35 research outputs found
Ljudabsorberande takpanel för offentlig miljö
No full textAkustik är läran om ljudet. I takt med att människan använder fler och fler tekniska apparater i sin
arbetsmiljö ökar också ljudvolymen. Det har även blivit vanligare med öppna kontorslandskap där
ljudet lättare sprider sig och problem som buller kan uppstå.
Buller kan leda till bl.a. talmaskering, stress och koncentrationssvårigheter. Ett sätt att motverka
dessa negativa effekter är att minska efterklangstiden samt ljudutbredningen i ett rum. För att göra
det kan olika typer av absorbenter användas. I detta projektet ligger fokus på takabsorbenter.
Detta projekt utfördes i samarbete med Akustikmiljö i Falkenberg AB med syfte att utveckla en
ljudabsorberande takpanel med tredimensionell design. Takpanelen ska bidra till att minska
ljudutbredningen i ett rum i förhållande till en vanlig takpanel, samt sänka efterklangstiden.
En SWOT-analys gjordes på befintliga konkurrenter till produkten och med hjälp av resultatet
utvecklades flertalet idéer. Dessa idéer skissades och därefter beräknades efterklangstiden för
respektive modell. Konceptval gjordes sedan med hjälp av en Kesselringmatris.
Resultatet blev att alla modellerna sänkte efterklangtiden mer eller mindre, men modellen med bäst
betyg enligt Kesselringmatrisen hade även bäst egenskaper för att sänka ljudutbredningen.
Den utvalda modellen modellerades i programmet PTC Creo Parametric 3.0 , där även ritningar togs
fram för att kunna producera en färdig prototyp.Acoustics is defined as the science of sound. Today, in our modern society, the use of high-tech
product gets more and more common, products which increases the sound level. Open offices is also
more common nowadays and this can cause problems such as noise annoyance since it's easier for
the sound to spread.
Noise annoyance can lead to stress, concentration difficulties and difficulties with understanding
what other people say. One way to reduce this is to reduce the reverberation time and the sound
propagation.
This project was made in cooperation with Akustikmiljö i Falkenberg AB with purpose of developing a
sound absorbing panel with three-dimensional design. The panel will help to reduce the
reverberation time relative to a normal, flat panel and also reduce the sound propagation.
A SWOT-analysis was made with the already existing competitors on the market and with the results
from the SWOT-analysis several ideas were born. Sketches were made and the reverberation time
was calculated for each model. Kesselring's matrix selection was then used to choose the best model.
The results shows that all of the models did lower the reverberation time more or less, but the model
chosen with Kesselring's matrix selection was better at reducing the sound propagation.
The chosen panel was modelled i PTC Creo Paramtric 3.0 and the same program was also used to
create the drawings
Framtagning av väska till elektrisk sparkcykel
No full textDet här arbetet är att samarbete med IKEA och dess syfte är att ta fram en lösning på hur en elektrisk sparkcykel ska förvaras och förflyttas då den inte används. Målet är att ta fram en prototyp samt ett produktionsunderlag för en enkel modell av förvaringslösningen samt ta fram ett förslag på en vidareutveckling av förvaringslösningen som erbjuder ytterligare funktioner. Dessutom ska en 3D-modell av sparken tas fram.
Framtagningen av den enklare väskan genomförs med hjälp av Ulrichs och Eppingers produktutvecklingsprocess med inriktning på konceptutvecklingsfasen. Skisser för olika koncept tas fram och därefter genomförs ett konceptval med hjälp av konceptpoängsättning. När konceptvalet är gjort tas en prototyp av väskan fram och när prototypen är tillfredsställande genomförs ett materialval varpå ett produktionsunderlag sammanställs.
De koncept som genereras för väska 2 är vidareutvecklingar av den enklare väskan. Koncepten presenteras även här i form av skisser varpå konceptens för och nackdelar vägs mot varandra vilket leder till det slutliga konceptvalet. Materialvalet för tyget till väskan genomförs på samma sätt som för den enklare väskan och materialvalet för den hårda delen genomförs med hjälp av CES EduPack. För att en FEM-simulering ska kunna genomföras tas en CAD-modell av den hårda delen fram. Resultatet av simuleringen används sedan för att dimensionera tjockleken på den hårda delen.
Vid sidan om arbetet med väskorna tas 3D-modellen av sparken fram. Detta då IKEA inte sedan tidigare har ett 3D-underlag för sparken. 3D-modelleringen görs i CAD-programmet SolidWorks.
Arbetet resulterar i en enkel väska i polypropylen med tillhörande produktionsunderlag och en mer avancerad väska med integrerad förvaring. Materialvalet för tyget till den mer avancerade väskan blir vaxad canvas och materialvalet för den hårda delen blir polystyren med 30 % glasfiber. Väskorna presenteras tillsammans med en renderad bild på CAD-modellen av sparken i resultatdelen.This project is a collaboration with IKEA and the purpose to develop a solution for storage and transportation of an electrical scooter when not in use. The aim is to develop a prototype of a simple bag that solves this problem and then develop this prototype further into a more advances bag that offers additional features. In addition to this a 3D model of the scooter will be made.
