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Application Of Damage Mechanics For Fatigue Life Assessment., Md. Mustaqur Rahman
Application Of Damage Mechanics For Fatigue Life Assessment., Md. Mustaqur Rahman
Electronic Theses and Dissertations
Traditional multiaxial fatigue assessment models are based on the definition of an equivalent uniaxial measurement of the stress and strain tensors in the critical region of the studied component. An equivalent uniaxial criterion is then used to assess the fatigue life. In this thesis, we study a new approach based on Continuum Damage Mechanics theory. The introduction of the Continuum Damage Mechanics (CDM) in late 1970s to model fatigue has opened a new arena of research for developing a suitable model for multiaxial fatigue. In CDM, constitutive equations are derived by using internal variables under the framework of the thermodynamics …
Dynamic Analysis Of Guyed Antenna Towers For Seismic Loads., Hussam M. Meshmesha
Dynamic Analysis Of Guyed Antenna Towers For Seismic Loads., Hussam M. Meshmesha
Electronic Theses and Dissertations
The increasing demand for personal communication services (PCS), such as digital cell phones and pagers, as well as digital television (DTV), has created new challenges for creating and maintaining telecommunications towers. For such communication tools, antenna towers are the best choice because they are relatively economical and effective for remote transmission, especially in North America where land area is large. Wireless firms are further pressured to complete digital systems within the next five years and to provide "seamless" coverage. The Canadian Standard for Antennas, Towers and Antenna-Supporting Structures, CSA-S37-01, provides guidance for seismic analysis of lattice towers. However, simplified design …
'Green' Manufacturing: A Life Cycle Inventory Of The Automotive Paint Process And Protocols For Industry Application., Angelos Anastassopoulos
'Green' Manufacturing: A Life Cycle Inventory Of The Automotive Paint Process And Protocols For Industry Application., Angelos Anastassopoulos
Electronic Theses and Dissertations
In response to growing interest in 'green' vehicles, Life Cycle Analysis (LCA) and Life Cycle Inventory (LCI) concepts can quantify the automobile's environmental impacts. Potential benefits include Design-for-Environment (DfE) opportunities, increased manufacturing efficiencies, and future application to consumer-based eco-rating systems. Detailed and up-to-date LCI data for general application by LCI practitioners does not exist at this time for the majority of Manufacturing/Assembly processes in North America, including the automotive paint process. With an Original Equipment Manufacturer (OEM) industry partner's commitment to a publicly available LCI database (i.e., NREL LCI Database), however, a representative vehicle assembly facility was selected for completion …
Investigation Of Total Gaseous Mercury In The Atmosphere Of The Great Lakes And St. Lawrence River Basin., Hongyu You
Investigation Of Total Gaseous Mercury In The Atmosphere Of The Great Lakes And St. Lawrence River Basin., Hongyu You
Electronic Theses and Dissertations
Mercury (Hg) is a highly toxic pollutant, and it can undergo long-range transport in the atmosphere. Hg is a pollutant of concern because of its tendency to accumulate and concentrate in biota. In this study, a statistical analysis of total gaseous mercury (TGM) was carried out using seven years of measurements at three Canadian Atmospheric Mercury Measurement Network (CAMNet) sites in the Great Lakes basin and three years measurements at two CAMNet sites in the St. Lawrence River basin. The average TGM concentrations ranged from 1.59 +/- 0.24 to 1.84 +/- 0.39 ng m-3 at the five sites. Two of …
Parametric Analysis Of Bolted Flange Connections Of Circular Monopoles., Olumadunwa Olusanya
Parametric Analysis Of Bolted Flange Connections Of Circular Monopoles., Olumadunwa Olusanya
Electronic Theses and Dissertations
The present study involved the parametric analysis of bolted flange connections of eighteen different circular monopoles. The parameters considered were the number of bolts (8, 6, and 4) and thickness of flange plate [25.4 mm (1.0 in.), 19.05 mm (0.75 in.) and 12.7 mm (0.50 in.)]. These were analyzed under stiffened and unstiffened conditions. Four, two and four stiffeners, 12.7 mm (0.50 in.) thick, were used with 8-, 6- and 4-bolt arrangements. Each finite element model is made up of a small diameter (171.5 mm) circular pipe and a large diameter (327 mm) circular pipe both welded to circular flanges. …
Two-Dimensional Scour Hole Problem: Role Of Fluid Structures, Alex Bey
Two-Dimensional Scour Hole Problem: Role Of Fluid Structures, Alex Bey
Electronic Theses and Dissertations
An experimental program was carried out to further understand the scour caused by a plane wall jet. To this end, a two-dimensional laser Doppler anemometer was used to characterize the velocity field at various stations in the scour hole region. Present observations indicate that different types of flow structures influence scour at different time periods. Following vigorous digging caused principally by jet shear forces and impingement at the start of the test, the flow was characterized by the presence of longitudinal axial vortices, turbulent bursts and movement of the jet impingement point during the later stages. Attempts have been made …
Use Of Acoustic Emission Signals Through Steel Reinforcement To Detect The Onset Of Corrosion, Weiben Chen
Use Of Acoustic Emission Signals Through Steel Reinforcement To Detect The Onset Of Corrosion, Weiben Chen
Electronic Theses and Dissertations
Corrosion processes produce elastic energy waves in the form of acoustic emission (AE). For corrosion in reinforced concrete structures, AE waves are emitted beginning with the depassivation of oxide layers of reinforcing steel, the initial stage of corrosion processes. This study examines the feasibility of using AE technique to detect corrosion through steel reinforcement, which has relatively lower attenuation than concrete. Comparison of coupling AE sensors on steel and on concrete was made. Accelerated corrosion regime and two-channel multifunctional AE equipment with piezoelectric sensors were employed for laboratory experiments. The detectable distance from corrosion source to sensor was estimated via …
