Dissertations / Theses on the topic 'Truss lattice'

Sandwich panels are extensively used in constructional, naval and aerospace structures due to their high stiffness and strength-to-weight ratios. In contrast, sound transmission properties of sandwich panels are adversely influenced by their low effective mass. Phase velocity matching of structural waves propagating within the panel and the incident pressure waves from the surrounding fluid medium lead to coincidence effects (often within the audible range) resulting in reduced impedance and high sound transmission. Truss-like lattice cores with porous microarchitecture and \emph{reduced} inter panel connectivity relative to honeycomb cores promise the potential to satisfy the conflicting structural and vibroacoustic response requirements. This study combines Bloch-wave analysis and the Finite Element Method (FEM) to understand wave propagation and hence sound transmission in sandwich panels with a truss lattice core. Three dimensional coupled fluid-structure finite element simulations are conducted to compare the performance of a representative set of lattice core topologies. Potential advantages of sandwich structures with a lattice core over the traditional shear wall panel designs are identified. The significance of partial band gaps is evident in the sound transmission loss characteristics of the panels studied. This work demonstrates that, even without optimization, significant enhancements in STL performance can be achieved in truss lattice core sandwich panels compared to a traditional sandwich panel employing a honeycomb core under constant mass constraint.<br>Applied Science, Faculty of<br>Mechanical Engineering, Department of<br>Graduate

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, February 2010.<br>This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.<br>Cataloged from student submitted PDF version of thesis.<br>Includes bibliographical references.<br>The Town lattice truss is proposed as an appropriate technology for the Tshumbe Diocese of the Democratic Republic of Congo. This proposal is made based on an understanding of rural transport and appropriate technology and an in-depth analysis of the details of the Town lattice truss. The nature and importance of rural transport and accessibility are presented, and bridges are identified as a key component in rural transport development. The concept of appropriate technology is presented along with a framework consisting of required and desired characteristics of any appropriate technology, including bridges. Structural materials are compared for use in bridges in rural areas of developing countries and timber is selected as the appropriate choice for the Tshumbe Diocese. Three existing timber bridges systems for developing countries are analyzed and compared, and the Town lattice truss is proposed as an alternative to all three. The Town lattice truss is presented and described in detail with reference to a study of forty existing bridges in the northeastern United States that was conducted as a part of this work. Appropriate characteristics of the truss are identified and used to compare the truss with other timber bridge systems. The wooden pegged connections and chord structure are identified as unique components of the Town lattice truss and are the subjects of further analysis. Equations are developed for strength prediction and stiffness estimation for the wooden pegged connections.<br>(cont.) The chord structure is analyzed for strength and stiffness, which are determined to be combinations of underlying component properties based on the chord termination pattern that is used. A comprehensive set of possible chord termination patterns is developed and the best patterns are proposed for use in design. Finally, truss moment capacity is determined as a function of chord strength and stiffness properties and a simple methodology is proposed for the design of new Town lattice truss bridges.<br>by Todd Craig Radford.<br>Ph.D.

Cellular materials, often called lattice materials, are increasingly receiving attention for their ultralight structures with high specific strength, excellent impact absorption, acoustic insulation, heat dissipation media and compact heat exchangers. In alignment with emerging additive manufacturing (AM) technology, realization of the structural applications of the lattice materials appears to be becoming faster. Considering the direction dependent material properties of the products with AM, by directionally dependent printing resolution, effective moduli of lattice structures appear to be directionally dependent. In this paper, a constitutive model of a lattice structure, which is an octet-truss with a base material having an orthotropic material property considering AM is developed. In a case study, polyjet based 3D printing material having an orthotropic property with a 9% difference in the principal direction provides difference in the axial and shear moduli in the octet-truss by 2.3 and 4.6%. Experimental validation for the effective properties of a 3D printed octet-truss is done for uniaxial tension and compression test. The theoretical value based on the micro-buckling of truss member are used to estimate the failure strength. Modulus value appears a little overestimate compared with the experiment. Finite element (FE) simulations for uniaxial compression and tension of octet-truss lattice materials are conducted. New effective properties for the octet-truss lattice structure are developed considering the observed behavior of the octet-truss structure under macroscopic compression and tension trough simulations.

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.