The development of the simple bag is made with the help of the product development process of Ulrich and Eppinger with focus on the concept development. Sketches of the different concepts are made and then the best concept is chosen with concept scoring. When the best concept I chosen a prototype of the bag is made. When the prototype is satisfying a choice of material for the bag is made. Finally a pattern of the bag is compiled.
The concepts that are generated for the more advanced bag are elaborations of the simple bag. The concepts are again presented as sketches whereupon the pros and cons of the concepts are weight against each other which leads to a favorite concept being chosen. The choice of material for the fabric of the bag is made in the same way as the choice of material for the simple bag. The choice of material for the bottom of the bag is made with the program CES EduPack. To enable a FEM simulation a 3D model of the bottom part of the bag is made. The result of the simulation is then used to dimension the thickness of the bottom part.
Alongside the development of the bags a 3D model of the scooter is made. This is done because IKEA does not have a 3D model of the scooter. All 3D modulation is done with the program SolidWorks.
The project result in a prototype and pattern of a bag made from polypropylene and a concept for the more advanced bag that offers integrated storage. The choice of material for the fabric of the more advanced bag is waxed canvas and the choice of material for the bottom part of the bag is polystyrene with 30% glass fibers. The bags and the 3D model of the scooter are presented in the result part of this paper
Multiscale modeling of dynamic recrystallization
No full textDuring thermomechanical processing of metals, changes occur in the microstructure of the material which affect its macroscopic properties. By understanding these transformations in the microstructure, it becomes possible to design the processes in a way which yields the desired properties in the finished product. For this purpose, computer simulation plays an increasingly important role.The present work is focused on developing an efficient numerical model that captures the macroscopic material behavior as well as the microstructure evolution. The main part of the thesis is made up of four papers, A-D. In paper A, different numerical solution methods for crystal plasticity are compared and implemented to run on the Graphical Processing Unit (GPU). The use of GPUs for scientific computation allows for considerable parallelism to be achieved in an ordinary desktop, or even laptop, computer, and has also been proven to be a cheap and energy efficient alternative for use in clusters. Since polycrystal plasticity is well suited for parallelization, it is shown that considerable speedup, up to a factor of 100 in some cases, can be achieved.In paper B, the crystal plasticity model is coupled with a vertex model of grain structure evolution. This provides a versatile framework which can be used to model dynamic recrystallization at large deformations. The crystal plasticity model captures hardening and texture evolution during deformation, while the vertex model describes the recrystallization process in terms of nucleation and grain growth. This model is then applied to simulations of a hot rolling process in paper C, making itpossible to study how temperature, and thereby recrystallization, affects the texture evolution during rolling, and also to study the development of inhomogeneities in the microstructure throughout the workpiece. In the final paper, D, the model from paper B is further developed such that it can also account for the effects of grain size hardening and particle pinning of migrating grain boundaries.Taken together, the four papers A-D provide a numerical simulation framework with multiscale capabilities. By taking advantage of recent developments in computer hardware and using a combination of modeling approaches, a versatile tool is established. The model is capable of describing development of crystallographic texture and dynamic recrystallization, including effects of temperature and impurities in the material. Employed in a finite element setting, the effects of the microstructure evolution on the macroscopic properties of the metal are captured, providing a powerfulconstitutive model for thermomechanical processing
Efficient crystal plasticity simulations of microstructure evolution
No full textOne of the common tools for studying the deformation behavior of the microstructure in polycrystalline materials is crystal plasticity models. These are used to describe texture evolution and hardening due to crystallographic slip. A drawback when using crystal plasticity models is that the calculation of the slip requires solving a set of stiff differential equations for each grain in the microstructure, yielding a high computational cost. In order to reduce this cost, the program has in the present work been ported to a graphical processing unit (GPU), to utilize the capabilities for parallel performance available on the GPU. Different strategies for the numerical implementation of crystal plasticity are investigated as well as a number of approaches to parallelization of the program execution. Crystal plasticity models based on the Taylor assumption are well suited for describing the plastic deformation of polycrystal grain structures, but are not equipped to model recrystallization since the topology of the grain structure is not defined, and there is no description of inter-connectivity between grains. Therefore the crystal plasticity model is combined with a graph-based vertex algorithm in this work. This formulation is capable of capturing finite-strain deformations, development of texture and microstructure evolution through recrystallization. The polycrystal plasticity model is employed in a finite element setting and allows tracing of stored energy build-up in the microstructure and concurrent reorientation of the crystal lattices in the grains. This influences the progression of recrystallization as nucleation occurs at sites with sufficiently high stored energy gradients and since the grain boundary mobility and energy is allowed to vary with crystallographic misorientation across the boundaries. The proposed graph-based vertex model describes the topological changes to the grain microstructure and keeps track of the grain inter-connectivity. Through homogenization, the macroscopic material response is also obtained. By the proposed modeling approach, grain structure evolution at large deformations as well as texture development are captured
Multiscale modeling of dynamic recrystallization
