Denne masteroppgaven bygger videre på samme problemstilling som i fordypningsprosjektet (TMM 4501)”Analyse av Al-ekstrudering for å forhindre rekrystallisasjon”,høsten 2011.Oppgaven er gjennomført i samarbeid med Benteler Aluminum Systems Norway AS på Raufoss. Problemstillingen handler om uønsket grovrekrystallisering i aksesymmetrisk Al-ekstrudering ved senere prosessering. Det er gjennomgått teori som tar for seg opphavet til forskjellige rekrystalliseringsfenomerer under varmdeformasjon av Al-legeringer. Teorien tar for seg fysiske og empiriske rekrystallisasjonsmodeller. Fysiske modeller er baset på kornvekst, dannelser av subkorn og korngrenseorienteringer. Empiriske modeller inkluderer parametere som temperaturer, tøyninger, tøyningshastigheter og ulike konstanter. I tillegg belyser teorien ulike ekstruderingsforsøk og datasimuleringer av ulike varmformingsprosesser. Litteraturen har opphav fra ulike forskningsmiljøer. Fra besøk hos Bentlers industrilokaler på Raufoss ble det tatt med ekstruderte Al-prøver av aksesymmetrisk stangprofil tilbake til NTNU. På Verkstedtekniske laboratorier ble det kappet tre diskprøver fra den samme aluminiumen. Deretter ble diskene slipt, varmebehandlet og etset for å spore opp grovrekrystallisering i det ytre sjiktet av profilen.En simuleringsmodell fra fordypningsprosjektet har i denne oppgaven blitt forandret og tilpasset Bentelers største ekstruderingspresse P40. To stangprofiler med 80 og 43 mm i diameter ble simulert i Deform 2D.I Deform 3D ble det forsøkt simulert en kompleks modell av to paralelle hulprofiler som brukes i bilkonstruksjoner. Fra simuleringsmodellene er det vist bilder med tilhørende forklaringer.Resultater fra undersøkelsen av teori, skiveprøver og simuleringer er oppsummert og diskutert i eget kappittel.Rapporten er skrevet i Microsoft Word og datasimuleringer er gjennomført i Deform 2D og Deform 3D (versjon 10.2 og 11.0).

The purpose of this study was to explore the posibilities and challenges with simulating fatigue crack growth (FCG) by the extended finite element method (XFEM). Another aim was to develope a procedure for XFEM FCG simulations in Abaqus by means of scripting. Finally was the procedure used to simulate FCG in an API standard, cone shaped threaded connection. Different FCG models were reviewed by a limited litterature search and a procedure 2D FCG simulations was carried out by a python script. The procedure succeeded with the simulation of FCG when applied to a model with refined mesh around the crack tip. In the suggested partial tasks of the thesis description were a procedure 3D FCG simulation also suggested, but as this required more computer capacity than available in the study this was not carried out.

The goal of this Thesis is to verify a winning solution for the DNV Fuel Fighter 2, the verification of the design and development will be achieved by a series of verification, validation and testing activities.The Literature review of the report represents the VVT activities during the entire life cycle. The Theory and Methods used in the Thesis are based on A. Engel’s “Verification, Validation and Testing activities of Engineered Systems”. The author has customized those VVT activities so they fit the time and resource constrains of the case of study.The case is the NTNU’s fifth entrance to the Shell Eco Marathon competition, The DNV Fuel Fighter 2. The actual repot is a reflection of the first time in SEM’s project where an entire Thesis reflects the VVT activities in order to qualify the vehicle.This Master Thesis follows the work that was done in the specialization project 2011 fall in the NTNU. The fall report was focused on the trade-off and requirement analysis and in the definition a high level architecture that could be use in the project. The project work was used as a foundation for the work that was done afterwards in this Master Thesis. The work done during the year is based on the systems engineering effort made from the previous year. The author along with the other system engineer of the project has upgraded the SE effort.The main contribution of the Thesis has been the development of the VVT activities and to prove that they are useful for projects with time and resource constrains. The suggested future work consists of continuing with the use of the VVT strategy performed this year and to upgrade it until the Acceptance stage; where the final user will be the responsible of performing the tests.