Advances in additive manufacturing technologies have brought a new paradigm shift to both design and manufacturing. There is a much bigger design space in which designers can achieve a level of complexity and customizability, which are infeasible using traditional manufacturing processes. One application of this technology is for fabrication of meso-scale lattice structures (MSLS). These types of structures are designed to have material where it is needed for specific applications. They are suitable for any weight-critical applications, particularly in industries where both low weight and high strength are desired. MSLS can easily have hundreds to thousands of individual strut, where the diameter of each strut can be treated as a design variable. As a result, the design process poses a computational challenge. Since the computational complexity of the design problem often scales exponentially with the number of design variables, topological optimization that requires multi-variable optimization algorithm is infeasible for large-scale problems. In previous research, a new method was presented for efficiently optimizing MSLS by utilizing a heuristic that reduces the multivariable optimization problem to a problem of only two variables. The method is called the Size Matching and Scaling (SMS) method, which combines solid-body analysis and predefined unit-cell library to generate the topology of the structure. However, the method lacks a systematic methodology to generate the initial ground geometry for the design process, which limits the previous implementations of the SMS method to only simple, axis-aligned structures. In this research, an augmented SMS method is presented. The augmented method includes the integration of free-mesh approach in generating the initial ground geometry. The software that embodies that ground geometry generation process is integrated to commercial CAD system that allows designer to set lattice size parameters through graphical user interface. In this thesis, the augmented method and the unit-cell library are applied to various design examples. The augmented SMS method can be applied effectively in the design of conformal lattice structure with highly optimized stiffness and volume for complex surface. Conformal lattice structures are those conformed to the shape of a part's surface and that can used to stiffen or strengthen a complex and curved surface. This design approach removes the need for a rigorous topology optimization, which is a main bottleneck in designing MSLS.

This thesis discusses how to test the mechanical properties of openlattice truss structures and hybrids being a tube containing a latticetruss structure. By properties we mean strength, stiffness, thermalconductivity and so forth.Mechanical testing was done on two different structures to betterunderstand how the load-bearing properties change when these structuresare subjected to tensile, compressive and bending forces. The structuresinvestigated were Diamond and Octagon built at 45° and 90°. Acousticemission was also used to evaluate and analyze the different behaviour ofthe structures. The test results were used to produce design criteria forproperties in different cell structures manufactured of Hastelloy X™. Amap with design criteria containing stiffness and weight per cubiccentimetre was produced for parts that would be subjected to compressiveforces.

