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The high speed mini or micro-turbo electrical power system¡]MTEPS¡^has been used widely as an important spare power source in different military purposes and all kinds of emergency facilities. The interaction between the centrifugal and pressure load on turbo blades of a high speed MTEPS system is investigated in this project. The effect of temperature on the strength variation of the turbo blades will be investigated by employing the thermal-mechanical- creep coupling model provided in the MARC finite element method package. The stress distribution of the compressor, turbine, rotor and blades are calculated. The combined effect of temperature, pressure and rotation speed on the stress and deformation of compressor and turbine blades was also evaluated and compared in this project.

This thesis describes a new computer-based method for the generation of finite element meshes. It relies upon the Schwarz-Christoffel transformation, a conformal mapping from conplex variable theory. This mapping is defined and some examples of its use in classical fluid dynamics are given. A practical method for evaluating the parameters defining this transformation is described and emphasis is placed on the efficiency of the solution process in order that coirputer run times may be kept as short as possible. A theorem in Euclidean geometry is stated and proved which links the theory of the Schwarz-Christoffel mapping and the geometrical use to which it is put here. Two such Schwarz-Christoffel transformations are used to construct a mapping between any two polygons. The desirable properties of a finite element mesh are stated and a method is described which atteirpts to generate such a mesh in any sinply-connected two-dimensional region. Numbering of the nodes is an inherent part of the generation scheme, thus ensuring that the optimum bandwidth of the resulting system of linear equations in the analysis phase is obtained. In order to be able to present example meshes, a particular element type, the three-noded triangle, is used and a section describing the enumeration of hexagons, all of whose internal angles are 2n/3, is included. The thesis includes a brief survey of existing methods of two-dimensional mesh generation as well as several example meshes.

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Master of Science / Department of Architectural Engineering and Construction Science / Kimberly Kramer / The flying buttress is one of the most prominent characteristics of Gothic architecture. Understanding stress distribution from the upper vaulted nave (high vault) to the flying buttress system would contribute greatly to preservation efforts of such iconic structures. Many investigations have emphasized structural analysis of Gothic flying buttresses, but only limited research how architectural design affects load distribution throughout the Gothic members exist. The objective of this investigation was to inspire engineers and architectural preservationists to develop further research in Gothic structural analysis and restoration by increasing understanding how architectural design of flying buttresses affects the load path being transmitted from the main superstructure to the lateral force resisting system. Several flying buttress designs under similar analytical parameters were compared in order to understand how member geometries affect stress distribution. Because Gothic design is architecturally complex, finite element analysis method was used to obtain member stress distribution (regions of compressive and tensile stresses). Architectural elevation schematics of the flying buttresses of prominent Gothic cathedrals were referenced when modeling the structural members to a computer software program (RAM Elements).

Braiding is a mesmerizing phenomenon since flow and sediment transport interact and are able to change the morphology of a channel in a rapid and complex fashion. Conventional two-dimensional morphodynamic models estimate bedload distribution using shear stress distribution. However, it is unclear if the use of such shear stress distributions is relevant or applicable for all situations when using two-dimensional morphodynamic modelling. This thesis strives to investigate whether shear stress distributions are useful to predict bedload transport pathways. This study focuses upon prediction of bedload transport pathways using a morphodynamic model (Delft3D) of an anabranch of the Rees River (New Zealand). Observed bedload transport pathways were compared to modelled bedload transport pathways in an attempt to validate the predictive ability of the model. Results show that there is a significant correlation between predicted bedload transport pathways and the apparent bedload transport pathways derived from the field measurements. Furthermore, bedload transport predictions were in good agreement with observed data in areas where the model’s predictions of high shear stress were comparable to field observations. However, substantial bedload transport predictions in low shear stress areas were not adequately captured by the model, suggesting that the observed pathways were not due to high shear stress, but rather to other sediment supply sources.

