Examensarbeten för masterexamen // Master Theses
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Browsar Examensarbeten för masterexamen // Master Theses efter Program "Applied mechanics (MPAME), MSc"
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- PostModeling of laminated veneer lumber - A study of the material properties for thick structural elements(2020) Ek, John; Norbäck, Viktor; Chalmers tekniska högskola / Institutionen för arkitektur och samhällsbyggnadsteknik (ACE); Jockwer, Robert; Atashipour, RasoulThis thesis studies the material properties of laminated veneer lumber (LVL). LVL is a timber product made of thin veneers of wood, glued together to form a laminate. The work has been carried out with the aim of providing a better understanding of LVL when designing large structures, in particular the thesis is related to the large scale application of wind turbine towers. The project consists of two major parts, initially a study of the possibility to use laminate theory for evaluation of LVL stiffness parameters. From this study it was found that the laminate theory used, in combination with the accessible material parameters provide an unfit description of the material. Consequently the second part of the project investigates the material behaviour using a more advanced three dimensional model, taking the effect of variability in veneer properties and the influence of knots, modeled as stiffness free voids, into account. The study reveal that increasing the number of veneers, increases the effect from the variability of veneers and reduces the influence of knots. Conclusions from the model suggests there are both beneficial and unfavourable effects when designing thick LVL structures. In order to account for these effects which currently is not practice, a more elaborate three dimensional model need to be studied, analyzing the material further.
- PostThe Influence of Natural and Forced Convection in Attics – A CFD Analysis(2014) Bengtson, Andreas; Fransson, Victor; Chalmers tekniska högskola / Institutionen för bygg- och miljöteknik; Chalmers University of Technology / Department of Civil and Environmental EngineeringIn this thesis project, the air and heat flow in a principal insulated cold attic model has been numerically investigated through the use of the commercial CFD software ANSYS Fluent. A numerical model for the heat transfer has been developed and verified with experiments on a simple box model containing insulation and an overlying horizontal air cavity. This numerical model was then applied on a cold attic model with insulation and wooden joists. Both situations with pure natural convection, caused by the temperature difference between the hot floor of the attic and the cold roof, as well as situations where the attic in addition was exposed to forced convection in the form of attic ventilation has been investigated. This project has been a collaboration between ÅF Industry AB and the Division of Building Technology at Chalmers University of Technology.
- PostTransient Simulation of Ventilation Rate and Moisture load for Cold Attic Constructions - A CFD Analysis(2015) Hellsvik, Ragnar; Chalmers tekniska högskola / Institutionen för bygg- och miljöteknik; Chalmers University of Technology / Department of Civil and Environmental EngineeringIn this Master's thesis, numerical modeling of transient air, heat and mass transport is investigated in a principal cold attic construction through the use of the commercial CFD software ANSYS Fluent. A numerical model that was developed and validated for steady state simulations in an earlier project is now being used for transient simulations over a total time of 24 hours to capture the daily variations in temperature and humidity levels. The attic model contain wooden joists lying in a layer of insulation at the bottom of the attic, and a triangular shaped air cavity. Natural convection due to the temperature gradients between the hot floor and the cold roof along with forced convection driven by the ventilation system is investigated. An hygrothermal analysis and numerical methods are applied to estimate the moisture load at the inner roof boundary for different ventilation rates. The project has been performed as a collaboration between ÅF Industry AB and the Division of Building Technology at Chalmers University of Technology.