The recent improvement of additive manufacturing has allowed designers to achieve a level of complexity and customizability that is difficult or impossible to accomplish using traditional manufacturing processes. As a result, much research has been conducted on developing new methods to utilize the larger design space brought by additive manufacturing. One such research area is in the design of mesoscale lattice structures. Mesoscale lattice structures are a type of cellular structure with support element sizes on the order of magnitude of centimeters. These types of structures are engineered for high performance and have applications in industries where both low weight and high strength are desired. However, due to the small size of their struts, these structures can easily have hundreds to thousands of individual struts. As a result, design poses a unique challenge. Current methods approach design of mesoscale lattice structures as a topological optimization problem, treating each strut diameter in the structure as a design variable. For structures with a fewer number struts, these optimization methods can converge, but will generally be very time-consuming. For structures with a large number of struts, the optimization problem becomes too large for current algorithms to solve. In previous research, a new, highly efficient design method for mesoscale lattice structures was presented that eliminates the need for global size or topological optimization. This method, termed the Size, Matching and Scaling method, used a unique combination of a solid-body finite element analysis and a library of pre-defined lattice configurations, termed the "unit-cell library," to generate lattice topologies. The results from this method were highly promising: design time was significantly reduced when compared to optimization methods. Furthermore, lattices designed using the SMS method had performance results that were either comparable or better than their optimized counterparts. However, the method developed was highly conceptual, lacking a true systematic methodology for generating topologies and suffering from some gaps in implementation. In this research, we present a modified Size Matching and Scaling (SMS) design method. Firstly, we introduce and outline the modified methodology. This methodology particularly includes an optimization step for determining strut diameters that replaces the manual search used in the original method. Secondly, we expand and explore the unit-cell library in an attempt to improve the performance of lattices generated using the SMS method. In particular, we optimize several unit-cell configurations and compare their performance in the context of the SMS method. Finally, we test the updated SMS methodology and unit-cell library using various design examples. Results from the various example problems indicate that optimization is not only a viable systematic method for determining diameter values, but is actually preferred to the manual, iterative process used in the original method. Furthermore, various optimization algorithms and approaches yield different results. Between the two optimization algorithms utilized in this method: constrained optimization and least-squares minimization, constrained minimization converges faster, but least-squares minimization yields slightly improved performance results. In addition to these algorithms, a one-variable approach using an untested, simplifying assumption, dubbed the "28% approach," was tested. Results indicate that this assumption was incorrect and cannot be utilized. Finally, results from the expanded unit-cell library indicate that the best unit-cell configuration is still the same original unit-cell configuration utilized in the first SMS method. The addition of more unit-cell does not improve the performance of structures generated using the SMS method. In fact, both performance and design time worsen when additional configurations are utilized.

Among the light bending structures currently available, truss core panels are one of the most efficient when properly designed. The proper selection of the truss core lattice allows the incorporation of additional functionality. To exploit the multi-functional advantages of truss core sandwich structures, it is crucial to understand how the materials survive in challenging environments. In this research, the strengths of truss core panels have been predicted. Numerical calculations and experiments were carried out to validate the predictions. The effects of damage and damage propagation on the overall strength of the panel were also addressed. The strength and failure surfaces of arrays of partially damaged truss core unit cells were calculated under shear and axial loading. The results highlight the modes and trends of damage propagation in truss core panel, and the estimated damaged strength. Experiments were also performed to validate the damaged strength.

Among the light bending structures currently available, truss core panels are one of the most efficient when properly designed. The proper selection of the truss core lattice allows the incorporation of additional functionality. To exploit the multi-functional advantages of truss core sandwich structures, it is crucial to understand how the materials survive in challenging environments. In this research, the strengths of truss core panels have been predicted. Numerical calculations and experiments were carried out to validate the predictions. The effects of damage and damage propagation on the overall strength of the panel were also addressed. The strength and failure surfaces of arrays of partially damaged truss core unit cells were calculated under shear and axial loading. The results highlight the modes and trends of damage propagation in truss core panel, and the estimated damaged strength. Experiments were also performed to validate the damaged strength.

