Composite sandwich structures are being used in the automotive and aerospace industries at an increasing rate due to their high strength and stiffness per unit weight.  Many teams in the world’s largest engineering competition for students, Formula Student, have embraced these types of structures and are using them in their chassis with the intent of increasing the torsional stiffness per unit weight.   The Formula Student team at Karlstad University, Clear River Racing, has since 2017 successfully built three carbon fiber based sandwich structure chassis. A big challenge when designing this type of chassis is the lack of strategy regarding torsional stiffness simulations. Thus, the goal of this thesis project was to provide the organization with a set of accurate yet relatively simple methods of modelling and simulating the torsional stiffness of the chassis.   The first step in achieving the goal of the thesis was the implementation of simplifications to the material model. These simplifications were mainly targeted towards the aluminum honeycomb core. In order to cut computational times and reduce complexity, a continuum model with orthotropic material properties was used instead of the intricate cellular structure of the core. To validate the accuracy of this simplification, the in-plane elastic modulus of the core was simulated in the finite element software Abaqus. The stiffness obtained through simulations was 0.44 % larger than the theoretical value. The conclusion was therefore made that the orthotropic continuum model was an accurate and effective representation of the core.   Furthermore, simplifications regarding the adhesive film in the core-carbon fiber interfaces were made by using constraints in Abaqus instead of modelling the adhesive films as individual parts. To validate this simplification and the overall material model for the sandwich structure, a three-point bend test was simulated in Abaqus and conducted physically. The stiffness for the sandwich panel obtained through physical testing was 2.4 % larger than the simulated stiffness. The conclusion was made that the simplifications in the material modelling did not affect the accuracy in a significant way.   Finally, the torsional stiffness of the 2020 CFRP chassis was found to be 12409.75 Nm/degree.   In addition to evaluating previously mentioned simplifications, this thesis also serves as a comprehensive guide on how the modelling of the chassis and how the three-point bend test can take place in regards to boundary conditions, coordinate system assignments and layup definitions.

Abstract Title: Case study: Lean in Outnorth's outbound process Researchers: Jana Gustafsson, Alison Karlsson & Ellen Wiss Gullberg Examinator: Helena Forslund Supervisor: Fredrik Lindblad   Background: At the company Outnorth the outbound process, picking and packing to customer, is of great importance. Working with Lean, meaning the strive to eliminate waste, has begun in their outbound process and the researchers had the possibility to complement Outbound's ongoing work. Through mapping a flowchart of the current process different kinds of waste were identified. Then recommendations of which Lean tools to implement were made in order to reduce the wastes in the outbound process.   Purpose: The study's purpose is to, through a status report of the outbound process at Outnorth, identify logistic improvement possibilities and to suggest solutions through the Lean perspective.   Research questions: (1) What does the current outbound process at Outnorth look like? (2) What wastes are identified in the outbound process at Outnorth according to Lean? (3) How can the improvement possibilities in the outbound process at Outnorth be implemented through the use of Lean?   Method: Through interviews, the outbound process was mapped out in a process flowchart. Through further interviews and surveys, different forms of waste according to Lean could be identified in the outbound process. Finally, theory about Lean was used in order to show how the different kinds of waste can be handled.   Conclusion:There are forms of waste according to Lean in Outnorth's outbound process and many of these can be eliminated through the use of Lean tools.   Keywords: Lean, Lean tools, 5S, five why, process, process flowchart and outbound.

Studiens syfte är att beskriva hur lärare i grundskolan F-3 arbetar med de fem förmågorna som grundar sig i kursplanen för matematik i sin matematikundervisning för att stödja elevers lärande. Studien har genomförts med en kvalitativ metod i form av enskilda semistrukturerade intervjuer med sex behöriga och verksamma lärare i grundskolan F-3. Insamlade data har transkriberats och sorterats i fem kategorier som är kopplade till forskningsfrågorna. Därefter analyserades data utifrån studiens teoretiska perspektiv, som är det didaktiska kontraktet och beliefs. Det framkommer i resultatet att lärare har skilda uppfattningar och visar osäkerhet över de fem förmågorna i kursplanen för matematik. Läromedlen dominerar lärares planering och undervisning i matematik. Vidare framkom att bedömningen är övervägande summativ utifrån färdiga diagnoser och lärarna tar inte alltid hänsyn till alla fem förmågor. Studiens slutsats är att lärarna har goda kunskaper och uppfattningar om vad matematik är och hur elever lär sig matematik, men trots det har lärarna svårt att omsätta det i matematikundervisningen för att stödja alla elevers lärande. / The aim of this study is to describe how teachers in primary class up to grade 3 works with the five competencies that the curricula in mathematics are based on, to support pupils' learning. The study was conducted with individual qualitative semi-structured interviews with six primary school teachers. The collected data has been transcribed and sorted into five categories linked to the research questions. The data were then analyzed from the theoretical perspective of the study, which is the didactic contract and beliefs. The result shows that teachers have different views and show uncertainty about the five competencies in the mathematics curricula. Textbooks dominate teachers' planning and teaching in mathematics. Furthermore, it was found that the assessment is mostly summative, based on completed diagnoses where the teachers don’t always consider all five competencies. The conclusion of this study is that teachers have good knowledge and perceptions of what mathematics is and how students learn mathematics, but despite this, teachers find it difficult to convert it into mathematics education to support all pupils' learning.

