Fraunhofer Chalmers Research Centre for Industrial Mathematics
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FEM the Wood Revolution In-depth FE-analysis of a wood-glue-steel joint in a wind turbine tower
No full textModvion is a company that develop 150m tall wind turbine towers made out of modules of Engineered Wood Products (EWP), specifically Laminated Veneer Lumber (LVL). One
of the big challenges in their design is the joining of the modules, which is the focus of this thesis. The joint design was given from the beginning along with physical test data from tensile tests performed at Research Institutes of Sweden (RISE). In this thesis a Finite
Element (FE)-model of the joint was created, with the aim to replicate the response obtained from the physical tensile tests using simulations. The main goal was to use the FE-model in order to describe the inner mechanics of the joint. The joining of two LVL panels is made with Loctite CR 421 Purbond and a perforated steel plate. The joint and its materials are studied using physical testing and the commercial softwares ANSA as pre-processor, Abaqus Unified FEA as solver, and META as postprocessor. The material parameters for the wood given by data sheets provided by the manufacturer are compared to physical test data. Remaining material parameters and
simulation parameters are calibrated through material validation and parameter studies. Finally a small study was performed on whether the joint can be improved by making modifications to the perforated steel plate. The effects of these modifications were studied in order to find the critical areas of the joint.
The obtained results show that the number of holes in the steel plate are critical for the performance of the joint when it comes to its tensile strength. This is because the holes enables the glue to create adhesive anchors that facilitates the stress transfer from the
glue to the steel. Since the steel plate is the component of the joint that can withstand the highest amount of loading, the efficiency of the stress transfer is crucial in order to prevent the glue from breaking entirely at relatively small loads, which would result in a
lower ultimate tensile strength of the joint.
Although, some insecurities remains in the implementation of the FE-model, the results in this thesis can be used as a foundation for future research on this topic
A System Study of Propulsion Concepts and Scenarios
No full textIn this thesis project, a complete fuel cell system submodel, including a fuel cell stack, supplying system, and water management system was modelled. One Fuel Cell Plug-in Hybrid Electric Vehicle (FC-PHEV) and one Fuel Cell Hybrid Electric Vehicle (FC-HEV) model, as well as different components and control strategies, were also implemented in the GT-Suite software to simulate the hydrogen consumption
under various driving cycles and scenarios. Furthermore, a cost analysis model is also developed to determine the optimal battery size for the FC-PHEV. Finally, a cost comparison among FC-PHEV, FC-HEV, and Battery Electric Vehicle (BEV)was made based on current data available from the U.S market. The Fuel Cell-PHEV model and the Fuel Cell-HEV model are validated against the WLTC and NEDC driving cycles. The functionality of the main control units
is also evaluated. The simulation results show that: For the Fuel Cell-PHEV, the combined hydrogen consumption is 0.29 kg/100 km for NEDC, and 0.34 kg/100 km for WLTC. For the Fuel Cell-HEV, the hydrogen consumption is 0.68 kg/100 km
for NEDC, and 0.82 kg/100 km for WLTC.
The results of the initial cost comparison of energy source, based on current data show the ranking from the cheapest to the most expensive is FC-HEV, FC-PHEV, and BEV. The ranking of the total cost of ownership, including running cost from
the cheapest to the most expensive is FC-PHEV, BEV, and FC-HEV. Overall, the Fuel Cell Plug-in Hybrid Electric Vehicle could be the best choice based on the current data
Felkorrigerande koder
No full textAtt skydda ett meddelande från fel som kan uppstå under en överföringsprocess är något som måste göras vid all möjlig data- och informationskommunikation. ReedSolomon-koder är en klass av felkorrigerande koder som gör just detta. Det här arbetetet innehåller en matematisk härledning av Reed-Solomon-kodernas optimala egenskaper samt en implementering av meddelandet KODNINGSTEORI i form av en QR-kod (Quick Response). Vi förklarar begrepp såsom kod och felkorrigering och studerar algebraiska begrepp inom ring-och kroppteori samt cykliska polynomkoder och primitiva polynom. Vi bevisar matematiskt att Reed-Solomon-koderna är optimala idenmeningattdeuppfyllerSingletonsgräns.DenQR-kodsomharimplementerashar kapacitet att korrigera upp till 15 % felaktig indata med hjälp av en Reed-Solomon-kod
Energy Estimations And The Creation Of An Artificial Immune System
No full textThe dawn of the information era is upon us and yet there are many unresolved
mysteries in the universe, one among them are the governing mechanism behind
our own immunity. By keep researching with relevant questions we might someday
find the answer to that simple question.
In order to investigate this question further one must first learn the basics
of immunology and from there try to advance towards the goal. Obviously this
question could not be answered, mostly due to lack in knowledge concerning energy
expenditure in immune cell activation and alike. Instead energy expenditures
by different systems/organs of our body are investigated and compared to our
recommended calorie intake, in order to see how well the numbers add up. This
comparison is important because the energy we eat should be equal to the energy
we spend daily (if we maintain the same weight), because today, food is the only
source of energy we know about.
The second part of this master’s Thesis concerns agent based models to simulate
an adaptive immune response. The results from the simulations are quite obvious
but the important thing is that the code capture some dynamics which the real
immune system shows. Usually one does not simulate an immune response because
it is too large to consider
Characterization of pharmaceutical materials to elucidate structure-material properties relationship
No full textCFD investigation on wheel modelling and car aerodynamics
No full textIt has been estimated that approximately 25% of the drag of a passenger vehicle
is due to the wheels and wheel housings. So studying the flow patterns around
them have been of great importance for several years. Traditionally, wind tunnel
experiments have been used to study the aerodynamic performance of vehicles but
with growing computational resources, CFD investigations have proven to be vital,
especially in the initial stages of development. With growing regulations on vehicle
performances, it is of paramount importance to be able to accurately simulate the
flow around wheels. The work included two studies: simulations of a rotating cylinder
to represent a simplified wheel geometry and simulations of a full scale car.
In the first study, the Rotating Wall(RW) and Sliding Mesh(SM) methods were investigated
on a cylinder and it was found that the case was extremely mesh and
timestep dependent. To obtain comparable results, very fine mesh and timestep
had to be employed which were computationally expensive. A parametric study
was performed on the SM case to understand the mesh, geometry and timestep dependency.
Investigations were done to see if pseudo-parallelization of mesh updating
in SM method could speed up the simulations. About 35% reduction in total time
and 68% reduction in mesh updating time was noted.
In the second study, aerodynamic analysis was performed on the car and wheels.
Moving Reference Frame(MRF) and SM wheel modelling approaches were investigated
and their differences were analyzed. Investigations on how blanking of rims
affect the aerodynamic performance of a car was performed. It was noted that
blanking reduced the drag by about 29 CdA counts and increased downforce by 21
ClA counts. An investigation on whether performing simulations with a timestep of
2.5e-4s on the mesh was done by comparing the results to a finer timestep of 1e-4s. It
was found that the 2.5e-4s yields acceptable results. Finally, pseudo-parallelization
of the interface updating was tested on the car by splitting the wheel interface into
three interfaces. About 21% reduction in updating time and 5% reduction in total
time was observed using this method. It was inferred that the method can be used
for speeding up SM simulation and it can be further improved by creating more
interfaces and evenly distributing the number of cells on each interface