This thesis examines the qualitative and quantitative variation in local plastic deformation and surface roughening due to crystallographic texture in body-centered cubic materials, specifically interstitial-free steel sheet and molybdenum foil and sheet. Complex forming operations currently used in industrial manufacturing lead to high material failure rates, due in part to the severity of the applied strain path. A multi-scale model was developed to examine the contribution of mesoscopic and local microscopic behaviour to the macroscopic constitutive response of bcc metals during deformation. The model integrated a dislocation-based hardening scheme and a Taylor-based crystal-plasticity formulation into the subroutine of an explicit dynamic FEM code, LS-DYNA. Numerical analyses using this model were able to predict not only correct grain rotation during deformation, but variations in plastic anisotropy due to initial crystallographic orientation. Simulations of molybdenum foil under uniaxial tension supported the existence of bending due to local variations in plastic anisotropy, confirmed with good quantitative agreement by experimental measurements of surface roughening. A series of two-stage strain-path tests were performed, revealing a prestrain-dependent softening of both the steel and molybdenum samples when an orthogonal secondary strain path is applied. Numerical analyses of these tests overestimate macroscopic hardening during complex loading, due in part to the dynamic nature of the FEM code used. / Thesis (Ph.D, Mechanical and Materials Engineering) -- Queen's University, 2009-04-15 11:51:04.518

This project proposes a reactor-based instrument, which retains most of the above advantages of spallation source engineering instruments, while maintaining the advantages inherent to steady-state instruments. The main idea is to allow the entire white beam from the reactor onto the sample---no monochromation. Diffraction is then allowed at a fixed angle, and information from two sample directions can be obtained simultaneously. Since a white beam is incident onto the sample, the diffraction condition is satisfied for multiple sample planes in the fixed angle of diffraction. Multiple analyzer/detector pairs are placed downstream from the sample and tuned to scatter only one of the diffracted wavelength bands. Monte Carlo methods were used to create models of both a standard two-axis engineering diffractometer, found on current reactor sources, and the proposed white beam instrument. There models were validated by experiments performed on a standard two-axis instrument, which was also modified to operate in a white beam configuration, in which the position of the sample and monochromator were interchanged. Both the models and the experiments of the white beam instrument showed proof of concept for this design and identified areas of concern that required special attention. Upon a comparison on the results from the standard two-axis instrument to the results from the white beam instrument (both simulation and experimental), it was found that the standard diffractometer showed a better performance in all aspects. However, this project proposes numerous areas where the white beam design can be improved upon in order to enhance its performance as an engineering instrument. The most important of these is the design of an appropriate analyzer/detector system, as the results overwhelmingly show this to be the area of greatest concern. Ideas for a few such designs are also given. / Thesis (Master, Physics, Engineering Physics and Astronomy) -- Queen's University, 2009-04-23 17:46:59.419

There exists considerable debate in the texture community about whether grain interactions are a necessary factor to explain the development of deformation textures in polycrystalline metals. Computer simulations indicate that grain interactions play a significant role, while experimental evidence shows that the material type and starting orientation are more important in the development of texture and microstructure. A balanced review of the literature on face-centered cubic metals shows that the opposing viewpoints have developed due to the lack of any complete experimental study which considers both the intrinsic (material type and starting orientation) and extrinsic (grain interaction) factors. In this study, a novel method was developed to assemble ideally orientated crystalline aggregates in 99.99\% aluminum (Al) or copper (Cu) to experimentally evaluate the effect of grain interactions on room temperature deformation texture. Ideal orientations relevant to face-centered cubic rolling textures, Cube $\{100\}\left<001\right>$, Goss $\{110\}\left<001\right>$, Brass $\{110\}\left<1\bar{1}2\right>$ and Copper $\{112\}\left<11\bar{1}\right>$ were paired in different combinations and deformed by plane strain compression to moderate strain levels of 1.0 to 1.5. Orientation dependent mechanical behavior was distinguishable from that of the neighbor-influenced behavior. In interacting crystals the constraint on the rolling direction shear strains ($\gamma_{_{XY}}, \gamma_{_{XZ}}$) was found to be most critical to show the effect of interactions via the evolution of local microstructure and microtexture. Interacting crystals with increasing deformations were observed to gradually rotate towards the S-component, $\{123\}\langle\bar{6}\bar{3}4\rangle$. Apart from the average lattice reorientations, the interacting crystals also developed strong long-range orientation gradients inside the bulk of the crystal, which were identified as accumulating misorientations across the deformation boundaries. Based on a statistical procedure using quaternions, the orientation and interaction related heterogeneous deformations were characterized by three principal component vectors and their respective eigenvalues for both the orientation and misorientation distributions. For the case of a medium stacking fault energy metal like Cu, the texture and microstructure development depends wholly on the starting orientations. Microstructural instabilities in Cu are explained through a local slip clustering process, and the possible role of grain interactions on such instabilities is proposed. In contrast, the texture and microstructure development in a high stacking fault energy metal like Al is found to be dependent on the grain interactions. In general, orientation, grain interaction and material type were found to be key factors in the development of rolling textures in face-centered cubic metals and alloys. Moreso, in the texture development not any single parameter can be held responsible, rather, the interdependency of each of the three parameters must be considered. In this frame-work polycrystalline grains can be classified into four types according to their stability and susceptibility during deformation. / Thesis (Ph.D, Mechanical and Materials Engineering) -- Queen's University, 2009-09-25 23:59:11.809

