This thesis describes a non-linear finite element model suitable for the analysis of reinforced concrete, or steel, structures under general three-dimensional states of loading. The 20 noded isoparametric brick element has been used to model the concrete and reinforcing bars are idealised as axial members embedded within the concrete elements. The compressive behaviour of concrete is simulated by an elasto-plastic work hardening model followed by a perfectly plastic plateau which is terminated at the onset the . crushing. In tension, a smeared crack model with fixed orthogonal cracks has been used with the inclusion of models for the retained post-cracking stress and the reduced shear modulus. The non-linear equations of equilibrium have been solved using an incremental-iterative technique operating under load control. The solution algorithms used are the standard and the modified Newton-Raphson methods. Line searches have been implemented to accelerate convergence. The numerical integration has been generally carried out using 15 point Gaussian type rules. Results of a study to investigate the performance of these rules show that the 15 point rules are accurate and computationally efficient compared with the 27(3X3X3) point Gaussian rule. The three- dimensional finite element model has been used to investigate the problem of elasto-plastic torsion of homogeneous members. The accuracy of the finite element solutions obtained for beams of different cross-sections subjected to pure and warping torsion have been assessed by comparing them with the available exact or approximate analytical solutions. Because the present work is devoted towards the analysis of reinforced concrete members which fail in shear or torsional modes, the computer program incorporates three models to account for the degradation in the compressive strength of concrete due to presence of tensile straining of transverse reinforcement. The numerical solutions obtained for reinforced concrete panels under pure shear and beams in torsion and combined torsion and bending reveal that the inclusion of a model for reducing the compressive strength of cracked concrete can significantly improve the correlation of the predicted post-cracking stiffness and the computed ultimate loads with the experimental results. Parametric studies to investigate the effects of some important material and solution parameters have been carried out. It is concluded that in the presence of a compression strength reduction model, the tension-stiffening parameters required for reinforced concrete members under torsion should be similar to those used for members in which bending dominates. / The scholarship of the Ministry of Higher Education of the Republic of Iraq.

Transverse ply cracking often leads to the loss of stiffness and reduction in thermal expansion coefficients. This paper presents the thermoelastic degradation of general cross-ply laminates, containing transverse ply cracks, subjected to biaxial extension, bending and thermal loading. The stress and displacement fields are calculated by using the state space equation method [Zhang D, Ye JQ, Sheng HY. Free-edge and ply cracking effect in cross-ply laminated composites under uniform extension and thermal loading. Compos Struct [in press].]. By this approach, a laminated plate may be composed of an arbitrary number of orthotropic layers, each of which may have different material properties and thickness. The method takes into account all independent material constants and guarantees continuous fields of all interlaminar stresses across interfaces between material layers. After introducing the concept of the effective thermoelastic properties of a laminate, the degradations of axial elastic moduli, Poisson's ratios, thermal expansion coefficients and flexural moduli are predicted and compared with numerical results from other methods or available test results. It is found that the theory provides good predictions of the stiffness degradation in both symmetric and antisymmetric cross-ply laminates. The predictions of stiffness reduction in nonsymmetric cross-ply laminates can be used as benchmark test for other methods.

Fuel channels are used to keep the components of a nuclear fuel bundle in place. The fuel channel of a new nuclear fuel which is being developed at Westinghouse has a complex geometry which creates challenges in the manufacturing process. FE simulations were developed of a two-stage forming process of the fuel channel. Three different simulations were developed, a simulation of the pre-bending, a simplified simulation of bending, and a combined simulation of the two-stage process of pre-bending and bending. The simulations were done in Ansys Workbench. The simulations of the pre-bending could be validated against experimental results. The simulations of the bending showed significant differences in results compared to experiments. A few different sources of error were investigated due to the difference in results. / Höljerör omsluter kärnbränslet i en kärnreaktor och håller komponenterna i bränslepaketet på plats. Höljeröret av ett nytt kärnbränsle som utvecklas på Westinghouse har en komplex geometri som skapar utmaningar i tillverkningsprocessen. FE simuleringar av en tvåstegsprocess av bockningen av höljeröret utvecklades. Tre typer av simuleringar utvecklades, en simulering av förbockningen, en förenklad simulering av bockningen, och en simulering av den kombinerade förbockningen och bockning. Simuleringarna gjordes i Ansys Workbench. Förbockningssimuleringarna kunde valideras mot experiment. Bockningssimuleringen visade dock signifikanta skillnader i resultat gentemot experiment. Några olika felkällor undersöktes på grund av skillnaderna i resultat.

<p> Various analytical methods for studying the behaviour of shallow conical shells on Euler-Winkler elastic foundation are presented. </p> <p> To account for the nature of concrete and the geometric properties of the shallow conical shell, Poisson's ratio and certain radial and circumferential deformations of the middle surface are neglected in deriving the basic differential equation. Analytical methods employed in the solution of this shell problem are the GECKELER and asymptotic types of approximations. </p> <p> The presentations of various methods of analysis are made for a representative case of dimensions and loadings of the conical shell to make them as applicable as possible to the cases of thin conical shell commonly encountered in industry. </p> <p> The shell structure studied is a tank in the form of a rotationally symmetrical cylindrical shell supported by a shallow conical shell foundation. The construction joint between the conical shell and the cylindrical shell is either monolithic or hinged. </p> <p> The analytical results of this water tank supported on Euler-Winkler elastic foundation are compared with the corresponding findings of W. Flügge, who assumed a uniform soil bearing pressure acting on the conical shell structure. </p> The method of analysis which possesses obvious advantages over the other methods studied is selected to examine the effect of different elastic stiffness coefficients of the soil. The validity of simplifying the soil bearing pressure to a uniform distribution by most designers can consequently be studied by comparing it to the bearing pressures of an ideal elastic soil which is postulated to react to its deformation like a bed of independent elastic springs. </p> / Thesis / Master of Engineering (ME)