Fracture mechanics plays an important role in the material science, structure design and industrial production due to the failure of materials and structures are paid high attention in human activities. For this reason, the fracture mechanics can be considered today one of the most important research fields in engineering. The attempts to predict the failure of a material are able to link different disciplines: in this dissertation, a very deep use of the statistical physics will be done in order to try to introduce the disorder of the medium into the breaking and to a give a new point of view to the fracture mechanics. In the following, we will introduce a new kind of model to evaluate the genesis of the crack: the statistical central force model. As we will see, this model tries to compute the genesis of the fracture in a medium by taking into account the presence of defects of the material that are the main cause of the differences between the critical theoretical strength of a material and the real one. This innovation introduced by this model which is difficult to find in other kinds of techniques existing today united to the fact that we try to predict the behaviour of a macro system by knowing exactly the statistical behaviour of the micro-components of the system itself (the trusses) like in complex systems happens, is the main innovation of the statistical central force model. The model consists of a truss structure in which each truss is representative of a little portion of the material. Since this model was already applied in static for a porous medium in literature, we will study it from a mathematical viewpoint and we will apply it to the study of the dynamic of a dry medium before (the applications could be for the study of the fracture in metals and composites with loads changing in time) and of a porous medium later (in order to study the fracking into soils and the fracture of the concrete). Further developments could bring us to develop the same method for the study of the spalling in the concrete because of the application of a thermal load. In the dissertation we will introduce the mathematical tools to understand this model and some simulation on generic media will be realized. This dissertation consists basically of five chapters. In chapter 1 a brief description of the state of the art will be given: we will leave from the birth of the classical elastic fracture mechanics and we will shortly talk about the fracture mechanics in a plastic field. After this we will describe two important techniques used today for the evaluation of the crack: the XFem and the Peridynamics; the first one is a numerical technique allowing the FEM to take into account the possibility to create a breaking into the material. This is done, as we will see, by adding further degrees of freedom to the finite elements. In this way a single finite element will have the possibility to “open” itself and to simulate a discontinuous field of displacements, which is the main problem concerning with FEM in calculating the fracture. The second one is a theory that postulates that each medium can be divided in particles and that each particle interacts with its own neighbours within a given horizon. From which we get the word “peri”. By this assumption it is possible to get some integro-equations that can be defined on the surfaces of the tips and of the cracks as well. In chapter 2 we will talk about the so called Fiber Bundle Model which is the basis of our statistical model. We will talk about the dry FBM that was already studied at the beginning of ’90s from a mathematical viewpoint : it consists of a bundle of fibers clamped at one edge and free to move to the other one. The model is one dimensional and it is probably one of the most naïve models to begin to study the fracture; however, despite to its simplicity, it contains an important tool: the possibility to take into account the defects of the medium by introducing the concept of variable thresholds in stress. As we will see, these thresholds will be picked up by a probability density function. Then we will apply the theory of the statistical ensembles to study one of the extensions of the FBM: the continuous fiber bundle model. This is necessary to have an idea of how the micro-components of our model, the trusses, behave in a truss structure subject to an external load. In chapter 3 we will report briefly the theory of the porous medium according to the mixture theories of De Boer. So an overview about the equations will be given and then we will discretize these equations according to the finite element technique. After this, we will briefly describe in which part of the algorithm the concept of imperfection/threshold in stress enters. We will do this for a dry medium and for a porous medium in dynamics. In chapter 4 we will report the numerical results. Some simulations in dynamics will be done both for a dry medium and for a porous medium. Furthermore we will introduce in the end a new damage law that will have a precise statistical meaning: it will be the average among all the possible realizations of the constitutive laws of our truss structure and for a big number of trusses, it will become the constitutive behaviour of our structure from which to get the damage law. And this result will take into account the disorder of the medium. In chapter 5 we will talk about a controversial argument: the Self Organized Criticality (SOC) that was sticked in previous papers to the statistical central model. We will try to understand what SOC is and if our system with our algorithm to compute the fracture gets the necessary and sufficient conditions to enter into the set of the SOC systems. At the end of our journey we will have hopefully done a first step into the description of a new numerical tool to evaluate the crack into a generic medium without needing an initial discontinuity to develop the crack itself. The next steps will be to validate this technique for existing materials and to compare it to other numerical tools like XFem or Peridynamics. After this, the future will be to extend the technique passing from trusses to 2D elements.<br>Fracture mechanics plays an important role in the material science, structure design and industrial production due to the failure of materials and structures are paid high attention in human activities. For this reason, the fracture mechanics can be considered today one of the most important research fields in engineering. The attempts to predict the failure of a material are able to link different disciplines: in this dissertation, a very deep use of the statistical physics will be done in order to try to introduce the disorder of the medium into the breaking and to a give a new point of view to the fracture mechanics. In the following, we will introduce a new kind of model to evaluate the genesis of the crack: the statistical central force model. As we will see, this model tries to compute the genesis of the fracture in a medium by taking into account the presence of defects of the material that are the main cause of the differences between the critical theoretical strength of a material and the real one. This innovation introduced by this model which is difficult to find in other kinds of techniques existing today united to the fact that we try to predict the behaviour of a macro system by knowing exactly the statistical behaviour of the micro-components of the system itself (the trusses) like in complex systems happens, is the main innovation of the statistical central force model. The model consists of a truss structure in which each truss is representative of a little portion of the material. Since this model was already applied in static for a porous medium in literature, we will study it from a mathematical viewpoint and we will apply it to the study of the dynamic of a dry medium before (the applications could be for the study of the fracture in metals and composites with loads changing in time) and of a porous medium later (in order to study the fracking into soils and the fracture of the concrete). Further developments could bring us to develop the same method for the study of the spalling in the concrete because of the application of a thermal load. In the dissertation we will introduce the mathematical tools to understand this model and some simulation on generic media will be realized. This dissertation consists basically of five chapters. In chapter 1 a brief description of the state of the art will be given: we will leave from the birth of the classical elastic fracture mechanics and we will shortly talk about the fracture mechanics in a plastic field. After this we will describe two important techniques used today for the evaluation of the crack: the XFem and the Peridynamics; the first one is a numerical technique allowing the FEM to take into account the possibility to create a breaking into the material. This is done, as we will see, by adding further degrees of freedom to the finite elements. In this way a single finite element will have the possibility to “open” itself and to simulate a discontinuous field of displacements, which is the main problem concerning with FEM in calculating the fracture. The second one is a theory that postulates that each medium can be divided in particles and that each particle interacts with its own neighbours within a given horizon. From which we get the word “peri”. By this assumption it is possible to get some integro-equations that can be defined on the surfaces of the tips and of the cracks as well. In chapter 2 we will talk about the so called Fiber Bundle Model which is the basis of our statistical model. We will talk about the dry FBM that was already studied at the beginning of ’90s from a mathematical viewpoint : it consists of a bundle of fibers clamped at one edge and free to move to the other one. The model is one dimensional and it is probably one of the most naïve models to begin to study the fracture; however, despite to its simplicity, it contains an important tool: the possibility to take into account the defects of the medium by introducing the concept of variable thresholds in stress. As we will see, these thresholds will be picked up by a probability density function. Then we will apply the theory of the statistical ensembles to study one of the extensions of the FBM: the continuous fiber bundle model. This is necessary to have an idea of how the micro-components of our model, the trusses, behave in a truss structure subject to an external load. In chapter 3 we will report briefly the theory of the porous medium according to the mixture theories of De Boer. So an overview about the equations will be given and then we will discretize these equations according to the finite element technique. After this, we will briefly describe in which part of the algorithm the concept of imperfection/threshold in stress enters. We will do this for a dry medium and for a porous medium in dynamics. In chapter 4 we will report the numerical results. Some simulations in dynamics will be done both for a dry medium and for a porous medium. Furthermore we will introduce in the end a new damage law that will have a precise statistical meaning: it will be the average among all the possible realizations of the constitutive laws of our truss structure and for a big number of trusses, it will become the constitutive behaviour of our structure from which to get the damage law. And this result will take into account the disorder of the medium. In chapter 5 we will talk about a controversial argument: the Self Organized Criticality (SOC) that was sticked in previous papers to the statistical central model. We will try to understand what SOC is and if our system with our algorithm to compute the fracture gets the necessary and sufficient conditions to enter into the set of the SOC systems. At the end of our journey we will have hopefully done a first step into the description of a new numerical tool to evaluate the crack into a generic medium without needing an initial discontinuity to develop the crack itself. The next steps will be to validate this technique for existing materials and to compare it to other numerical tools like XFem or Peridynamics. After this, the future will be to extend the technique passing from trusses to 2D elements.