Projektet omfattade en jämförelsestudie avseende stomsystem. Studien undersökte ramverk och fackverk/balk/pelar-system och genomfördes självständigt med stöttning av Ramböll AB´s kontor i Falun. Syftet var främst att undersöka vilka skillnader det finns mellan tvåledsramar och fackverk/balk/pelar-system för lätta hallbyggnader och försöka få klarhet i varför fackverk/balk/pelar-system är det dominerande systemet i Sverige eftersom övriga Europa har tagit en annan utveckling och domineras av tvåledsramar. Studien undersöker skillnaderna mellan systemen i en hallbyggnad med förutbestämda mått i stål.Inledningsvis gjordes en litteraturstudie för att få en bredare bakgrund av systemen och en bättre förståelse om förutsättningarna för varje system. Efter litteraturstudien kunde sedan ett typhus och beräkningsunderlag för jämförelsestudien tas fram. Även en enkätstudie gjordes med syftet att skapa en tydlig bild av vilket stomsystem konstruktörer i Sverige oftast väljer och varför. Resultatet av studien visade att tvåledsramar ger en ökad kostnad jämfört med fackverk/balk/pelar-system i materialåtgång och framställning samt att beräkningarna blir mer komplicerade. Skulle fortsatta studier göras med dessa system i byggnader med andra mått skulle det kanske gå att få fram speciella mått på byggnader där kostnaden för tvåledsramar blir densamma som för fackverk/balk/pelar-system och därför är ett likvärdigt alternativ som stomsystem.En viktig slutsats från projektet är att tvåledsramar används mycket mer sällan än fackverk/balk/pelar-system som stomsystem i lätta hallbyggnader i Sverige på grund av att kostnaderna blir mycket högre med tvåledsramar och att det är ett mer komplicerat system i beräkningsarbetet. De viktigaste slutsatserna från jämförelsestudien går att sammafatta som följande: Tvåledsramar är dyrare att använda. Tvåledsramar är ett mer komplicerat system beräkningsmässigt. Traditionen av att använda tvåledsramar finns inte och därför används inte systemet. / The project included a comparison study on frame systems. The study investigated framework and truss/beam/column-system and was conducted independently with support of Ramboll AB 's office in Falun. The aim was primarily to examine what differences there are between frameworks with two joints and truss/beam/column-systems for light industrial buildings and try to determine why the truss/beam/column-system is the dominant system in Sweden because the rest of Europe has taken a different development and dominated by framework with two joints. The study examines the differences between the systems in a industrial building with predetermined dimensions in steel.Initially, a literature study was conducted to gain a broader view of the systems and to create a better understanding for the conditions for each system. After the literature study was conducted could a exampelhouse and underlay for the comparison study be developed. A survey study were also conducted and the purpose was to create a clear picture of which system the frame system designers in Sweden usually choose and why. The results of the study showed that frameworks with two joints give an increased cost compared with truss/beam/column-system in material consumption and production, and the calculations become more complicated for the framwork. Should further studies be done with these systems in buildings with other measurements, it might possible to obtain specific measures of buildings where the cost of frameworks with two joints will be the same as for a building with truss/beam/column-system and therefore become an equivalent alternative.An important conclusion of this project is that a framework with two joints is used much more rarely than truss/beam/column-system as frame systems in light industrial buildings in Sweden because the cost will be much higher with a framework with two joints and that it is a more complicated system in the computational work . The main conclusions from comparative study can be summarized as follows: Framwork with two joints is more expensive to use. Framework with two joints is a more complicated system computationally. The tradition of using framework with two joints does not exist and it's therefore the system does not being used.

