Sustainable materials such as cross-laminated timbers (CLT) are increasingly being used in the construction of green buildings worldwide. Such products may be exposed to cyclic environmental conditions and exhibit moisture-induced damage. The main objective of this study is to develop and validate an efficient, physically-based tool to simulate the moisture transport, and consequently moisture-induced stresses and deformation in laminated orthotopic composites. Predicting the moisture profile variation with time is the first step toward understanding the performance of CLT panels under extreme environmental loads. A comprehensive literature review was conducted to determine the most critical parameters in moisture transport phenomena in CLT panels to ensure the capability of the framework to capture the essential moisture transport mechanisms. Thermal moisture analogy theory was used for simulating the moisture transport across the composite material cross-section. Unlike previous studies, the moisture adsorption curve of the material was used instead of employing the surface emission coefficient to estimate moisture flux at the surfaces. The method was verified and validated based on a simple one-dimensional (1-D) analytical model and experimental data, respectively. A series of parametric studies were conducted using the validated model to highlight the effect of glue lines, wood species, boundary conditions, panel dimension, and orientation of CLT layers on the moisture transport across the composite panel. After predicting the moisture profile of CLT panels, the numerical model was used to determine the stresses caused by humidity differences on panel surfaces. The applied transient load in the model was obtained from the moisture transport simulation. The total strain rate is assumed as the sum of the elastic and the moisture-induced strain rate. The mechano-sorptive strain is omitted from the material model since it is assumed that samples are not under mechanical loading. The stress model was successfully validated by experimental data reported in the literature. Parametric studies were conducted to investigate the significant role of panel bonding lines (i.e. elasticity modulus and moisture diffusivity) on moisture-induced stresses. A failure analysis was completed to determine how wood species affect laminated composite failure. The same approach was followed to determine the moisture-induced deformation through a finite element analysis. Finally, the effect of adhesive elasticity and its moisture diffusivity on the deformed shape of CLT panels was investigated parametrically. This study showed that the choice of adhesive along with the combination of wood species, could significantly affect the panel’s moisture profile and developed stresses even after 14 days under similar environmental conditions. As demonstrated in this thesis, simulating moisture transport in CLT panels is crucial in determining stresses and deformation caused by environmental conditions. / Graduate / 2023-12-01

A recently published experimental study by Xia and Steen examines the connection between the contact line velocity and contact angle of liquid drops on an oscillating substrate that display contact angle hysteresis. Of particular interest in this experimental study is the analysis of the dependence of contact angle deviation on contact line velocity. Indeed it is found that for small angular displacements, there is a linear relationship between the two. Moreover, the oscillating drop exhibits contact angle hysteresis that is much greater than that measured from quasi-static experiments. Here we use a phase-field model of dynamic wetting which directly includes the contact angle hysteresis to simulate the results of the aforementioned authors. A thorough derivation of the governing equations is presented, starting from the pioneering work of Cahn and Hilliard. Our model is unique due to the explicit inclusion of contact angle hysteresis, a phenomenon that has proven quite difficult to model. We demonstrate that by choosing appropriate parameters, our model can achieve very good agreement with experimental data. Further, we compare to our results to those computed using another model, further validating our method. We then investigate the effects of contact line friction and the hysteresis window, which are otherwise very difficult to explore experimentally. / Master of Science / When a drop of liquid comes into contact with a solid surface, it forms a semi-spherical cap having a fixed contact angle defined as that between the wall and the line tangent to the liquid drop, at the point where the liquid meets the solid. In recent decades, researchers in fields as varied as mathematics, physics, chemistry and materials science have studied the spreading and contraction of liquid drops on solid surfaces of various chemical compositions. Of particular interest to this paper is a phenomenon called `contact angle hysteresis' (CAH), in which a liquid drop can remain stationary at multiple distinct contact angles. The presence of hysteresis in physical systems significantly complicates the analysis of the physical problem and has been a motivating factor for the development of mathematical models that can contend with CAH. Here we present a model for describing the motion of liquid drops which explicitly takes CAH into account.