Customized cellular material is a relatively new area made possible by advancements in rapid manufacturing technologies. Rapid manufacturing is ideal for the production of customized cellular structure, especially on the meso scale, due to the size and complexity of the design. The means to produce this type of structure now exist, but the processes to design the structure are not well developed. The manual design of customized cellular material is not realistic due to the large number of features. Currently there are few tools available that aid in the design of this type of material. In this thesis, an automated tool to design customized cellular structure is presented.

The aim the diploma thesis is the design and the assessment of the main structure of the shopping centre in the Hradec Králové. The shape of the construction is the cylindrical hall with dimensions 120 x 32 m. The structure is formed by lattice trusses, solid purlins, columns and composite construction. The model of the structure and some calculations were provided by the program Dlubal RFEM.

Made available in DSpace on 2016-12-08T17:19:19Z (GMT). No. of bitstreams: 1 Danilo Guth.pdf: 5524444 bytes, checksum: 0d000481efd76a74f714599b9ac7f404 (MD5) Previous issue date: 2012-08-24<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior<br>Inspirados por materiais encontrados na natureza, pesquisadores têm estudado a utilização de materiais celulares em diversas aplicações como biomedicina, engenharia aeroespacial e militar. O ganho em relação ao material base é a excelente relação entre peso e propriedades diversas como: rigidez ao cisalhamento; condutividade térmica/elétrica; absorção de impacto, ruído e vibrações. Uma classe específica são os materiais constituídos por células treliçadas. Estes possuem estrutura periódica, formada por células-base constituídas de barras distribuídas espacialmente no domínio da célula. Modernos processos de fabricação vêm viabilizando a confecção das células em escalas micro e nanométricas. Técnicas para obtenção de novas configurações são objeto de diversos estudos que buscam obter estruturas ótimas para uma dada função multiobjetivo. O presente trabalho implementa o uso de programação quadrática sequencial para a obtenção de células-base otimizadas para funções termomecânicas incluindo a maximização do módulo de cisalhamento, módulo volumétrico, coeficiente de Poisson e condutividade térmica, permitindo a inclusão de restrições de isotropia. A determinação das propriedades macroscópicas é obtida através do método da homogeneização. Diversos resultados são obtidos para os casos bidimensional e tridimensional.