Small-scale fracture behavior of four model alloy systems were investigated in the order of increasing microstructural complexity, namely: (i) a Ni-based Bulk Metallic Glass (Ni-BMG) with an isotropic amorphous microstructure; (ii) a single-phase high entropy alloy, HfTaTiVZr, with body centered cubic (BCC) microstructure; (iii) a dual-phase high entropy alloy, AlCoCrFeNi2.1, with eutectic FCC (L12) -BCC (B2) microstructure; and (iv) a Medium-Mn steel with hierarchical microstructure. The micro-mechanical response of these model alloys was investigated using nano-indentation, micro-pillar compression, and micro-cantilever bending. The relaxed Ni-BMG showed 6% higher hardness, 22% higher yield strength, and 26% higher bending strength compared to its as-cast counterpart. Both the as-cast and corresponding relaxed BMGs showed stable notch opening and blunting during micro-cantilever bending tests rather than unstable crack propagation. However, pronounced notch weakening was observed for both the structural states, with the bending strength lower by ~ 25% for the notched samples compared to the un-notched samples. Deformation behavior of HfTaTiVZr was evaluated by micropillar compression and micro-cantilever bending as a function of two different grain orientations, namely [101] and [111]. The [111] oriented micropillars demonstrated higher strength and strain hardening rate compared to [101] oriented micropillars. The [111] oriented micropillars showed transformation induced plasticity (TRIP) in contrast to dislocation-based planar-slip for the [101] oriented micropillars, explaining the difference in strain hardenability for the two orientations. These differences in deformation behavior for the two orientations were explained using Schmid factor calculations, transmission electron microscopy, and in-situ deformation videos. For the dual-phase AlCoCrFeNi2.1 high entropy alloy, the L12 phase exhibited superior bending strength, strain hardening, and plastic deformation, while the B2 phase showed limited damage tolerance during bending. The microstructure and deformation mechanisms were characterized for a few different medium-Mn steels with varying carbon (0.05-0.15 at%) and manganese (5-10 at%) content. The alloy with 10 at% Mn and 0.15 at% C (1015 alloy) showed hierarchical microstructure of retained austenite and ferrite with lamellae 200 nm to 300 nm wide. Micro-pillar compression at different strain levels for this alloy revealed that deformation in austenite is primarily accommodated through transformation to martensite, thereby increasing the strain hardening rate.

Detta arbete inriktar sig på bockning av plåt med hjälp av utskrivna verktyg(knivar). Dessa verktyg har som mål att bocka ett flertal 4 mm plåtar utan att deformeras och ge ett liknande resultat som ett verktyg av stål skulle ha gjort. Målet är att minska mängden material som används i ett bockningsverktyg. Det skulle sänka vikten och kostnaden samt förbättra arbetsmiljön för de som arbetar med att byta verktyg. Man vill ta reda på nackdelar och fördelar som eventuellt uppstår av att använda additiv tillverkning i denna miljö.  Dessa tas fram med hjälp av dataanalyser av material och med ett simulerat lastfall. De skrivs ut med hjälp av en 3d-skrivare och testas genom att pressas ihop i en maskin kallad för INSTRON som ger mätvärden att analysera. Flera mindre prototyper testas och en slutlig prototyp skrivs ut i fullskalig storlek. Dessa presenteras och testas hos företaget Jonsson och Paulsson tills ett godtagbart verktyg är färdigt. Projektet lyckades med detta och verktyget klarade av mål och syfte. / This work focuses on bending sheet metal using printed tools (punch). These tools aim to bend a number of 4 mm sheets without deforming and give a similar result as a steel tool would have done. The goal is to reduce the amount of material used in a bending tool. It would reduce weight and cost and improve the working environment for those working on changing tools. One wants to find advantages and disadvantages that may arise from using additive manufacturing in this environment. These are produced using data analyzes of materials and with a simulated load case. They are printed using a 3d printer and are tested by being pressed together in a machine called INSTRON that provides metrics to analyze. Several smaller prototypes are tested and a final prototype is printed in full-scale. These are presented and tested at the company Jonsson and Paulsson until a satisfactory tool is ready. The project succeeded in this and the tool met its goals and purposes. / <p>Betygsdatum ?</p>

The flexural behavior of a light-weight wood-based composite system was studied through destructive experiments. The composite panel system consisted of profiled dimensional lumber, which makes up the surface layers, and 1"-thick boards running across the surface layers. Considering the changes in cross-sections along the panel due to the presence of the embedded boards, classical theories such as the Euler-Bernoulli beam and Kirchhoff-Love plate could not be implemented. Instead, the deflections and maximum failure loads of the composite system under full- and short-span bending tests were measured during their destructive bending testing, and were compared against the mechanical properties of the conventional three-ply CLT panel with the same thickness as the panel with embedded cross-laminations. According to maximum failure loads and deflections, it was concluded that full-span panels with embedded cross-laminations exhibited higher strength and stiffness, whereas short-span panels exhibited higher strength and lower stiffness properties compared to conventional CLT panels.

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