Experimental And Numerical Investigations Of Chemical Grouting In Heterogeneous Porous Media., Tirupati Bolisetti
Experimental And Numerical Investigations Of Chemical Grouting In Heterogeneous Porous Media., Tirupati Bolisetti
Electronic Theses and Dissertations
The objective of the present study is to understand the processes influencing the colloidal silica grout injection into porous media through experimental and numerical investigations. Experimental studies include viscosity measurements, grout injection into columns and grouted sand testing. The grout viscosities are measured during gelation under shear. Colloidal silica grout injection experiments are performed on two different sizes of columns to understand the grouting processes as well as to generate data for numerical simulations. The larger diameter column experiments are performed by varying colloidal silica solution and the type of water. The smaller diameter column (slim tube) experiment was conducted …
Reliability Analysis Of Laterally Loaded Piles Embedded In Soft Clay Below Water Table., Sunghan Lee
Reliability Analysis Of Laterally Loaded Piles Embedded In Soft Clay Below Water Table., Sunghan Lee
Electronic Theses and Dissertations
This study will present the theoretical formulation and numerical investigation of laterally loaded piles embedded in soft clay below the water table with random design variables. For the given statistical data on design parameters, it will determine the assessment of statistical performance of laterally loaded piles. The pile behavior depends on: the soil-pile material parameters (EI, b, epsilon50, c, gamma), which are considered as the random variables; type of load (force, bending moment); magnitude of load (nonlinear behavior); type of constraints (free head or fixed head) and type of structural system (single isolated pile or pile group). For single piles, …
Scour By Submerged Square Wall Jets At Low Densimetric Froude Numbers., Partha Sarathi
Scour By Submerged Square Wall Jets At Low Densimetric Froude Numbers., Partha Sarathi
Electronic Theses and Dissertations
In this research an effort is made to better understand the scour caused by submerged square jets in a cohesionless bed. The variables of interest are the densimetric Froude number, the tailwater depth and sediment grain size. Experiments were carried out at three different values of densimetric Froude numbers (= 3.9, 6.6 and 10.0), a range of tailwater conditions varying from low to very high submergence, and two different sand bed grain sizes. Velocity measurements were conducted using a laser Doppler anemometer. At a given densimetric Froude number, progressing from the start of the test towards asymptotic conditions, the geometric …
Modal Identification Using Optimization Approach., Li Li
Modal Identification Using Optimization Approach., Li Li
Electronic Theses and Dissertations
In this thesis, the modal identification problem is pursued using two different optimization approaches. The first approach is a deterministic optimization approach that minimizes the output model error in the time domain between a direct solution using the modal model and the measured response. Examples of single-input single-output identification are used to illustrate this method; it has been shown this approach is robust against noise and can be used to fine-tune the modal parameter, especially for the damping. The second approach is based on probabilistic optimization; the objective function is defined as the a posteriori probabilistic density of the parameters …
P-Delta Effect For Leg Members Of Latticed Communication Towers., Mitul Shah
P-Delta Effect For Leg Members Of Latticed Communication Towers., Mitul Shah
Electronic Theses and Dissertations
Guyed Latticed Communication Towers are highly complex structures which are very difficult to model and analyze. Because of their geometric non-linearity, P-D effects are significant. To evaluate this, a sample guyed tower with one set of guys was modeled and linear and non-linear analyses were carried out to show the effect of P-D. Because of P-D effect, the moments are magnified by 1.29. The results show clearly that P-D effect cannot be ignored. Three representative guyed towers of 76.8 m (252 ft), 212 m (697 ft) and 583 m (1914 ft) height with four, five and nine guy levels respectively …
Characteristics Of Confined Square Jets In The Vicinity Of A Free Surface., Girish Sankar
Characteristics Of Confined Square Jets In The Vicinity Of A Free Surface., Girish Sankar
Electronic Theses and Dissertations
The results of an experimental investigation of a turbulent jet flow issuing from a square nozzle in the vicinity of a free surface are presented. Experiments were conducted using a two-dimensional laser Doppler anemometer and a particle image velocimeter. The focus of this study was the near region of the jet (X/B < 30). Here, B refers to the nozzle width and X is the distance from the nozzle exit. LDA measurements were conducted at eight stations downstream of the nozzle exit along the centerline of the jet. Four tailwater depths were used in this study. Additional measurements were also conducted to identify axis switching and to this end measurements were obtained at various transverse locations. PIV measurements were conducted in the near jet region (X/B < 3) corresponding to a tailwater depth of 2.5B. A good comprehension of the fluid dynamics of a square jet expanding in the vicinity of the free surface is achieved. Higher order moments were calculated to provide information on the coherent structures and study the role of velocity fluctuations. Two local peaks on either side of the jet centerline is observed. The difference in magnitudes of the peaks indicate differences in the prevailing entrainment characteristics on the top and bottom portions of the jet. Through the quadrant analysis, sweep and ejection type events were observed. To better understand these events, four kinds of eddies are classified for simplicity and their behavior is discussed.* (Abstract shortened by UMI.) *This dissertation is a compound document (contains both a paper copy and a CD as part of the dissertation). The CD requires the following system requirements: Microsoft Office.Dept. of Civil and Environmental Engineering. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis2005 .S26. Source: Masters Abstracts International, Volume: 44-03, page: 1441. Thesis (M.A.Sc.)--University of Windsor (Canada), 2005.