This research takes a multidisciplinary approach to comprehensively investigate the material and mechanical properties as well as pore water chemistry of the Bearpaw shale. This made it possible to characterize how these properties relate to the mechanical strength of this material. The results of this research challenge our ideas of the hydrogeology and of the geological history of the region. Core samples of the Bearpaw Formation and the overlying glacial till were collected from a field site in southern Saskatchewan, Canada. A combination of laboratory tests including multi-staged oedometer tests, constant rate of strain oedometer tests, specialized triaxial swell tests, along with pore water chemistry and finite element modelling were used to meet the following objectives: (1) To investigate the material properties and compression behaviour of the Bearpaw in addition to assessing disturbance due to specimen size; (2) Examine the time dependent behaviour of the Bearpaw and the transferability of time rate models developed for soft soils to stiff soils; (3) Examine the swelling potential and behaviour of the Bearpaw Formation and the influence of boundary conditions on this behaviour, while assessing the applicability of the swell concepts developed for compacted materials to a naturally swelling clay material; and (4) Constrain the depositional age of the till overlying the Bearpaw Shale. Contrary to what is seen in soft soils, smaller sized specimens were found to reduce disturbance, and produce more accurate and consistent results. Creep was found to follow the same laws as it does in soft soils, calling into question whether the use of preconsolidation pressure to predict geological history in stiff clays is appropriate. There was significant variation in the observed swell pressures of samples of the same size and depth. Finally, the glacial till at site was found to belong uniquely to the Battleford Formation and ranges in age from 22,500 to 27,500 years which is much younger (over 100,000 years younger) than previously believed. / Thesis (Ph.D, Geological Sciences & Geological Engineering) -- Queen's University, 2010-01-29 01:34:14.071

Nuclear reactor steam generator tubes, manufactured from Nickel alloys such as Inconel 690 (INC690), are potentially susceptible to failure by Stress Corrosion Cracking where crack initiation may be exacerbated by internal stress fields. A more comprehensive understanding of this potential failure mechanism was gained via an exploration of a model of INC690’s behaviour under Constrained loading conditions in compression and tension. An Elasto-Plastic Self-Consistent (EPSC) model was used to predict the lattice stresses and strains resulting from Constrained loading in INC690 for four crystallographic planes. The internal strain fields generated under such conditions were shown to be markedly different from those developed under Uniaxial loading. Finite Element Modeling was used to design tensile and compression samples as well as a testing rig that would allow the application of a compressive load along one axis of the specimen with simultaneous constraint along another and free-deformation along the third. Lattice strain measurements were done for both compressive and tensile loading using Time-Of-Flight neutron diffraction. The predicted and experimental values showed reasonable agreement; mainly in terms of crystallographic plane interaction and behaviour. Iterative computer modeling was used to achieve a more realistic depiction of the lattice strains developed. This research allowed for an extension on the Uniaxial findings by examining the material’s behaviour under more complex loading that better approximates steam generator tube operating conditions. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2010-08-31 16:19:23.331

Robert Agnew’s general strain theory (1992, 2001, 2006a) proposes that strain leads to crime and deviance. Substance use is a specific type of criminal behaviour that the theory attempts to explain. This thesis uses general strain theory to examine how a number of specific types of strain – homelessness, childhood abuse, criminal victimisation, and sex work – are related to substance use. In addition, the relationships between strain and negative emotions are examined. This thesis also examines how the relationships between strain and substance use are conditioned by negative emotionality/low constraint, deviant peers, deviant values, coping skills, self-esteem, and emotional support. Finally, the role of gender in all of the above-mentioned relationships is explored. In short, this thesis represents a fairly comprehensive test of general strain theory as it applies to substance use. In order to conduct this test, data was obtained between May 2009 and August 2010 by administering a survey to 400 homeless street youth in Toronto, Ontario. The results yield substantial support for some of GST’s main propositions. In particular, support is found for hypothesized relationships between strain and substance use as well as strain and negative emotions. Additionally, certain factors are found to condition the relationships between strain and substance use. Finally, gender differences in the relationships between strain and substance use are observed. These supportive results suggest that general strain theory is a novel way of explaining substance use by homeless street youth in Canada. Consequently, suggestions for future research and social policy are offered. / Thesis (Master, Sociology) -- Queen's University, 2011-09-27 02:09:39.94

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No description available.

Structural Health Monitoring (SHM) is widely used to monitor the short and long-term behavior of intelligent structures. This monitoring can help prolong the useful service lives and identify deficiencies before possible damage of such structures. The sensing systems that are usually deployed are intended to faithfully relay readings that reflect the true conditions of these structures. Unfortunately, this is seldom the case due to the presence of errors in the collected data. The electrical strain gauges used in SHM environments for instrumentation purposes are susceptible to numerous sources of error. Apparent strain is known to be the most serious of all such errors. However or whichever way temperature variations of the gauge’s environment occurs, apparent strain is introduced. This work focuses on modeling apparent strain in an SHM environment using National Instruments’ (NI) hard and software. The results of this work are applicable for thermal compensation in current test programs.

This work investigates the extinction limits of laminar diffusion counterflow flames for various gaseous (methane, syngas, biogas) fuels using a high flow rate counterflow burner designed and built for this work. Equal momenta of the fuel and oxidizer streams were not maintained to provide data to check the fidelity of the numerical schemes and their chemical mechanisms at "non-standard" conditions. Strain rate values at extinction were obtained as a function of fuel mole fraction. Preliminary work with the new burner found that the methane extinction limit results were consistent with results from literature. The results provide insight into the extinction limit conditions of the aforementioned fuels. The strain rate was found to increase with increasing fuel mole fraction. Extinction limit results indicated that fuels with the highest concentration of hydrogen have the greatest extinction limit, which is believed to be attributed to the high diffusivity and reactivity of hydrogen.