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Vibrations is a phenomenon that can cause problems to systems if not dealt with. In heavy duty trucks, vibrations are mainly caused by uneven roads and from the combustion engine. Vibrations can damage components, reduce their service life and cause discomfort for the driver. To manage the problem, vibration isolators can be used to absorb energy and thus reduce the vibrations. Rubber is a commonly used material for vibration isolators thanks to its viscoelastic properties. However, due to the characteristics of rubber, there are difficulties to make accurate simulation models of components such as vibration isolators. To improve the accuracy in simulations, physical testing can be performed to measure the material properties and characteristics such as hysteresis to get a better understanding of how the material and the component will behave. The purpose of the master thesis was to generate and develop concepts of a test rig for a specific vibration isolator from Scania where the force as a function of displacement in the component’s Z-direction should be measured as well as the force in the component’s Y-direction. Further, the component should be compressed in a vertical linear motion. Based on the background information, the following research questions were stated: - How can a hysteresis curve based on frequency input be found by performing physical testing? - How can a test rig be designed to test and measure the material properties of a rubber component in order to parametrize the material? The vibration isolator was investigated and analyzed. From the analysis, seven concepts were generated and were evaluated with a Pugh matrix. From the evaluation, two concepts were chosen to be further developed before a final evaluation using a desirability chart was made. The master thesis resulted in two concepts that were developed named Hinged beam and Guiding plates. Guiding plates was the concept that scored the best in the final evaluation, but the concepts had different strength and weaknesses. Both concepts fulfilled the requirement of compressing the vibration isolator in a vertical linear motion but the measurement of the force in the component’s Y-direction needs to be further investigated. / Vibrationer är ett fenomen som kan orsaka problem för olika typer av system om det inte hanteras. I lastbilar är vibrationer huvudsakligen orsakade av ojämnt underlag samt av förbränningsmotorn. Vibrationerna kan orsaka skada på komponenter, reducera deras livslängd och även orsaka obehag för föraren. Det här problemet kan hanteras genom användning av vibrationsisolatorer som minskar effekten fr.n vibrationerna genom att absorbera dess energi. Gummi är ett material som ofta används för att isolera vibrationer tack vare dess viskoelastiska egenskaper. Egenskaperna gör det dock svårt att skapa noggranna simuleringsmodeller av komponenter så som vibrationsisolatorer. För att öka noggrannheten i simuleringarna kan fysisk testning genomföras och materialegenskaper så som hysteres kan mätas för att få en bättre förståelse för hur både material och komponent beter sig med olika laster. Syftet med det här masterexamensarbetet var att generera och utveckla koncept för testriggar för en specifik vibrationsisolator tillhandahållen av Scania. Kraft som funktion av förskjutning i komponentens Z-riktning samt kraft i dess Y-riktning skulle vara möjligt att mätas. Utöver det var ett krav att komponenten endast ska komprimeras i en vertikal linjär rörelse. Baserat på bakgrundinformationen kunde följande forskningsfrågor formuleras: - Hur kan en frekvensbaserad hystereskurva tas fram genom fysisk testning? - Hur kan en testrigg designas för att kunna testa och mäta materialegenskaper hos en gummikomponent för att kunna parametrisera materialet? Vibrationsisolatorn undersöktes och analyserades. Efter analysen genererades sju koncept som utvärderades med en Pugh matris. Utvärderingen resulterade i att de två bäst presterande koncepten valdes för vidareutveckling innan en sista utvärdering genomfördes med hjälp av ett så kallat desirability chart. Masterexamensarbetet resulterade i två koncept som vidareutvecklades, ett som kallas Hinged beam och ett vid namn Guiding plates. Guiding plates var det konceptet som presterade bäst i den slutgiltiga utvärderingen, men de olika koncepten har dock olika styrkor och svagheter. Båda koncepten uppnådde kraven gällande att kompression av vibrationsisolatorn endast ska ske i en vertikal rätlinjig rörelse men hur krafterna i komponentens Y-riktning ska mätas behöver vidare undersökning.

