Från slutet på 1800-talet till runt 1970-talet gjordes tennisracket i trä och då tekniken inte var så avancerad var de tunga och böjliga. På 1970-talet började dock andra material som exempelvis kolfiber användas som var styvare och gav ett lättare racket. Över tid har metoderna för tillverkningen i trä fallit i glömska vilket gör att undersökningar som denna är intressanta att utföra. Då kolfiber framställs av råolja kan materialet bli mindre attraktivt både ur ett miljö- och ekonomiskt perspektiv då oljepriserna stiger. På grund av detta har företaget Epok Tennis, som arbetet har utförts ihop med, valt att experimentera och prova sig fram i tillverkningen av racket i trä i jakt efter den mest optimala uppsättningen och konstruktionen. Kunskapsläget är dåligt inom området då studie av denna typen generellt görs på större element för användning i exempelvis bostäder och dessa består då framför allt av gran och furu. Därför är det intressant för Epok Tennis att se inverkan av olika träslag som inte vanligtvis används i balkar av i små dimensioner som är jämförbara med tennisracket.Epok Tennis har undersökt hur träracketen byggdes förr och försökt implementera tekniken moderna racket byggs, detta för att skapa en träprodukt som kan fungera lika bra som en modern racket. De viktigaste parametrarna att ta hänsyn till i arbetet var produkternas vikt, styvhet och hållfasthet. I arbetet undersöktes 21 kors- och parallellimmade balkar bestående av totalt sex nordiska träslag. Träslagen i fråga var ask, björk, bok, ek, lönn och valnöt. Sju av balkarna var korslimmade och 14 parallellimade. De korslimmade elementen varierade mellan ett och två tvärgående skikt. Två av balkarna innehöll även produkter som kolfiberduk och linnetyg vilka inte beaktades i beräkningarna men vars resultat var av intresse att analysera. Syftet med arbetet var att undersöka hur olika kombinationer av olika träfanérskivor påverkarböjstyvheten och hållfastheten för en tennisrackets konstruktion. Målet var sedermera att fastställa vilken av balkarna som har högst böjstyvhetoch hållfasthet samt ge förslag om optimal komposituppsättning. Teoretiska beräkningar samt experiment av fyrpunktsböjning utfördes på balkarna där resultaten jämfördes och analyserades. Experimenten utfördes både i balkarnas flat- och kantvisa riktning. Även densiteterna noterades för elementen då konstruktionens totala vikt i slutändan är av stor betydelse.Resultaten av studien visade att de homogena parallellimmade balkarna av björk, lönn och valnöt hade högst böjstyvhet. Vid analys av resultaten noterades att korslimning av elementen generellt försvagade dem i både flat- och kantvis riktning. Till detta ändamål kan det därför vara klokt att endast använda parallellimmade element. I resultatet redovisas även balkarnas knäcklast i kantvisa riktningen.Förekomsten av kvistar i lamellerna ansågs ha en stor inverkan på balkarnas hållfasthet. Därför bör lameller med kvistar försöka undvikas vid framställningen av ramarna till tennisracketen. I förslaget om optimal komposituppsättning har en kombination av lönn och valnöt angetts då dessa visade högst böjstyvhet med avsevärt lägre densitet än björk som dock liknande värde på böjstyvheten.Enligt resultaten av studien är slutsatserna som dragits kortfattat att korslimning generellt försvagar elementen gentemot parallellimning och att bästa komposituppsättning består av lönn och valnöt, i kombination med varandra eller var för sig. / The knowledge of creating wooden tennis rackets has been lost since the emergence of materials like carbon fibre. In this study 21 cross- and parallel laminated beams have been examined, seven of which are cross laminated and 14 parallel laminated. The wood species used were ash, beech, birch, maple, oak and walnut.The purpose of the study was to determine how different combinations of wood lamellas affect strength and stiffness of the beams in terms of bending.The goal was to determine which of the 21 beams had the highest bending stiffness and to give a recommendation of what would be the optimal composite set.Calculations and experiments of four point bending were done in the flat- and edgewise directions, the results of which were compared and analyzed.The results of the study showed that the homogenous parallel laminated beams consisting of birch, maple and walnut had the highest bending stiffness. When analyzing the results, it was found that the parallel laminated beams were generally stronger and stiffer than the cross laminated specimens, for both flat- and edgewise bending.In the recommendation of optimal construction, a combination of maple and walnut has been suggested due to them having similar bending stiffness to birch but significantly lower density.