This thesis is a practical application of Systems Engineering in a full-scale project. The author has participated as a member of NTNU's Eco-marathon team, who has spent the last two semesters designing and manufacturing an energy-efficient car for the Shell Eco-marathon competition 2012. The author made an assessment of the project to find the areas where he should focus his effort. The author also applied Lean Thinking to find the Systems Engineering methods that would best aid the team improve within the areas uncovered in the assessment. The areas where the team needed improvement were Knowledge management and Continuous improvements of the product development process. By using Model-based Systems Engineering processes the author produced a system model acting as a knowledge repository. Then, the author used methods from Lean Thinking for knowledge capture, namely Knowledge Briefs and learning events.For improving the product development process, the author introduced the team to Visual Workflow Management to help the team become more agile, and to visualize project progress from multiple perspectives in order to discover parts of the system which is not evolving at the desired rate.Key concepts in this thesis include:Lean Thinking, Lean Systems Engineering, Model-based Systems Engineering, Model-based Documentation, Knowledge management, Knowledge briefs, A3 method, system modelling, functional analysis, functional flow block diagrams (FFBDs), system architecture, Visual Workflow Management, Stand-up meetings, Visual project board, risk management

The main goal for this thesis has been to perform fatigue life predictions on large components.Dierent methods were to be chosen and reviwed critically. Experimental datafor girth welded pipes was assessed by means of a version of BS7910 which were modeledfrom scratch. This version was veried with results from CrackWise, and used to predictthe fatigue life for loade cases matching the selected experimental data. The fatigue assessmenttool P-FAT was used to predict the fatigue life for the same experimental data,and the results were compared. Except for some deviations recorded for embedded cracks,a generally good agreement was found between the two tools.Both the modeled BS7910 and P-FAT predicted conservative but accurate fatigue livesfor the experimental data that had signicant defects. They predicted non conservativeresults for specimens that did not have signicant defects, when the initial crack depthwas set to 0.1 mm. When the initial crack depth was set to 0.5 mm the modeled versionpredicted fatigue lives in agreement with the experimental results.Fatigue life predictions were also performed by assistance of S-N curves provided by DNVRP-C203.The results from these predictions were in agreement with the experimentaldata, except for four specimens. These four specimens had signicant aws, which reducedthe fatigue life signicantly.A review of a two-phase fatigue assessment model was made. This model uses a strainedbased approach to assess the fatigue crack initiation phase, and the fracture mechanicapproach suggested in the BS7910 to assess fatigue crack growth. This method haveshown promising results for fatigue assessment of llet welds in the literature, but themodel needs further investigation and calibration to be used to predict fatigue life ofgirth welded structures. A specic area to investigate is the proposed transition depth of0.1 mm. This depth is dubious based on the results

This paper is a master thesis written at NTNU for the Co-Patch project. The Co-Patch project is an EU-funded consortium of 15 organizations from 8 different countries, developing a standard for composite patch repair of steel structures in fire hazard areas. The standard includes methods for dimensioning against delamination. This thesis looks at the fatigue properties in delamination of patches from their substrates. By testing Double Cantilever Beam and End-Notched Flexure specimens in fatigue loading, G-N curves were made for Mode I and Mode II fatigue fracture. This gives an indication of the lifetime of a patch given a specific cyclic load condition and a pre-existing crack. The longest cycle life recorded was 4.35E5 cycles at 104 J/m2 for Mode I and 1.23E5 cycles at 122 J/m2 for Mode II.Furthermore, a relation for crack propagation rate and energy release rate in Mode I was found for low cycle life estimation. From this relation, the crack front position may be estimated for a given set of cycles through calculations using Paris’ law. Based on the quasi-static data of a previous report, and the fatigue data found in this thesis, a numerical simulation procedure for crack propagation was proposed. Using direct cyclic fatigue analysis and Virtual Crack Closure Technique based on linear elastic fracture modelling, the crack propagation may be estimated for patches exposed to combined conditions, such as plane strain/plane stress and different fracture modes, as well as on advanced geometries. The procedure was validated as a viable simulation, but more work needs to be done on the model for accurate estimates. 

