Jianghui Yin, Ryerson University

Date of Award

2007

Degree Type

Thesis

Degree Name

Master of Applied Science (MASc)

Department

Mechanical Engineering

First Advisor

Jun Cao

Abstract

A detailed non-isothermal computational fluid dynamics (CFD) model for proton electrolyte membrane (PEM) fuel cells is developed in this thesis. This model consists of the equations of continuity, momentum, energy, species concentrations, and electric potentials in different regions of a PEM fuel cell. In particular, the fairly thin catalyst layers of the fuel cell are assigned a finite thickness instead of being treated as nil thickness interfaces in other PEM fuel cell models. Various source/sink terms are presented to associate the conservation equations with the electrochemical reaction kinetics. The water balance in the

membrane is modeled by coupling diffusion of water, pressure variation, and the electro-osmotic drag. The membrane swelling effect is explicitly considered the newly derived model, leading to a set of novel water and proton transport equations for a membrane under the partial hydration condition. The electron transport in the catalyst layers, gas diffusion layers and bipolar plates are also described. The PEM fuel cell model developed has been implemented into a commercial CFD software package for simulating various flow and transport phenomena arising in operational PEM fuel cells, analyzing the impact of design and operating parameters on the cell performance, and optimizing the PEM fuel cell design.

Modeling and simulation

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Janaka S. Weerasinghe, Ryerson University

Date of Award

2007

Degree Type

Thesis

Degree Name

Master of Applied Science (MASc)

Department

Mechanical Engineering

First Advisor

Filippo A Salustri

Abstract

Concept Maps and wikis were examined as tools that compliment the engineering design process and better facilitate collaboration between geographically dispersed design teams. Concept maps are a visual knowledge capture medium that can be used to promote the understanding of the design problem and in providing an organizational reference for the entire project. Wikis are editable websites that give the users the freedom to add content in any manner, thus providing a project management platform for design teams. This thesis reports on five studies by the author in which concept maps and wikis are used as

both tools for the design process as well as collaborative tools in various modes of interaction. Recommendations to improve concept maps and wiki technologies were determined based on the feedback from the participants in these studies. The wiki was used extensively as a project management tool but required some push for the participants to use. The hierarchical layout structure has been shown to be the favoured pattern by participants in the engineering field. Concept maps are also shown to be a clearer visualization tool than another accepted tool, Unified Modelling Language.

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Lan Shang, Ryerson University

Date of Award

2007

Degree Type

Thesis

Degree Name

Master of Applied Science (MASc)

Department

Mechanical Engineering

First Advisor

Guangjun Liu

Abstract

This thesis investigates temperature control of an aircraft engine bleed air system, aiming at reducing ram air usage to reduce fuel consumption while maintaining fast temperature control response. To achieve both of the objectives, a system configuration is designed to control both ram air and bypass flows. The analytical equations describing the systems dynamics are derived and utilized in developing the overall bleed air system model. Optimal state feedback control and output feedback control are applied in the

temperature control system. Computer simulations and experiments have been conducted, and the proposed configuration and control strategy are shown to be effective in minimizing ram air usage and

Thermal

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Lan Shang, Ryerson University

Date of Award

2007

Degree Type

Thesis

Degree Name

Master of Applied Science (MASc)

Department

Mechanical Engineering

First Advisor

Guangjun Liu

Abstract

This thesis investigates temperature control of an aircraft engine bleed air system, aiming at reducing ram air usage to reduce fuel consumption while maintaining fast temperature control response. To achieve both of the objectives, a system configuration is designed to control both ram air and bypass flows. The analytical equations describing the systems dynamics are derived and utilized in developing the overall bleed air system model. Optimal state feedback control and output feedback control are applied in the

temperature control system. Computer simulations and experiments have been conducted, and the proposed configuration and control strategy are shown to be effective in minimizing ram air usage and maintaining fast temperature control response in the meantime.

Thermal

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Imtiaz Ahmed Shaik, Ryerson University

Date of Award

2007

Degree Type

Thesis Project

Degree Name

Master of Engineering (MEng)

