungsgrößen, sowie Spannungen im Rahmen der linearen Elastizitätstheorie zu bestimmen. Eine weitere fundamentale Eigenschaft von Tragwerken ist der Grad der statischen Unbestimmtheit und deren Verteilung innerhalb des Tragwerks. Die Redundanzmatrix liefert diese Information und stellt damit ein lastfallunabhängiges Maß zur Beurteilung von Tragwerken hinsichtlich Robustheit, Assemblierbarkeit und Adaptierbarkeit zur Verfügung.
BibTeX
@inproceedings{forster2024alternative, abstract = {Zur Analyse von Tragwerken ist es in frühen Entwurfsphasen häufig ausreichend, Schnitt- und Verschiebungsgrößen, sowie Spannungen im Rahmen der linearen Elastizitätstheorie zu bestimmen. Eine weitere fundamentale Eigenschaft von Tragwerken ist der Grad der statischen Unbestimmtheit und deren Verteilung innerhalb des Tragwerks. Die Redundanzmatrix liefert diese Information und stellt damit ein lastfallunabhängiges Maß zur Beurteilung von Tragwerken hinsichtlich Robustheit, Assemblierbarkeit und Adaptierbarkeit zur Verfügung.}, author = {Forster, David and von Scheven, Malte and Bischoff, Manfred}, booktitle = {Berichte der Fachtagung Baustatik – Baupraxis 15, 04. und 05. März 2024, Hamburg}, doi = {10.15480/882.9247}, editor = {Oesterle, Bastian and Bögle, Annette and Weber, Wolfgang and Striefler, Lukas}, pages = {67--74}, title = {Alternative Beurteilung von Tragwerken mit Hilfe der Redundanzmatrix}, year = 2024 }
Forster, D., Kannenberg, F., von Scheven, M., Menges, A., & Bischoff, M. (2023). Design and Optimization of Beam and Truss Structures Using Alternative Performance Indicators Based on the Redundancy Matrix. In K. Dörfler, J. Knippers, A. Menges, S. Parascho, H. Pottmann, & T. Wortmann (Eds.), Advances in Architectural Geometry 2023 (pp. 455--466). De Gruyter. https://doi.org/10.1515/9783111162683-034
- Abstract
- BibTeX
Abstract
In structural optimization processes, a common goal is to limit deflectionsor stresses through topological changes, shape adaption or cross-sectional adjust-ments. Beyond these well-established performance indicators, alternative measuresfor the assessment of structures based on the redundancy matrix can be used in thedesign and optimization process. This contribution shows the extension of the redun-dancy calculation to three-dimensional beam structures in detail. Using the conceptof redundancy for the design of structures, one goal is to homogeneously distributeredundancy within a structure in order to make an overall collapse due to failure ofindividual elements less likely. Furthermore, the sensitivity towards imperfections isquantified by the redundancy matrix, offering the opportunity to design connectionsof substructures, such that no constraint forces are introduced during the assemblyprocess. Those two concepts are showcased exemplarily within this contribution. Themethod is embedded into a computational co-design framework, which allows forquick, interactive feedback on design changes to strengthen the interplay between thedesign and engineering process.
BibTeX
@inproceedings{forster2023design, abstract = {In structural optimization processes, a common goal is to limit deflectionsor stresses through topological changes, shape adaption or cross-sectional adjust-ments. Beyond these well-established performance indicators, alternative measuresfor the assessment of structures based on the redundancy matrix can be used in thedesign and optimization process. This contribution shows the extension of the redun-dancy calculation to three-dimensional beam structures in detail. Using the conceptof redundancy for the design of structures, one goal is to homogeneously distributeredundancy within a structure in order to make an overall collapse due to failure ofindividual elements less likely. Furthermore, the sensitivity towards imperfections isquantified by the redundancy matrix, offering the opportunity to design connectionsof substructures, such that no constraint forces are introduced during the assemblyprocess. Those two concepts are showcased exemplarily within this contribution. Themethod is embedded into a computational co-design framework, which allows forquick, interactive feedback on design changes to strengthen the interplay between thedesign and engineering process.}, address = {Berlin, Boston}, author = {Forster, David and Kannenberg, Fabian and von Scheven, Malte and Menges, Achim and Bischoff, Manfred}, booktitle = {Advances in Architectural Geometry 2023}, doi = {10.1515/9783111162683-034}, editor = {Dörfler, Kathrin and Knippers, Jan and Menges, Achim and Parascho, Stefana and Pottmann, Helmut and Wortmann, Thomas}, pages = {455--466}, publisher = {De Gruyter}, title = {Design and Optimization of Beam and Truss Structures Using Alternative Performance Indicators Based on the Redundancy Matrix}, year = 2023 }

