Detta projekt var ett samarbete mellan Luleå tekniska universtiet och CranabSlagkraft och har behandlat ett förbättringsprojekt av befintliga inner- och yttergripklor med namnet E36 tillhörande skogsgrip CE360. Produkten hade en dåvarande konstruktionslösning som företaget länge inte har varit nöjd med. Klorna hade plåtar som svetsades fast på sidan av gripklorna för att skapa stabilitet. Utan dem skulle gripen inte ha tillräcklig hållfasthet då klorna skulle böjas och deformeras omgående vid användning. Sedan hade gripen även problem med stora nötningsproblem. Denna grip ville företaget förbättra då den var både ekonomisk kostsam och tidskrävande att bygga. Produkten var inte heller ekonomisk gynnsam för slutanvändarna då produkten hade så kort teknisk livslängd. Detta projekt har bearbetat dessa problem noggrant med grundlig analys på ett ingenjörsmässigt sätt som resulterat i en slutgiltig lösning med ett ritningsunderlag som har presenterats godkänts och byggdes till en prototyp under 2012. / This project was a collaboration between Luleå University of Technology and CranabSlagkraft and has addressed an improvement project of existing inner and outer gripc laws named E36 belonging to the forestry grip CE360. The product had a previous design solution that the company had long been dissatisfied with. The claws had plates welded to the sides of the grip claws to create stability. Without them, the grip would not have sufficient strength as the claws would bend and deform immediately during use. Furthermore, the grip also had significant wear issues. The company wanted to improve this grip as it was both economically costly and time-consuming to build. The product was also not economically beneficial for end-users as it had such a short technical lifespan. This project has meticulously addressed these problems with thorough analysis in an engineering manner, resulting in a final solution with a drawing basis that has been presented, approved, and built into a prototype in 2012.

The exploration of Microelectromechanical systems (MEMS) represents a crucial aspect in the advancement of modern science and technology. They offer low-cost solutions to miniaturize numerous devices. The increasing use of MEMS applications in biological research has created a pressing need for reliable micromanipulation tools. In this context, microgrippers have emerged as promising tools for the precise handling and characterization of biological samples. This thesis presents a novel biocompatible microgripper that utilizes electrothermal actuation integrated with a rotary capacitive position sensor. To overcome the limited displacement possibilities associated with electrothermal actuators, this microgripper incorporates conjugate surface flexure hinges (CSFH). These hinges enhance the desired tweezers output displacement. The designed microgripper can in principle manipulate biological samples ranging in size from 15 to 120 μm. Based on the sensitivity calculation of the rotary capacitive position sensors, the sensitivity of the displacement measurement is 102 fF/μm. By employing a kinematics modeling approach based on the pseudo-rigid-body method (PRBM), an equation for the displacement amplification factor is developed, and this equation is subsequently verified through FEM-based simulations. By comparing the amplification ratio value obtained from the analytical modeling and simulations, there is an excellent match, with a relative difference of only ~1%, thus demonstrating the effectiveness of the PRBM approach in modeling the kinematics of the structure under investigation. In addition to this, by using analytical modeling based on finite elements method (FEM), the design of the electrothermal actuator and the heat dissipation mechanism is optimized. FEM-based simulations are used to validate the theoretical modeling, demonstrating good agreement between the displacements derived from analytical modeling and simulations. The temperature difference (∆T) across a range from room temperature to 278°C exhibits a relative difference of ~2.8%. Moreover, underpass technology is implemented to ensure that electrical signals or disturbances from other parts of the device, such as the electrothermal actuation system, do not interfere with the operation and integrity of the gripping mechanism. Ultimately, the microgripper is fabricated using conventional MEMS technology from a silicon-on-insulator (SOI) wafer through the deep reactive ion etching (DRIE) technique. The integration of theoretical modeling, simulations, and practical fabrication highlights a compelling approach that has the potential for transformative applications in the field of micromanipulation and biological sample handling. Furthermore, we propose a C-shaped structure with a curved beam mechanism to improve the movement provided by the thermal actuators. The design of experiment (DOE) method is used to optimize the geometrical parameters of our proposed device. Analytical modeling based on Castigliano's second theorem and finite element method (FEM) simulations are used to predict the behavior of the symmetrical C-shaped structure; the results are in good agreement. The MEMS-based rotational structures are fabricated on silicon-on-insulator (SOI) wafers using bulk micromachining and deep reactive ion etching (DRIE). The fabricated devices are tested; our findings reveal that our proposed MEMS rotational structure outperforms the symmetrical lancet structure by 28% in terms of delivered displacement. Furthermore, the experimental results agree well with those obtained through numerical analysis.