Over the past three decades, technological innovations with respect to cemented paste backfill (CPB) as a means of ground support has allowed for increased production within the mining industry, management mine waste costs, as well as the improvement of the overall health and safety of underground mining operations. Despite the extensive use of this relatively new ground support material, many fundamental factors affecting the design of safe and economical CPB structures are still not well understood.Recently, a significant amount of academic and industry research has been conducted to better understanding the distribution of stress with respect to primary-secondary extraction sequencing for stope-and-fill mining operations. While current, as well as past research, as provided a wealth of knowledge on the distribution of stress through the fill material itself, it lacks in providing an examination into the mechanism by which stress is able to redistribute itself through the backfill material as well as within the surrounding rockmass. The scope of this work is to optimize stope-and-fill extraction sequencing through the analysis of stress distributions as well as local and global stability of multiple narrow verticalfully-drained backfilled stopes. Scientific investigations into the behavior of the CPB material and surrounding rockmass will result in animproved understanding of how to better implement engineered paste-fill materials as a means of ground support for underground mining operations. Numerical simulations (FLAC3D and RocScience) were utilized in analyzing hypothetical (literature) as well as site-specific (field) case studies. While these simulations confirm generalized stress behaviors within the backfill material for single and adjacent stopes, stress redistributions within the surrounding rockmass as well as the rock-pillarindicate the development of tensile and compressive zones. From these results, one is able to better approximate ground and CPB instability with respect to site-specific conditions, geometries, and material properties. These simulations have been validated with respect to published analytical solutions, numerical simulations, and site-measurements for single (isolated) and adjacent narrow vertical fully-drained backfilled stopes.

This study identifies mechanisms controlling interface shearing between pipes and granular materials and develops a predictive jacking force calculation model. The surface roughness of six pipe materials, including Hobas (Centrifugally Cast Fiber Reinforced Polymer Mortar), Polycrete (Polymer Concrete), Permalok Steel (Rolled Steel with a Painted Surface), Wet Cast Concrete, Packerhead Concrete, and Vitrified Clay pipe, have been characterized to determine the role of surface roughness on the soil-pipe interface shearing mechanism. Interface shear tests were performed between pipe materials and two characteristically different granular soils: Ottawa 20/30 sand and Atlanta Blasting sand. Shearing behavior between the sands and the pipe materials was evaluated to determine the mechanisms of shearing on materials with varied roughness values. Interface friction values were established for the pipe materials and soils. A model was developed to jacking forces based on modifications to Terzaghi's Arching Theory for predicting normal stresses and interface friction coefficients developed in the laboratory. Field research on fourteen case histories of microtunneling and pipe jacking projects was presented. Pertinent project details were provided including pipe materials, site geometry, geotechnical information, construction sequencing, lubrication injection, and jacking force records. Jacking force records for each project were separated into isolated segments along the alignment to analyze jacking stresses. Unlubricated segments of the microtunneling drive records were analyzed to compare actual and predicted jacking forces using the proposed model. The predictive model was compared to other models currently available for predicting the frictional component of jacking forces. Lubrication effects on jacking forces were analyzed to determine how the interface friction coefficient changed once lubrication was applied to the pipeline. Two types of lubrication strategies were identified and predicted lubricated jacking forces were shown. A step-by-step guide for using the jacking force predictive model was presented for design applications and estimating lubricated interface friction values.

Unconventional oil and gas, which is of major interest in petroleum industry, often occur in reservoirs with transversely isotropic rock properties such as shales. Overlooking transverse isotropy may result in deviation in stress distribution around wellbore and inaccurate estimation of fracture initiation pressure which may jeopardize safe drilling and efficient fracturing treatment. In this work, to help understand the behavior of transversely isotropic reservoirs during drilling and fracturing, the principle of generalized plane-strain finite element formulation of anisotropic poroelastic problems is explained and a finite element model is developed from a plane-strain isotropic poroelastic model. Two numerical examples are simulated and the finite element results are compared with a closed form solution and another FE program. The validity of the developed finite element model is demonstrated. Using the validated finite element model, sensitivity analysis is carried out to evaluate the effects of transverse isotropy ratios, well azimuth, and rock bedding dip on pore pressure and stress distribution around a horizontal well. The results show that their effect cannot be neglected. The short term pore pressure distribution is sensitive to Young’ modulus ratio, while the long term pore pressure distribution is only sensitive to permeability ratio. The total stress distribution generally is not sensitive to transverse isotropy ratios. The effective stress and fracture initiation are very sensitive to Young’ modulus ratio. As the well rotates from minimum horizontal in-situ stress to maximum horizontal in-situ stress, the pore pressure and stress distributions tend to be more unevenly distributed around the wellbore, making the wellbore easier to fracture. The pore pressure and stress distributions tend to "rotate" in correspondence with the rock bedding plane. The fracture initiation potential and position will alter when rock bedding orientation varies.

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