In this thesis by articles, I propose and demonstrate the full design, fabrication and characterization of optical biosensors based on (Bloch) Long Range Surface Plasmon Polaritons (LRSPPs). Gold waveguides embedded in CYTOP with an etched microfluidic channel supporting LRSPPs and gold waveguides on a one-dimensional photonic crystal (1DPC) supporting Bloch LRSPPs are exploited for biosensing applications. Straight gold waveguides embedded in CYTOP supporting LRSPPs as a biosensor, are initially used to measure the kinetics constants of protein-protein interactions. The kinetics constants are extracted from binding curves using the integrated rate equation. Linear and non-linear least squares analysis are employed to obtain the kinetics constants and the results are compared. The device is also used to demonstrate enhanced assay formats (sandwich and inhibition assays) and protein concentrations as low as 10 pg/ml in solution are detected with a signal-to-noise ratio of 20 using this new optical biosensor technology. CYTOP which has a refractive index close to water is the fluoropolymer of choice in current state of the art waveguide biosensors. CYTOP has a low glass transition temperature which introduces limitations in fabrication processes. A truncated 1D photonic crystal can replace a low-index polymer cladding such as CYTOP, to support Bloch LRSPPs within the bandgap of the 1DPC over a limited ranges of wavenumber and wavelength. Motivated by quality issues with end facets, we seek to use grating couplers in a broadside coupling scheme where a laser beam emerging from an optical fiber excites Bloch LRSPPs on a Au stripe on a truncated 1D photonic crystal. Adiabatic and non-adiabatic flared stripes accommodating wide gratings size-matched to an incident Gaussian beam are designed and compared to maximise the coupling efficiency to LRSPPs. The gratings are optimized, initially, through 2D modelling using the vectorial finite element method (FEM). Different 3D grating designs were then investigated via 3D modelling using the vectorial finite difference time domain (FDTD) method. Given their compatibility with planar technologies, gratings and waveguides can be integrated into arrays of biosensors enabling multi-channel biosensing. A multi-channel platform can provide, e.g., additional measurements to improve the reliability in a disease detection problem. Thus, a novel optical biosensor based on Bloch LRSPPs on waveguide arrays integrated with electrochemical biosensors is presented. The structures were fabricated on truncated 1D photonic crystals comprised of 15 period stack of alternating layers of SiO2/Ta2O5. The optical biosensors consist of Au stripes supporting Bloch LRSPPs and integrate grating couplers as input/output means. The Au stripes also operate as a working electrode in conjunction with a neighboring Pt counter electrode to form an electrochemical sensor. The structures were fabricated using bilayer lift-off photolithography and the gratings were fabricated using overlaid e-beam lithography. The planar waveguides are integrated into arrays capable of multichannel biosensing. The wafer is covered with CYTOP as the upper cladding with etched microfluidic channels, and wafer-bonded to a borofloat silica wafer to seal the fluidic channels and enable side fluidic interfaces. The proposed device is capable in principle of simultaneous optical and electrochemical sensing and could be used to address disease detection problems using a multimodal strategy.