Em experimentos com um cilindro flexível com rigidez a flexão ortotrópica, proporcionando razão entre frequências naturais longitudinal e transversal muito próximas a quatro (fx1fy1/=4,08), Fujarra et al (2001) [17] revelaram um ramo de resposta em VIV em alta velocidade. Tal ramo de respostas estável, excitado por perturbações a montante, era caracterizado por amplitudes transversais ao escoamento com ordem de 1 diâmetro e componentes de alta frequência no espectro de energia, estendendo-se por faixa de velocidade reduzida 12 < U* < 20 e esvaindo-se a partir da emergência de oscilações no segundo modo de vibração. Almejando aprofundar as investigações acerca deste intrigante achado experimental, uma nova campanha investigativa foi planejada e executada. Quatro cilindros flexíveis com distintas razões de rigidez ortotrópica foram construídos em resina polimérica, com enrijecedores internos de seções retangulares feitos de alumínio, resultando um conjunto com frequências naturais, correspondentes a modos longitudinais e transversais, com razões relativas: 4:1, 3:1, 2:1 e 1:1. Os cilindros foram verticalmente fixados a uma célula de carga 3D. Uma série de ensaios foi conduzida, sob velocidade de escoamento crescente e decrescente. As vibrações dos cilindros flexíveis foram capturadas através de um sistema óptico subaquático, posicionado a jusante, que rastreava a posição de alvos constituídos por fitas refletivas afixadas ao longo do comprimento do cilindro. Clássicas técnicas de análise espectral, decomposição modal no domínio do tempo e a Transformada de Hilbert-Huang foram utilizadas de modo encadeado e recursivo com o fim de determinar as respostas de vibração, em amplitude e frequências dominantes, em função da velocidade reduzida. O ramo de resposta em altas velocidades reduzidas foi recuperado nos experimentos com os quatro cilindros. Análise comparativa sistemática permitiu concluir que o ramo de resposta em tela se deve ao lock-in de modos longitudinais, que são excitados em velocidades reduzidas tão mais altas quanto maior for a razão de frequências considerada. Empregando-se, então, os deslocamentos e velocidades modais medidos em formulação de Mineto (2013) [23], foi realizada estimativa de potência elétrica a ser extraída pelo emprego de finos filmes de material piezelétrico depositados sobre as lâminas enrijecedoras internas aos cilindros. / A previous work by Fujarra et al. (2001) revealed a \"high speed mode branch\" in cantilevered flexible cylinders subjected to VIV. That work studied a flexible cylinder with orthotropic bending stiffness in a recirculating water channel, by setting the ratio between the first natural frequencies, in the in-line and cross-wise directions to the flow, very close to four (fx1fy1/=4,08). Such a new stable response branch, triggered by upstream hydrodynamic perturbations, was characterized by amplitudes, perpendicular to the flow, of order of one diameter and by high frequencies components in the energy spectrum. The branch extends from reduced velocity circa 12 up to 20, being extinguished by the onset of the second vibration mode lock-in. Aiming at investigating further this intriguing experimental finding, a new campaign has been planned and performed. Four flexible cylinders with distinct orthotropic bending ratios were built, by molding thin aluminum stiffeners, of rectangular cross section, inside the cylinders made of a flexible resin. The respective natural frequencies ratio, between in-line and cross-wise bending modes, was set to 4:1, 3:1, 2:1 and 1:1. The flexible cylinders were vertically clamped to a 3D load cell. A series of experimental runs were carried out, under ascending and descending flow speeds. The flexible cylinder vibration was captured trough an underwater optical system, placed downstream, by tracking 3D Cartesian coordinates of reflective strips placed all along the span, at equi-spaced cross sections. Besides standard spectral analysis techniques, modal decomposition in time domain and the Hilbert-Huang Transform have been recursively used together to determine amplitude and dominant response frequencies. The \"high speed mode branch\" revealed for all four cylinders tested. Systematic comparative analysis allowed us to conclude that such a response branch is caused by the lock-in of longitudinal modes, excited at reduced velocities ranges that increase with the frequency ratio considered. Finally, using measured modal responses in Mineto (2013) [23] formulation, the electric power that would be extracted by the use of thin piezoelectric layers deposited over the internal stiffeners blades was estimated.