In the 1970s, the tandem shaped charge was developed to overcome countermeasures like active armor and thicker armor. It uses a leading charge to clear a path for the main trailing charge, theoretically improving penetration. However, disturbances from shock waves can cause under-performance. To address this, the leading charge's shock waves must be minimized to protect the main charge. Designing a part with shock wave attenuating properties can help achieve this.There is limited information on grenade structures that reduce shock wave stresses from impact and detonation. Most studies on shock wave attenuation focus on protecting buildings and humans, with few addressing structures designed to withstand and then halt the transmission of shock waves. Here we report on simulations in IMPETUS Afea where an explicit FEM solver approach have been made to compare four different concepts to an original structure. Physical theories about attenuation of shock waves in solids has been applied. The first concept utilize a mass with different area increases in the propagation path of the shock wave. The second concept use the characteristics of interfaces between two different materials, with different shock wave impedance which will reflect and transmit the incoming wave. The third concept incorporate a brittle ceramic which should shatter when a shock wave propagates to it, if the brittle structure fracture, no more shock waves can be transmitted. The fourth concept utilize the properties of porous metals. All concepts shows shock wave attenuating effects, but only the third concept which totally disconnects the leading shaped charge to the main charge might be a full solution. The fourth concept compared to the third has other advantages, it attenuate the shock wave to more than 90%, not halt the transmission. Configuration of the porosity in the structural part can be made to have characteristics that can solve the problem. Concept three and four are the main recommendations for a feasibility study. / På 1970-talet utvecklades tandem-RSV laddningar för att övervinna motmedel som aktivt pansar och tjockare pansar. De använder en förladdning för att skapa en väg för den efterföljande huvudladdningen, vilket teoretiskt sett förbättrar prestandan. Störningar från tryckvågor från olika källor orsaka prestandaförluster. För att hantera detta måste islagets och förladdningens tryckvågor minimeras för att skydda huvudladdningen. Att designa en mellandel med egenskaper som dämpar tryckvågor kan hjälpa till att uppnå detta. Information om granatstrukturer som minskar tryckvågsbelastningar från islag och detonation är begränsad. De flesta studier om dämpning av tryckvågor fokuserar på att skydda byggnader och människor, med få som behandlar strukturer designade för att motstå och sedan stoppa överföringen av tryckvågor. Här rapporterar vi om simuleringar genomförda i IMPETUS Afea med en explicit FEM-lösare för att jämföra fyra olika koncept mot en originalstruktur. Fysiska teorier om dämpning av tryckvågor i fasta material har tillämpats. Det första konceptet utnyttjar en massa med olika areaökningar i tryckvågens propagationsväg. Det andra konceptet använder egenskaperna hos gränsytor mellan två olika material med olika tryckvågsimpedanser som kommer att reflektera och transmittera den inkommande tryckvågen. I det tredje konceptet appliceras en spröd keram som bör splittras när en tryckvåg fortplantas till den. Om den spröda strukturen spricker kan då inga fler tryckvågor överföras genom strukturen. Det fjärde konceptet utnyttjar egenskaperna hos porösa metaller. Alla koncept visar tryckvågsdämpande effekter. Men endast det tredje konceptet som helt kopplar bort förladdningen från huvudladdningen kan vara en fullständig lösning. Det fjärde konceptet jämfört med det tredje har andra fördelar; det dämpar tryckvågen till mer än 90%, men stoppar inte överföringen helt. Konfigurationen av porositeten i den strukturella delen kan utformas för att ha egenskaper som kan lösa problemet. Koncept tre och fyra är de huvudsakliga rekommendationerna för en genomförbarhetsstudie.