Šiame darbe projektuojamas statybinių medžiagų centras, Šiauliuose, Metalistų gatvėje, su prekybinėmis patalpomis, sandėliu bei buitinėmis – adminitracinėmis patalpomis. Aprašomas sklypo planas, pastato patalpų išplanavimas, kontrukciniai sprendimai bei inžineriniai tinklai. Suprojektuota 18 m metalinė santvara SN-18, parinkta 5,6 m ilgio dvitėjo profilio sija SI-5.6, suprojektuota 5,94 m ilgio gelžbetoninė perdangos plokštė PP 594-120-22. Sudaryta perdangų montavimo technologin÷ kortelė, perdangų montavimui parinktas automobilinis kranas. Sudaryti pagrindinių konstrukcijų darbų kiekių žiniaraščiai ir pagal juos sudaryta lokalinė sąmata. Paskaičiuoti administracinių – buitinių patalpų šilumos laidumo koeficientai, šilumos nuostoliai. Pagal šiuos apskaičiuotus duomenis parinkti šildymo prietaisai. / In this work, there is a centre of building materials that is being designed in Siauliai, Metalistu Street. It consists of trading rooms, warehouse and domestic – administrative rooms. Description of the plan of the plot, layout of rooms, construction decisions and engineering networks. Designed 18 m metallic truss SN-18, selected 5,6 m length HEA-beam SI-5.6, designed 5,94 m length reinforced floor slab PP 594-120-22. Made out of floors installation technological card, for floors installing selected truck crane. Formed sheets of quantity of main constructial workings and accordingly formed local estimation. calculated administrative – domestic rooms heat-transferring coefficient, heat ranges. According to the calculated data, heating devices were chosen.

Šiame darbe projektuojamas viešbutis numatomas statyti, Radviliškio r., Baisogalos miestelyje, R. Žebenkos gatvėje, su konferencijų sale ketvirtame aukšte, restoranu pirmame aukšte, gyvenamaisiais kambariais, apželdintu stogu - terasa virš trečio aukšto denginio, liftu ir pagalbinėmis patalpomis. Aprašomas sklypo planas, pastato patalpų išplanavimas, konstrukciniai sprendimai, bei inžineriniai tinklai. Suprojektuota 14,7 m metalinė santvara SN-147, suprojektuota 12 m ilgio, 2 m pločio monolitinė gelžbetoninė perdangos plokštė, ir suprojektuota kiaurymėta nepertraukto formavimo gelžbetoninė perdanga PK640-120-26,5. Sudaryta eksploatuojamo apželdinto stogo įrengimo technologinė kortelė, perdangų, santvarų montavimui ir kitų medžiagų tiekimui parinktas ratinis kranas DEMAG AG 155. Nuo pamatų iki dalinės vidaus apdailos sudaryti darbų kiekių žiniaraščiai ir pagal juos sudaryta lokalinė sąmata. / The hotel designed in this thesis is projected to be built in Radviliškis district, Baisiogala town, R. Žebenkos Street; it includes a conference hall in the fourth floor, a restaurant in the ground floor, guest rooms, a terraced roof over the third floor roofing, an elevator and the utility rooms. It describes the plan of the plot, the layout of the premises, the structural solutions, and the engineering networks. Designed a steel truss SN-147 of 14.7 m, designed a monolithic reinforced concrete floor slab of 12 metres long and 2 metres width, designed a reinforced concrete slab of a hollow core continuous formation PK640-120-26.5. Made a technological card for setting the terraced roof, a truck crane DEMAG AG 155 was chosen for assembling slabs and trusses and providing other materials. The sheets for the amount of work from the base to the partial interior finishing were formed and according to them, the local estimate was given.