The design and analysis of an automotive structure is an important stage of the vehicle design process. The structural characteristics have significant impact on the vehicle performance. During the design process it is necessary to have knowledge about the structural characteristics; however in the preliminary design stages detailed information about the structure is not available. During this period of the design process the structure is often simplified to a representative model that can be analyzed and used as the input for the detailed design process. A vehicle model is developed based on the space frame structures where the frame is the load carrying portion of the structure. Preliminary design analysis is conducted using a static load condition applied to the vehicle as pure bending and pure torsion. The deflections of the vehicle based on these loading conditions are determined using the finite element method which has been implemented in developed software. The structural response, measured as the bending and torsion stiffness, is used to evaluate the structural design. An optimization program is implemented to improve the structural design with the goal of reducing weight while increasing stiffness. Following optimization the model is completed by estimating suitable plate thicknesses using a method of substructure analysis. The output of this process will be an optimized structural model with low weight and high stiffness that is ready for detailed design. / UOIT

Size effects in out-of-plane bending stiffness of honeycomb cellular materials were studied using analytical mechanics of solids modeling, fabrication of samples and mechanical testing. Analysis predicts a positive size-effect relative to continuum model predictions in the flexure stiffness of a honeycombed beam loaded in out-of-plane bending. A method of determining the magnitude of that effect for several different methods of constructing or assembling square-celled and hexagonal-celled materials, using both single-walled and doubled-walled construction methods is presented. Hexagonal and square-celled honeycombs, with varying volume fractions were fabricated in Nylon 12 using Selective Laser Sintering. The samples were mechanically tested in three-point and four point-bending to measure flexure stiffness. The results from standard three-point flexure tests, did not agree with predictions based on a mechanics of solids model for either square or hexagonal-celled samples. Results for four-point bending agreed with the mechanics of solids model for the square-celled geometries but not for the hexagonal-celled geometries. A closed form solution of an elasticity model for the response of the four-point bending configuration was developed, which allows interpretation of recorded displacement data at two points and allows separation the elastic bending from the localized, elastic/plastic deformation that occurs between the loading rollers and the specimen’s surface. This localized deformation was significant in the materials tested. With this analysis, the four-point bending data agreed well with the mechanics of solids predictions. / text

The primary aim of this research was to investigate the bending behaviour of helically wound steel cables of various types (i.e. normal spiral strands, sheathed spiral strands and locked coil cables) in the presence of friction and to propose more efficient computational models for their analysis under combined tension and bending. The proposed model fully takes into account interwire contact forces both in the radial direction (point contact between wires in different layers) and hoop direction (line contact within the wires in the same layer). Extensive theoretical parametric studies have been undertaken on a variety of cable constructions covering a wide range of geometrical and material parameters. Explicit formulations have been developed for the smooth transition of the bending stiffness from no-slip to full slip regimes, as a function of cable curvature. Based on these formulations, it is now possible to calculate the relative displacements of the wires, as well as the tensile, bending and hoop stresses in the individual wires of the cable. Furthermore, bending stiffness of the cable is shown to decrease by a factor of 2 to 16, depending upon the friction coefficient between wires and the type of cable construction. Wherever possible, the theoretical results have been compared with experimental results from the available literature and are found in very good agreement with them. A simple method for the determination of the bending stiffness of large diameter multi-layered cable has been developed. The simplified method is further shown to provide estimates of the bending stiffness which are very close to those calculated by the original theory, allowing hand calculations for an easier use in industry. The proposed formulations have been extended to cater for the effects of external hydrostatic pressure on sheathed spiral strands in deep water applications. These forces are shown to have a great influence on the pattern of interwire contact forces and hence the interlayer slippage between the wires in the strand. Numerical results have been obtained and analysed for three different 127 mm diameter strands with lay angles of 12°, 18° and 24° respectively, experiencing a wide range of external hydrostatic pressures of 0 to 2,000 metres. The significant increase in normal contact force between wires is shown to suppress the slippage of wires in the cable. However, the no-slip and full slip values of the effective bending stiffness of the cable is shown to be independent of the level of hydrostatic pressure. A theoretical model is also proposed for estimating wire kinematics, pattern of interwire slippage, contact forces as well as the flexural rigidity of locked coil cables with outer layers made of shaped wires. In order to validate this model, numerical results are reported for two different locked coil cables. It is shown that the shaped wires in the outer layers of locked coil cables play an important role in the distribution of contact forces, slip initiation and cable unwinding.

