Dissertations / Theses: 'Structural topology/design'

1

Deaton, Joshua D. "Design of Thermal Structures using Topology Optimization." Wright State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=wright1401302982.

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Lu, Bodi. "Conceptual design using multilevel continuum structural topology optimization." Thesis, University of Iowa, 2014. https://ir.uiowa.edu/etd/4685.

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Continuum topology optimization is a mathematical/computational method to find optimal conceptual structural designs for given loads and boundary conditions. To provide realistic design solutions for structures such as long-span bridges, the method must deal with sparse structures on large, finely meshed domains. Consequently, the method can be very computationally intensive. In this study we attempt to reduce the computational intensity by applying both a multi-level refinement method and an analysis problem size reduction technique. The proposed techniques are found in this study to reduce the computational effort required by a factor of about 3. To make sure that design solutions obtained with the proposed methods are both constructible and convergent with mesh refinement, a perimeter control method is employed in this framework. Besides, analysis is made on both structural layout and objective function curve diagram during optimization process.

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Rawat, Sharad. "DEEP LEARNING BASED FRAMEWORK FOR STRUCTURAL TOPOLOGY DESIGN." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1559560543458263.

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Wang, Jingwen M. Eng Massachusetts Institute of Technology. "Trabecular topology : computational structural design inspired by bone remodeling." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/111530.

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Thesis: M. Eng., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2017.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 59-60).
Bone remodeling is the process by which the internal morphology of bones in a healthy person or animal will adapt to the loads under which it is placed. This process makes bone stronger and performs better under daily loadings. It also gives a special topology to the trabecular bone. This thesis proposes a new computational structural design approach inspired by the trabecular bone topology and remodeling process and it can be applied to the 2D, 3D and building-scale structures. It reveals the importance of the connectivity in the structures and provides a innovative bio-inspired method for the future structural topology design.
by Jingwen Wang.
M. Eng.

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Wang, Lyang Suan. "Automating Parametric Redesign of Structural Thin-Walled Frames Based On Topology Optimized Structure." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu156618342438725.

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Ciftci, Erhan. "Evolutionary Algorithms In Design." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/2/12607983/index.pdf.

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Evolutionary Structural Optimization (ESO) is a relatively new design tool used to improve and optimise the design of structures. In this method, a few elements of an initial design domain of finite elements are iteratively removed. Such a process is carried out repeatedly until an optimum design is achieved, or until a desired given area or volume is reached. In structural design, there is the demand for the development of design tools and methods that includes optimization. This need is the reason behind the development of methods like Evolutionary Structural Optimization (ESO). It is also this demand that this thesis seeks to satisfy. This thesis develops and examines the program named EVO, with the concept of structural optimization in the ESO process. Taking into account the stiffness and stress constraints, EVO allows a realistic and accurate approach to optimising a model in any given environment. Finally, in verifying the ESO algorithm&rsquo
s and EVO program&rsquo
s usefulness to the practical aspect of design, the work presented herein applies the ESO method to case studies. They concern the optimization of 2-D frames, and the optimization of 3-D spatial frames and beams with the prepared program EVO. Comparisons of these optimised models are then made to those that exist in literature.

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Muir, Martin James. "Superior structural design through automated topology optimization and advanced manufacturing." Thesis, University of Leeds, 2018. http://etheses.whiterose.ac.uk/21920/.

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Challenging times lie ahead for commercial aerospace, facing regulatory pressure to reduce emissions on one side and the potential of increased competition on the other, a continuation of the business and engineering philosophies which led to such a healthy orderbook in the past, cannot be guaranteed for the future – substantial, disruptive change is required. Additive Manufacturing (AM) and Topology Optimization (TO) are two technologies under investigation by Airbus and others which have promised to deliver such change. Problematically, both are expert level technologies with enormous complexities and thus their application is commonly applied only where justification of such skills for such lengths of time can be considered to be economically viable. However, whilst there are indeed gains to be had in such large, complex structures, their numbers on commercial aircraft are few. Conversely, there are literally thousands of small, heavy, metallic components which would benefit from the application of these technologies if the cost of technology application could be reduced. The aim of this research is to deskill the application of TO and AM by automating the process of TO specific to manufacturing via AM and thus reduce the cost of its implementation and increase the practicality of its application. Through a survey of the Airbus user community, a standardised series of tools, inputs, outputs and process was developed, culminating in an analysis of time consumed during a series of optimization tasks. From this list of tasks and the time lost to each, a series of targets for automation were identified and researched. Using a series of interconnected codes and scripts, pre-processing phases such as design space creation, meshing and loading application were automated and applied to a common FEM template. Within this template, generic material and geometric capability figures for AM Ti64 Grade 5 were established via bespoke testing on a range of AM platforms under common parameters and builds. After this, methods for automated design extraction back to parametric CAD were investigated and performed, establishing a direct link between the FEM and the output CAD to enable rapid design development. The combined series of automation steps leads to an almost 75% reduction in total non-recurring cost for optimization and design of small components. Whilst not, as yet, wholly industrialised and implemented within Airbus, research from the early phases is now in use for MDO tools within Airbus and Airbus Group.

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Kaveh, Mohammad. "Topological optimization of rigidly jointed space frames." Thesis, Cardiff University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.238227.

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Peto, Marinela. "Topology and Lattice-Based Structural Design Optimization for Additively Manufactured Medical Implants." Thesis, University of North Texas, 2019. https://digital.library.unt.edu/ark:/67531/metadc1505245/.

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Topology-based optimization techniques and lattice structures are powerful ways to accomplish lightweight components with enhanced mechanical performance. Recent developments in additive manufacturing (AM) have led the way to extraordinary opportunities in realizing complex designs that are derived from topology and lattice-based structural optimization. The main aim of this work is to give a contribution, in the integration between structural optimization techniques and AM, by proposing a setup of a proper methodology for rapid development of optimized medical implants addressing oseeointegration and minimization of stress shielding related problems. The validity of the proposed methodology for a proof of concept was demonstrated in two real-world case studies: a tibia intramedullary implant and a shoulder hemi prosthetics for two bone cancer patients. The optimization was achieved using topology optimization and replacement of solid volumes by lattice structures. Samples of three lattice unit cell configurations were designed, fabricated, mechanically tested, and compared to select the most proper configuration for the shoulder hemi prosthesis. Weight reductions of 30% and 15% were achieved from the optimization of the initial design of the tibia intramedullary implant and the shoulder hemiprosthesis respectively compared to initial designs. Prototypes were fabricated using selective laser melting (SLM) and direct light processing (DLP) technologies. Validation analysis was performed using finite element analysis and compressive mechanical testing. Future work recommendations are provided for further development and improvement of the work presented in this thesis.

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Noguchi, Yuki. "An optimum structural design methodology for acoustic metamaterials using topology optimization." Kyoto University, 2019. http://hdl.handle.net/2433/242492.

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Sato, Yuki. "A structural design methodology based on multiobjective and manufacturing-oriented topology optimization." Kyoto University, 2019. http://hdl.handle.net/2433/242490.