Bachelor and Master Thesis

Forster, D. (2019). Entwicklung einer Methode zur optimierten Platzierung von Aktoren in adaptiven Tragwerken. Masterarbeit 19/17. Betreuer: Jan Gade und Florian Geiger. Institut für Baustatik und Baudynamik, Universität Stuttgart.
- Abstract
- BibTeX
Abstract
Aufgrund von hohem Energie- und Ressourcenverbauch im Bauwesen gibt es Bestrebungen, aktivierbare Elemente in Tragwerken zu verwenden um materialsparend auf äußere Lasten reagieren zu können. Es existieren bereits Arbeiten, die sich mit dem Problem der Platzierung von Aktoren beschäftigen. Dabei werden zumeist heuristische Verfahren angewendet, da es sich bei der Aktorplatzierung um ein diskretes Optimierungsproblem handelt. In der hier vorliegenden Arbeit wird zunächst die stationäre Störgrößenkompensierbarkeit als Eigenschaft der Kompensierbarkeit äußerer Lasten hergleitet. Hierbei wird für ein korrektes Ergebnis ein Eingriff in die Berechnung der Pseudoinversen mit MATLAB notwendig, was anhand von zwei Beispielen erläutert wird. Anschließend werden die Spur, der maximale Eigenwert und die Frobeniusnorm der Gramschen Matrix als Gütemaße für die Aktorplatzierung vorgestellt. Diese Gütemaße werden anhand von Fachwerken untersucht, wobei die Eigenschaften Symmetrie und Grad der statischen Unbestimmtheit betrachtet werden. Die Spur stellt dabei ein Maß der durchschnittlichen Kompensierbarkeit dar, wohingegen der maximale Eigenwert und die Frobeniusnorm Rückschlüsse auf besonders ungünstige Einwirkungen zulassen. Die Kompensierbarkeit äußerer Lasten ist dabei für Verschiebungen deutlich höher als für Kräfte. In einem weiteren Schritt wurden zwei varianten des Greedy-Algorithmus und Simulated Annealing als heuristische Optimierungsverfahren für die Aktorplatzierung getestet und verglichen. Der vorwärtsgerichtete Greedy-Algorithmus liefert hierbei sowohl für den Eingriff in die Kräfte als auch bei den Verschiebungen das jeweils beste Ergebnis. Zudem wird in der vorliegenden Arbeit eine Möglichkeit vorgestellt, die Aktorplatzierung in ein kontinuierliches Problem zu überführen. Dadurch sind prinzipiell auch gradientenbasierte Optimierungsverfahren auf das Platzierungsproblem übertragbar.
BibTeX
@mastersthesis{forster2019entwicklung, abstract = { Aufgrund von hohem Energie- und Ressourcenverbauch im Bauwesen gibt es Bestrebungen, aktivierbare Elemente in Tragwerken zu verwenden um materialsparend auf äußere Lasten reagieren zu können. Es existieren bereits Arbeiten, die sich mit dem Problem der Platzierung von Aktoren beschäftigen. Dabei werden zumeist heuristische Verfahren angewendet, da es sich bei der Aktorplatzierung um ein diskretes Optimierungsproblem handelt. In der hier vorliegenden Arbeit wird zunächst die stationäre Störgrößenkompensierbarkeit als Eigenschaft der Kompensierbarkeit äußerer Lasten hergleitet. Hierbei wird für ein korrektes Ergebnis ein Eingriff in die Berechnung der Pseudoinversen mit MATLAB notwendig, was anhand von zwei Beispielen erläutert wird. Anschließend werden die Spur, der maximale Eigenwert und die Frobeniusnorm der Gramschen Matrix als Gütemaße für die Aktorplatzierung vorgestellt. Diese Gütemaße werden anhand von Fachwerken untersucht, wobei die Eigenschaften Symmetrie und Grad der statischen Unbestimmtheit betrachtet werden. Die Spur stellt dabei ein Maß der durchschnittlichen Kompensierbarkeit dar, wohingegen der maximale Eigenwert und die Frobeniusnorm