A distribuição de temperatura, as deformações e as forças na zona de corte durante a formação de cavacos são muito importantes, pois têm grande influência nos resultados dos processos de usinagem como um todo. O desgaste das ferramentas, a precisão das operações de usinagem (dilatação térmica) e o acabamento superficial são alguns desses resultados que afetam a economia do processo. Este trabalho tem o objetivo uma avaliação das potencialidades oferecidas pela simulação da formação de cavacos usando-se FEM (Finite Element Method). Quatros modelos com princípios bastante diferentes são utilizados explorando-se as mais recentes inovações em termos de recursos oferecidos pelo software ABAQUS/Explicit. Nos modelos utilizam-se ferramentas de substrato WC recoberto com TiN usinado aços AISI 4340. As simulações proporcionam o estudo e exame detalhado da distribuição de temperatura, deformações, forças de corte, fluxo de material e uma enorme quantidade de informações que poderão ser muito úteis para a análise de novos processos, otimização de processos existentes, além de abrir novos horizontes no estudo da formação de cavacos. As simulações também demonstram que a complexidade da formação de cavacos cria muitas dificuldades para sua análise usando equações analíticas baseadas em constantes. / The distribution of temperature, the deformations and the cutting forces in the cutting zone during chip formation are very important aspects of the process. Therefore they have great influence in results of machining. Tool wear, the precision of the machining operations and the finishing superface are some of these results that affect the economy of the process. This work has the objective of an evaluation offered potentialities for simulating chip formation using FEM (Finite Element Method). Four models with sufficiently different principles are used to exploring the most recent innovations in terms of resources offered by ABAQUS/Explicit software. In the models, WC tools coated TiN was used to machine AISI 4340 steel. The simulations provide a study and detailed examination of temperature distribution, deformations, cutting forces, flow of material and an enormous amount of information that could be useful for the analysis of new processes and optimization of existing processes. Additionally, they open new horizon in the study of the chip formation. The simulations also demonstrate the complexity of the chip formation process, which creates many difficulties for its analysis using based analytical equations in constants. Some comparisons are established with experimental results found in temperature measurements.

A distribuição de temperatura, as deformações e as forças na zona de corte durante a formação de cavacos são muito importantes, pois têm grande influência nos resultados dos processos de usinagem como um todo. O desgaste das ferramentas, a precisão das operações de usinagem (dilatação térmica) e o acabamento superficial são alguns desses resultados que afetam a economia do processo. Este trabalho tem o objetivo uma avaliação das potencialidades oferecidas pela simulação da formação de cavacos usando-se FEM (Finite Element Method). Quatros modelos com princípios bastante diferentes são utilizados explorando-se as mais recentes inovações em termos de recursos oferecidos pelo software ABAQUS/Explicit. Nos modelos utilizam-se ferramentas de substrato WC recoberto com TiN usinado aços AISI 4340. As simulações proporcionam o estudo e exame detalhado da distribuição de temperatura, deformações, forças de corte, fluxo de material e uma enorme quantidade de informações que poderão ser muito úteis para a análise de novos processos, otimização de processos existentes, além de abrir novos horizontes no estudo da formação de cavacos. As simulações também demonstram que a complexidade da formação de cavacos cria muitas dificuldades para sua análise usando equações analíticas baseadas em constantes. / The distribution of temperature, the deformations and the cutting forces in the cutting zone during chip formation are very important aspects of the process. Therefore they have great influence in results of machining. Tool wear, the precision of the machining operations and the finishing superface are some of these results that affect the economy of the process. This work has the objective of an evaluation offered potentialities for simulating chip formation using FEM (Finite Element Method). Four models with sufficiently different principles are used to exploring the most recent innovations in terms of resources offered by ABAQUS/Explicit software. In the models, WC tools coated TiN was used to machine AISI 4340 steel. The simulations provide a study and detailed examination of temperature distribution, deformations, cutting forces, flow of material and an enormous amount of information that could be useful for the analysis of new processes and optimization of existing processes. Additionally, they open new horizon in the study of the chip formation. The simulations also demonstrate the complexity of the chip formation process, which creates many difficulties for its analysis using based analytical equations in constants. Some comparisons are established with experimental results found in temperature measurements.