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Richardson, James. "Topology optimization of truss-like structures, from theory to practice." Doctoral thesis, Universite Libre de Bruxelles, 2013. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209534.

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The goal of this thesis is the development of theoretical methods targeting the implementation of topology optimization in structural engineering applications. In civil engineering applications, structures are typically assemblies of many standardized components, such as bars, where the largest gains in efficiency can be made during the preliminary design of the overall structure. The work is aimed mainly at truss-like structures in civil engineering applications, however several of the developments are general enough to encompass continuum structures and other areas of engineering research too. The research aims to address the following challenges:

- Discrete variable optimization, generally necessary for truss problems in civil engineering, tends to be computationally very expensive,

- the gap between industrial applications in civil engineering and optimization research is quite large, meaning that the developed methods are currently not fully embraced in practice, and

- industrial applications demand robust and reliable solutions to the real-world problems faced by the civil engineering profession.

In order to face these challenges, the research is divided into several research papers, included as chapters in the thesis.

Discrete binary variables in structural topology optimization often lead to very large computational cost and sometimes even failure of algorithm convergence. A novel method was developed for improving the performance of topology optimization problems in truss-like structures with discrete design variables, using so-called Kinematic Stability Repair (KSR). Two typical examples of topology optimization problems with binary variables are bracing systems and steel grid shell structures. These important industrial applications of topology optimization are investigated in the thesis. A novel method is developed for topology optimization of grid shells whose global shape has been determined by form-finding. Furthermore a novel technique for façade bracing optimization is developed. In this application a multiobjective approach was used to give the designers freedom to make changes, as the design advanced at various stages of the design process. The application of the two methods to practical

engineering problems, inspired a theoretical development which has wide-reaching implications for discrete optimization: the pitfalls of symmetry reduction. A seemingly self-evident method of cardinality reduction makes use of geometric symmetry reduction in structures in order to reduce the problem size. It is shown in the research that this assumption is not valid for discrete variable problems. Despite intuition to the contrary, for symmetric problems, asymmetric solutions may be more optimal than their symmetric counterparts. In reality many uncertainties exist on geometry, loading and material properties in structural systems. This has an effect on the performance (robustness) of the non-ideal, realized structure. To address this, a general robust topology optimization framework for both continuum and truss-like structures, developing a novel analysis technique for truss structures under material uncertainties, is introduced. Next, this framework is extended to discrete variable, multiobjective optimization problems of truss structures, taking uncertainties on the material stiffness and the loading into account. Two papers corresponding to the two chapters were submitted to the journal Computers and Structures and Structural and Multidisciplinary Optimization. Finally, a concluding chapter summarizes the main findings of the research. A number of appendices are included at the end of the manuscript, clarifying several pertinent issues.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished

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Zuo, Zihao, and Zhihao zuo@rmit edu au. "Topology optimization of periodic structures." RMIT University. Civil, Environmental and Chemical Engineering, 2009. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20091217.151415.

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This thesis investigates topology optimization techniques for periodic continuum structures at the macroscopic level. Periodic structures are increasingly used in the design of structural systems and sub-systems of buildings, vehicles, aircrafts, etc. The duplication of identical or similar modules significantly reduces the manufacturing cost and greatly simplifies the assembly process. Optimization of periodic structures in the micro level has been extensively researched in the context of material design, while research on topology optimization for macrostructures is very limited and has great potential both economically and intellectually. In the present thesis, numerical algorithms based on the bi-directional evolutionary structural optimization method (BESO) are developed for topology optimization for various objectives and constraints. Soft-kill (replacing void elements with soft elements) formulations of topology optimization problems for solid-void solutions are developed through appropriate material interpolation schemes. Incorporating the optimality criteria and algorithms for mesh-independence and solution-convergence, the present BESO becomes a reliable gradient based technique for topology optimization. Additionally, a new combination of genetic algorithms (GAs) with BESO is developed in order to stochastically search for the global optima. These enhanced BESO algorithms are applied to various optimization problems with the periodicity requirement as an extra constraint aiming at producing periodicity in the layout. For structures under static loading, the present thesis addresses minimization of the mean compliance and explores the applications of conventional stiffness optimization for periodic structures. Furthermore, this thesis develops a volume minimization formulation where the maximum deflection is constrained. For the design of structures subject to dynamic loading, this thesis develops two different approaches (hard-kill and soft-kill) to resolving the problem of localized or artificial modes. In the hard-kill (completely removing void elements) approach, extra control measures are taken in order to eliminate the localized modes in an explicit manner. In the soft-kill approach, a modified power low material model is presented to prevent the occurrence of artificial and localized modes. Periodic stress and strain fields cannot be assumed in structures under arbitrary loadings and boundaries at the macroscopic level. Therefore being different from material design, no natural base cell can be directly extracted from macrostructures. In this thesis, the concept of an imaginary representative unit cell (RUC) is presented. For situations when the structure cannot be discretized into equally-sized elements, the concept of sensitivity density is developed in order for mesh-independent robust solutions to be produced. The RUC and sensitivity density based approach is incorporated into various topology optimization problems to obtain absolute or scaled periodicities in structure layouts. The influence of this extra constraint on the final optima is investigated based on a large number of numerical experiments. The findings shown in this thesis have established appropriate techniques for designing and optimizing periodic structures. The work has provided a solid foundation for creating a practical design tool in the form of a user-friendly computer program suitable for the conceptual design of a wide range of structures.

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14

Mansouri, Ahmad, and David Norman. "Strategy Development of Structural Optimization in Design Processes." Thesis, Linköping University, Linköping University, Department of Management and Engineering, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-17418.

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This thesis aims toward developing strategies in the area of structural optimization and to implement these strategies in design processes. At

GM Powertrain Sweden where powertrains are designed and developed, two designs of a differential housing have been chosen for this thesis. The main tasks have been to perform a topology optimization of a model early in a design process, and a shape optimization on a model late in a design process. In addition the shape optimization strategies have also been applied on a fork shifter. This thesis covers the theory of different optimization strategies in general. The optimization processes are explained in detail and the results from the structural optimization of the differential housings as well as the fork shifter are shown and evaluated. The evaluation of the thesis provides enough arguments to suggest an implementation of the optimization strategies in design processes at GM Powertrain

. A Structural Optimization group has great potential of closing the gap between structural designers and structural analysis engineers which in long terms mean that better structures can be developed in less time. To be competitive in the automotive industry these are two of the most important factors for being successful.

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15

Gillman, Kevin M. "Optimization of Shape, Size, and Topology Design Variables in Trusses with a Genetic Algorithm." Diss., CLICK HERE for online access, 2005. http://contentdm.lib.byu.edu/ETD/image/etd683.pdf.

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16

Baldock, Robert David. "Structural optimisation in building design practice : case-studies in topology optimisation of bracing systems." Thesis, University of Cambridge, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.612227.

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Patel, Jiten. "Optimal design of mesostructured materials under uncertainty." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31829.

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Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2010.
Committee Chair: Choi, Seung-Kyum; Committee Member: Muhanna, Rafi; Committee Member: Rosen, David. Part of the SMARTech Electronic Thesis and Dissertation Collection.