Master thesis deals with static analysis of construction of hall type for waste treatment. Thesis includes design and structural assessment of main support elements of construction. This is two-aisled combined skeleton object. The roof system is composed of steel truss structure.

Main task of this thesis is to design a roofing of multi-purpose sport hall. Multipurpose sport hall has a floor dimensions 48 x 35 m and is 16.0 m high. The hall is composed of cross-linked steel girders saved on rolled profiles of columns, which transmit loads into concrete pile foundations. Gable roof has a slope 7° and it is hidden behind a parapet which consists of steel square profiles. The construction consists of thin-walled purlins made by the company Voestalpine. Rigidity is ensured by steel elements in the plane of the roof structure in the longitudinal plane and gable walls. The thesis is carried out in compliance with the Eurocodes.

The objective of this Master´s thesis is to create and examine two versions of the project for a bearing steel structure of a multi-purpose sports building) in Polička. The multi-purpose sports hall has dimensions 33 x 48 metres with a terraced floory part that has dimensions 18 x 24 metres. The hall is made of cross-links from lattice truss placed on fixed columns. The structure ridgidity is by wind braces. The storey part is made coupled steel-conrete slabs attached to the columns. The ridgidity of the storey part is provided by lattice braces in traverse and longitudinal direction. The thesis in its detail focuses on individual parts of the construction and is carried out in compliance with the Eurocodes

A utilização de treliças para o escoramento de elementos estruturais de concreto armado e aço é considerada uma solução eficaz para o atual sistema de construção de engenharia civil. Uma mudança de atitude no processo de construção, associado com a redução dos custos causou um aumento considerável na utilização de treliças tridimensionais em aço com maior capacidade de carga. Infelizmente, o desenho destes sistemas estruturais baseia-se em cálculos muito simplificados relacionadas com vigas de uma dimensão, com propriedades de inércia constantes. Tal modelagem, muito simplificada, não pode representar adequadamente a resposta real dos modelos estruturais e pode levar a inviabilidade econômica ou mesmo inseguro desenho estrutural. Por outro lado, estas estruturas treliçadas estão relacionadas com modelos de geometria complexa e são desenhados para suportar níveis de cargas muito elevadas. Portanto, este trabalho de investigação propôs modelos de elementos finitos que representam o caráter tridimensional real do sistema de escoramento, avaliando o comportamento estático e dinâmico estrutural com mais confiabilidade e segurança. O modelo computacional proposto, desenvolvido para o sistema estrutural não linear de análise estática e dinâmica, aprovou as habituais técnicas de refinamento de malha presentes em simulações do método de elementos finitos, com base no programa ANSYS [1]. O presente estudo analisou os resultados de análises linear-elástica e não linear geométrica para ações de serviço, físicos e geométricos para as ações finais. Os resultados do presente estudo foram obtidas, com base na análise linear-elástica e não linearidade geométrica e física, e comparados com os fornecidos pela metodologia simplificada tradicional de cálculo e com os limites recomendadas por normas de concepção.<br>The use of lattice structures for shoring of steel, composite and reinforced concrete structures is considered an effective solution in the construction of civil engineering systems. An attitudinal change in the construction process associated with costs reduction has caused a considerable increase in the use of three-dimensional lattice steel truss systems with greater load capacity. Unfortunately, the design of these structural systems is based on very simplified calculations related to one-dimensional beams with constant inertia properties. Such a very simplified modeling cannot adequately represent the actual response of the structural models and can lead to uneconomic or even unsafe structural design. On the other hand, these lattice steel structures are related to three-dimensional models of complex geometry and are designed to support very high loading levels. Therefore, this work research has proposed finite element models that represent the actual three-dimensional character of shoring system, evaluating the static and dynamic structural behavior with more reliability and security. The proposed computational model, developed for the structural system non-linear static and dynamic analysis, adopted the usual mesh refinement techniques present in finite element method simulations, based on the Annoys program. The present study has considered the results of a linear-elastic and non-linear geometric analysis for serviceability actions, physical and geometrical nonlinear analysis for ultimate actions. The results of the present investigation were obtained, based on linear-elastic and non-linear geometric and physical analysis, and compared with those supplied by the traditional simplified methodology of calculation and with the limits recommended by design standards.