<p> <p>Syftet med detta projekt är att göra en marknadsundersökning av dimensioneringsprogram för byggnadskonstruktörer och att ge en rekommendation till Byggteknik AB för val av programvara. Metoden är att först genomföra en marknadsundersökning, sedan utvärdera lämpliga program och sist ge en rekommendation. Utvärderingen och rekommendationen ska grundas på användarvändlighet, pris, support, uppdateringar, långsiktig ägare, landsstandarder och utbildningsbehov. Resultatet från användandet gav stora differenser, med över 50% större maximalt moment i StruSoft FEM- Design och över dubbelt så stor nedböjning i Robot Millennium.</p><p> </p><p>Jämförelsen mellan programmen visar att Robot Millennium har en bättre användarvänlighet och lägre pris. Dock har StruSoft FEM- Design svensk support, automatiska uppdateringar och hanterar svensk landsstandard. Båda programmen är likvärdiga gällande långsiktig ägare och utbildningsbehov. Programmen är således relativt likvärdiga men rekommendationen till Byggteknik AB blir StruSoft FEM- Design, främst för att Robot Millennium inte hanterar svensk landsstandard och inte tillhandahåller en ordentlig svensk support. Det är dock viktigt att framhålla att de två personer som genomfört detta projekt har mycket liten erfarenhet från dimensioneringsprogram varför risken för felaktigt handhavande finns.</p></p> / <p> <p>The purpose of this project is to do a market research of analysis software for building design and to recommend a specific software for Byggteknik AB. The methodology of this project is to first implement a market research, then evaluate suitable software and finally give a recommendation. The evaluation and the recommendation will be based on application handiness, price, customer support, software updates,  sustainable ownership, country code and education requirements. The results showed a great difference with over 50% larger maximum moments in StruSoft FEM-Design and more then twice the deflection in Robot Millennium.</p><p> </p><p>The comparison between the two software applications shows that Robot Millennium has a more developed application handiness and a lower price then FEM-Design. FEM-Design on the other hand has a Swedish costumer support, automatic updates and handles the Swedish country code BKR. Both software applications are equal concerning sustainable ownership and education requirements. Even though the two software applications are quit similar to each other this recommendation for Byggteknik AB will be StruSoft FEM-Design. Mostly because Robot Millennium doesn’t handle Swedish country code and has no proper Swedish customer support. It is important however, to accentuate the lack of experience in analysis software among the two people who carried out this project, hence the accuracy of the results may be questionable.</p></p>

Syftet med detta projekt är att göra en marknadsundersökning av dimensioneringsprogram för byggnadskonstruktörer och att ge en rekommendation till Byggteknik AB för val av programvara. Metoden är att först genomföra en marknadsundersökning, sedan utvärdera lämpliga program och sist ge en rekommendation. Utvärderingen och rekommendationen ska grundas på användarvändlighet, pris, support, uppdateringar, långsiktig ägare, landsstandarder och utbildningsbehov. Resultatet från användandet gav stora differenser, med över 50% större maximalt moment i StruSoft FEM- Design och över dubbelt så stor nedböjning i Robot Millennium.   Jämförelsen mellan programmen visar att Robot Millennium har en bättre användarvänlighet och lägre pris. Dock har StruSoft FEM- Design svensk support, automatiska uppdateringar och hanterar svensk landsstandard. Båda programmen är likvärdiga gällande långsiktig ägare och utbildningsbehov. Programmen är således relativt likvärdiga men rekommendationen till Byggteknik AB blir StruSoft FEM- Design, främst för att Robot Millennium inte hanterar svensk landsstandard och inte tillhandahåller en ordentlig svensk support. Det är dock viktigt att framhålla att de två personer som genomfört detta projekt har mycket liten erfarenhet från dimensioneringsprogram varför risken för felaktigt handhavande finns. / The purpose of this project is to do a market research of analysis software for building design and to recommend a specific software for Byggteknik AB. The methodology of this project is to first implement a market research, then evaluate suitable software and finally give a recommendation. The evaluation and the recommendation will be based on application handiness, price, customer support, software updates,  sustainable ownership, country code and education requirements. The results showed a great difference with over 50% larger maximum moments in StruSoft FEM-Design and more then twice the deflection in Robot Millennium.   The comparison between the two software applications shows that Robot Millennium has a more developed application handiness and a lower price then FEM-Design. FEM-Design on the other hand has a Swedish costumer support, automatic updates and handles the Swedish country code BKR. Both software applications are equal concerning sustainable ownership and education requirements. Even though the two software applications are quit similar to each other this recommendation for Byggteknik AB will be StruSoft FEM-Design. Mostly because Robot Millennium doesn’t handle Swedish country code and has no proper Swedish customer support. It is important however, to accentuate the lack of experience in analysis software among the two people who carried out this project, hence the accuracy of the results may be questionable.