Em experimentos com um cilindro flexível com rigidez a flexão ortotrópica, proporcionando razão entre frequências naturais longitudinal e transversal muito próximas a quatro (fx1fy1/=4,08), Fujarra et al (2001) [17] revelaram um ramo de resposta em VIV em alta velocidade. Tal ramo de respostas estável, excitado por perturbações a montante, era caracterizado por amplitudes transversais ao escoamento com ordem de 1 diâmetro e componentes de alta frequência no espectro de energia, estendendo-se por faixa de velocidade reduzida 12 < U* < 20 e esvaindo-se a partir da emergência de oscilações no segundo modo de vibração. Almejando aprofundar as investigações acerca deste intrigante achado experimental, uma nova campanha investigativa foi planejada e executada. Quatro cilindros flexíveis com distintas razões de rigidez ortotrópica foram construídos em resina polimérica, com enrijecedores internos de seções retangulares feitos de alumínio, resultando um conjunto com frequências naturais, correspondentes a modos longitudinais e transversais, com razões relativas: 4:1, 3:1, 2:1 e 1:1. Os cilindros foram verticalmente fixados a uma célula de carga 3D. Uma série de ensaios foi conduzida, sob velocidade de escoamento crescente e decrescente. As vibrações dos cilindros flexíveis foram capturadas através de um sistema óptico subaquático, posicionado a jusante, que rastreava a posição de alvos constituídos por fitas refletivas afixadas ao longo do comprimento do cilindro. Clássicas técnicas de análise espectral, decomposição modal no domínio do tempo e a Transformada de Hilbert-Huang foram utilizadas de modo encadeado e recursivo com o fim de determinar as respostas de vibração, em amplitude e frequências dominantes, em função da velocidade reduzida. O ramo de resposta em altas velocidades reduzidas foi recuperado nos experimentos com os quatro cilindros. Análise comparativa sistemática permitiu concluir que o ramo de resposta em tela se deve ao lock-in de modos longitudinais, que são excitados em velocidades reduzidas tão mais altas quanto maior for a razão de frequências considerada. Empregando-se, então, os deslocamentos e velocidades modais medidos em formulação de Mineto (2013) [23], foi realizada estimativa de potência elétrica a ser extraída pelo emprego de finos filmes de material piezelétrico depositados sobre as lâminas enrijecedoras internas aos cilindros. / A previous work by Fujarra et al. (2001) revealed a \"high speed mode branch\" in cantilevered flexible cylinders subjected to VIV. That work studied a flexible cylinder with orthotropic bending stiffness in a recirculating water channel, by setting the ratio between the first natural frequencies, in the in-line and cross-wise directions to the flow, very close to four (fx1fy1/=4,08). Such a new stable response branch, triggered by upstream hydrodynamic perturbations, was characterized by amplitudes, perpendicular to the flow, of order of one diameter and by high frequencies components in the energy spectrum. The branch extends from reduced velocity circa 12 up to 20, being extinguished by the onset of the second vibration mode lock-in. Aiming at investigating further this intriguing experimental finding, a new campaign has been planned and performed. Four flexible cylinders with distinct orthotropic bending ratios were built, by molding thin aluminum stiffeners, of rectangular cross section, inside the cylinders made of a flexible resin. The respective natural frequencies ratio, between in-line and cross-wise bending modes, was set to 4:1, 3:1, 2:1 and 1:1. The flexible cylinders were vertically clamped to a 3D load cell. A series of experimental runs were carried out, under ascending and descending flow speeds. The flexible cylinder vibration was captured trough an underwater optical system, placed downstream, by tracking 3D Cartesian coordinates of reflective strips placed all along the span, at equi-spaced cross sections. Besides standard spectral analysis techniques, modal decomposition in time domain and the Hilbert-Huang Transform have been recursively used together to determine amplitude and dominant response frequencies. The \"high speed mode branch\" revealed for all four cylinders tested. Systematic comparative analysis allowed us to conclude that such a response branch is caused by the lock-in of longitudinal modes, excited at reduced velocities ranges that increase with the frequency ratio considered. Finally, using measured modal responses in Mineto (2013) [23] formulation, the electric power that would be extracted by the use of thin piezoelectric layers deposited over the internal stiffeners blades was estimated.