In this project the main goal was to establish a routine for making a microfluidic flow cell (MFFC) using soft lithography methods, and test the flow cell with different electrolytes, sulphuric acid and a ruthenium red-ox couple, and eventually use the established routine to make a microfluidic fuel cell and test it. A routine was established using the negative photoresist ma-N405. The photoresist was overdeveloped to make sure an undercut profile was reached, which proved to be necessary for the subsequent metal lift-off. Titanium (10 nm) and platinum (25 nm) were vapor deposited on the glass chips, and the lift-off process was completed in a couple of days. Flow channels of two different heights (about 15 and 100 µm) were made by making an impression in PDMS. A low flow channel, height of 15 µm, showed a significant electrolyte resistance in the experimental electrochemical work, and none of the experiments gave the expected results. The electrolyte resistance was measured by electrochemical impedance spectroscopy and taken to be the value corresponding to the high frequency intersection of the real axis. In addition, this resistance was estimated from cyclic voltammetry and taken to be the reciprocal of the slope of the curve, and was found to vary between 104-107 Ω. The results from EIS and CV were compared, and they overlapped quite well. An MFFC with a channel height of 100 µm and 500 µm electrodes, resulted in a significant decrease in measured electrolyte resistance and gave improved electrochemical results. The electrolyte resistance was measured from EIS and was reduced a lot to about 300 - 10000 Ω. These results were not compared with linear regression of the linear hydrogen area since the hydrogen area was no longer linear. The cell was tested with a ruthenium red-ox couple (hexaammineruthenium(II)chloride and hexaammineruthenium(III)chloride), and an external hydrogen reference electrode placed in the outlet was found to be simpler to control than an internal reference electrode. The potential limits were -0.3 and 0.3 V vs. an external hydrogen electrode in the same electrolyte. The effect of flow rate, sweep rate and oxygen content in the electrolyte was investigated.

An experimental study of Carbon Nanotube (CNT) growth has been performed by using radio frequency plasma enhanced chemical vapour deposition with methane (CH4) as the hydrocarbon source. The experimental results have been compared towards earlier experiments and theories that exist. A study of the effect by changing parameters during thermal- and plasma- pretreatment has been conducted which have led to successful yield of vertically aligned CNTs forests. Different growth conditions have been conducted in order to see the influence of the following: Methane (CH4) flow, plasma power, growth time, temperature, methane (CH4)/ammonia (NH3) mixtures during growth, no barrier layer, thermal- versus plasma-pretreatment and oxidizing pretreatment. The conclusion from this experiment is that oxidizing pretreatment seems yields the tallest vertically aligned CNTs with the narrowest diameter.

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A procedure for texturing of lead-free piezoelectric ceramics based on sodium potassium niobate (KNN) was investigated with respect to texturing procedure and choice of materials.Material compositions that were considered include KNN with and without addition of 0.5 mol% MnO, and KNN modified with Li and Ta (KNNLT), and Mn substituted into the A or B site of the perovskite structure. The two compositions KNN-Mn and KNNLT-Mn(A) compositions were further investigated as candidate materials for texturing.Textured samples of the two materials were made by tape casting and templated grain growth, using needle-shaped KNN particles as templates, while non-textured reference samples were made by conventional sintering of powders. Both textured and non-textured dense materials were characterized with respect to density, degree of texture and piezoelectric and dielectric properties. The non-textured materials sintered to high relative densities of 93.9 % for KNN-Mn and 96.7 % for KNNLT-Mn(A). A converse piezoelectric coefficient of over 250 pm/V was measured for non-textured KNNLT-Mn(A), and around 200 pm/V for KNN-Mn.Texturing led to a lower relative density of both compositions, 89.1 % for KNN-Mn and 92.1 % for KNNLT-Mn(A). The piezoelectric performance of KNN-Mn was not significantly affected by the texturing procedure, while the piezoelectric performance of KNNLT-Mn(A) became significantly poorer. This is due to the formation of a secondary phase in KNNLT-Mn(A) during sintering, which is probably caused by the compositional mismatch between the templates and the fine-grained matrix powder.Based on the results, and a theoretical consideration of the texturing procedure, a different choice of template particles is suggested for further work on texturing of KNN-based materials.