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Schön, Sofia. "Design Space Exploration for Structural Aircraft Components : A method for using topology optimization in concept development." Thesis, Linköpings universitet, Maskinkonstruktion, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-159955.

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When building aircrafts, structural components must be designed for high strength, low cost, and easy assembly.To meet these conditions structural components are often based upon previous designs, even if a new component is developed.Refining previous designs can be a good way of preserving knowledge but can also limit the exploration of new design concepts. Currently the design process for structural aircraft components at SAAB is managed by design engineers. The design engineer is responsible for ensuring the design meets requirements from several different disciplines such as structural analysis, manufacturing, tool design, and assembly.Therefore, the design engineer needs to have good communication with all disciplines and an effective flow of information. The previous design is refined, it is then reviewed and approved by adjacent disciplines.Reviewing designs is an iterative process, and when several disciplines are involved it quickly becomes time consuming.Any time the design is altered it has to be reviewed once more by all disciplines to ensure the change is acceptable.So there is a need for further customizing the design concept to decrease the number of iterations when reviewing. Design Space Exploration DSE is a well known method to explore design alternatives before implementation and is used to find new concepts.This thesis investigates if DSE can be used to facilitate the design process of structural aircraft components and if it can support the flow of information between different disciplines.To find a suitable discipline to connect with design a prestudy is conducted, investigating what information affect structural design and how it is managed.The information flow is concluded in a schematic diagram where structural analysis is chosen as additional discipline. By using topology optimization in a DSE, design and structural analysis are connected.The design space can be explored with regards to structural constraints.The thesis highlights the possibilities of using DSE with topology optimization for developing structural components and proposes a method for including it in the design process.

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Ma, Jiachen. "Comparative Study of Structural Optimization Methods for Automotive Hood Frames." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu159353142765874.

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Ulu, Erva. "Enhancing the Structural Performance of Additively Manufactured Objects." Research Showcase @ CMU, 2018. http://repository.cmu.edu/dissertations/1188.

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The ability to accurately quantify the performance an additively manufactured (AM) product is important for a widespread industry adoption of AM as the design is required to: (1) satisfy geometrical constraints, (2) satisfy structural constraints dictated by its intended function, and (3) be cost effective compared to traditional manufacturing methods. Optimization techniques offer design aids in creating cost-effective structures that meet the prescribed structural objectives. The fundamental problem in existing approaches lies in the difficulty to quantify the structural performance as each unique design leads to a new set of analyses to determine the structural robustness and such analyses can be very costly due to the complexity of in-use forces experienced by the structure. This work develops computationally tractable methods tailored to maximize the structural performance of AM products. A geometry preserving build orientation optimization method as well as data-driven shape optimization approaches to structural design are presented. Proposed methods greatly enhance the value of AM technology by taking advantage of the design space enabled by it for a broad class of problems involving complex in-use loads.

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Sato, Ayami. "A structural optimization methodology for multiscale designs considering local deformation in microstructures and rarefied gas flows in microchannels." Kyoto University, 2019. http://hdl.handle.net/2433/242495.

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Descamps, Benoît. "Optimal shaping of lightweight structures." Doctoral thesis, Universite Libre de Bruxelles, 2013. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209362.

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Designing structures for lightness is an intelligent and responsible way for engineers and architects to conceive structural systems. Lightweight structures are able to bridge wide spans with a least amount of material. However, the quest for lightness remains an utopia without the driving constraints that give sense to contemporary structural design.

Previously proposed computational methods for designing lightweight structures focused either on finding an equilibrium shape, or are restricted to fairly small design applications. In this work, we aim to develop a general, robust, and easy-to-use method that can handle many design parameters efficiently. These considerations have led to truss layout optimization, whose goal is to find the best material distribution within a given design domain discretized by a grid of nodal points and connected by tentative bars.

This general approach is well established for topology optimization where structural component sizes and system connectivity are simultaneously optimized. The range of applications covers limit analysis and identification of failure mechanisms in soils and masonries. However, to fully realize the potential of truss layout optimization for the design of lightweight structures, the consideration of geometrical variables is necessary.

The resulting truss geometry and topology optimization problem raises several fundamental and computational challenges. Our strategy to address the problem combines mathematical programming and structural mechanics: the structural properties of the optimal solution are used for devising the novel formulation. To avoid singularities arising in optimal configurations, the present approach disaggregates the equilibrium equations and fully integrates their basic elements within the optimization formulation. The resulting tool incorporates elastic and plastic design, stress and displacements constraints, as well as self-weight and multiple loading.

Besides, the inherent slenderness of lightweight structures requires the study of stability issues. As a remedy, we develop a conceptually simple but efficient method to include local and nodal stability constraints in the formulation. Several numerical examples illustrate the impact of stability considerations on the optimal design.

Finally, the investigation on realistic design problems confirms the practical applicability of the proposed method. It is shown how we can generate a range of optimal designs by varying design settings. In that regard, the computational design method mostly requires the designer a good knowledge of structural design to provide the initial guess.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished

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Mativo, John M. "System Design of Composite Thermoelectrics for Aircraft Energy Harvesting." University of Dayton / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1607959975788155.

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Hayashi, Kazuki. "Reinforcement Learning for Optimal Design of Skeletal Structures." Doctoral thesis, Kyoto University, 2021. http://hdl.handle.net/2433/263614.

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井原, 久., Hisashi Ihara, 昌利下田, Masatoshi Shimoda, 秀幸畔上, Hideyuki Azegami, 俊明桜井, and Toshiaki Sakurai. "均質化理論に基づく位相最適化法によるホモロガス変形問題の数値解法." 日本機械学会, 1997. http://hdl.handle.net/2237/7246.

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井原, 久., Hisashi Ihara, 昌利下田, Masatoshi Shimoda, 秀幸畔上, Hideyuki Azegami, 俊明桜井, and Toshiaki Sakurai. "位相最適化と形状最適化の統合による多目的構造物の形状設計(均質化法と力法によるアプローチ)." 日本機械学会, 1996. http://hdl.handle.net/2237/7242.

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Frabolot, Ferdinand. "Optimisation de forme avec détection automatique de paramètres." Thesis, Compiègne, 2015. http://www.theses.fr/2015COMP2182/document.