Varaktig vattenavvisning från engelskans Durable Water Repellents (DWR) är en kemi som appliceras på textil för att göra den motståndskraftig mot vätska. En DWR-kemi som visat sig vara till stor belastning för miljön och därför genomgått en utfasning inom industrin är fluorkarboner. Detta har lett till fluorfria alternativ och även modifierade fluorkarboner vilka det finns bristande information kring gällande risker för miljö och hälsa. I och med övergången från fluorerade DWR till de fluorfria alternativen aktualiserades frågan kring hur ”durable”, alltså motståndskraftiga mot tvätt och användning, dessa verkligen är. Detta har resulterat i ett stort utbud av konsumentprodukter för återupplivning av vattenavvisning på beklädnad i hemmamiljö. Dessa konsumentprodukter har benämnts som återimpregneringar i denna studie. Återimpregneringar kan göra att användaren förblir nöjd med beklädnaden och detta minskar i sin tur det textila avfallet. Området är outforskat och industrin vill veta mer om dessa konsumentprodukter inklusive hur det textila materialet påverkas av dem. Studien har utgått från ett kundperspektiv vid val av relevanta parametrar och på ett kreativt sätt översatt dessa till laborativa testmetoder. De parametrar som funnits med i studien har varit vattenavvisning, färgförändring, luftgenomsläpplighet samt känsla vilka har använts för analys och jämförelse mellan åtta stycken fluorfria återimpregneringar. Två etablerade appliceringstekniker, wash-in och spray-on, har undersökts på fyra olika textilier som skulle kunna representera frilufts- samt arbetskläder. Två av textilierna var av polyester och två var av polyamid. Samtliga återimpregneringar gav en ökad vattenavvisande effekt. Resultatet varierade beroende på vilket textilt material och vilken återimpregnering som användes. De övriga testmetoderna, färgförändring, luftgenomsläpplighet och böjstyvhet, visade även de liknande variationer i resultaten. Wash-in och spray-on teknikerna kunde generellt visa på statistiska skillnader. Även produkter med samma varumärke applicerade med wash-in och spray-on teknik visade skilda resultat. De laborativa testmetoderna som valts ut visade sig vara användbara verktyg för utvärdering av återimpregneringar vid textilapplicering.  Utifrån litteraturens rön och denna studies resultat har slutsatsen dragits att konsumentprodukter för återimpregnering av textil har betydande skillnader beroende av vilken DWR-kemi de består av samt textiliens konstruktion och fibersort. Det säkraste fluorfria alternativet ur miljösynpunkt tros av rapportförfattarna vara vax som klassas som en kolväteskemi, men det finns mycket kvar att utforska innan en sådan slutsats kan dras med säkerhet. Denna studie har varit ett inledande steg mot att undersöka återimpregneringar som förhoppningsvis i framtiden kan leda till ett minskat textilt avfall med minsta möjliga miljöbelastning. / The textile industry uses durable water repellents (DWR) to achieve water repellency on textiles. One of these DWR chemistries, fluorocarbons, is an environmental issue and has therefore been phased-out in the industry. This has resulted in a market where both modified fluorocarbons and fluorine-free alternatives are available and there is a lack of information about these DWR regarding health and environmental aspects. Due to the changeover from the fluorinated DWR to the non-fluorinated options, the question was raised about how durable these really are. This resulted in a wide range of do-it-yourself consumer products for the water repellency revival. These consumer products have been referred to as reimpregnations in this study. The purpose of reimpregnations is to give clothing a longer life cycle. The customer remains satisfied with the garment and this in turn reduces the textile waste. The industry wants to know more about these unexplored consumer products, including how the textile material is affected by them. A customer perspective has been the basis for selecting relevant parameters in this study, which has been creatively translated into laboratory test methods. Parameters in this study have been water repellency, color change, air permeability and fabric hand. These have been used for analysis and comparison of eight fluorine-free reimpregnations. The techniques used were wash-in and spray-on and have been investigated on four different textiles representing outdoor clothing and workwear, two made of polyester and two of polyamide. All the reimpregnations showed an increased effect in water repellency. The result varied depending on which textile material and what kind of reimpregnation that was used. The other test methods also showed variation according to these factors. Over all the wash-in and spray-on techniques showed a statistical significance. Products from the same brand applied with wash-in and spray-on techniques also showed different results. The selected laboratory test methods proved to be useful tools for evaluation of reimpregnations in textile applications. Based on the literature combined with the results from this study the conclusion has been made that reimpregnation, of textile materials, has a significant difference between DWR chemistries as well as the construction and fibre type of the textile. The safest fluorine-free option, from an environmental point of view, is believed to be wax, which is classified as a hydrocarbon chemistry, however there is much left to explore before such a conclusion can be made with certainty. This study has been an initial step towards the investigation of reimpregnations, which hopefully in the future can lead to reduced textile waste with as little environmental impact as possible.

