Plastic deformation processes transform material fromas-received state to products meeting certain requirements inproperties, microstructure and shape. To achieve thistransformation, the relationship between material response andprocess conditions should be understood. This is usuallycomplicated by the complex conditions describing the actualprocess. Numerous techniques including empirical, physical,analytical and numerical can be employed. In this thesis, numerical technique supported by lab- andfull-scale experiments has been employed to analyse the formingparameters. The first part of the thesis is focused on the useof such parameters to predict occurrence of material poresduring manufacturing of bearing rings. The second part dealswith the influence of forming parameters on the grain sizeduring fabrication of large copper canisters for encapsulationof nuclear waste. The primary task has been to study with thehelp of commercial FE-codes the magnitude and distribution offorming parameters such as accumulated effective strain,temperature, instantaneous hydrostatic pressure and materialflow at different stages of the forming process. In the firstpart, two types of ring manufacturing routes, which result inpore free and pore loaded rings are studied and compared.Material elements located in different areas of the workpiecehave been traced throughout the process. Results of theaccumulated strain and instant hydrostatic pressure have beenanalysed and presented in pressure-strain space. It’sassumed that high hydrostatic pressures together with higheffective strains are favourable for pore closure. Area of theworkpiece with unfavourable parameters have been identified andcompared with ultrasonic test results. Good agreement has beenobtained. Based on the results of this analysis, a new conceptfor avoiding pores in manufacturing of yet heavier rings hasbeen presented. The concept proposes a lighter upsetting in theinitial stage of the process and a more efficient piercingwhich results in higher hydrostatic pressure and bigger andbetter distributed effective strain. In the second part of the thesis, the influence of formingparameters such as effective strain and temperature on thefinal grain size of the product has been studied in laboratoryscale. As-cast billets of cylindrical shape were extruded atdifferent temperatures and reductions. It has been shown thatthe grain size in the final product should be small in order toenable ultrasonic tests and to guarantee resistance towardscreep and corrosion. Simulations for different materialelements located at different distances from the axis ofsymmetry of the initial cylindrical workpiece have been carriedout. In this way, the parameters describing the deformationhistory of the elements have been determined as functions oftime. Experimentally obtained pre- and post deformation grainsize in the corresponding locations of the material weredetermined. It’s concluded that low temperature coupledwith high effective strain are conducive for obtaining a smallgrain size. Based on the beneficial conditions for extrusion ofcopper, a more detailed FE-analysis of a full-scale industrialprocess is carried out. A coarse-grained cast ingot of purecopper is heated and by upset forging formed into a cylinder,which is then punched into a hollow blank for subsequentextrusion. The blank is extruded over a mandrel through a45-degree semi-angle die. Accumulated effective strain andtemperatureas functions of the tubular wall thickness havebeen studied at five different locations along the tubularaxis. Forming load requirement as function of tool displacementfor each stage of the process has been determined. Strain andtemperature levels obtained have been related to the grain sizeinterval obtained in the earlier work. It has been concludedthat the levels reached are within the interval that ensures asmall grain size. A similar analysis has been carried out forforging of large copper lids and bottoms. Die designmodifications to improve the grain size in the lid and tooptimise the forging process with respect to forging load andmaterial yield have been proposed. A method requiring a smallforging load for fabrication of the lids has been analysed <b>Keywords:</b>Pores; grain size; low forging load; effective strain;temperature; hydrostatic pressure; extrusion; forging;canister; lid; rings