The continuous growth in road transportation demand requires the development towards sustainable strategies. The concept of Smart Roads is arising as a convergence of technologies that will lead the mobility by road into a more efficient and interactive system between infrastructure, environment and vehicles. Within this context, e-mobility appears as one of the key components. The implementation of e-mobility based on Electric Vehicles (EVs) has been restricted by numerous shortcomings such as their driving range, the battery size, the dependence on charging stations and the time required for its charging. However, the electrification of the road infrastructure, which will enable a dynamic charging of the EVs while driving, is becoming a potential solution to overcome these deficiencies. This study aims to contribute for the future introduction of electrified roads (eRoads) into the current network, by focusing on the effects and consequences of embedding Inductive Power Transfer (IPT) systems in the road infrastructure. A structural design of an eRoad is conducted through a Finite Elements Analysis (FEA) by analysing the behaviour of a pavement structure based on Swedish conditions subjected to traffic loading. Valuable conclusions can be displayed from this analysis and thus, a summary concerning considerations and effects over the design, construction and maintenance of eRoads can be built. Nevertheless, this analysis must be complemented and coordinated from a lifetime perspective to reach the social, environmental and economic requirements related to the development of road infrastructure nowadays. Hence, a guideline from a life cycle approach is stated over the integration of eRoads in order to enable the assessment of the infrastructure during its different phases. To be sustainable, the development of road infrastructure must reach not just structural and appropriate performance requirements, but also preserve the environmental and economic impact. This thesis pretends to combine all these aspects as a state of the art, providing a basis that stands out the most relevant issues related to the feasible implementation of eRoads in the mid-long term.

The present study utilizes finite element analysis in order to simulate a surgical operation in the treatment of a hallux rigidus case, as designed and developed by Episurf Medical AB (Stockholm, Sweden). The surgical intervention includes an initial cheilectomy as well as an insertion of an orthopedic implant. The goal of the study was to evaluate the current concept of the medical intervention as it is manifested today, as well as to give design suggestions as how to further improve the pre-planning of the surgery. MRI-images of the first metatarsophalangeal joint in the hallux was collected from a patient suffering from hallux rigidus, and used in order to build case-specific geometrical images to be used in the FE analysis. The simulation was setup as to simulate a normal motion in the first metatarsophalangeal joint during a normal gait pattern. The first simulation was conducted without any intervention, while the second was conducted after a pre-determined operation plan in accordance with the surgical operation that Episurf Medical AB wants to perform. The results was then compared and analyzed in order to determine the post-surgical effects that such an operation could have on the patient. A third and final simulation was then performed, by using optimization algorithms in order to make suggestions to the pre-planned cheilectomy shape, as well as orientation of the implant. Two parameters were being investigated in order to assess the surgical intervention as designed by Episurf Medical AB; the contact stress on the articular side of the metatarsal head, and the strain on the implant shaft. The current manifestation of the cheilectomy did not reduce the contact stress compared to the untreated condition, as the implant failed to be a load baring surface due to the two dimensional nature of which it is conceived. Instead, the contact surface area is reduced and positioned medial and lateral to the implant head. The optimization algorithm could reduce the maximum contact stress significantly, from 295MPa and 400MPa in the treated and untreated conditons respectively, to 160MPa after the optimization algorithm. It became clear that the angle of the cheilectomy as well as the orientation of the implant angle has an incriminating effect on the post-operative results. However, the shape of the cheilectomy as well as the design of the implant would need to be revised in future embodiments, as the current concept failed to provide joint with a new articulating surface. Further development of the models formulated in this thesis is advised, as well as validating the findings with clinical data. / Den aktuella studien använder finita elementmetoden i syfte att simulera en kirurgisk operation som har utvecklats av Episurf Medical AB (Stockholm, Sverige) för att behandla ett hallux rigidus fall. Det kirurgiska ingreppet utgörs av en inledande cheilectomi,  som sedan följs av att operera in ett ortopediskt implantat. Målet med studien var att utvärdera det nuvarande konceptet för det medicinska ingrepp så som den är uttänkt idag, samt att ge designförslag för hur man ytterligare kan förbättra planeringen av operationen. MR-bilder av den första metatarsalleden i stortån samlades in från en patient som lider av hallux rigidus, som användes sedan för att bygga patient specifika geometriska bilder för att användas i FE-analysen. Simuleringen var modellerad för att simulera en normal rörelse i första metatarsofalangealleden under en normal gångcykel. Den första simuleringen genomfördes utan något ingripande, medan den andra genomfördes efter en förutbestämd operationsplan i enlighet med det kirurgiska ingreppet som Episurf Medical AB vill utföra. Resultaten jämfördes sedan och analyserades för att bestämma de resultaten som en sådan operation skulle kunna innebära för patienten postoperativt. En tredje och sista simulering utfördes sedan, med hjälp av optimeringsalgoritmer för att ge förslag på förbättringar för den förplanerade cheilectomin, samt orienteringen av implantatet. Två parametrar undersöktes för att bedöma det kirurgiska ingrepp som designats av Episurf Medical AB, kontaktbelastningen på artikulära sidan av metatarsalhuvudet, och påfrestningen på implantatet. Den nuvarande utformningen av cheilectomin minskade inte kontaktbelastningen jämfört med det obehandlade tillståndet, då implantatet inte vart belastat på grund av den tvådimensionella profilen i dess utformning. Optimeringsalgoritmen kunde minska den maximala kontaktbelastningen markant, från 295MPa i den behandlade och 400MPa i den obehandlade simuleringarna, till 160MPa efter optimeringsalgoritmen. Det blev tydligt att vinkeln på cheilectomin samt orienteringen av implantatet har en avgörande betydelse för det postoperativa resultatet. Dock skulle formen på cheilectomin liksom designen av implantatet behöva revideras i framtida utformningar, då det nuvarande konceptet inte lyckades att ge leden en ny ledyta. Vidareutveckling av de modeller som utvecklats i avhandlingen rekommenderas, samt att validera resultaten med annan kliniska data.