Since the construction industry has a significant impactful footprint on the climate, a transition to sustainable solutions is imperative. Concrete is the predominant material for load-bearing structures in multi-residential buildings and is usually used in more walls than necessary, resulting in unnecessary excess of carbon dioxide. This study aims to climate-optimize the intended load-bearing structure in a multi-residential building project by evaluating the possibility of an alternative load-bearing structure. Concrete party walls, those which are unnecessary for load-bearing purposes, are removed in the alternative load-bearing structure and replaced with stud walls that meet sound and fire requirements. The comparison is made between the alternative and intended load-bearing structures concerning structural performance and overall climate impact. To comprehend the subject, an extensive literature study was conducted. Subsequently, the load-bearing structures were modelled in FEM-design program to analyse and compare structural aspects. Using FEM-Climate, life-cycle analyses (LCAs) were performed for both load-bearing structures to assess the difference in the total amount of carbon dioxide equivalents ( ). The results indicate that utilization rates are optimized in the alternative load-bearing structure with the reduction of concrete walls. Furthermore, the results show that the deflection value in the alternative load-bearing structure increases relative to the intended, which is deemed acceptable according to the established requirements. Moreover, LCA results show that the total amount of carbon dioxide equivalents ( ) decreased by approximately 6.5% kg   per gross area in the alternative load-bearing structure. However, with the replacement of stud walls, the total amount of   increased by about 6% kg   per gross area. This resulted in the alternative load-bearing structure being a less favourable solution than the intended one, as no optimization had been achieved from a climate perspective according to the LCA calculations and   values. Since the construction industry has a significant impactful footprint on the climate, a transition to sustainable solutions is imperative. Concrete is the predominant material for load-bearing structures in multi-residential buildings and is usually used in more walls than necessary, resulting in unnecessary excess of carbon dioxide. This study aims to climate-optimize the intended load-bearing structure in a multi-residential building project by evaluating the possibility of an alternative load-bearing structure. Concrete party walls, those which are unnecessary for load-bearing purposes, are removed in the alternative load-bearing structure and replaced with stud walls that meet sound and fire requirements. The comparison is made between the alternative and intended load-bearing structures concerning structural performance and overall climate impact. To comprehend the subject, an extensive literature study was conducted. Subsequently, the load-bearing structures were modelled in FEM-design program to analyse and compare structural aspects. Using FEM-Climate, life-cycle analyses (LCAs) were performed for both load-bearing structures to assess the difference in the total amount of carbon dioxide equivalents ( ). The results indicate that utilization rates are optimized in the alternative load-bearing structure with the reduction of concrete walls. Furthermore, the results show that the deflection value in the alternative load-bearing structure increases relative to the intended, which is deemed acceptable according to the established requirements. Moreover, LCA results show that the total amount of carbon dioxide equivalents ( ) decreased by approximately 6.5% kg   per gross area in the alternative load-bearing structure. However, with the replacement of stud walls, the total amount of   increased by about 6% kg   per gross area. This resulted in the alternative load-bearing structure being a less favourable solution than the intended one, as no optimization had been achieved from a climate perspective according to the LCA calculations and   values.

In fighter jets there are many different systems that make the plane fly, and one of these is the fuel system consisting of multiple parts including tanks and tubes. During flight, the pressure in these tubes can vary and occasionally pressure spikes can occur. Pressure spikes can be described as high increased pressure at a high rate and decreased pressure at an equally high rate during a limited time span. Depending on the peak pressure and duration of this pressure spike, damage or failure might occur in the tube structure. This is a problem that SAAB is analyzing and wants to find a less conservative approach of analyzing the effect of pressure spikes regarding the structural strength of tubes. In this master’s thesis this is explored. A method for applying pressure spikes to two different tube structures has been created. The pressure spike propagates through the liquid and applies the pressure spike to the tube through Mortar contact. The tube is modelled with shell elements and normal Lagrangian element formulation. The liquid is modelled with solidelements and Arbitrary Lagrangian Eulerian element formulation. The two different tube structures analyzed in this report have the same tube dimensions, a combination of the biggest radius and smallest wall thickness that occur in SAAB’s tubes. The difference between the two is that one structure is straight whilst the other is curved. A parametric study was carried out to analyze at what pressure peak different durations of the pressure spikes would result in a critical effective plastic strain. This critical effective plastic strain was chosen to be 0.08 for the aluminum tube. This is conservative since the fracture strain for the material is 0.12. Results froma static case was compared with the dynamic results from the described method to see how conservative this new method of pressure spike analysis is. The results from the comparison showed that the dynamic method allowed 65% higher pressure peak thanthe static solution. Using a pressure spike with 1ms duration and pressure peak at 19.5MP a in the straight tube compared with the internal pressure of 11.4MP a in the static method for the straight tube. For the curved tube, the dynamic method allowed 90% higher peak pressure for a pressure spike with 1ms duration and peak pressure of 18.5MP a. This pressure spike in the curved tube is compared with the static method for the curved tube which reached critical effective plastic strain at 9.4MP a. For pressure spikes with durations of 20ms in straight tubes, the dynamic and static results are similar. For pressure spikes with durations of 10ms in curved tubes, the dynamic and static results are similar. In these cases, it is reasonable to use the quicker static method instead of the new method of pressure spike analysis. The impulses in both the straight tube and the curved tube cases have a linear relationships with the duration of the pressure spike. For the longer durations the energy needed to reach critical deformation is higher since the affected area is larger. Shorter durations need less energy to reach critical deformation since the affected area is smaller.