Rückschlüsse auf besonders ungünstige Einwirkungen zulassen. Die Kompensierbarkeit äußerer Lasten ist dabei für Verschiebungen deutlich höher als für Kräfte. In einem weiteren Schritt wurden zwei varianten des Greedy-Algorithmus und Simulated Annealing als heuristische Optimierungsverfahren für die Aktorplatzierung getestet und verglichen. Der vorwärtsgerichtete Greedy-Algorithmus liefert hierbei sowohl für den Eingriff in die Kräfte als auch bei den Verschiebungen das jeweils beste Ergebnis. Zudem wird in der vorliegenden Arbeit eine Möglichkeit vorgestellt, die Aktorplatzierung in ein kontinuierliches Problem zu überführen. Dadurch sind prinzipiell auch gradientenbasierte Optimierungsverfahren auf das Platzierungsproblem übertragbar.}, author = {Forster, David}, publisher = {Masterarbeit 19/17. Betreuer: Jan Gade und Florian Geiger. Institut für Baustatik und Baudynamik, Universität Stuttgart}, title = {Entwicklung einer Methode zur optimierten Platzierung von Aktoren in adaptiven Tragwerken}, year = 2019 }
Forster, D. (2017). Festigkeitseinfluss der Querlagendicke bei Rollschubbeanspruchung von Brettsperrholzelementen aus Fichtenholz. Bachelorarbeit. Betreuer: Dr. Simon Aicher, Institut für Werkstoffe im Bauwesen, MPA.
- Abstract
- BibTeX
Abstract
Brettsperrholz ist ein innovatives Produkt der Holzindustrie, das durch die voranschreitende Technik seit den Neunzigerjahren vor allem in Deutschland und Österreich zunehmend an Bedeutung gewonnen hat 1. Durch die vielseitigen Einsatzmöglichkeiten, insbesondere im mehrgeschossigen Wohnungsbau hat sich die Forschung im Bereich von Brettsperrholz (kurz: BSP; engl: CLT, X-Lam) deutlich intensiviert. In dieser Arbeit wird zunächst auf das Material Brettsperrholz und dessen Vorteile eingegangen und im Anschluss daran wird anhand mehrerer Versuchsreihen die Bestimmung der Rollschubfestigkeit aufgezeigt. Im Rahmen einer gezielten Prüfserie wurde der Größeneinfluss bei Rollschubbeanspruchung untersucht. Ziel war es, festzustellen ob bei gleichem Seitenverhältnis der Querlagen in Brettsperrholzelementen die Rollschubfestigkeit von der Größe, d.h. insbesondere von der Dicke der Querlage abhängt oder nicht.
BibTeX
@mastersthesis{forster2017festigkeitseinfluss, abstract = {Brettsperrholz ist ein innovatives Produkt der Holzindustrie, das durch die voranschreitende Technik seit den Neunzigerjahren vor allem in Deutschland und Österreich zunehmend an Bedeutung gewonnen hat [1]. Durch die vielseitigen Einsatzmöglichkeiten, insbesondere im mehrgeschossigen Wohnungsbau hat sich die Forschung im Bereich von Brettsperrholz (kurz: BSP; engl: CLT, X-Lam) deutlich intensiviert. In dieser Arbeit wird zunächst auf das Material Brettsperrholz und dessen Vorteile eingegangen und im Anschluss daran wird anhand mehrerer Versuchsreihen die Bestimmung der Rollschubfestigkeit aufgezeigt. Im Rahmen einer gezielten Prüfserie wurde der Größeneinfluss bei Rollschubbeanspruchung untersucht. Ziel war es, festzustellen ob bei gleichem Seitenverhältnis der Querlagen in Brettsperrholzelementen die Rollschubfestigkeit von der Größe, d.h. insbesondere von der Dicke der Querlage abhängt oder nicht.}, author = {Forster, David}, publisher = {Bachelorarbeit. Betreuer: Dr. Simon Aicher, Institut für Werkstoffe im Bauwesen, MPA}, title = {Festigkeitseinfluss der Querlagendicke bei Rollschubbeanspruchung von Brettsperrholzelementen aus Fichtenholz}, year = 2017 }