Department

Mechanical Engineering

Abstract

Currently in the electronics industry there is a desire to increase component reliability. Fatigue failure in solder joints is an important design consideration for electronic packaging. In through-hole components, fatigue failure of leads has been observed to antecede fatigue failure of solder joints. The main objective of the study for a solder joint in a plated-through-hole bearing the pin during the temperature cycle was to ascertain the thermo mechanical behavior and the dominant deformation mode. The Digital Speckle Correlation (DSC) technique, which is a computer vision technique, was applied for the measurement of solder joint deforamtion for a prescribed outlined temperature and time. The dimensions for the area of the solder joint under study were 21 by 21 um, located at the centre of the hole. And computation of

averaged shear strains at 6 data points for this area was done. R Darveaux's constitutive model was applied for the data analysis such as the solder joint yields stress with respect to the time and temperature. On achieving the stress solution, the measured total strains were partitioned into elastic, plastic and creep terms separately and hence the creep strain was evaluated. From the analysis, it was found that the dominant deformation mode was shear deformation due to mismatch of coefficient of thermal expansion between pin and copper plating material of through-hole under thermal loading. And the dominant deformation mechanism was creep strain while stress started to relax at the end of ramp up and continued throughout the test and creep strain rate decreased during high temperature dwell. In Addition, the elastic strain was dominating during the initial stage of thermal cycle but later it was neglibible when compared to creep strain.

Thermo mechanical analysis

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AmirAbbas Sartipi, Ryerson University

Date of Award

2007

Degree Type

Thesis

Degree Name

Master of Applied Science (MASc)

Department

Mechanical Engineering

First Advisor

Abdelaziz (Aziz) Laouadi

Second Advisor

David Naylor

Abstract

Domed skylights are important architectural design elements to deliver daylight and solar heat into buildings and connect buildings' occupants to outdoors. To increase the energy efficiency of skylighted buildings, domed skylights employ a number of glazing layers forming enclosed spaces. The latter are subject to complex buoyancy-induced convection heat transfer. Currently, existing fenestration design computer tools and building energy simulation programs do not, however, cover such skylights to quantify their energy performance when installed in buildings.

his work presents a numerical study on natural laminar convection within concentric and vertically eccentric domed cavities. The edges of domed cavities are assumed adiabatic and the temperature of the interior and exterior surfaces are uniform and constant. The concentric and vertically eccentric domed cavities were studied when heated from inside and heated from outside, respectively. A commercial CFD package employing the control volume approach is used to solve the laminar convective heat transfer within the cavity.

The obtained results showed steady flow for small Grashof numbers. For moderate and large Grashof numbers, depending on the gap ratio and the cases of heating from inside or outside, the flow may be steady or transient periodic with a single vortex-cell or multi vortex-cells. The Nusselt number for the case of heated from inside is greater than the case of heated from outside. The numerical results show that the changes in the gap ratio have smaller effect on Nusselt number in high profile domed skylights than lower profile domed skylights.

Thermal

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Derek Roeleveld, Ryerson University

Date of Award

2007

Degree Type

Thesis

Degree Name

Master of Applied Science (MASc)

Department

Mechanical Engineering

First Advisor

David Naylor

Abstract

A simplified model was developed to predict the radiative and convective heat transfer in complex fenestration systems, including the effect of solar radiation. The focus of the current work was on Venetian blinds mounted adjacent to the indoor window surface. From the perspective of convection, the model used a convective flat plate flow between the blind and ambient surroundings and a convective channel flow between the window and blinds. It was necessary to develop new empirical correlations to predict the average channel Nusslet numbers of the hot and cold walls separately.

Therefore, a CFG study of free convection in an asymmetrically heated channel was performed. Then, the new empirical correlations were used to develop a simplified one-dimensional model of the heat transfer in the system. The radiative heat exchange between the blind, window and room was calculated using a four surface grey-diffuse model. Sample predicted results were compared with existing experimental and numerical data from the literature.

Thermal

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Derek Roeleveld, Ryerson University

Date of Award

2007

Degree Type

Thesis

Degree Name

Master of Applied Science (MASc)

Department

Mechanical Engineering

First Advisor

David Naylor

Abstract

A simplified model was developed to predict the radiative and convective heat transfer in complex fenestration systems, including the effect of solar radiation. The focus of the current work was on Venetian blinds mounted adjacent to the indoor window surface. From the perspective of convection, the model used a convective flat plate flow between the blind and ambient surroundings and a convective channel flow between the window and blinds. It was necessary to develop new empirical correlations to predict the average channel Nusslet numbers of the hot and cold walls separately.

Therefore, a CFG study of free convection in an asymmetrically heated channel was performed. Then, the new empirical correlations were used to develop a simplified one-dimensional model of the heat transfer in the system. The radiative heat exchange between the blind, window and room was calculated using a four surface grey-diffuse model. Sample predicted results were compared with existing experimental and numerical data from the literature.