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L’objectif de ce travail de thèse est de pouvoir intégrer totalement l’optimisation de forme des raidisseurs de capot dans un processus de conception industrielle et cela afin d’optimiser la forme et la distribution des raidisseurs dans un contexte multi-objectif (voire multi-disciplinaire) d’une structure 3D surfacique. Pour ce faire, nous avons tout d’abord établi un aperçu de l’état de l’art dans l’optimisation de forme des structures en classifiant les différentes méthodes de paramétrage de forme, en trois catégories ; les méthodes basées sur la géométrie (telle la paramétrisation d’un modèle de type CAO), les méthodes basées sur une grille fixe (telles que les méthodes d’optimisation topologique) et les méthodes basées sur le maillage (telles que les méthodes de régularisation du maillage). Toutefois, aucune de ces méthodes ne satisfait pleinement aux objectifs posés. Nous introduisons ainsi dans cette thèse la méthode FEM-CsG : Finite Element Mesh - Constructive surface Geometry. Imprégnée d’un fort contexte industriel, cette méthode propose une réponse à des contraintes telles que la possibilité de représenter la solution optimale par un ensemble de paramètres CAO, la possibilité d’adapter le modèle EF à l’analyse souhaitée et la garantie d’une représentation géométrique et d’un maillage robuste. En proposant d’intégrer des formes élémentaires paramétrées et prémaillées issues d’une bibliothèque de formes dans une structure coque 3D maillée par l’utilisation des variables issues de la CAO, la méthode FEM-CsG permet une évolution constante de la topologie guidée par l’optimisation. Ainsi, même si la topologie est modifiée la forme résultante reste conforme avec une représentation CAO par construction, correspondant davantage à la réalité des optimisations réalisées en avant-projet. La méthode FEM-CsG a été validée sur deux études de cas, de complexité variable, permettant de mettre en avant la robustesse de cette dernière. Ainsi, avec un choix intelligent et cohérent des variables de formes, les problèmes d’optimisation peuvent avec un nombre restreint de variables explorer un nombre important de topologies ou de formes. Les changements de topologies s’effectuent de manière continue, validant ainsi la méthode à tout type d’analyse souhaitée
The objective of this thesis work is to be able to completely integrate shape optimization of car inner hood stiffeners in a complex industrial process, in order to fully optimize the shape and distribution of the stiffeners in a multi-objective approach (or even multi-disciplinary) of a 3D surfacic structure. To this end, we established, at the outset, an insight of the state-of-the-art in shape optimization of structures by classifying the different shape parametrizations in three distinct categories : geometry-based methods (a shape parametrization such as a CAD model), grid-based methods (such as topology optimization methods) and mesh-based methods (such as morphing methods or mesh regulation). However, none of these methods fully satisfies the set objectives. Thus, we will introduce in this work the FEM-CsG method : Finite Element Mesh - Constructive surface Geometry. Bolstered by its strong industrial context, this method offers a response to such constraints, i.e. the possibility to represent the optimal solution by a system of CAD parameters, the possibility to adapt the FE model to the wanted analysis and the guarantee of a robust geometrical representation and mesh stability. We offer to incorporate premeshed parameterized elementary forms into a 3D sheet meshed structures. Hence, these forms are arising from a CAD parameterized elementary form library. Furthermore, the FEM-CsG method uses a set of operators acting on the mesh allowing a constant evolution of the topology guided by optimization. Therefore, even if the topology may vary, the resulting shapes comply with CAD representations by construction, a solution better reflecting the reality of optimizations performed during the preliminary development stage. The FEM-CsG method has been validated on two simple case studies in order to bring forward its reliability. Thus, with an intelligent and coherent choice of the design variables, shape optimization issues may, with a restrictive number of variables, explore an important number of shapes and topologies. Topology changes are accomplished in a continuous manner, therefore validating the FEM-CsG method to any desired analysis

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Sigmund, Ole. "Design of material structures using topology optimization /." Online version, 1994. http://bibpurl.oclc.org/web/34025.

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Howard, Micah A. "Computational design of shape changing structures via topology optimization." Connect to online resource, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1447665.

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Alzahrani, Mahmoud Ali. "Design of truss-like cellular structures using density information from topology optimization." Thesis, Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/52275.

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The advances in additive manufacturing removed most of the limitations that were once stopping designers when it comes to the manufacturability of the design. It allowed designers to produce parts with high geometric complexity such as cellular structures. These structures are known for their high strength relative to their low mass, good energy absorption, and high thermal and acoustic insulation compared to their relative solid counter-parts. Lattice structures, a type of cellular structures, have received considerable attention due to their properties when producing light-weight with high strength parts. The design of these structures can pose a challenge to designers due to the sheer number of variables that are present. Traditional optimization approaches become an infeasible approach for designing them, which motivated researchers to search for other alternative approaches. In this research, a new method is proposed by utilizing the material density information obtained from the topology optimization of continuum structures. The efficacy of the developed method will be compared to existing methods, such as the Size Matching and Scaling (SMS) method that combines solid-body analysis and a predefined unit-cell library. The proposed method shows good potential in structures that are subjected to multiple loading conditions compared to SMS, which would be advantageous in creating reliable structures. In order to demonstrate the applicability of the proposed method to practical engineering applications, the design problem of a commercial elevator sling will be considered.

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Shende, Sourabh. "Bayesian Topology Optimization for Efficient Design of Origami Folding Structures." University of Cincinnati / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1592170569337763.

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Oval, Robin. "Recherche de topologie de motifs pour la conception de structures." Thesis, Paris Est, 2019. http://www.theses.fr/2019PESC1042.

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Hunkeler, Stephan. "Topology optimisation in crashworthiness design via hybrid cellular automata for thin walled structures." Thesis, Queen Mary, University of London, 2014. http://qmro.qmul.ac.uk/xmlui/handle/123456789/8295.

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Crashworthiness design is one of the most critical areas of automotive design. It is really demanding for the structure and can therefore have a large influence on the final design. It is also difficult to model accurately and costly to simulate which has an important impact on the design process. Most car companies have now stopped addressing crashworthiness design with trial and error approaches, in favour of more advanced automated structural optimisation methods. While most relevant applications so far use size or shape optimisation, the ultimate way to achieve significant mass reduction is to use topology optimisation. However, topology optimisation methods for crashworthiness design are still a work in progress. Due to the high non-linearity of crash simulations, well-established classic topology optimisation methods cannot be applied directly to crashworthiness design. Alternative methods have been and keep being developed such as the Equivalent Static Loads method, the Ground Structure Approach or the Hybrid Cellular Automata (HCA). This thesis introduces an adapted version of Hybrid Cellular Automata using thin-walled ground structures. It combines the advantages of computing a real crash simulation while producing as an output a thin walled based topology needing minimal post-processing effort to be translated into a realistic design. In this method, the topology optimisation domain is filled up with a ground structure of thin walls which constitutes the elementary cells of the HCA method. These macro-elements replace the solid mesh elements used in the classic HCA approach. The details and implementation of the method are presented and discussed. Different application examples are detailed, including defining reinforcement patterns within extruded beams. Enriched space fillings patterns are studied and industrial application examples are presented. Eventually, recommendations for further studies and applications of the method are given.

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Palanisamy, Povendhan. "Methodology Development for Topology Optimization of Power Transfer Unit Housing Structures." Thesis, KTH, Skolan för industriell teknik och management (ITM), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-281816.