La première réalisation de ce travail est la construction unifiée et automatique d’un milieu continu équivalent à un treillis de poutres, dans le domaine élastique, en adoptant un modèle de poutres de Bernoulli. Une extension a été réalisée au domaine plastique, selon un algorithme de suivi de la loi de comportement après écrouissage. Suivant l’ordre des développements asymptotiques choisi, on obtient pour le comportement élastique un milieu continu classique ou micropolaire. On se restreint dans ce dernier cas aux treillis à cellules élémentaires centro-symétriques. Les codes de calculs obtenus fournissent de façon automatique les lois de comportement effectives et les modules mécaniques homogénéisés. Une grande variété de treillis, existants ou originaux, a été étudiée. Les résultats ont été systématiquement comparés aux données de la littérature et vérifiés par des simulations éléments finis avec une bonne concordance. La méthode utilisée montre également une capacité à prédire et comprendre le comportement atypique de certains treillis dits auxétiques présentant des coefficients de contraction négatifs. L’homogénéisation dans le domaine plastique a été limitée aux treillis à dominante extensionnelle. Le domaine de résistance élastique a été construit pour différents treillis, et un algorithme d’évolution du comportement avec écrouissage, de type retour-radial a été conçu et implémenté dans un code dédié. Un modèle de poutre élastoplastique à écrouissage isotrope est utilisé. L’application de l’algorithme à une simulation de charge-décharge montre une bonne concordance entre le treillis homogénéisé et les simulations éléments finis<br>The first achievement of this work is to construct a unified and effective continuum equivalent to a lattice of beams, in the elastic domain, using a Bernoulli beam model. An extension has been done to calculate the elastic domain resistance of such lattices and to build an algorithm for monitoring the constitutive law taking into account work hardening. The choice of the asymptotic expansions leads to a classical continuous or to a micropolar elastic continuum. We restrict in this last case our study to lattices with centro-symmetric unit cells. The numerical codes developed provide the stress-strain relationship and the effective mechanical moduli. A wide variety of trusses has been studied, either existing or original, including typical geometries of foams and various auxetic lattices, exhibiting negative contraction coefficients. The results were systematically compared with data from literature and verified by finite element simulations with a good agreement. The homogenization in the plastic range has been limited to stretching dominated lattices. The equilibrium equations of the discrete asymptotic homogenization have been used to automatically obtain the elastic resistance domain for several trusses, and a return-mapping algorithm for the follow up of the stress-strain relationship including hardening has been conceived and implemented in a dedicated code. An isotropic hardening elastoplastic model of the beam has been used. The application of the algorithm to the simulation of a loading-unloading cycle shows a good agreement between the homogenized lattice and finite element simulations

The new building Nursery school is situated in Tisnov. Under the two storey building partialy runs basement. On the ground floor is located two departments nursery school with economic part. On the second floor is the classrooms and socialrooms. In the basement are mainly storerooms and utility rooms. The building is made of ceramic bricks and insulation contact system. The first storey is partly roofed with a flat roof and the second storey is sloped roof roofed. The building is constructed on footing foundations.

In this thesis is solved by building technological project of an office building in Zlin Januška Compressors - Lukov focusing on selected technological stage. Namely, the implementation of large wooden roof trusses and performing thermal insulation composite system. For these technological steps are processing all documents that are necessary for their implementation. It's technical report on construction technology project, time and financial plan of the building, study the implementation of major technological stages of the main building structure, design of the main building mechanisms, the project site equipment with appropriate drawings and calculations of the costs of site, technical regulations implementing the activities related to monitoring and test plans.

This thesis solves the design documentation for implementation of kindergarten. The building site is situated in the urban area of village Vlčnov. The building site is sloping. The slope is oriented to the southeast. Kindergarten is designed as detached brick building with two floors and without basement. On each floor there are two departments for children. The total projected number of children is 60. Kindergarten is accessed from the local road. Each floor has its own entrance from southeast and northwest. The first floor is partially roofed by flat roof – terrace and green roof. Second floor is roofed by gabled roof, consisting of wooden lattice trusses. The building includes a garden for movement and play of children.

