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No description available.

The problem of this study was to investigate the effect of the rotation around two axes of the body upon static balance as measured by the stork stand, the headstand, and the one foot balance.

Measurement of the electrostatic nature of materials is an essential step towards understanding the underlying processes and to the eventual modification of charge behaviour. Indirect monitoring was achieved by resistivity measurements, however, this approach is limited to studying the material and not the electrostatic charge and is, in general, not a satisfactory method. Electrostatic field meters allowed the electrical behaviour of polyethylene to be monitored; its charge accumulation and decay processes were accurately monitored, thus giving a good information base for material modification later in the programme. The use of a data-logging system (based on the Apple//e computer) allowed the manipulation and long term storage of information, whilst giving improved presentation of results. High Density Polyethylene is an intrinsically insulating polymer whose electrostatic properties can be greatly modified by the use of internal antistats. Such additives migrate to a surtace and become effective [at reducing surtace resistivity] over a period of time depending on the diffusivity of the antistat species, and on the external atmospheric conditions, particularly humidity. The effusion of antistat onto a surface was monitored by surtace analysis techniques including X-ray photoelectron scattering, goniometry and infra-red spectroscopy, however, whilst such techniques offered a direct indication of the surtace state and the effect of any surtace modification, electrostatic testing was found to be the most sensitive technique for following antistat action. It is possible to tailor individual antistats to specific applications, however such usage provides only specific protection (fast acting but short lived, or slow acting but long lived). Two single antistat species were combined, and a synergistic effect was obtained for fast acting and long lived systems. It was found that antistats operate by welting (coating) an insulating surtace, and then absorbing atmospheric water vapour, thus lowering the surtace resistivity. Complete surtace coverage is not possible over an HDPE surtace due to its low surtace energy (28mNm'1), however, more complete surtace coverage was achieved by surtace oxidation [raising the polar surlace energy). Natural HDPE is not readily susceptible to surface oxidation; therefore oxidation treatment had only a limited effect. An addition of the fully compatible polymer LLDPE raised the oxidation level and allowed more complete antistat coverage, thereby improving antistatic activity and raising the level of protection gained by using a standard level of antistat. A patent is being taken out covering the use of LLDPE in conjunction with mixed antistat systems.

The catastrophic consequences associated with landslides necessitate predictions of these hazards to be made with as much certainty as possible. However, the often complex nature of these events make predictions highly challenging. In this thesis, a number of hypotheses related to the triggering mechanisms and subsequent consequences of landslides in a loose-granular soil were investigated. The investigation was conducted using small-scale geotechnical centrifuge models, and a new flume facility developed to examine landslide behavior in a reduced-scale model. The first hypothesis explored in this research was that static liquefaction might preferentially occur in the saturated granular soil located at the base of the landslide rather than the well-drained inclined portion of the slope. Using a geotechnical centrifuge model, it was found that a small initial toe failure did act as a monotonic loading trigger to shear the loose contractile saturated sand at the base of the slope and caused liquefaction to occur. The second hypothesis investigated whether the consequences of a landslide triggered under elevated groundwater antecedent conditions are higher than scenarios under drier antecedent conditions. Results from five centrifuge models subjected to different antecedent groundwater conditions show that higher groundwater conditions can result in landslides with velocities about three times higher and travel distances eight times higher than low antecedent conditions. The third hypothesis investigated the influence of slope inclination on landslide consequences. Seven geotechnical centrifuge models were built and tested, comparing the consequences of landslides triggered in 20° and 30° sloped models with different groundwater conditions. The results of these tests found that the influence of slope angle on the mobility consequences of a triggered landslide are highly dependent on the antecedent groundwater conditions. The most significant case was under high groundwater conditions, where the shallower 20° slope travelled twice the distance and speed of the steeper 30° slope. A new flume facility was developed to examine landslide behaviour in a reduced-scale model, and a direct comparison was made to one of the centrifuge models from the research. The comparison demonstrated the challenges associated with using reduced-scale models to study suction-dominated problems such as hydraulically-induced landslides in loose granular soils. / Thesis (Ph.D, Civil Engineering) -- Queen's University, 2014-04-29 16:45:11.335

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No description available.

This thesis introduces a versatile finite element package, which is tailored for the static and dynamic analysis of radial tyres. A new axisymmetric solid-of-revolution element which takes into consideration, large deformation, the influence of composite orthotropic material and the viscoelasticity and the nonlinearity of the material properties, has been developed for a general loaded tyre. The finite element package has been verified by comparing its results with available analytical, numerical and experimental results. A full static and dynamic investigation has been carried out for a commercial tyre 175 HR 14 and results obtained by using the package have been compared with available experimental results developed by DUNLOP or carried out at Cranfieid. The package has proved to be reliable, flexible, efficient, economic and accurate. The numerical instability problems which are prevalent in this type of analysis have been overcome by the derivation of a developed Newton-Raphson iterative scheme.

The aim of this research project is to investigate, experimentally and analytically, the effects of reinforcement corrosion on the flexural, shear and blast behaviours of reinforced concrete beams. As part of the experimental study, twenty-four beams reinforced were tested under quasi-static and simulated blast loads using the University of Ottawa Shock tube. All beams had dimensions of 125 mm x 250 mm x 2400 mm and were tested under four-point bending. Tension reinforcement consisted of either 2 – 10M (ρ= 1%) or 2 – 15M bars (ρ= 1.6%) for the flexure dominant specimens, and 2 – 25 M bars (ρ= 4%) for the shear-dominant specimens. In all cases, transverse reinforcement consisted of 6 mm stirrups spaced at s = 100 mm (d/2) throughout the beam span. Eighteen of the specimens were subjected to an accelerated corrosion process to induce different amount of mass loss in the longitudinal and transverse steel reinforcement. The test variables included: the type of corrosion (i.e. on the longitudinal or transverse reinforcement), the amount of corrosion (i.e. % mass loss in the steel reinforcement) and the extent / location of corrosion on the tension steel reinforcement (i.e. over the full length, middle span or end spans). The results from the experimental tests showed that corrosion of the tension and transverse steel reinforcement decreased the strength and ductility of the reinforced concrete beams under static loading, ultimately changing the failure mode. Similarly, the results from the blast tests showed that corrosion of the longitudinal and transverse reinforcement affected maximum displacements and support rotations, reduced blast capacity, increased damage and fragmentation, and ultimately changed the failure process from ductile to brittle. Results under both static and blast loads were sensitive to the amount and extent/location of the corrosion. As part of the analytical study, the static results were predicted using 2D finite nonlinear element (FE) modelling. The effects of corrosion were considered using several modeling features including: reduction in steel bar cross-sectional area, modification of the steel stress-strain response, and introducing corrosion-induced cracking using applied pre-strains. The predicted results from the FE simulations were to provide acceptable predictions in terms of load capacity and failure mode when compared to the experimental static test results. The blast results were predicted using two approaches, including: 1) single-degree of freedom (SDOF) analysis (with the resistance functions developed using FE modelling); and 2) the blast analysis capabilities of FE software VecTor2. Overall both approaches led to acceptable predictions of maximum mid-span displacements when compared to the experiments.