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Simulation driven design is a method and process that has been developed over many years, and with today’s advanced software, the possibility to embed simulation into the design process has become a reality. The advantages of using simulation driven design in the product development process is well known and compared to a more traditional design process, the simulation driven design process can give the user the possibility to explore, optimize and design products with reduced lead time. One of the methods that is applied in simulation driven design is the use of topology optimization (structural optimization). Topology optimization is something that GKN uses in the design process. Due to the complexity of the products GKN design and manufacture, the output from the topology optimization lacks good design interpretability and the design process requires a lot of time and effort. The purpose of the thesis is to explore different simulation tools used for topology optimization and improve the methodology and process with higher design interpretability for a static topology optimization. This requires a good understanding of the component and the product development process. It is imperative that the topology result must have high design interpretability, and the visualization of the result must show the formation of clear rib structures. The software’s used for performing topology optimization in this thesis are Inspire, SimLab, HyperMesh, and OptiStruct (HyperWorks suite). Static topology optimization is conducted, and manufacturing constraints for the casting process are considered. The methodology developed is robust for similar gearbox housing structures, and the process is set up to be efficient. The proposed method is verified by implementing it on a housing structure. The resulting concept from the topology optimization is deemed to have higher design interpretability which improves knowledge transfer in the design process when compared to the current topology results. The weight of the product is reduced, and a more optimum design is reached with a lesser number of iterations.
Simuleringsdriven design är en metod och process som har utvecklats i många år, och med dagens avancerade programvaror har möjligheten att få in simulering direkt i designprocessen blivit verklighet. Fördelarna med att använda simuleringsdriven design i produktutvecklingsprocessen är välkända och jämfört med en mer traditionell designprocess kan den simuleringsdrivna designprocessen ge användaren möjlighet att utforska, optimera och designa produkter med reducerade ledtider som följd. En av de metoder som tillämpas i simuleringsdriven design är användning av topologioptimering (strukturoptimering). Topologioptimering är något som GKN använder i designprocessen. På grund av komplexiteten hos produkterna GKN designar och tillverkar kräver designprocessen mycket ingenjörsarbete och tid. Produktionen har också problem med att tolka topologioptimeringsresultaten.. Syftet med avhandlingen är att utforska olika simuleringsverktyg som används för topologioptimering och förbättra metodiken och processen för att öka designtolkningen av en statisk topologioptimering. Detta kräver en god förståelse för komponenten och produktutvecklingsprocessen. För att förbättra osäkerheterna i resultaten från optimeringen, är det nödvändigt att dessa resultat är lätta att tolka, och visualiseringen av resultaten ska vara tydliga och visa hur lastvägarna går och därmed vart ribbor ska läggas. Programvarorna som användes för att utföra topologioptimering i denna avhandling är Inspire, SimLab, HyperMesh och OptiStruct (HyperWorks suite). Statisk topologioptimering är utförd och tillverkningsbegränsningar för gjutningsprocesser har inkluderats. Den metod som utvecklats är robust för liknande växellådshusstrukturer, och processen som föreslås är mera effektiv. Den föreslagna metoden har verifierats genom att den tillämpats för ett växellådshus. Det resulterande topologikonceptet antas ha en bättre designtolkningsbarhet, vilket möjliggör en förbättrad kommunikation och kunskapsöverföring i konstruktionsprocessen, jämfört med den nuvarande processen. Produktens vikt minskas, och en mer optimal design nås med färre iterationer.

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Lövgren, Sebastian, and Emil Norberg. "Topology Optimization of Vehicle Body Structure for Improved Ride & Handling." Thesis, Linköpings universitet, Maskinkonstruktion, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-71009.

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Ride and handling are important areas for safety and improved vehicle control during driving. To meet the demands on ride and handling a number of measures can be taken. This master thesis work has focused on the early design phase. At the early phases of design, the level of details is low and the design freedom is big. By introducing a tool to support the early vehicle body design, the potential of finding more efficient structures increases. In this study, topology optimization of a vehicle front structure has been performed using OptiStruct by Altair Engineering. The objective has been to find the optimal topology of beams and rods to achieve high stiffness of the front structure for improved ride and handling. Based on topology optimization a proposal for a beam layout in the front structure area has been identified. A vital part of the project has been to describe how to use topology optimization as a tool in the design process. During the project different approaches has been studied to come from a large design space to a low weight architecture based on a beam-like structure. The different approaches will be described and our experience and recommendations will be presented. Also the general result of a topology-optimized architecture for vehicle body stiffness will be presented.

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Zhang, Botao. "Design of Variable-Density Structures for Additive Manufacturing Using Gyroid Lattices." University of Cincinnati / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1535374427634743.

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Cohen, Brian S. Ph D. Massachusetts Institute of Technology. "Multidisciplinary design of thermally radiating structures using a level set based topology optimization approach." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/119287.

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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2018.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 267-282).
The need for efficient thermally radiating structures for aerospace applications is apparent in many system designs including satellites, launch vehicles and hypersonic aircraft. While multidisciplinary structural optimization methods have been employed to design these systems, few have incorporated thermal radiation as part of their multi-physics analysis capability. Moreover, with the rapid advancement of manufacturing technologies, the ability to fabricate flight hardware with unprecedented geometric complexity has challenged the limits of human design intuition. As a result, there is a critical need for free-form design methods to harness the full potential of these new manufacturing techniques. This thesis presents a level set based topology optimization approach for designing thermally efficient radiating structures considering multiple objectives, constraints and disciplines. Level set based methods offer a key advantage of defining crisp structural boundaries while seamlessly handling complex geometric transformations. The first contribution of this thesis is deriving a shape sensitivity of the thermal heat power radiated objective function using the adjoint method. This sensitivity is a necessary ingredient for our gradient-based algorithm. The second contribution is developing a topology optimization framework capable of handling multiple objectives and constraints via the augmented Lagrangian method. Both von Mises stress and first mode frequency constraints are implemented since they are commonly found in aerospace design problems where severe structural loads can lead to catastrophic failure. The final contribution is testing several data mining techniques to identify prominent topological features of a large set of designs found using our topology optimization approach. The CUR matrix decomposition is best suited for identifying the principal designs and also aids in categorizing the solution topologies. These contributions are demonstrated on several 2D example problems where the goal is to identify thermally efficient radiating structures able to reject heat using limited material. Both von Mises stress and first mode frequency constraints are enforced to ensure that solutions are sufficiently rigid. The results indicate that many locally optimal solutions exist in the design tradespace with topologically diverse features. Additionally, we show that the thermal compliance objective function commonly used to design conductive structures is not sufficient when a radiating surface exists.
by Brian S. Cohen.
Ph. D.

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Warshawsky, Brandon Lee. "Practical application of topology optimization to the design of large wind turbine towers." Thesis, University of Iowa, 2015. https://ir.uiowa.edu/etd/1928.