A study of an influence of strengthening steel beams using reinforcement based on FRP on a moment bearing resistance and bending stiffness. Evaluation of the theoretical calculation methods based on the performed experimental verification. Description of the production of carbon fibres and composite materials on the basis of carbon fibres.

Schaut man durch ein Mikroskop auf eine biologische Zelle mit angefärbten Zytoskelett, so erblickt man lange, mehr oder minder gerade Objekte. Mit ziemlicher Sicherheit gehören diese zu einer von drei Arten von Zytoskelettfilamenten -- Aktin- oder Mikrofilamente, Intermediärfilamente und Mikrotubuli. Schon seit mehreren Jahrzehnten versucht man die mechanischen Eigenschaften lebender Zellen nicht nur zu beschreiben, sondern ihr Verhalten von zwei tieferen Ebenen ausgehend zu verstehen: Inwiefern beschreiben die Eigenschaften von Filamentnetzwerken und -gelen die Zellmechanik und, noch tiefgreifender, wie bestimmen eigentlich die einzelnen Filamente die Netzwerkmechanik. Das Verständnis der Mechanik homogener und isotroper, verhedderter als auch quervernetzter Gele ist dabei erstaunlich detailreich, ohne jedoch vollständig dem jüngeren Verständnis von Zellen als glassartige Systeme zu entsprechen. In den letzten Jahren sind daher anisotrope Strukturen mehr und mehr in den Fokus gerückt, die die Bandbreite möglichen mechanischen Verhaltens enorm bereichern. Die vorliegende Arbeit beschäftigt sich mit solch einem hochgradig anisotropen System -- nämlich Aktinbündeln -- unter drei Gesichtspunkten. Mit Hilfe von aktiven Biegedeformationen wird ein funktionales Modul, das eine differentielle Antwort auf verschiedenen Zeitskalen liefert, identifiziert. Es handelt sich um Aktinfilamente, die durch transiente Quervernetzer gebündelt werden. Während sich das System nach kurz anhaltenden Deformation völlig elastisch verhält, sorgt eine Restrukturierung der Quervernetzer während langanhaltender Deformationen für eine plastische Verformung des Bündels. In einem weiteren Aspekt widmet sich die Arbeit der frequenz- und längenabhängigen Biegesteifigkeit. Die Methode des Bündel-Wigglings, das Induzieren von \"Seilwellen\", wird dabei genutzt, um aus der Wellenform die Biegesteifigkeit zu berechnen. Bündel von Aktinbündeln zeigen dabei ein Verhalten, das vom klassischen Worm-like-chain-Modell abweicht und stattdessen durch das Worm-like-bundle-Modell beschrieben werden kann. Der letzte Aspekt dieser Arbeit untersucht den Musterbildungsprozess bei der Entstehung von Aktinbündeln. Gänzlich unerwartet entstehen quasi-isotrope Strukturen mit langreichweitiger Ordnung, wenn der Bündelungsprozess erst nach der Polymerisation von Filamenten frei von zusätzlichen mechanischen Einwirkungen einsetzt. Da dieser Zustand nicht von der klassischen Flüssigkristalltheorie vorhergesagt wird, soll eine Simulation eine Hypothese zum Entstehungsmechanismus testen. Die Annahme einer lateralen Kondensation von Filamenten zu Bündeln reicht demnach aus, um die beobachteten Strukturen zu erzeugen. Diese Arbeit leistet somit einen Beitrag zum Verständnis hochgradig anisotroper Strukturen und deren Überstrukturen, wie sie auch in lebendigen Zellen reichlich vorhanden sind.:1 Actin filament bundles and patterns 1.1 Actin and other cytoskeletal filaments 1.2 Filament and bundle mechanics 1.2.1 Polymer models 1.2.2 Worm-like bundle theory 1.3 Filament bundling 1.4 Active crosslinkers – contraction and pattern formation 2 Materials and Methods, Instruments and Software 2.1 Actin purification and labeling 2.2 Optical tweezers 2.3 Software libraries for instrument integration 3 Bundle mechanics in the time domain 3.1 Bundle formation and sample preparation 3.2 Bundle bending experiment 3.2.1 LabView VI for bundle bending 3.2.2 Bundle bending 3.2.3 Image analysis and data survey 3.3 Bundle workout – Results of the bending experiments 3.3.1 Multiple bends and elastic response 3.3.2 Endurance test – Plastic response after longer holds 3.3.3 Purely elastic depletion-force induced bundles 3.4 Elastic and plastic deformations