Fatigue cracking is one of the most common distresses of asphalt pavements, whereas healing is a counter process to cracking which alleviates cracking damage and extends fatigue life of asphalt pavements. Most of existing methods to characterize fatigue cracking and healing are generally empirical or phenomenological in nature, which does not satisfy the need to develop mechanistic-based pavement design methods. The objective of this study is to characterize fatigue cracking and healing of asphalt mixtures using an energy-based mechanistic approach. A controlled-strain repeated direct tension (RDT) test is selected to generate both fatigue cracking and permanent deformation in an asphalt mixture specimen. Fatigue cracking is separated from permanent deformation from a mechanical viewpoint. The development of fatigue cracking is described by the evolution of the damage density and the increase of the average crack size with the increase of loading cycles. A creep and step-loading recovery (CSR) test is designed to measure the internal stress in the recovery phase of an asphalt mixture specimen. The internal stress and the strain measured in the recovery phase are used to conduct the mechanistic analysis of recovery and healing of the asphalt mixture specimen. Then healing is described using the decrease of the damage density and average crack size with time. Different types of asphalt mixtures produce distinctly different fatigue cracking and healing characteristics. The effect of mixture composition, temperature, and aging are evaluated using the approach above. The entire series of tests for fatigue, permanent deformation and healing can be completed in one day, with the healing part requiring only a matter of minutes. The methods proposed in this study characterize fatigue cracking and healing of asphalt mixtures using its essential cause and effect relationship.

Vi arbetar idag mindre tid än vad den arbetande människan gjort under tidigare årtionden, och många hävdar att vi måste arbeta mer för att vi ska kunna bibehålla vår standard. Men sammantaget, betalt och obetalt arbete, sett ur en familjs perspektiv arbetar många väldigt mycket idag, och med högt ställda krav både på jobbet och i hemmet.Ett antal försök med förkortad arbetstid har gjorts på olika arbetsplatser i landet, de flesta inom kommun och landsting, men få har genomförts med både för- och efterstudie. Vi har i vår studie utgått från den arbetstidsförkortning som genomfördes på Radiumhemmet 2003 där vi genomförde en förstudie där alla som skulle delta i försöket fick svara på en enkät innan projektet påbörjades. När projektet pågått tre månader skickade vi ut ytterligare en enkät till deltagarna. Utöver de som deltagit i projektet med arbetstidsförkortning har vi även genomfört motsvarande studie med en kontrollgrupp bestående av sjuksköterskor som arbetade med normal arbetstid. Vi har i vår undersökning fokuserat på Karaseks krav- och kontrollmodell och deltagarnas välbefinnande före och efter införandet av arbetstids-förkortningen. Frågorna vi har använt oss av utgår från samma som i undersökningarna av levnadsförhållanden (ULF). Eftersom vi också tror att, hur vi använder vår fritid påverkar hur vi mår på vårt arbete, har vi utöver Karaseks krav/kontrollmodell, också använt oss av The role strain theory då vi har studerat hur deltagarna har använt sin nyvunna fria tid och ställt dessa svar i relation till hur nöjda de var med sina nya arbetstider.Resultaten av vår studie visade att arbetstidsförkortningen inneburit ökade krav såsom att arbetet blivit mer jäktigt och att den psykiska stressen hade ökat samtidigt som kontrollen hade minskat då det blivit svårare att hinna med sina arbetsuppgifter. Trots detta visade resultaten att den kortare arbetstiden kan lätta den totala arbetsbördan genom att frigöra tid till annat än betalt arbete, såsom hushålls- och hemarbete samt fritidssysselsättningar och på så sätt öka individens välbefinnande.

In this paper, Finite Element method and full-scale experiments have been used to study a hot forging method for fabri-cation of a spindle using reduced initial stock size. The forging sequence is carried out in two stages. In the first stage, the hot rolled cylindrical billet is pre-formed and pierced in a closed die using a spherical nosed punch to within 20 mm of its base. This process of piercing or impact extrusion leads to high strains within the work piece but requires high press loads. In the second stage, the resulting cylinder is placed in a die with a flange chamber and upset forged to form a flange. The stock mass is optimized for complete die filling. Process parameters such as effective strain distribution, material flow and forging load in different stages of the process are analyzed. It is concluded from the simulations that minor modifications of piercing punch geometry to reduce contact between the punch and emerging vertical walls of the cylinder appreciably reduces the piercing load. In the flange chamber, a die surfaces angle of 52° instead of 45° is pro-posed to ensure effective material flow and exert sufficient tool pressure to achieve complete cavity filling. In order to achieve better compression, it is also proposed to shorten both the length of the inserted punch and the die “tongues” by a few mm.