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Structural topology optimization is a mathematical approach developed to perform design optimization with the purpose of reducing the material usage, while maximizing structural performance, in accordance to specific design constraints. The principles behind this technique have been around for many decades, but recent advancements in the processing power of computers have allowed for the solving of complex problems, such as the optimization of tall wind turbine towers, bridges, and the bracing systems in skyscrapers. There are two approaches commonly used in structural topology optimization: discrete and continuum. This thesis uses continuum topology optimization, which involves adjusting the distribution of a porous elastic solid material to extremize the design objective(s) and to satisfy constraints. The material porosity is the design variable that is adjusted during the optimization process. The design domain is broken down into a system of continuum degenerated finite elements, which are used for both structural analysis and to create a mesh representation of the structural system, just as pixels make up a picture. Solid elements are modeled as having no porosity, while void spaces have total porosity. As the optimization process occurs, the shape of the boundaries, and the number and size of internal holes are altered in order to best meet the design objective(s) and constraint(s). The purpose of performing continuum structural topology optimization of structural elements is to obtain promising concepts which provide a basis upon which to begin the design process. The steps taken in this thesis to optimize the wind turbine tower are: 1. Create a solid model of the tower domain 2. Define the material properties 3. Determine the equivalent static design wind forces using the extreme loading conditions outlined in IEC 61400 4. Formulate the optimization problem by specifying the objective and constraint functions. 5. Solve the optimization problem and interpret the results. This study on continuum topology optimization on the tower shell, indicates even with a significant reduction in material from the original design space, the structure is capable of meeting the design criteria. The results indicate that opening void spaces in the shell of the tower and creating an open lattice shape may be an effective method to reduce the volume of wind turbine towers, as it has in other applications. This concurs with the stated goal of my research, which is to show that topology optimization has the potential to be used in a multitude of practical applications in order to increase efficiency, and reduce cost of the production of wind power.

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Venugopal, Vysakh. "Design of Multi-Material Lattice Structures with Tailorable Material Properties using Density-Based Topology Optimization." University of Cincinnati / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1553252070840125.

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Ramin, Ettore. "Automated design of trabecular structures." Thesis, Loughborough University, 2010. https://dspace.lboro.ac.uk/2134/6378.

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Additive manufacturing technologies are enabling newfound degrees of geometrical complexity to be realised, particularly with regards to internal structures. All of these manufacturing technologies are dependant on their prior design in an appropriate electronic form, either by reverse engineering, or, primarily, by computer-aided design. Within these emerging applications is the design of scaffolds with an intricate and controlled internal structure for bone tissue engineering. There is a consensus that ideal bone scaffold geometry is evident in biological trabecular structures. In their most basic topological form,these structures consist of the non-linear distribution of irregular interconnecting rods and plates of different size and shape. Complex and irregular architectures can be realised by several scaffold manufacturing techniques, but with little or no control over the main features of the internal geometry, such as size, shape and interconnectivity of each individual element. The combined use of computer aided design systems and additive manufacturing techniques allows a high degree of control over these parameters with few limitations in terms of achievable complexity. However, the design of irregular and intricate trabecular networks in computer aided design systems is extremely time-consuming since manually modelling an extraordinary number of different rods and plates, all with different parameters, may require several days to design an individual scaffold structure. In an attempt to address these difficulties, several other research efforts in this domain have largely focussed on techniques which result in designs which comprise of relatively regular and primitive shapes and do not represent the level of complexity seen biologically. Detailed descriptions of these methods are covered in chapter 1. An automated design methodology for trabecular structures is proposed by this research to overcome these limitations. This approach involves the investigation of novel software algorithms, which are able to interact with a conventional computer aided design program and permit the automated design of geometrical elements in the form of rods, each with a different size and shape. The methodology is described in chapter 2 and is tested in chapter 3. Applications of this methodology in anatomical designs are covered in chapter 4. Nevertheless, complex designed rod networks may still present very different properties compared to trabecular bone geometries due to a lack detailed information available which explicitly detail their geometry. The lack of detailed quantitative descriptions of trabecular bone geometries may compromise the validity of any design methodology, irrespective of automation and efficiency. Although flexibility of a design methodology is beneficial, this may be rendered inadequate when insufficient quantitative data is known of the target structure. In this work a novel analysis methodology is proposed in chapter 5, which may provide a significant contribution toward the characterisation and quantification of target geometries, with particular focus on trabecular bone structures. This analysis methodology can be used either to evaluate existing design techniques or to drive the development of new bio-mimetic design techniques. This work then progresses to a newly derived bio-mimetic automated design technique, driven by the newly produced quantitative data on trabecular bone geometries. This advanced design methodology has been developed and tested in chapter 6. This has demonstrated the validity of the technique and realised a significant stage of development in the context and scope of this work.

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Moulton, Brian D. ""Intelligent" Design of Molecular Materials: Understanding the Concepts of Design in Supramolecular Synthesis of Network Solids." [Tampa, Fla.] : University of South Florida, 2003. http://purl.fcla.edu/fcla/etd/SFE0000603.

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Pospíšil, Jan. "Výroba dílů s odlehčenou strukturou a topologickou optimalizací." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-417569.

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This thesis deals vith the design of welding torch holder using topology optimization and lattice structure. The objective of this thesis is gaining knowledge about topology optimization in different software and aplication of methods to that part. Conclusion of this thesis is about production design and economic evaluation.

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Boguslawski, Pawel. "Modelling and analysing 3D building interiors with the dual half-edge data structure." Thesis, University of South Wales, 2011. https://pure.southwales.ac.uk/en/studentthesis/modelling-and-analysing-3d-building-interiors-with-the-dual-halfedge-data-structure(ac1af643-835a-4093-90cd-3d51c696e280).html.

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While many systems and standards like CAD systems or CityGML permit the user to represent the geometry and the semantics of building interior models, their use for applications where spatial analysis and/or real-time modifications are required are limited since they lack the possibility to store topological relationships between the elements. In this thesis a new topological data structure, the dual half-edge (DHE) is presented. It permits the representation of the topology of building models with the interior included. It is based on the idea of simultaneously storing a graph in 3D space and its dual graph, and to link the two. Euler-type operators for incrementally constructing 3D models (for adding individual edges, faces and volumes to the model while updating the dual structure simultaneously), and navigation operators (for example to navigate from a given point to all the connected planes or polyhedra) are proposed. The DHE also permits the assigning of attributes to any element. This technique allows the handling of important query types and performs analysis based on the building structure, for example finding the nearest exterior exit to a given room, as in disaster management planning. As the structure is locally modifiable the model may be adapted whenever a particular pathway is no longer available. The proposed DHE structure adds significant analytic value to the increasingly popular CityGML model, and to the CAD field where the dual structure is of growing interest.

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Suzuki, Seiichi [Verfasser], and Jan [Akademischer Betreuer] Knippers. "Topology-driven form-finding : interactive computational modelling of bending-active and textile hybrid structures through active-topology based real-time physics simulations, and its emerging design potentials / Seiichi Suzuki ; Betreuer: Jan Knippers." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2020. http://d-nb.info/1210926245/34.

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Baran, Ismet. "Optimization Of Vibration Characteristics Of A Radar Antenna Structure." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12612978/index.pdf.

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Radar antenna structures especially array antennas which are integrated onto structures of aerial vehicles are subject to dynamic structural and aerodynamic loads. Due to occurrences of these dynamic loads there will be certain dynamic deformations which affect the antenna&rsquo
s performance in an adverse manner. The influence of deformations and vibrations are important on array antenna structures, since they cause a change in orientation of elements of the phased array antenna which affects the gain of the antenna negatively. In this study, vibration characteristics of a particular radar antenna structure are optimized using topology and stiffener design optimization methods such that negative effects of mechanical vibrations on functional performance of radar antenna are minimized. Topology and stiffener design optimization techniques are performed separately by the use of ANSYS Finite Element (FE) software in order to modify the design of the radar antenna structure such that its critical natural frequencies in the range of 0-500 Hz are shifted out of the dominant peak sinusoid frequency range of the air platform. As a result of this, it will be possible to minimize the vibration response of the phased array elements in the frequency range of 0-500 Hz
hence better antenna performance can be achieved. In addition to this, it will also be possible to minimize the broadband random vibration response of base excitation coming from air platform.