The Swedish model for final disposal of nuclear fuel waste is based on copper canisters as a corrosion barrier with an inner pressure holding insert of cast iron. One of the methods to seal the copper canister is to use the Friction Stir Welding (FSW), a method invented by The Welding Institute (TWI). This work has been focused on characterisation of the FSW joints, and modelling of the process, both analytically and numerically. The first simulations were based on Rosenthal’s analytical medium plate model. The model is simple to use, but has limitations. Finite element models were developed, initially with a two-dimensional geometry. Due to the requirements of describing both the heat flow and the tool movement, three-dimensional models were developed. These models take into account heat transfer, material flow, and continuum mechanics. The geometries of the models are based on the simulation experiments carried out at TWI and at Swedish Nuclear Fuel Waste and Management Co (SKB). Temperature distribution, material flow and their effects on the thermal expansion were predicted for a full-scale canister and lid. The steady state solutions have been compared with temperature measurements, showing good agreement. Microstructure and hardness profiles have been investigated by optical microscope, Scanning Electron Microscope (SEM), Electron Back Scatter Diffraction (EBSD) and Rockwell hardness measurements. EBSD visualisation has been used to determine the grain size distribution and the appearance of twins and misorientation within grains. The orientation maps show a fine uniform equiaxed grain structure. The root of the weld exhibits the smallest grains and many annealing twins. This may be due to deformation after recrystallisation. The appearance of the nugget and the grain size depends on the position of the weld. A large difference can be seen both in hardness and grain size between the start of the weld and when the steady state is reached. / QC 20101207

Preservation and protection of the head segment is of upmost importance due to the criticality of the functions entailed in this section of the body by the brain and the nervous system. Numerous events in daily life situations such as transportation and sports pose threats of injuries that may end or change a person’s life. In the European Union, statistics report that almost 4.2 million of road users are injured non-fatally, out of which 18% is represented by motorcyclist and 40% by cyclists, being head injuries 34% for bicyclists, and 24% for two-wheeled motor vehicles. Not only vehicles, are a source of injuries for the human head according to the injury report, 6,1 million people are admitted in hospitals for sports related injuries, where sports such as hockey, swimming, cycling presented head injuries up to 28%, 25% and 16% respectively (European Association for Injury Prevention and Safety Promotion, 2013).  According to records the vast majority of head crashes result in an oblique impact (Thibault & Gennarelli, 1985). These types of impacts are characterized for involving a rotation of the head segment which is correlated with serious head injuries. Even though there is plenty of evidence suggesting the involvement of rotational forces current helmet development standards and regulations fail to recognize their importance and account only for translational impact tests. This thesis contains an evaluation for a different developed method for testing oblique impacts. In consequence a new test rig was constructed with basis on a guided free fall of a helmeted dummy head striking an oblique (angled) anvil which will induce rotation. The results obtained are intended to be subjected to a comparison with another oblique test rig that performs experiments utilizing a movable sliding plate which when impacted induces the rotation of a dropped helmeted dummy head. The outcome will solidify the presence of rotational forces at head-anvil impact and offer an alternative testing method. After setting up the new test rig; experiments were conducted utilizing bicycle helmets varying the velocities before impact from 5m/s to 6m/s crashing an angled anvil of 45°. Results showed higher peak resultant values for rotational accelerations and rotational velocities in the new test rig compared to the movable plate impact test, indicating that depending on the impact situation the “Normal Force” has a direct effect on the rotational components. On the other hand a performed finite element analysis predicted that the best correlation between both methods is when the new angled anvil impact test is submitted to crashes with a velocity before impact of 6 m/s at 45° and the movable sliding impact test to a resultant velocity vector of 7,6m/s with an angle of 30° . In conclusion the new test method is meant to provide a comparison between two different test rigs that will undoubtedly have a part in the analysis for helmet and head safety improvements.