of F-actin bundles – Discussion 3.4.1 Bundle formation process and bundle thickness 3.4.2 Elastic response 3.4.3 Elastic versus plastic response 3.5 Differential mechanical response – Summary 4 Bundle mechanics in the frequency domain 4.1 Bundle wiggling – the method 4.2 Bundle formation and sample preparation 4.3 Bundle wiggling experiment 4.3.1 LabView VI for bundle wiggling 4.3.2 Wiggling images to wiggle data 4.4 Bundle wiggling – Results 4.4.1 Bead at end 4.4.2 Wiggling bundled bundles 4.4.3 Thick bundles connected to networks 4.5 Frequency-dependent elastic response of bundles – Discussion 5 Actin bundle networks 5.1 Actin condensation in confined environments – The experiment 5.2 Simulating filament condensation 5.2.1 Implementation details 5.3 Simulation of filament condensation to bundle networks 5.4 Condensation drives pattern formation – Discussion 6 Conclusion A Calculations A.1 Subcircular bending arc and radius of curvature A.2 Correction factor for relaxations times of bundles with bead B Protocols B.1 G-actin from rabbit skeletal muscle B.1.1 Acetone powder prep B.1.2 Actin prep B.1.3 Actin gel-filtration B.2 Buffers B.3 NEM-myosin beads B.3.1 NEM-inactivated myosin B.3.2 NEM-myosin coated beads B.4 Bundle preps B.4.1 Depletion force induced and ff-actinin crosslinked bundles B.4.2 Depletion force induced bundles for wiggling experiments Bibliography / Being the most basic unit of living organisms, the cell is a complex entity comprising thousands of different proteins. Yet only very few of which are considered to play a leading part in the cell’s mechanical integrity. The biopolymers actin, intermediate filaments and microtubules constitute the so-called cytoskeleton – a highly dynamic, constantly restructuring scaffold endowing the cell not only with integrity to sustain mechanical perturbations but also with the ability to rapidly reorganize or even drive directed motion. Actin has been regarded to be the protagonist and tremendous efforts have been made to understand passive actin networks using concepts from polymer rheology and statistical mechanics. In bottom-up approaches isotropic, homogeneous actin-gels are well-characterized with rheological methods that measure elastic and viscous properties on different time scales. Cells, however, are not exclusively isotropic networks of any of the mentioned filaments. Rather, actin alone can already be organized into heterogeneous and highly anisotropic structures like bundles. These heterogeneous structures have only come into focus recently with theoretical work addressing bundle networks. and, in the case of the worm-like bundle theory, individual bundles. This work aims at characterizing bundles and bundle-crosslinker systems mechanically in two complementary approaches – in the time as well as in the frequency domain. In addition, it illuminates a bundle formation mechanism that leads to bundle networks displaying higher ordering.:1 Actin filament bundles and patterns 1.1 Actin and other cytoskeletal filaments 1.2 Filament and bundle mechanics 1.2.1 Polymer models 1.2.2 Worm-like bundle theory 1.3 Filament bundling 1.4 Active crosslinkers – contraction and pattern formation 2 Materials and Methods, Instruments and Software 2.1 Actin purification and labeling 2.2 Optical tweezers 2.3 Software libraries for instrument integration 3 Bundle mechanics in the time domain 3.1 Bundle formation and sample preparation 3.2 Bundle bending experiment 3.2.1 LabView VI for bundle bending 3.2.2 Bundle bending 3.2.3 Image analysis and data survey 3.3 Bundle workout – Results of the bending experiments 3.3.1 Multiple bends and elastic response 3.3.2 Endurance test – Plastic response after longer holds 3.3.3 Purely elastic depletion-force induced bundles 3.4 Elastic and plastic deformations of F-actin bundles – Discussion 3.4.1 Bundle formation process and bundle thickness 3.4.2 Elastic response 3.4.3 Elastic versus plastic response 3.5 Differential mechanical response – Summary 4 Bundle mechanics in the frequency domain 4.1 Bundle wiggling – the