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Tommasi, Ilaria. "Branch Making Shells: applicazione di sistemi multi-agente alla formazione di strutture monosuperficie con topologia ramificata." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/23407/.

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Con questa tesi si studiano le potenzialità di un agent-system per la generazione di strutture monosuperficie con topologia ramificata, con l’intento di generare architetture inseribili in contesti esistenti. Gli agenti agiscono leggendo informazioni date dall’ambiente e dal sistema stesso, adattandovi parametri di comportamento. Il sistema creato parte dalle logiche dell’algoritmo di Space Colonization (utilizzato per simulare la crescita di strutture ramificate presenti in natura), basandosi quindi su punti attrattori nello spazio che guidano lo sviluppo di ramificazioni. Lo studio si è concentrato sull’applicazione del sistema lungo superfici modellate sfruttando le potenzialità del territorio. L’analisi strutturale di queste, fornisce dati che influenzano la distribuzione dei punti, quindi lo sviluppo e la variabilità del pattern (direzionalità, frequenza e angolo di ramificazione) in funzione delle logiche costruttive proposte. La complessità e variabilità del pattern generato, applicato a superfici a doppia curvatura non consente una standardizzazione degli elementi costruttivi: sono perciò state prese in considerazione diverse possibilità, cercando compromessi tra semplicità esecutiva ed estetica. Si è scelto un sistema materiale che lavora per elementi discreti, traducendo le tracce digitali in una tettonica organizzata in elementi curvi in legno collegati ai nodi con pezzi metallici.

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Robin, Julien. "Cristallochimie de nouveaux polymères de coordination chiraux poreux à corps central fluorène pour la séparation et la catalyse énantiosélective : synthèses, structures cristallines et réactivité." Thesis, Rennes 1, 2013. http://www.theses.fr/2013REN1S164/document.

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Ce travail porte sur la cristallochimie de polymères de coordination poreux, ou Metal-Organic Frameworks (MOFs), pour la séparation et la catalyse énantiosélective. Les molécules chirales sont d'une importance capitale et jouent un rôle important dans la reconnaissance moléculaire. Il est donc nécessaire de pouvoir synthétiser un seul énantiomère ou de pouvoir séparer un mélange. La particularité des polymères de coordination à bénéficier d'une partie organique est la possibilité d'introduire des fragments chiraux dans la structure-même des matériaux. Nous avons décidé d'introduire la chiralité dans les MOFs par utilisation de ligands carboxylates originaux chiraux à cœur fluorène. Le premier chapitre de ce mémoire est consacré à l'étude bibliographique des MOFs avec une description des concepts de cette chimie qui permet de comprendre la stratégie mise en place dans cette étude. Le deuxième chapitre décrit la stratégie de synthèse des ligands ainsi que leurs caractérisations. Les trois chapitres suivants décrivent la synthèse, les structures cristallines et les caractérisations physico-chimiques de séries de MOFs regroupés par métal utilisé pour leur élaboration (Zn, Cd et Cu). Ces trois chapitres exposent les problématiques généralement rencontrées avec les MOFs, comme la perte de porosité par interpénétration des réseaux, et les stratégies mises en place pour les contourner, comme l'augmentation de la taille et de la fonctionnalité des ligands utilisés. Enfin la réactivité thermique et chimique des MOFs a été investiguée par diffraction des rayons X par la poudre afin de comprendre les mécanismes réactionnels et la création éventuelle de sites acides en vue d'applications en catalyse. Les techniques expérimentales sont détaillées dans le dernier chapitre de ce mémoire. Enfin un récapitulatif de cette étude est présenté afin de conclure sur la stratégie exposée dans ce mémoire et les perspectives offertes par cette étude
This work deals with crystallochemistry of new porous coordination polymers or Metal-Organic Frameworks (MOFs) for enantioselective separation and catalysis. Chiral molecules are of a key role in molecular recognition as a consequence the ability to synthesize only one enantiomer or to separate a mixture is priority for chemistry. The particularity of coordination polymers to possess an organic part gives the possibility to introduce chiral fragments in the material structure. We decided to introduce chirality on MOFs by using originals chiral carboxylates ligands with fluorene core. The first chapter is devoted to the bibliographic study of porous coordination polymers. The second chapter describes the ligands synthesis strategy and characterizations. The next three chapters group the crystal structures and physicochemical characterizations of coordination polymers according to the metal used for their preparation (Zn, Cd et Cu). These three chapters explore also the general issues related to MOFs as the loss of porosity consequent to frameworks interpenetration, and strategies implemented to circumvent, such as increasing the size and functionality of the ligands used. Finally the thermal and chemical reactivity of MOFS has been investigated by powder X rays diffraction in order to understand reactions mechanisms and eventually the creation of acid sites for catalytic applications. The experimental technics are detailed in the last chapter. Finally a summary of this work closes this thesis showing the future perspectives of this work

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Gerth, Robert. "The Role of Production Topology in Information Based Structuring of Organizations : The design of craft-based and industrialized construction firms." Doctoral thesis, KTH, Produktionssystem, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-133918.

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Industrialization of construction is a business strategy to significantly improve competitiveness. However, the organization structure of the construction firms needs to support the new production system. The knowledge on why and how this business development can be accomplished is scarce, both within academia and in business practice. This research seeks to fill this knowledge gap. The purpose of organization structure and the production system have is to coordinate the firm’s processes and control the work performing resources. Information is one of the most fundamental dimensions for steering and controlling the work. The different information types are determined by the firm’s product customization strategy and the production system flexibility. Further, diverse information types are managed in different extent by the organizational steering mechanisms. Consequently, firms with dissimilar customization strategy or production flexibility should organizationally be designed differently in order to be efficient. The developed model identifies four generic production topologies: “engineer-to-order” (ETO), “manufacture-to-order” (MTO), “assembly-to-order” (ATO), and “make-standard-products” (MSP). The differences between the topologies can be related to the location of the “customer-order-decoupling-point” (CODP) in the product realization process; and to what extent the upstream and downstream processes continuously use stored information or process information to accomplish the work of each product order. The model predicts which organization structure mechanisms that should be used for which processes for each production topology. It is the specific configuration of the mechanisms that gives each production topology their organizational capability. The model has been validated by case studies in four organizations, each representing one of the four generic production topologies. Three cases considered housing and one studied truck manufacturing. It has been shown that the conventional housing firms have an ETO-production topology, while industrialized housing firms belonging to one of the others, i.e. MTO, ATO or MSP. The reason is that ETO-firms rely on crafts-based production to manage the work, while the other topologies base their steering mechanisms on industrial principles. These two types of production are fundamentally different, which also explain the need for different organization structures. The research complements previous knowledge and significantly increases the ability to predict, analyze and explain an organization’s design and behavior. The model can be used in practice to guide business development work and performance improvement programs.