Osteochondral lesions of the talus (OLTs) are the third most common type of osteochondral lesion and can cause pain and instability of the ankle joint. Episurf Medical AB is a medical technology company that develops individualized implants for patients who are suffering from focal cartilage lesions. Episurf have recently started a project that aims to implement their implantation technique in the treatment of OLTs. This master thesis was a part of Episurf’s talus project and the main goal of the thesis was to find the optimal implantation angle of the Episurf implant when treating OLTs. The optimal implantation angle was defined as the angle that minimized the maximum equivalent (von Mises) strain acting on the implant shaft during the stance phase of a normal gait cycle. It is desirable to minimize the strain acting on the implant shaft, since a reduction of the strain can improve the longevity of the implant. To find the optimal implantation angle a finite element model of an ankle joint treated with the Episurf implant was developed. In the model an implant with a diameter of 12 millimeters was placed in the middle part of the medial side of the talar dome. An optimization algorithm was designed to find the implantation angle, which minimized the maximum equivalent strain acting on the implant shaft. The optimal implantation angle was found to be a sagittal angle of 12.5 degrees and a coronal angle of 0 degrees. Both the magnitude and the direction of the force applied to the ankle joint in the simulated stance phase seemed to influence the maximum equivalent strain acting on the implant shaft. A number of simplifications have been done in the simulation of this project, which might affect the accuracy of the results. Therefore it is recommended that further, more detailed, simulations based on this project are performed in order to improve the result accuracy. / Fokala broskskador på talusbenet är den tredje vanligaste typen av fokala broskskador och kan ge upphov till smärta och instabilitet av fotleden. Episurf Medical AB är ett medicintekniskt företag som utvecklar individanpassade implantat för patienter med fokala broskskador. Episurf har nyligen påbörjat ett projekt där deras teknik ska användas i behandlingen av fokala broskskador på talusbenet. Den här masteruppsatsen var en del i Episurfs talusprojekt och dess huvudmål var att finna den optimala implantationsvinkeln av Episurfs implantat i behandlingen av fokala broskskador på talusbenet. Den optimala implanteringsvinkeln definierades som den vinkel som minimerade den effektiva von Mises-töjningen som verkade på implantatskaftet under stance-fasen i en normal gångcykel. Det är eftersträvansvärt att minimera belastningen på implantatskaftet eftersom en reducering av belastningen kan förbättra implantatets livslängd. En finita element-modell av en fotled behandlad med Episurfs implantat utvecklades för att för att finna den optimala implantationsvinkeln. I modellen placerades ett implantat med en diameter på 12 millimeter på mittendelen av talus mediala sida. En optimeringsalgoritm utformades för att finna implantationsvinkeln som minimerade den effektiva von Mises-töjningen på implantatskaftet. Den funna optimala implantationsvinkeln bestod av en vinkel på 12.5 grader i sagittalplan och en vinkel på 0 grader i koronalplan. Både storleken och riktningen på kraften som applicerats på fotleden under den simulerade stance-fasen av gångcykeln verkade påverka belastningen på implantatskaftet. Ett antal förenklingar har gjorts i projektets simuleringar, vilket kan påverka noggrannheten i resultatet. Därför rekommenderas att ytterligare, mer detaljerade simuleringar baserade på det här projektet görs för att förbättra resultatets noggrannhet.

Functionally graded materials (FGMs) are advanced materials and their main characteristic is microstructure and composition variation over the volume of the specimen. This variation of the composition results in changing of material properties in the component. In FGMs usually there are two different types of powder materials such as metal and ceramic powders which are mixed to build up the graded region. These grade layers are placed between the metal and ceramic layers and by this approach a smooth and gradual transient from metal to ceramic can be achieved.Sintering is the main technique to manufacture these types of materials. During the sintering process, cooling of the specimen from sintering temperature to room temperature results in generation of thermal residual stresses within the material. These thermal stresses may cause crack propagation and failure of the material.Distribution analysis of these thermally induced stresses within the material has been carried out in this thesis work. Finite element package ABAQUS has been used in order to simulate the distribution of the thermal residual stresses in the materials. In order to achieve the optimal design for different geometries the parametric study also has been performed. For example influence of number of layers, mixing ratio and porosity has been investigated.Based on the finite element results for cylindrical and cuboid models, non-linear composition variation for both geometries has no improving effect in terms of induced thermal residual stresses. Porous material shows less thermal stress than non-porous material. As the amount of porosity for individual layer was considered in simulation process, this approach resulted in decreasing of thermal stresses within the material. Moreover, non-uniform thickness of graded layers was not beneficial for stress reduction. This variation of thickness results in increasing of thermal residual stresses within the material.