No description available.

Fiber optic sensors are designed to measure various parameters. The distributed fiber optics sensor has been a very promising candidate for the structural health monitoring. In this thesis, we characterized LEAF (Large Effective Area Fiber) fiber’s Brillouin scattering spectrum and investigated its potentiality for the distributed Brillouin temperature and strain sensor. Optical fibers with complex refractive index profiles are applied to improve the Brillouin threshold by varying the Brillouin linewidth. As LEAF fiber has a modified refractive index profile, we investigated its Brillouin linewidth’s dependence on the square of the pump light’s frequency. We verified the Brillouin frequency’s variation with input SOP experimentally for LEAF fiber in the spontaneous regime. This sets a limitation for the frequency resolution of distributed Brillouin sensors. We also realized a simultaneous temperature and strain sensor with LEAF fiber applying the Brillouin optical time domain analysis. Based on the direct detection of LEAF beat frequencies, a simultaneous strain and temperature sensor was demonstrated.

Hollow section members are widely used in industrial applications for the design of many machine and structural components. These components are often fabricated at lower cost by welding rather than by casting or forging. For instance, in agricultural machinery, the hollow tubes are typically connected together through welding to form T-joints. Such T-joint connections are also employed in other engineering applications such as construction machinery, offshore structures, bridges, and vehicle frames. In this dissertation, the behaviour of tubular T-joint connections, in particular square hollow section (SHS)-to-SHS T-joints, subjected to static and cyclic loads is studied both experimentally and numerically. The techniques used for the fabrication of the T-joint connections can affect their strengths to different degrees. With modern advances in manufacturing technologies, there are many alternatives for the fabrication of the T-joint connections. For instance, in recent years, the use of the laser beam has become increasingly common in industrial applications. From a manufacturing point of view, the T-joint connections can be fabricated by using traditional mechanical cutting or laser cutting techniques. Currently, for the fabrication of the T-joint connections, the straight edge of one tube is cut using mechanical tools (e.g., flame cutting) and then welded to the body of the other tube. A major contribution of this research work is investigating the feasibility of using laser cutting to produce welded square hollow-section T-joints with similar or higher fatigue strengths than their conventional mechanical cut counterparts. For this purpose, a total of 21 full-scale T-joint samples, typical of those found in the agricultural machinery, are included for the study. Finite Element (FE) models of the T-joints manufactured with the different cutting techniques are also developed and the FE results are verified with the experiments. The results of the numerical and experimental study on the full-scale T-joint samples show that the fatigue strength of the samples that are manufactured with laser cutting is higher than those fabricated with conventional mechanical cutting. From a structural analysis view point, despite of the wide use of tubular T-joint connections as efficient load carrying members, a practical but yet simple and accurate approach for their design and analysis is not available. For this purpose, engineers must often prepare relatively complicated and time consuming FE models made up of shell or solid elements. This is because unlike solid-section members, when hollow section members are subjected to general loadings, they may experience severe deformations of their cross-sections that results in stress concentrations in the connections vicinity. One of the objectives/contributions of this research work is the better understanding of the behaviour of SHS-to-SHS T-joint connections under in-plane bending (IPB) and out-of-plane bending (OPB) loading conditions. Through a detailed Finite Element Analysis (FEA) using shell and solid elements, the stiffness and stress distribution at the connection of the tubular T-joints are obtained for different loading conditions. It is observed that at a short distance away from the connection of the T-joints, the structure behaves similar to beams when subjected to loadings. The beam like stresses cease to be valid only in the vicinity of the connection. Therefore, several parameters are defined to recognize the joints stress concentrations and the bending stiffness reduction. These parameters permit the accurate modelling of the tubes and the T-connection by simple beam elements with certain modifications. The models consisting of beam elements are significantly easier to prepare and analyze. Through several numerical examples, it is shown that the modified beam models provide accurately all important information of the structural analysis (i.e. the stresses, displacements, reaction forces, and the natural frequencies) at substantially reduced computational effort in comparison with the complicated Finite Element (FE) models built of shell or solid elements. Another contribution of this research work is the FE modelling of the weld geometry and its effect on the stresses at the vicinity of the connection. The results of the FE modelling are verified through a detailed experimental study. For the experimental study, two test fixtures with hydraulic actuators capable of applying both static and cyclic loadings are designed and used. Strain gauges are installed at several locations on full-scale T-joint samples to validate the developed FE models. It is shown that the membrane stresses which occur at the mid-surface of the tubes remain similar regardless of the weld geometry. The weld geometry only affects the bending stresses. It is also shown that this effect on bending stresses is highly localized and disappears at a distance of about half of the weld thickness away from the weld-toe. To reduce the stress concentrations at the T-joint, plate reinforcements are used in a number of different arrangements and dimensions to increase the load carrying capacity of the connection.