Bridge bearing is an essential component with the function of connecting the superstructure and substructure of the bridge, transmitting load and providing movability to the superstructure. Under dynamic conditions, the internal friction of bridge bearing dissipates the vibration energy and therefore reduces the dynamic response of the bridge. Meanwhile, bearing friction is considered to have possible contribution to some nonlinear dynamic behaviour of the bridge structure, which requires further investigation.However, bearing friction, in most cases, are ignored or considered roughly and implicitly as part of structural damping in current bridge designing codes and methods. Most previous research was also focusing on bearing friction’s effect under high-amplitude vibration conditions, such as earthquake or heavy wind load. Bearing friction’s effect under common low-amplitude vibration in SLS such as train-induced vibration and vehicle-induced vibration is less attended. Although the effect of such low-amplitude vibration is less significant to structural safety, it plays an essential role to the bridge’s traffic safety and comfort. Meanwhile, the cumulative effect of such vibration can significantly influence the life and durability of bridge bearings due to its high occurring frequency. Hence, a clearer understanding of bearing dynamic behaviour is required to improve the understanding of bridge and bearing dynamics.In this thesis, an advanced numerical tool is developed for dynamic analysis of bearing friction. A 3D pot bearing finite element that can be implemented in commercial FE software ABAQUS, is programmed based on the mathematical friction models developed in previous research and the Bouc-Wen hysteretic model. Numerical results that accord with the results of relevant friction tests are produced by the calibrated and validated bearing finite element, giving proof that the element is capable to reflect the dynamic friction response of bridge pot bearing in reality.The 3D shell numerical model of Banafjäl bridge located on the Bothnia Line in Norrland, Sweden, is built as a study case of bridge dynamic analysis in this thesis, with implementation of the newly developed bearing element. The feasibility of implementing the bearing element in bridge dynamic analysis is proven by the numerical results. The nonlinear influence of bearing friction on the dynamic response of bridge structure, especially the influence on structural damping properties, is discussed preliminarily. The analysis results show that with the consideration of bearing friction, the damping presents a clear amplitude-dependency, which accords the phenomenon reported in previous research.

Groundwater quality in karst systems is difficult to monitor because the extreme heterogeneity within the recharge area and complex subsurface flow network makes flowpaths and travel rates difficult to predict. Understanding how flowpaths vary during storm events is important because water transmitted through conduit flowpaths can travel fast, may come from long distances, and has little filtration of contaminants. The hypothesis tested in this project is that ion ratios in spring discharge will show the timing of changes from diffuse to quick flow depending on storm intensity and antecedent conditions and provide more detail than total ion conductivity. Cedar Run Spring is located in the Cumberland Valley of south-central Pennsylvania. The valley is part of the larger Great Valley Section and is composed of Cambro-Ordovician aged carbonate units, collectively known as the Cumberland Valley Sequence. Initial background monitoring with data loggers and monthly samples indicated that Cedar Run Spring had a conduit component within the flow network. An automated stormwater sampler was installed at the spring and collected twenty-four water samples for major-ion analysis. Storm-intensity conditions ranged from high to low for the four storm events collected. In addition, the antecedent conditions varied from wet to dry. The Mg/Ca ratio characterizes the flowpath through which the water moves. A higher ratio indicates more diffuse flow because slower flow paths are needed to dissolve dolomite (which contains Mg), while a lower ratio indicates more conduit flow because calcite (Ca dominant) dissolves more readily. Hysteresis loops of conductivity versus discharge rotated counterclockwise because conductivity decreased on the rising limb of storm response, followed by an increase on the falling limb for all but the winter storm, which was influenced by road salt. In contrast, hysteresis loops for Mg/Ca versus discharge rotated in a clockwise direction for all but one of the storm events because of an increase in Mg/Ca that indicated a flush of older matrix water. The storm event that did not display in initial increase in Mg/Ca was apparently flushed by a recent previous storm event. Mg/Ca hysteresis for the storm events that were diffuse displayed several sharp increases and decrease in addition to several smaller hysteresis loops in response to multiple slugs of recharge water. These variations were not indicated in overall conductivity. High intensity events displayed a quick switch in flowpaths, as indicated by the increase in Mg/Ca early on the rising limb, and a single hysteresis loop. The rapid change in Mg/Ca suggested that during storm events water was able to enter the karst system through sinkholes, then activated flowpaths with older matrix water. Mg/Ca proved to be better at tracking the variability in flowpaths during storm events than the overall conductivity, because Mg/Ca is directly related to water-rock interactions. / Geology

Magnetic properties of ferrite structures are known to cause fluctuations in Earth's magnetic field around the object. These fluctuations are known as the object's magnetic signature and are unique based on the object's geometry and material. It is a common practice to neutralize magnetic signatures periodically after certain time intervals, however there is a growing interest to develop real time degaussing systems for various applications. Development of real time degaussing system is a challenging problem because of magnetic hysteresis and difficulties in measurement or estimation of near-field flux data. The goal of this research is to develop a real time feedback control system that can be used to minimize magnetic signatures for ferrite structures. Experimental work on controlling the magnetic signature of a cylindrical steel shell structure with a magnetic disturbance provided evidence that the control process substantially increased the interior magnetic flux. This means near field estimation using interior sensor data is likely to be inaccurate. Follow up numerical work for rectangular and cylindrical cross sections investigated variations in shell wall flux density under a variety of ambient excitation and applied disturbances. Results showed magnetic disturbances could corrupt interior sensor data and magnetic shielding due to the shell walls makes the interior very sensitive to noise. The magnetic flux inside the shell wall showed little variation due to inner disturbances and its high base value makes it less susceptible to noise. This research proceeds to describe a nonlinear controller to use the shell wall data as an input. A nonlinear plant model of magnetics is developed using a constant to represent domain rotation lag and a gain function to describe the magnetic hysteresis curve for the shell wall. The model is justified by producing hysteresis curves for multiple materials, matching experimental data using a particle swarm algorithm, and observing frequency effects. The plant model is used in a feedback controller and simulated for different materials as a proof of concept. / Electrical and Computer Engineering