Presentations

Presentations at Conferences

David Forster, William F. Baker, Manfred Bischoff. Structural Analysis Using the Redundancy Matrix and Graph Theory. IASS 2024 - Redefining the Art of Structural Design, Zurich, Switzerland, August 26–29, 2024.

David Forster, Malte von Scheven, Manfred Bischoff. Alternative Beurteilung von Tragwerken mit Hilfe der Redundanzmatrix. 15. Fachtagung Baustatik – Baupraxis (BB15), Hamburg, Germany, March 4–5, 2024.

David Forster, Fabian Kannenberg, Malte von Scheven, Achim Menges, Manfred Bischoff. Design and Optimization of Beam and Truss Structures Using Alternative Performance Indicators Based on the Redundancy Matrix. Advances in Architectural Geometry (AAG 2023), Stuttgart, Germany, October 6–7, 2023.

David Forster, Malte von Scheven, Ann C. Sychterz, Manfred Bischoff. Analysis and design of deployable structures using the redundancy matrix. 10th GACM Colloquium on Computational Mechanics (GACM 2023), Vienna, Austria, September 10–13, 2023.

David Forster, Ann Sychterz, Manfred Bischoff. Analysis of Coreless Filament Wound Structures Using Alternative Performance Indicators. Engineering Mechanics Institute Conference 2023 (EMI 2023), Atlanta, Georgia, June 06–09, 2023.

Bastian Oesterle, Florian Geiger, David Forster, Manuel Fröhlich, Manfred Bischoff. A study on the approximation power of NURBS and the significance of exact geometry in isogeometric pre-buckling analyses of shells. Isogeometric Analysis 2022 (IGA 2022), Banff, Canada, November 06–09, 2022.

David Forster, Malte von Scheven, Manfred Bischoff. Optimization of Beam and Truss Structures Using Alternative Performance Indicators. 9th GACM Colloquium on Computational Mechanics (GACM 2022), Essen, Germany, September 21–23, 2022.

David Forster, Malte von Scheven, Manfred Bischoff. Multigrid Methods for Real-time Structural Feedback. 6th ECCOMAS Young Investigators Conference (YIC 2021), Valencia, Spain (Virtual Congress), July 7–9, 2021.

Awards

2024: 1st price for the best young generation plenary lecture. Title of the lecture at the 15. symposium „Baustatik - Baupraxis“: „Alternative assessment of structures using the redundancy matrix“
2024: IntCDC best publication award as Co-author for the article „Toward reciprocal feedback between computational design, engineering and fabrication to co-design coreless filament-wound structures“ in the Journal of Computational Design and Engineering (JCDE)

Further Activities in the Scientific Community

External profiles

Committee Activities at the University of Stuttgart

2020–2023: Member of the Faculty Council of Faculty 2

Organization of Conferences and Mini Symposia

2020: 14. Fachtagung Baustatik-Baupraxis (BB14), Stuttgart, Germany, March 23–24, 2020 (Local Organizing Team).