Thermal

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Ivan Nikolaev, Ryerson University

Date of Award

2007

Degree Type

Thesis

Degree Name

Master of Applied Science (MASc)

Department

Mechanical Engineering

Abstract

A guarded hot plate apparatus was used to generate comprehensive sets of thermal conductivity for two types of soils, namely Ottawa sand and Richmon Hill clay-loam, for temperature variation from 2 to 92°C and moisture content variation from complete dryness to full saturation with measurement errors of less than 3%. Numerical simulation of heat transfer within the apparatus with sample inside was performed to validate the experimental design and setup. To prepare the samples, a consistent specimen preparation technique was developed for the cases of dry, barely-to-moderately moist, and highly-to-fully saturated moist soils.

On the basis of gathered datasets, empirical correlations for soil thermal conductivity were developed as a function of both temperature and moisture content. The proposed correlations produced excellent fit to majority of the experimental data, and could be easily integrated into numerical analysis of underground heat transfer. As an application example, one of the correlations was employed to evaluate soil thermal conductivity in a numerical study of underground heat loss from a basement wall and floor, in order to illustrate the importance of considering the dependence of soil thermal conductivity on soil texture, temperature and degree of saturation.

Thermal

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Hossein Najmi, Ryerson University

Date of Award

2007

Degree Type

Thesis

Degree Name

Master of Applied Science (MASc)

Department

Mechanical Engineering

First Advisor

A Varvani-Farahani

Abstract

The present study intends to develop a fatigue damage model to assess the fatigue response of human cortical bone by incorporating stiffness degradation of bone materials as the number of loading cycles progresses. The proposed fatigue damage model is defined based on mechanical properties and biological parameters of human cortical bone subjected to repeated loads. Stiffness loss in bone and bone constituents was used as a damage index to model the response of fatigue damage. The proposed damage model in this thesis considered bone as a natural composite material consisting of Haversian osteons (fibres) embedded in interstitial bone (matrix) and separated by weak cement-line intrfaces.

Predicted fatigue damage results were found in good agreement with many experimentally obtained damage results of human cortical bone. The proposed damage equation also showed a higher degree of success in damage assessment of cortical bone samples tested by different laboratories as compared to other earlier developed damage models.

The proposed damage model, for the first time, successfully correlated the mechanical and histological properties of human cortical bone with damage accumulation of bone constituents. These parameters represent mechanical and histological properties of cortical bone specimens such as osteon volume fraction, donor age, cyclic stress magnitude, secant modulus of osteons, cement line interfacial strength and other bone constituent mechanical properties.

A computer program was also developed to assess fatigue damage of cortical bone by the proposed damage model and evaluate the proposed model with experimental data extracted from the literature.

Fatigue

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Richard P. Mohamed, Ryerson University

Date of Award

2007

Degree Type

Thesis

Degree Name

Master of Applied Science (MASc)

Department

Mechanical Engineering

First Advisor

Jeff Xi

Second Advisor

Guangjun Liu

Abstract

n this thesis, a newly developed kinetostatic model for modular reconfigurable robots (MRRs) is presented. First, a kinetmatic computational method was created to allow for simple connectivity between modules which included the possibilities of angular offsets. Then, a flexibility analysis was performed to determine the static and dynamic flexibility of link and join modules and the regions of flexibility were plotted to determine exactly which of the components can be considered flexible or rigid,

depending on their sizes. Afterwards, the kinetostatic model was developed and compared to a finite element model and results give essentially the same tip deflections between the two models. This kinetostatic model was then used to determine the maximum allowable payload and maximum deflection position for a given MRR. Additionally, a direct method was created to determine the cross section properties of all modules in a given MRR for a given payload and maximum desirable tip deflection.

kinetostatic analysis

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Elena Miroshnichenko, Ryerson University

Date of Award

2007

Degree Type

Thesis

Degree Name

Master of Applied Science (MASc)

Department

Mechanical Engineering

First Advisor

Donatus Oguamanam

Abstract

A functionally graded (FG) beam with an active constrained-layer damping (ACLD) treatment is modeled and analyzed. ACLD consists of a passive element, in the form of a viscoelastic layer bonded to the host structure, and an active constraining element which is represented by a piezoelectric fiber-reinforced composite (PFRC) laminate. It is assumed in the current formulation that the field variables are expressible as polynomials through the thickness of the beam and are cubically interpolated across the span. Hamilton's principle is used in the derivation of the equations of motion,

which are solved using the Newmark time-integration method. The versatility of the formulation is demonstrated using different support mechanisms in the form of analysis of cantilevered, fixed-end partially-constrained and simply-supported beam cases. The effects of ply orientation in PFRC laminate and varying elastic modulus in the FG beam are also examined.

Finite Element method

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