The construction industry in Sweden face increasing demands for sustainability and reduced greenhouse gas emissions and with the introduction of climate declarations for new projects marking a significant development. There is a rising interest in sustainable materials like cross laminated timber (CLT). Analyzing CLT-joists and their complementary materials impact on projects economically, environmentally, and structural performance can enhance decision-making in the early stages of a project. This study conducted a structural-, climate impact-, and cost analysis along with a multicriteria assessment. The structural analysis, based on Eurocodes and using the software FEM-design showed that all joist types met structural requirements, with type 3 being more versatile due to its cooperation with concrete. It also showed that type 11 with its lighter weight made it easier for installations and a possible reduced transport emission. The climate impact analysis, done through an LCA in OneClick LCA, revealed that type 3 had the highest impact mainly due to its concrete layer, while type 9 had the lowest impact. In term of costs, a cost analysis was done with the use of BidCon. The results of the cost analysis showed that type 3 is the most expensive due to its longer installation time and material costs, while type 11 was the cheapest. CLT and concrete were identified as the costliest materials. The multicriteria assessment concluded that type 11 is preferred for its affordability, sustainability, and performance efficiency. However, if solely pursuing sustainability, type 9 could be considered despite its slightly higher costs.

Uppsatsen synliggör hur matematikböcker under de senaste 50 åren erbjuder elever i åk 5–6 ett algebraiskt tänkande utifrån Kierans aktiviteter och Blantons stora algebraiska idéer. Kierans aktiviteter är en modell inom algebra där uppgifter i matematikböcker kategoriseras utifrån tre aktiviteter: skapande, transformella- och globala meta-aktiviteterna. I de skapande aktiviteterna ska elever själva skapa eller skriva ett uttryck eller ekvation. I de transformella aktiviteterna ska elever lösa en ekvation eller förenkla ett uttryck och i de globala meta-aktiviteterna ska elever möta problemlösning, generalisera och se strukturer. Aktiviteterna hjälper oss att på ett djupare plan analysera om uppgifterna erbjuder ett algebraiskt tänkande eller inte. Uppsatsen analyserar även uppgifter genom Blantons fem stora idéer för att kategorisera algebrans delar och för att de, om de framförs på ett visst sätt, erbjuder ett algebraiskt tänkande. I uppsatsen används en kvalitativ och kvantitativ innehållsanalys av läromedel. Resultatet av de analyserade läromedlen visar att de äldre läromedlen erbjuder ett algebraiskt tänkande genom generaliserande uppgifter (GA) i kombination med globala meta-aktiviteter, samtidigt som de nyare läromedlen erbjuder ett algebraiskt tänkande genom algebraiska strukturer och variabler (EEEI + VAR) i skapande aktiviteter. Tidigare forskning förespråkar generaliserad aritmetik i uppgifter för att erbjuda ett algebraiskt tänkande, vilket enligt uppsatsens resultat inte syns i hög grad. Dessutom menar forskning att algebraiskt tänkande inte måste förutsättas genom vissa uppgifter av kombinationer av stora idéer eftersom de i vissa fall kan lösas med hjälp av aritmetiska procedurer.