No full textDuring thermomechanical processing of metals, changes occur in the microstructure of the material which affect its macroscopic properties. By understanding these transformations in the microstructure, it becomes possible to design the processes in a way which yields the desired properties in the finished product. For this purpose, computer simulation plays an increasingly important role. The present work is focused on developing an efficient numerical model that captures the macroscopic material behavior as well as the microstructure evolution. The main part of the thesis is made up of four papers, A-D. In paper A, different numerical solution methods for crystal plasticity are compared and implemented to run on the Graphical Processing Unit (GPU). The use of GPUs for scientific computation allows for considerable parallelism to be achieved in an ordinary desktop, or even laptop, computer, and has also been proven to be a cheap and energy efficient alternative for use in clusters. Since polycrystal plasticity is well suited for parallelization, it is shown that considerable speedup, up to a factor of 100 in some cases, can be achieved. In paper B, the crystal plasticity model is coupled with a vertex model of grain structure evolution. This provides a versatile framework which can be used to model dynamic recrystallization at large deformations. The crystal plasticity model captures hardening and texture evolution during deformation, while the vertex model describes the recrystallization process in terms of nucleation and grain growth. This model is then applied to simulations of a hot rolling process in paper C, making it possible to study how temperature, and thereby recrystallization, affects the texture evolution during rolling, and also to study the development of inhomogeneities in the microstructure throughout the workpiece. In the final paper, D, the model from paper B is further developed such that it can also account for the effects of grain size hardening and particle pinning of migrating grain boundaries. Taken together, the four papers A-D provide a numerical simulation framework with multiscale capabilities. By taking advantage of recent developments in computer hardware and using a combination of modeling approaches, a versatile tool is established. The model is capable of describing development of crystallographic texture and dynamic recrystallization, including effects of temperature and impurities in the material. Employed in a finite element setting, the effects of the microstructure evolution on the macroscopic properties of the metal are captured, providing a powerful constitutive model for thermomechanical processing
An extended vertex and crystal plasticity framework for efficient multiscale modeling of polycrystalline materials
No full textA multiscale modeling framework for polycrystal materials is established, using a combination of an extended vertex model and a crystal plasticity formulation. The 2D vertex model is cast to incorporate a range of mesoscale processes such as grain structure evolution and the influence of second-phase particles. It is combined with a finite strain crystal plasticity formulation whereby also texture development and stored energy accumulation is traced. Computational efficiency is enhanced by GPU-parallelization. The full model captures a wide range of microstructure processes such as dynamic recrystallization, grain growth, texture evolution, anisotropic grain boundary properties as well as particle pinning effects. The macroscale material behavior is directly coupled to the evolving microstructure, for example in terms of a grain size dependent flow stress behavior. Illustrative numerical examples are provided to show the capabilities of the model. For example, the interplay between particle strengthening and grain size influence on macroscopic flow stress behavior is shown, as well as effects due to dynamic recrystallization. Special attention is given to the formulation of the vertex model as the combination of stored energy, particle pinning and anisotropic grain boundary properties give rise to intricate topological transformations which have not been previously addressed
Modeling of a Crack-induced Hydride Formation at a Grain Boundary in Metals
No full textCrack-induced hydride formation can occur in specific metallic structures, reducing their mechanical properties and facilitating failure. Grain boundaries are observed to be preferential sites for hydride formation. We present a phasefield approach describing the kinetics of crack-induced hydride formation at a grain boundary, by using the Allen-Cahn formulation and including the increase in grain boundary energy. Hydride development is found to occur at the crack tip and in the grain boundary. These regions seemingly evolve independently, except when the crack is very close to or lies in the grain boundary.
Phase-field modelling : effect of an interface crack on precipitation kinetics in a multi-phase microstructure
No full textPremature failures in metals can arise from the local reduction of the fracture toughness when brittle phases precipitate. Precipitation can be enhanced at the grain and phase boundaries and be promoted by stress concentration causing a shift of the terminal solid solubility. This paper provides the description of a model to predict stress-induced precipitation along phase interfaces in one-phase and two-phase metals. A phase-field approach is employed to describe the microstructural evolution. The combination between the system expansion caused by phase transformation, the stress field and the energy of the phase boundary is included in the model as the driving force for precipitate growth. In this study, the stress induced by an opening interface crack is modelled through the use of linear elastic fracture mechanics and the phase boundary energy by a single parameter in the Landau potential. The results of the simulations for a hydrogenated (α+β) titanium alloy display the formation of a precipitate, which overall decelerates in time. Outside the phase boundary, the precipitate mainly grows by following the isostress contours. In the phase boundary, the hydride grows faster and is elongated. Between the phase boundary and its surrounding, the matrix/hydride interface is smoothened. The present approach allows capturing crack-induced precipitation at phase interfaces with numerical efficiency by solving one equation only. The present model can be applied to other multi-phase metals and precipitates through the use of their physical properties and can also contribute to the efficiency of multi-scale crack propagation schemes
Model of dynamic recrystallization at large deformations by linking vertex and crystal plasticity models
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