Lithium-ion battery responses to bipolar pulse perturbations of less than two minute duration and one C-rate amplitude are studied as general-purpose diagnostics signals that encode the cell impedance, remaining charge, and degradation level. It is shown that the information is derived from a combination of the linear and nonlinear system dynamics of the electrochemical overpotentials, open-circuit voltage change, and hysteresis of the cell. Experimental data is analyzed using an equivalent circuit composed of a conventional resistor-capacitor pair model, a square-root-order convolution-defined diffusion element, and a piece-wise-linear open-circuit voltage element. This bipolar pulse model disaggregates the battery voltage response into its constituent dynamics and allows the nonlinearities to be isolated. The nonlinearities are crucial features which allow the battery charge, health, and incremental capacity features to be regressed directly from the pulse voltage response using ridge regression and feedforward neural networks. Assessment of different pulse shapes suggests that the diagnostics power of the pulse may increase with higher amplitude and shorter duration. Real-world applications are then investigated, including the estimation of charge imbalance using the series-module pulse response, and state-space formulation of the convolution-defined diffusion element. Further refinement of the pulse techniques could simplify battery diagnostics by providing, from a single pulse diagnostic, the key states of charge, health, and power necessary to operate a reliable system.

A novel, general, numerical model is described that is capable of predicting the load-displacement relationship up to and at failure of multiple-bolt joints in timber of various configurations. The model is not tied to a single input function and bolt holes are permitted to be drilled oversize resulting in a slack system. The model consists of five parts. A new mathematical hysteresis model describes the stiffness of the individual bolt at each time step increment and accounts for non-linear and slack behavior; a mechanically-based structural stiffness model explains the interaction of one bolt with another bolt within a joint; an analytically-based failure model computes the stresses at each time step and initiates failure if crack length equals fastener spacing; a stochastic routine accounts for material property variation; and a heuristic optimization routine estimates the parameters needed. The core model is a modified array of differential equations whose solution describes accurate hysteresis shapes for slack systems. Hysteresis parameter identification is carried out by a genetic algorithm routine that searches for the best-fit parameters following evolutionary principles (survival of the fittest). The structural model is a linear spring model. Failure is predicted based on a newly developed 'Displaced-Volume-Method' in conjunction with beam on elastic foundation theory, elastic theory, and a modified Tsai-Wu Failure criterion. The devised computer model enhances the understanding of the mechanics of multiple-bolt joints in timber, and yields valid predictions of joint response of two-member multiple-bolt joints. This research represents a significant step towards the simulation of structural wood components. / Ph. D.

Possibilities for increasing the upper limit of floatable particle sizs in the froth flotation process have been examined since the early beginnings of mineral flotation. The economic implications of such an incresae are far ranging; from decreased grinding costs and increased recoveries to simplified flow-sheet design and increased throughput, all leading to increased revenue. Bubble-particle detachment has been studied to better understand the factors influencing the strength of attachment and the energies involved. Direct measurements of bubble particle detachment were performed using a hanging balance apparatus (KSV Sigma 70 tensiometer) and using a submerged hydrophobic plate in water. Three experiments were used; direct force measurement of bubble-particle detachment, detachment force and energy of a bubble from a submerged hydrophobic plate, and detachment force and energy of a cetyltrimethylammonium bromide coated silica sphere from a flat bubble. Octadecyltrichlorosilane was used as a hydrophobic coating in the first two experimental methods. These experiments were recorded with a CCD camera to identify the detachment processes involved. Energies for both methods were calculated and divided into the two main steps of the detachment process: Three-Phase-Contact pinning and three phase contact line sliding. The first step represents the energy barrier which must be overcome before detachment can begin. It is directly related to contact angle hysteresis. Detachment occurs during the second step, where the solid-vapor interface is replaced by solid-liquid and liquid-vapor. This step corresponds to the work of adhesion. The effects of surface tension, contact angle and hysteresis were well demonstrated with the three experimental methods. Good correlation was found between theoretical work of adhesion and measured energies. / Master of Science