Adhesive joints are used extensively in the automotive industry. There are many ongoing studies on the area of application of joining composite to other material using adhesive joints. In this study, an analysis of mechanical behaviour of composite single lap-joint (SLJ) for carbon fibre reinforced polymer (CFRP) assembled with steel is presented and the analyses are divided into three phases. The first phase consists of a parametric study on a SLJ using Volkersen analytical model (AM), which is the effect of adhesive thickness and overlap length of the SLJ under tensile load. It was found that with increasing the adhesive thickness the final peak load (strength of the joint) increases. The peak load also increases with increasing the overlap joint, but the limit value for the overlap length varies for different adhesive thickness. For example for the case of adhesive thickness of 0.5 mm, the curve reaches to its plateau with overlap length of 40 mm. It was also observed the increase of adhesive thickness leads to decrease of maximum shear stress at the edges of the single lap joint, but it increases as it approaches the middle of the overlap length. Phase two of this study consist of a shear stress comparison with the Volkersen AM with the finite element model (FEM) using ANSYS Parametric Design Language(APDL) software. The purpose of this comparison was to validate the AM. It was found that the AM has a good agreement with the numerical-model (NM). However, the shear stress from the AM at the edge is a little higher than the NM, this is because the analytical method only takes into account the shear stress in one direction but the NM also takes into account the normal shear stress in the other direction. Phase three of this study consists of an experimental analysis of SLJ mechanical behaviour due to the change in temperature of 180 degrees and change in adhesive thickness and also a comparison with the NM. Three adhesive thickness 1, 0.5 and 1.5 mm were tested. Different boundary conditions (BC), namely as with frame and fixed BC are tested for NM. The one with frame BC is to compare with experimental setup and the fixed BC is the equivalent to Volkersen’s geometry. Both experimental and numerical results, show that the relative deformation of the SLJ decreases with the increase of the adhesive thickness. Although the experimental values were much lower than the numerical one, they agree well with the numerical result in term of trend of relative deformation. In experimental analysis, it was found that increasing the adhesive thickness from 0.5 mm to 1.5 mm decrease the relative deformation from 7.8% to 5.3%. It was concluded that increasing the adhesive thickness decreases the stiffness of the joint and allows more thermal movement in the joint.

Godkänd; 1998; 20070404 (ysko)

The research described in the thesis concerns phase transformations and fatigue properties in the Ti-6Al-4V alloy. The need to weld the alloy for certain engine components can expose the alloy locally to non-optimum thermal cycles and it is therefore of importance to gain an understanding of the kinetics involved in the phase transformations during heating and cooling. Moreover, for the purpose of modelling and computer simulations of heat treatments and welding processes, quantitative descriptions of the transformation are necessary. One focus in this work has been to examine the feasibility of using high temperature X-ray diffraction (HT-XRD) to study the phase transformation kinetics. In addition, two components of Ti- 6Al-4V produced by ring-rolling and closed die forging, respectively, showed unexpected differences in low cycle fatigue (LCF) under certain loading conditions. Quantitative metallographic studies and texture examinations were conducted in order to find possibly reasons for the observed difference in fatigue properties. The HT-XRD technique was successfully used to monitor the alpha-to-beta transition during heating and the beta-to-alpha transition during cooling and including the transformation kinetics during isothermal hold. From the recorded spectra the thermal expansion properties for the alpha and beta phases could be extracted up to a temperature of 1050°C, enabling the determination of the overall thermal expansion for the alloy by using rule of mixture (ROM) calculations. Quantitative metallographic studies revealed that the closed die forged material exhibited a finer primary alpha grain size and a finer Widmanstätten platelet colony size which would be expected to provide a superior resistance to fatigue crack initiation. Observed differences in the texture of the two materials as determined by electron back-scattered diffraction might also have contributed to the difference in fatigue properties. / Godkänd; 2002; 20070224 (ysko)

Godkänd; 1998; 20070404 (ysko)

<p>Godkänd; 1992; 20080407 (ysko)</p>

No description available.

The pressure has a major impact when it comes to control of chemical processes. A method for integrating electrical pressure sensors in high-pressure microfluidic chips has, however, so far not been developed and the aim of this project was therefore to study how capacitive pressure sensors could be designed and fabricated to measure pressures between 1-100 bar. Based on analytical calculations and simulations of the thickness and the deflection of the diaphragms, touch mode capacitive pressure sensors were designed, and the fabrication involved exploring both isotropic plasma etching with SF6 and wet etching using KOH to fabricate a diaphragm on a Si wafer. The method which was found to be most suitable was to etch the diaphragm by plasma etching with SF6, even though a pressure resistance of only 23.4 bar could be accomplished, which is believed to be a consequence of the surface roughness, resulting in an Ra-value of 0.43 µm. The surface roughness lead to that chips had to be assembled by aligning them with an IR-camera and glued together with UV-epoxy, which enabled low precision. A method which do not leave any large etching effects on the diaphragm’s surface is therefore recommended for future work, to both potentially increase the pressure resistance and enable chips to be anodically bonded.

No description available.

I mitt examensarbete undersöker jag hur jag som möbelsnickare och produktutvecklare kan bidra i en designprocess. I samarbete med arkitekt- och designkontoret Claesson Koivisto Rune har vi utvecklat en trästol från en första skiss till färdig produkt, där jag har fungerat som produktutvecklare hela vägen igenom designprocessen. Examensarbetet visar på produktutvecklarens roll i en designprocess. ”Från idén om en förenklad konstruktion och sammansättning till en produktionsfärdig trästol med perfekt sittkomfort. Endast tre grunddelar – ben, sits och ryggstöd som gör stolen till en stabil helhet. En alternativ designprocess utan inblandning av industriell produktutvecklingsavdelning.”

The three boiling water reactors (BWR) in Oskarshamn produce about 10 % of the electrical power in Sweden. The combination of intense radiation fluxes and high temperatures in nuclear reactors creates an extraordinary environment. Therefore, a number of material challenges arise at a nuclear power plant that needs to be solved in order to maintain the nuclear power production, safety and reliability. Dissimilar metal welds can be found at a lot of places in nuclear power plants and due to reparations or replacement some dissimilar metal welds need to be welded on site. The technical regulations for the Swedish nuclear power plants specifies that welding of dissimilar joints shall be made with gap of at least 1.5 mm and in horizontal position. Welding a dissimilar joint on site makes it difficult to follow the technical regulations, therefore, the aim with this study is to determine if different welding positions of dissimilar metal welds affect the structure and composition of the weld metal in a negative way and to investigate the importance of a gap in the root. In this study six samples were welded in three different welding positions, horizontal, vertical and reversed vertical with or without a gap of 1.5 mm in the root. The samples were evaluated by non-destructive testing, optical microscopy, chemical analysis, tensile testing, bend testing and hardness measurements. The results shows that two of the samples welded without gap failed the transverse root bend test, the same samples did also have high hardness values in the root bead. The conclusions are that the welding position, horizontal, vertical or reversed vertical does not affect the weld negative in a noticeable way. However, the gap and a good dilution with the filler metal are important.