Research funder: SBUF (The development fund of the Swedish construction industry). QC 20131113

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Xia, Liang. "Towards optimal design of multiscale nonlinear structures : reduced-order modeling approaches." Thesis, Compiègne, 2015. http://www.theses.fr/2015COMP2230/document.

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L'objectif principal est de faire premiers pas vers la conception topologique de structures hétérogènes à comportement non-linéaires. Le deuxième objectif est d’optimiser simultanément la topologie de la structure et du matériau. Il requiert la combinaison des méthodes de conception optimale et des approches de modélisation multi-échelle. En raison des lourdes exigences de calcul, nous avons introduit des techniques de réduction de modèle et de calcul parallèle. Nous avons développé tout d’abord un cadre de conception multi-échelle constitué de l’optimisation topologique et la modélisation multi-échelle. Ce cadre fournit un outil automatique pour des structures dont le modèle de matériau sous-jacent est directement régi par la géométrie de la microstructure réaliste et des lois de comportement microscopiques. Nous avons ensuite étendu le cadre en introduisant des variables supplémentaires à l’échelle microscopique pour effectuer la conception simultanée de la structure et de la microstructure. En ce qui concerne les exigences de calcul et de stockage de données en raison de multiples réalisations de calcul multi-échelle sur les configurations similaires, nous avons introduit: les approches de réduction de modèle. Nous avons développé un substitut d'apprentissage adaptatif pour le cas de l’élasticité non-linéaire. Pour viscoplasticité, nous avons collaboré avec le Professeur Felix Fritzen de l’Université de Stuttgart en utilisant son modèle de réduction avec la programmation parallèle sur GPU. Nous avons également adopté une autre approche basée sur le potentiel de réduction issue de la littérature pour améliorer l’efficacité de la conception simultanée
High-performance heterogeneous materials have been increasingly used nowadays for their advantageous overall characteristics resulting in superior structural mechanical performance. The pronounced heterogeneities of materials have significant impact on the structural behavior that one needs to account for both material microscopic heterogeneities and constituent behaviors to achieve reliable structural designs. Meanwhile, the fast progress of material science and the latest development of 3D printing techniques make it possible to generate more innovative, lightweight, and structurally efficient designs through controlling the composition and the microstructure of material at the microscopic scale. In this thesis, we have made first attempts towards topology optimization design of multiscale nonlinear structures, including design of highly heterogeneous structures, material microstructural design, and simultaneous design of structure and materials. We have primarily developed a multiscale design framework, constituted of two key ingredients : multiscale modeling for structural performance simulation and topology optimization forstructural design. With regard to the first ingredient, we employ the first-order computational homogenization method FE2 to bridge structural and material scales. With regard to the second ingredient, we apply the method Bi-directional Evolutionary Structural Optimization (BESO) to perform topology optimization. In contrast to the conventional nonlinear design of homogeneous structures, this design framework provides an automatic design tool for nonlinear highly heterogeneous structures of which the underlying material model is governed directly by the realistic microstructural geometry and the microscopic constitutive laws. Note that the FE2 method is extremely expensive in terms of computing time and storage requirement. The dilemma of heavy computational burden is even more pronounced when it comes to topology optimization : not only is it required to solve the time-consuming multiscale problem once, but for many different realizations of the structural topology. Meanwhile we note that the optimization process requires multiple design loops involving similar or even repeated computations at the microscopic scale. For these reasons, we introduce to the design framework a third ingredient : reduced-order modeling (ROM). We develop an adaptive surrogate model using snapshot Proper Orthogonal Decomposition (POD) and Diffuse Approximation to substitute the microscopic solutions. The surrogate model is initially built by the first design iteration and updated adaptively in the subsequent design iterations. This surrogate model has shown promising performance in terms of reducing computing cost and modeling accuracy when applied to the design framework for nonlinear elastic cases. As for more severe material nonlinearity, we employ directly an established method potential based Reduced Basis Model Order Reduction (pRBMOR). The key idea of pRBMOR is to approximate the internal variables of the dissipative material by a precomputed reduced basis computed from snapshot POD. To drastically accelerate the computing procedure, pRBMOR has been implemented by parallelization on modern Graphics Processing Units (GPUs). The implementation of pRBMOR with GPU acceleration enables us to realize the design of multiscale elastoviscoplastic structures using the previously developed design framework inrealistic computing time and with affordable memory requirement. We have so far assumed a fixed material microstructure at the microscopic scale. The remaining part of the thesis is dedicated to simultaneous design of both macroscopic structure and microscopic materials. By the previously established multiscale design framework, we have topology variables and volume constraints defined at both scales

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Yedeg, Esubalewe Lakie. "Analysis, Control, and Design Optimization of Engineering Mechanics Systems." Doctoral thesis, Umeå universitet, Institutionen för datavetenskap, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-119978.

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Abstract:

This thesis considers applications of gradient-based optimization algorithms to the design and control of some mechanics systems. The material distribution approach to topology optimization is applied to design two different acoustic devices, a reactive muffler and an acoustic horn, and optimization is used to control a ball pitching robot. Reactive mufflers are widely used to attenuate the exhaust noise of internal combustion engines by reflecting the acoustic energy back to the source. A material distribution optimization method is developed to design the layout of sound-hard material inside the expansion chamber of a reactive muffler. The objective is to minimize the acoustic energy at the muffler outlet. The presence or absence of material is represented by design variables that are mapped to varying coefficients in the governing equation. An anisotropic design filter is used to control the minimum thickness of materials separately in different directions. Numerical results demonstrate that the approach can produce mufflers with high transmission loss for a broad range of frequencies. For acoustic devices, it is possible to improve their performance, without adding extended volumes of materials, by an appropriate placement of thin structures with suitable material properties. We apply layout optimization of thin sound-hard material in the interior of an acoustic horn to improve its far-field directivity properties. Absence or presence of thin sound-hard material is modeled by a surface transmission impedance, and the optimization determines the distribution of materials along a “ground structure” in the form of a grid inside the horn. Horns provided with the optimized scatterers show a much improved angular coverage, compared to the initial configuration. The surface impedance is handled by a new finite element method developed for Helmholtz equation in the situation where an interface is embedded in the computational domain. A Nitschetype method, different from the standard one, weakly enforces the impedance conditions for transmission through the interface. As opposed to a standard finite-element discretization of the problem, our method seamlessly handles both vanishing and non-vanishing interface conditions. We show the stability of the method for a quite general class of surface impedance functions, provided that possible surface waves are sufficiently resolved by the mesh. The thesis also presents a method for optimal control of a two-link ball pitching robot with the aim of throwing a ball as far as possible. The pitching robot is connected to a motor via a non-linear torsional spring at the shoulder joint. Constraints on the motor torque, power, and angular velocity of the motor shaft are included in the model. The control problem is solved by an interior point method to determine the optimal motor torque profile and release position. Numerical experiments show the effectiveness of the method and the effect of the constraints on the performance.

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Dissertations / Theses on the topic 'Structural topology/design'

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