In this dissertation an approach is presented for the three-dimensional electrical resistivity tomography (ERT) using unstructured discretizations. The geoelectrical forward problem is solved by the finite element method using tetrahedral meshes with linear and quadratic shape functions. Unstructured meshes are suitable for modelling domains of arbitrary geometry (e.g., complicated topography). Furthermore, the best trade-off between accuracy and numerical effort can be achieved due to the capability of problem-adapted mesh refinement. Unstructured discretizations also allow the consideration of spatial extended finite electrodes. Due to a corresponding extension of the forward operator using the complete electrode model, known from medical impedance tomography, a study about the influence of such electrodes to geoelectrical measurements is given. Based on the forward operator, the so-called triple-grid-technique is developed to solve the geoelectrical inverse problem. Due to unstructured discretization, the ERT can be applied by using a resolution dependent parametrization on arbitrarily shaped two-dimensional and three-dimensional domains. A~Gauss-Newton method is used with inexact line search to fit the data within error bounds. A global regularization scheme is applied using special smoothness constraints. Furthermore, an advanced regularization scheme for the ERT is presented based on unstructured meshes, which is able to include a-priori information into the inversion and significantly improves the resulting ERT images. Structural information such as material interfaces known from other geophysical techniques are incorporated as allowed sharp resistivity contrasts. Model weighting functions can define individually the allowed deviation of the final resistivity model from given start or reference values. As a consequent further development the region concept is presented where the parameter domain is subdivided into lithological or geological regions with individual inversion and regularization parameters. All used techniques and concepts are part of the open source C++ library GIMLi, which has been developed during this thesis as an advanced tool for the method-independent solution of the inverse problem.

Det har av olika anledningar blivit mer populärt att bygga flervåningshus i trä vilket har lett till en utveckling av material i trä. Korslimmat trä även kallat KL-trä är en konsekvens av denna utveckling i Sverige och precis som för andra stommaterial används datorprogram för att rita hus i KL-trä. Syftet med denna rapport är att få lärdom om KL-trä samt undersöka hur programmet FEM-Design kan användas för att dimensionera ett flervåningshus i KL-trä. Därtill, har FEM-Design också använts för att räkna materialmängden för att kunna göra en klimatdeklaration, för båda materialen betong och trä. Resultatet av klimatdeklarationen visar att träbyggnaden får ett lägre utsläpp i byggskedet jämfört med betongbyggnaden i byggskedet, men Boverkets databas som har använts i denna rapport är något konservativ. Värdena i Boverkets databas i framför allt skede A1-A3 avviker något jämfört med EPD:er (miljövarudeklaration) från olika företag inom betongindustrin. KL-träbyggnaden är lättare än betongbyggnaden vilket gör att betongfundamenten till träbyggnaden borde kunna göras mindre för att klara av lasterna jämfört med betong. Däremot får träbyggnaden något tjockare bjälklag för att klara av ljud-, brand- och brukskraven som då medför en lägre rumshöjd om inte förändring görs av den totala byggnadshöjden. För att uppnå samma rumshöjd på 2,6 m i betongbyggnaden skulle det krävas att träbyggnaden byggs 1,2 m högre vilket leder till större materialåtgång. / For various reasons, it has become more popular to build multi-storey houses in wood, which has led to the development of materials in wood. Cross laminated timber also called CLT is a consequence of this development in Sweden and just like other frame materials, computer programs are used to draw houses in CLT. The aim of this report is to get knowledge of CLT and investigate how the software FEM-Design can be used to design a multi-storey building in CLT. In addition, FEM-Design has also been used to calculate the amount of material necessary to make a climate declaration, for both materials concrete and wood. The result based on the climate declaration shows that the wooden building has a lower emission in the construction phase compared with the concrete building, but the National Board of Housing, Building and Planning's database that has been used in this report is somewhat conservative. The values in the National Board of Housing, Building and Planning's database, primarily in stages A1-A3, differ slightly compared with EPDs (environmental product declaration) from different companies in the concrete industry. The CLT building is lighter than the concrete building, which means that the concrete foundations for the wooden building may be made smaller to handle the loads compared to concrete. On the other hand, the wooden building gets a slightly thicker floor to cope with the sound, fire and use requirements, which then results in a lower room height if the total height of the building still is the same. In order to achieve the same room height of 2.6 m in the concrete building, it would be required that the wooden building be built 1.2 m higher, which leads to greater material consumption.