En kåpa till en bärplanssurfbräda konstruerades av glasfiber. Med målsättningen att skydda elektronik som möjliggör autonom drift, togs specifikation och kravspecifikation fram. Olika koncept togs fram i samarbete med kravställaren och en specifik modell valdes. En modell skapades sedan i CAD, varpå den analyserades och tjockleken optimiserades i Ansys. Tillverkningen började därefter med att en noskon skapades, som ett gränssnitt mellan kåpan och surfbrädan. Noskonen tillverkades med vakuuminfusion direkt på surfbrädan. Därefter tillverkades kåpan med vakuuminfusion på en gjutform. Gjutformen var i sin tur skapad med glasfiberkomposit genom handuppläggning på en beskuren plugg av extruderad polystyren. Total vikt uppgick till cirka 3,7 kg.

Fatigue fracture is one of the main causes of failure in engineering structures. However, its simulation still remains a challenge. To this end, an efficient phase-field model for fatigue fracture is introduced. The phase-field method regularizes the crack description and allows for a straight-forward simulation of crack initiation and arbitrary crack patterns. The effects of fatigue are included in the model via the Local Strain Approach. This concept introduces assumptions on the cyclic stress-strain behavior and the fatigue resistance of the material, making use of experimental cyclic material data. In this way, the phase-field model can remain elastic, while the introduced fatigue damage still includes cyclic plasticity in a simplified way. Therefore, the model reduces computational time significantly compared to other phase-field fatigue models, also, because it can cover several load cycles in just one computation increment. The model is parametrized and validated for aluminum sheet material and proves to be able to reproduce the typical fatigue crack growth behavior of this material. Details on the implementation are provided. The model is presented in a general framework for phase-field models for fatigue fracture, which is also used for a comprehensive overview and classification of existing models in the literature. The model is extended to deal with residual stresses in the material, which exert great influence on the fatigue crack growth behavior, as experiments and simulations show consistently. Also, anisotropic material properties are included through yet another model extension. Particularly, the direction-dependent fracture toughness of rolled aluminum sheets is considered. Simulations reproduce characteristic crack paths caused by this anisotropy. Finally, the model's assumptions regarding cyclic plastic material behavior are put to a test. To this end, a phase-field fatigue ansatz with elastic-plastic material model of Armstrong-Frederick type is implemented. It serves as a reference to define the range of application of the efficient, yet simplified fatigue model presented in this thesis.

<p>Detta examensarbete har utförts på Fläktwoods AB i Växjö, som producerar stora axialfläktar för olika industriapplikationer. Syftet är att öka kunskapen om fettsmorda axiella kullager genom FE analyser.</p><p>Projektet har genomförts i fem delsteg för att avgöra påverkan av en eller några få parametrar i taget. De studerade parametrarna är: elementstorlek, kontaktstyvhet, last, lagergeometri (dvs. oskulation), ickelinjär geometri och ickelinjära materialegenskaper (dvs. plasticitet).</p><p>Slutsatsen är att elementstorleken bör väljas fint nog för att ge ett jämnt resultat men grovt nog för att beräkningstiden skal vara rimlig. Kontaktstyvheten har inte stor, men tydlig, inverkan på kontakttrycket och penetrationen. Förändringar av oskulationen leder till förändringar i kontaktellipsens form medan olika laster inte påverkar formen på ellipsen, utan snarare storleken. När det handlar om plasticitet är sträckgränsen den viktigaste faktorn att beakta.</p> / <p>This thesis project was carried out at Fläktwoods AB in Växjö who produces large axial fans for different industry applications. The purpose is to increase the knowledge of grease lubricated axial ball bearings through FE analyses.</p><p>The project was executed into five sub steps to determine the influence of one or few parameters at a time. The studied parameters are: mesh density, contact stiffness, load, bearing geometry (i.e. osculation), geometrical nonlinearity and material nonlinearity (i.e. plasticity).</p><p>It is concluded that the mesh density should be selected fine enough to give a smooth result but course enough to give a reasonable calculation time. The contact stiffness has not a major, but a clear, impact on the contact pressure and penetration. Changes of the osculation lead to changes of the contact ellipse shape and applying different load level does not affect the shape of the ellipse but rather the size. When dealing with plasticity the yield strength is the most important factor to take in consideration.</p>