method 4.2 Bundle formation and sample preparation 4.3 Bundle wiggling experiment 4.3.1 LabView VI for bundle wiggling 4.3.2 Wiggling images to wiggle data 4.4 Bundle wiggling – Results 4.4.1 Bead at end 4.4.2 Wiggling bundled bundles 4.4.3 Thick bundles connected to networks 4.5 Frequency-dependent elastic response of bundles – Discussion 5 Actin bundle networks 5.1 Actin condensation in confined environments – The experiment 5.2 Simulating filament condensation 5.2.1 Implementation details 5.3 Simulation of filament condensation to bundle networks 5.4 Condensation drives pattern formation – Discussion 6 Conclusion A Calculations A.1 Subcircular bending arc and radius of curvature A.2 Correction factor for relaxations times of bundles with bead B Protocols B.1 G-actin from rabbit skeletal muscle B.1.1 Acetone powder prep B.1.2 Actin prep B.1.3 Actin gel-filtration B.2 Buffers B.3 NEM-myosin beads B.3.1 NEM-inactivated myosin B.3.2 NEM-myosin coated beads B.4 Bundle preps B.4.1 Depletion force induced and ff-actinin crosslinked bundles B.4.2 Depletion force induced bundles for wiggling experiments Bibliography

Glas är ett styvt material som används bland annat inom byggbranschen och fordonsindustrin. Glas har hög styvhet och hög hållfasthet men är ett sprött material. När en spricka uppstår i en laminerad glasbalk minskas dess bärförmåga och styvhet och säkerhetsrisken ökar. För att garantera en hög säkerhet används laminerat glas där tunna plastfilmer limmar ihop flera skikt av glas (som även kallas för lameller). När glaset lamineras fungerar det som ett paket där spänningarna kan överföras mellan de olika lamellerna. Användningsområden inom byggbranschen kan vara plana element, till exempel för fönster eller balkonräcken, dessutom finns både liggande balkar (böjning i den tunna riktningen) samt stående balkar. Även i balkar av laminerat glas kan sprickor i en av lamellerna uppstå. Dessa fångas dock upp av de andra lamellerna så att hela balken förblir intakt och hålls på plats. En sprucken balk tappar då en del av bärförmågan och styvheten jämfört med en osprucken balk. Spruckna balkar kan alltså inte bära samma last. Syftet med arbetet är att öka kunskapen om beteendet hos laminerat glas som är sprucket och få bättre förståelse för hur laminerat glas beter sig när det går till brott. Målet är att verifiera den numeriska beräkningsmodellen av Abdul Khader, Basim &amp; Reshid (2020) genom experimentella försök. Modellen beskriver liggande balkar av laminerat glas, både spruckna och ospruckna balkar. I detta examenarbete användes olika metoder: litteraturundersökning, tillämpning av en beräkningsmodell samt experiment. Litteratundersökningen gav ett fördjupande förståelse dels om ämnet glas exempelvis om olika typer av glas och glasets generella egenskaper, dels om laminerat glas, hur det är uppbyggt, tillverkat och egenskaper förbättras genom lamineringen. Beräkningsmodellen som detta arbete bygger på är från en tidigare studie, där en beräkningsmetod för spruckna glasbalkar beskrevs med hjälp av den så kallade effektiva tjockleksmetoden för böjstyvhet av laminerat glas. Experiment genomfördes för att studera hur laminerade glasbalkar med och utan spricka i mitten beter sig när de utsätts för belastning. Resultaten visar skillnaden mellan ospruckna och spruckna balkar av laminerat glas med två skikt när det gäller böjstyvheten och bärförmågan. Experimenten visar att nedböjningen för spruckna balkar är dubbelt så stor som för ospruckna balkar. Skillnaden beror på att böjstyvheten hos spruckna balkar är lägre än hos ospruckna balkar. På grund av sprickan i mitten överförs lasterna endast i en skiva, och dessutom minskas böjstyvheten i den ospruckna delen. Beräkningsmodellen överensstämde väl med resultaten från de utförda experimenten. Detta bekräftar att modellen kan tillämpas för laminerade glasbalkar. Mer omfattande studier bör dock genomföras där de ingående parametrarna varieras, till exempel genom längre balkar, sprickor på andra ställen än i mitten, samt att olika material för mellansiktet används.