The theme of this Master´s thesis is to design and assess the load Bering steel structure of the hippodrome in Napajedla. The hippodrome is solved as a hall object in two alternatives. Both alternatives are elliptical in shape with dimensions of 40 and 80 m. Load bearing structure of the chosen alternative is formed by transversely oriented column binding with the axial spacing of 6,0 m. Transversely oriented binding is formed from spatial lattice truss supported by fixed solid columns. The spatial rigidity of the structure is ensured by fixing columns in the transverse direction and by using transverse braces in the longitudinal direction. The longitudinal braces help to ensure the spatial rigidity. The work consists of the design and assessment of the main load bearing components, the solution of chosen details of joints and columns´ anchoring, solution of construction component and the elaboration of statement of material and drawings´ documentation.

The topic of the thesis is a project of roof of a multifunctional sport object with a ground-plan covering area 35x48m, and maximum height of 16m. This construction is projected for Brno and its surroundings. The project of roofing is evolved in two different variants. First one is formed by double-jointed arched latticed truss. Supporting components such as purlins, lateral and longitudal bracings, frontal column and anchorage are designed and assessed in static calculation. At the end of the thesis, comparison of both variants is elaborated. Design documentation, which consists of dispositional drawing, drawing of truss for manufacturing, drawing of indicative details and plan of anchorage, is a part of the thesis.

碩士<br>國立臺灣大學<br>機械工程學研究所<br>106<br>My research is about how to try to produce octet-truss lattice mateial by Digital Light Processing(DLP) with the effect of by Two-photon Polymerization. The technique of DLP not only buys some pieces of equiment in low price but also takes short time to produce. The only obstacle I have to overcome is how to produce it with the high resolution by using four factors, exposure time, slice thickness, Sudan and brightness, and finally produce 120, 100 and 80 micrometer-scale octet-truss lattice material. The aim of research is using less material to produce transparent octet-truss with the high strength.

This study investigates the possibility of fabricating periodic cellular materials (PCMs) via the lost foam casting (LFC) process using aluminum alloy A356 and magnesium alloy AZ91. This approach combines the structural efficiency of PCM architectures with the processing advantages of near-net-shape LFC. An initial feasibility study fabricated corrugated A356 panels. This was followed by a study of casting variables such as pattern design, vacuum assistance, and alloying additions in order to improve the fillability of the small cross-section struts. Finally, integrated pyramidal sandwich panels having different relative densities were subjected to artificial aging treatments and subsequently tested in uniaxial compression. The A356 PCMs experienced a continuous increase after yielding while the AZ91 PCMs exhibited strut fracture after peak strength. The results showed the compressive yield strengths of this study are comparable with those previously reported PCMs produced by different fabrication methods.

We present a framework for the efficient, yet accurate description of general periodic truss networks based on concepts of the quasicontinuum (QC) method. Previous research in coarse-grained truss models has focused either on simple bar trusses or on two-dimensional beam lattices undergoing small deformations. Here, we extend the truss QC methodology to nonlinear deformations, general periodic beam lattices, and three dimensions. We introduce geometric nonlinearity into the model by using a corotational beam description at the level of individual truss members. Coarse-graining is achieved by the introduction of representative unit cells and a polynomial interpolation analogous to traditional QC. General periodic lattices defined by the periodic assembly of a single unit cell are modeled by retaining all unique degrees of freedom of the unit cell (identified by a lattice decomposition into simple Bravais lattices) at each macroscopic point in the simulation, and interpolating each degree of freedom individually. We show that this interpolation scheme accurately captures the homogenized properties of periodic truss lattices for uniform deformations. In order to showcase the efficiency and accuracy of the method, we compare coarse-grained simulations to fully-resolved simulations for various test problems, including: brittle fracture toughness prediction, static and dynamic indentation with geometric and material nonlinearities, and uniaxial tension of a truss lattice plate with a cylindrical hole. We also discover the notion of stretch locking --- a phenomenon where certain lattice topologies are over-constrained, resulting in artificially stiff behavior similar to volumetric locking in finite elements --- and show that using higher-order interpolation instead of affine interpolation significantly reduces the error in the presence of stretch locking in 2D and 3D. Overall, the new technique shows convincing agreement with exact, discrete results for a wide variety of lattice architectures, and offers opportunities to reduce computational expenses in structural lattice simulations and thus to efficiently extract the effective mechanical performance of discrete networks.