This thesis investigates the effect of microstructural strengthening mechanisms on the overall mechanical performance of micro-truss periodic cellular metals (PCMs). Prior to the author’s work, the primary design considerations of micro-truss PCMs had been topological issues, i.e. the architectural arrangement of the load-supporting ligaments. Very little attention had been given to investigate the influence of microstructural effects within the cellular ligaments. Of the four broad categories of strengthening mechanisms in metals, only solute and second phase strengthening had previously been used in micro-trusses; the potential for strengthening micro-truss materials by work-hardening or grain size reduction had not been addressed. In order to utilize these strengthening mechanisms in micro-truss PCMs, two issues needed to be addressed. First, the deformation-forming method used to produce the micro-trusses was analyzed in order to map the fabrication-induced (in-situ) strain as well as the range of architectures that could be reached. Second, a new compression testing method was developed to simulate the properties of the micro-truss as part of a common functional form, i.e. as the core of a light-weight sandwich panel, and test the effectiveness of microstructural strengthening mechanisms without the influence of typical high-temperature sandwich panel joining processes, such as brazing. The first strengthening mechanism was achieved by controlling the distribution of plastic strain imparted to the micro-truss struts during fabrication. It was shown that this strain energy can lead to a factor of three increase in compressive strength without an associated weight penalty. An analytical model for the critical inelastic buckling stress of the micro-truss struts during uniaxial compression was developed in terms of the axial flow stress during stretch forming fabrication. The second mechanism was achieved by electrodeposition of a high-strength nanocrystalline metal sleeve around the cellular ligaments, producing new types of hybrid nanocrystalline cellular metals. It was shown that despite the added mass, the nanocrystalline sleeves could increase the weight-specific strength of micro-truss hybrids. An isostrain model was developed based on the theoretical behaviour of a nanocrystalline metal tube network in order to predict the compressive strength of the hybrid materials.

Low-density cellular solids have demonstrated superior mechanical properties as well as multifunctional characteristics, which may provide a basis for the development of novel structured materials. In particular, cellular solids offer great design flexibility, owing to their topology, which can provide desired functionalities via targeted geometric design and proper selection of the constituent material. While stochastic configurations such as metallic foams have proven to be effective for both thermal insulation and mechanical-energy absorption, the topology of deterministic architectures is not constrained by physical processes. This allows for a variety of configurations to be tailored to simultaneously fulfill disparate tasks. An additional aspect of deterministic cellular structures is the possibility of assembling materials or structures by the spatial repetition of a unit cell. The resulting periodicity of such systems simplifies the characterization of physical properties, which can be established by analyzing the unit cell only, and will provide new opportunities in the fields of structural dynamics, where periodicity-induced impedance leads to the control of both constructive and destructive interference on propagating waves. The objective of this work is to investigate the application of the chiral cellular topology for the design of novel macrostructural, mesostructural and microstructural configurations. A truss-core airfoil, and a truss-core beam are employed as a basis to demonstrate both large-displacement capabilities within the elastic regime of the constituent material, as well as operational deflection shapes with localized dynamic deformations. Large deformation capabilities and unique operational deflection shapes are to be attributed to the unusual deformation mechanism of the chiral lattice. Mesostructural and microstructural configurations, on the other hand, are characterized by an unique mechanical behavior, complex geometry, as well as geometric design flexibility to control both static and dynamic phenomena. The propagation of elastic waves, moreover, is characterized by significant band-gap density as well as strong energy focusing dependent on frequency and wavenumber. These features suggest the chiral topology as a basis for the development of acoustic meta-materials.

The advent of rapid manufacturing has enabled the realization of countless products that have heretofore been infeasible. From customized clear braces to jet fighter ducts and one-off dental implants, rapid manufacturing allows for increased design complexity and decreased manufacturing costs. The manufacturing capabilities of this process have evolved to the point that they have surpassed current design capabilities. Meso-scale lattice structures can now be built that contain more lattice struts than it is reasonable to efficiently define. This work has attempted to create a method for designing such lattice structures that is efficient enough to allow for the design of large or complex problems. The main hindrance to the design of complex meso-scale lattice problems is essentially the need to define the strut diameters. While it is obvious that a large design would contain more struts than can be specified by hand, designs also quickly surpass the current capabilities of computational optimization routines. To overcome this problem, a design method has been developed that uses a unit-cell library correlated to finite element analysis of the bounding geometry to tailor the structure to the anticipated loading conditions. The unit-cell library is a collection of base lattice primitives, or unit-cells, that have been specialized for certain applications. In this case, primitives have been created that perform best under the types of stress analyzed by finite element analysis. The effectiveness of this process has been demonstrated through several example problems. In all cases, the unit-cell library approach was able to create structures in less time than current methods. The resulting structures had structural performance slightly lower than similar models created through optimization methods, although the extent of this degradation was slight. The method developed in this work performs extremely well, and is able to create designs for even the most complex lattice structures. There is room for future development, however, in the streamlining of the design process and consideration of higher-order affects within unit-cells.

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.