Teaching

Computerorientierte Methoden für Kontinua und Flächentragwerke (M.Sc.), winter term 2019/2020
Baustatik (B.Sc.), summer terms 2020, 2021 and winter terms 2020/2021, 2021/2022
Nichtlineare Baustatik (B.Sc.), summer term 2022

Supervision of Theses

Master Theses

Simon Briem. Entwicklung einer Methode zur optimierten Platzierung von Stützen (24/10). Master Thesis. Supervisor: David Forster und Dr.-Ing. Cristóbal Tapia (MPA). Institute for Structural Mechanics, University of Stuttgart. 2024.
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- Poster with results
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Maximilian Mahler. Traglastverfahren mithilfe von Redundanzmatrizen (23/14). Master Thesis. Supervisor: David Forster. Institute for Structural Mechanics, University of Stuttgart. 2023.
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- Poster with results
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Henrik Jakob. Isogeometric Analysis of trimmed NURBS (23/11). Master Thesis. Supervisor: David Forster und Alexander Müller. Institute for Structural Mechanics, University of Stuttgart. 2023.
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- Poster with results
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Andrea Habrich. Investigations on the Optimization of the Redundancy Distribution in Truss Structures (23/22). Master Thesis. Supervisor: Malte von Scheven und David Forster. Institute for Structural Mechanics, University of Stuttgart. 2023.
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- Poster with results
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Adnan Ali Imran. Material Modeling and Simulation of Wood for Anchoring Applications (22/09). Master Thesis. Supervisor: David Forster und Vincent de Groof (Hilti AG, Liechtenstein). Institute for Structural Mechanics, University of Stuttgart. 2022.

Bachelor Theses

Elisabeth Drabarek. Tragverhalten von Gitterschalen unter Zwangslastfällen (23/07). Bachelor Thesis. Supervisor: David Forster. Institute for Structural Mechanics, University of Stuttgart. 2023.
- Abstract
- Poster with results
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Jonas Neuscheler. Identifikation und Verarbeitung von statischen Systemen mit neuronalen Netzen (22/10). Bachelor Thesis. Supervisor: David Forster und Sami Bidier (str.ucture). Institute for Structural Mechanics, University of Stuttgart. 2022.
- Abstract
- Poster with results
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Henrik Jakob. Analyse der Schalenstrukturen von Heinz Isler (21/03). Bachelor Thesis. Supervisor: David Forster. Institute for Structural Mechanics, University of Stuttgart. 2021.
- Abstract
- Poster with results
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Nawras Alsayed. Tragverhalten von Bogenbrücken mit aufgeständerter Fahrbahn (21/12). Bachelor Thesis. Supervisor: David Forster. Institute for Structural Mechanics, University of Stuttgart. 2021.
- Abstract
- Poster with results
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Maximilian Mahler. Stabilitätsuntersuchungen von Schalen (21/17). Bachelor Thesis. Supervisor: David Forster. Institute for Structural Mechanics, University of Stuttgart. 2021.
- Abstract
- Poster with results
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Lars Greinert. Verformungsuntersuchungen bei Querschnittsschwächungen (20/14). Bachelor Thesis. Supervisor: David Forster und Frédéric Hilchenbach (f2k ingenieure gmbh). Institute for Structural Mechanics, University of Stuttgart. 2020.
- Abstract
- Poster with results
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Further Theses

Thomas Stegmeyer. Statische Untersuchung von Fahrradrahmen (22/04). Project Thesis. Supervisor: David Forster. Institute for Structural Mechanics, University of Stuttgart. 2022.
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- Poster with results
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