Large-scale production of plant secondary metabolites is of interest because of their application in production of many valuable products. Recent advances in the area of DNA recombinant technology has made it possible to produce these valuable compounds using microbial routes. The objective of this work was, to design a platform strain of Saccharomyces cerevisiae with improved intracellular tyrosine pools using computational modeling. This engineered yeast could be used as a host for producing important plant secondary metabolites on an industrial-scale. In this study, a combination of steady-state and dynamic modeling methods were used for strain design. Initial strain design was performed using steady-state modeling, and the predictions from steady-state modeling were prioritized for experimental validation using dynamic modeling. The final strategy proposed included deletion of PDC1, ZWF1, ARO10; over-expression of ALD6, and alleviation of tyrosine feedback resistance in shikimate pathway. Initial experiments for validation of this strategy showed promising results.

Large-scale production of plant secondary metabolites is of interest because of their application in production of many valuable products. Recent advances in the area of DNA recombinant technology has made it possible to produce these valuable compounds using microbial routes. The objective of this work was, to design a platform strain of Saccharomyces cerevisiae with improved intracellular tyrosine pools using computational modeling. This engineered yeast could be used as a host for producing important plant secondary metabolites on an industrial-scale. In this study, a combination of steady-state and dynamic modeling methods were used for strain design. Initial strain design was performed using steady-state modeling, and the predictions from steady-state modeling were prioritized for experimental validation using dynamic modeling. The final strategy proposed included deletion of PDC1, ZWF1, ARO10; over-expression of ALD6, and alleviation of tyrosine feedback resistance in shikimate pathway. Initial experiments for validation of this strategy showed promising results.

Two behavioural studies were conducted at the University of Saskatchewan beef feedlot. In the first study, the temperament of 400 steers was determined using both objective and subjective measures. The consistency of temperament, over repeated tests and between different measures, was also tested. The objective behavioural tests were conducted during the individual restraint of the steers using strain gauges and an MMD (movement-measuring-device). The time required for the steers to exit the area was also recorded. Subjective assessment of animals responsiveness during restraint was recorded on a scale of 1-5 (calm to wild). The consistency of individual differences in a steers response within the evaluation series and across repetitions, shows that this trait may represent a stable personality of the animal. The significant relationship between objective and subjective measures demonstrates that objective measures of temperament can be used to replace the traditional subjective scale as it has the added advantage of reducing inter- and intra-observer variability. The positive relationship of subjective scores and MMD values with the steers performance (average daily weight gain) shows not only that a calm temperament is conducive to productivity, but also that objective measures can replace subjective techniques for assessing temperament for performance evaluation. In the second study the reactivity of a subset of the original 400 steers (262 animals from 8 pens) to a novel stimulus was assessed. The purpose of this experiment was to determine if a steers behavioural response in the novel test was correlated to its temperament assessment determined in the first study. A remote controlled ball was dropped from the ceiling of a salt feeder while a steer licked the salt. Two overhead cameras connected to a monitor through a VCR and time lapse recorder permitted us to observe and document the response. A lack of correlation between measures of handling and novelty measures show that reactivity of animals in the handling chute and their responsiveness to the novel stimulus do not represent one and the same trait.