Prediction of fatigue damage due to fretting is complex due to the number of influential factors and the competitive interaction between wear and fatigue. The majority of current fretting damage modeling approaches are limited to narrow ranges of conditions where little competition between damage mechanisms occurs. Recent models which account for damage interaction are largely phenomenological in nature and are still limited to a narrow range of applicability. A method to characterize and model the level of fatigue damage due to fretting was developed in this work to address the shortcomings of the current methods available by extending the range of conditions captured and enhancing the physical basis of the damage model. Baseline material properties for thin sheets of AISI 301 stainless steel in the full hard condition were determined as a function of temperature through tensile tests, fatigue tests, and metallography. Fretting experiments were performed for contact between 301 stainless steel and each ANSI A356 aluminum and AISI 52100 steel. Fretting experiments were performed over a range of material combinations, normal forces, displacement amplitudes, atmospheres, and temperatures. Subsequent characterization of the damage due to fretting was performed to determine the level of wear and fatigue damage incurred for each condition tested. A finite element model of the experiment was created to determine the cyclic stress-strain behavior and local frictional energy dissipation for each condition. Fatigue damage metrics were evaluated to determine the effects of the contact conditions on the driver for fatigue damage. A new model for fatigue damage due to fretting was developed which incorporates the wear behavior to describe the effect of wear on the level of fatigue damage caused by fretting. The level of fatigue damage is influenced using a function of frictional energy dissipation and wear rate to account for differences in wear mechanisms and changes in the severity of wear caused by changes in oxidation behavior and mechanical properties which result from changes in temperature or contacting materials.

A welding procedure specification is the document describing how a weld joint should be constructed. Arc weld processes are characterized by transient thermal behavior, leading to rapid changes in material properties and dynamic interaction between weld and base material. The objective of the project is to explore how the use of an improved CWM-platform affects representative stress and strain fields in order to assess welding procedure qualification records. Forthis project, the accumulated thermal and mechanical influences from the first run to the final run are brought forward, in one and the same meshed geometrical model. Both the thermal and mechanical material model of the platform are designed to be used for modelling of the base- and weld material,promoting the simulation of the intricate combination of the thermal, elastic,and plastic strains on the plastic strain hardening and the formation of residual stress fields. The output of the simulation is mainly weld cooling times, residual stresses, and deformations. This analysis is taken further by examining how residual stresses influence crack driving force under elastic and plastic loading. In addition, the output from the simulations can be used to assess the realism of the proposed welding parameters. The main experimental welding procedure examined comes from the IIW RSDP Round Robin Phase II benchmark project, where the main aim was to benchmark residual stress simulations. This work was found to contain many applicable challenges of a CWM-analysis project.