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In this thesis, a new method is proposed for measuring the surface specific acoustic impedance of sound absorbing materials using th e input electrical impedance of an electro-acoustic speaker. Master of Engineering (MPE)

This report features the work on contact stresses in engineering problem. The main focus is on the problem of a beam in three-point bending. Prior to this, standard textbook models such as cylinder to cylinder and cylinder to plate were used to validate the feasibility of the specific finite element software in solving contact problem. Master of Science (Precision Engineering)

Stress and strain are two familiar terms to designers and that is why, in most rubber companies, surface tension strain, and strain energy density are the two terms most often used for the prediction of rubber failure. Tearing energy or crack growth approach, even thought it has been around since 1920s, was hardly used in rubber industry due to its complexities and intensive computational needs. But with computers becoming faster every year, this method is more becoming the method of the choice. Master of Science (Mechanics & Processing of Materials)

In our current research, problems on a Zener-Stroh crack initiated at the interface of various multi-layered structures are analyzed in the context of linear elastic fracture mechanics. The solution of each of the problems begins with the derivation of the stress field due to an interfacial dislocation in the relevant multi-layered structures. The obtained stress fields are then used as Green function solutions to simulate corresponding Zener-Stroh crack with the aid of the distributed dislocation technique. Doctor of Philosophy (MPE)

Theoretical investigation on the crack growth behavior of two edge cracks emanating from a circular hole in zirconia toughened ceramics and to investigate the transient elastic field of dynamic inclusions, and their interactions with a nearby penny-shaped crack in 3-dimensional solids. Doctor of Philosophy (MPE)

In this dissertation, the stress field around a mixed dislocation lying in the (110) plane of a cubic crystal is investigated. It can be concluded that the dislocation line orientation, the elastic anisotropy and the Burgers vector direction all have significant influence on the stress field around the dislocation. Master of Science (Mechanics & Processing of Materials)

This project presents a method of constructing a computer-based presentation of 3D graphical facial model using free form Bezier surface representation. A facial model is constructed by using 36 Bezier patches. Each individual patch will have its own defined control points. Master of Science (Computer Integrated Manufacturing)

This thesis will extend the Battelle Two Curve approach to the effects of frozen backfill and crack arrestors by modifying Charpy energy. Master of Science (Mechanics & Processing of Materials)

Knowledge sorting is one way to organize the knowledge acquired from the domain expert(s) and various sources. Well-organized knowledge representation will make rule extraction much easier. In this work, a knowledge sorting process was adapted to facilitiate the rule extraction for a knowledge-based diagnosing piping system. Master of Science (Computer Integrated Manufacturing)

In this study, a copper heat sink, which is an electronic component with heat sinking function, is identified as a sample to verify the effectiveness of finite element simulation. Master of Science (Mechanics & Processing of Materials)

(This thesis consists of 2 sections) Aims to study the vibration and dynamic stability of cylindrical and conical shells, as well as the corresponding panels. The classical theory of thin shells is used and the mesh-free methodology is implemented for the vibration and dynamic stability analyses of cylindrical and conical shells/panels. Doctor of Philosophy (MPE)

This thesis reports the applicability of the Reproducing Kernel Particle Method (RKPM) for the analysis of laminated composite plates. The work includes linear and nonlinear analysis of laminated composite plates by the presented RKPM approaches, incorporating first-order shear deformation plate theory (FSDT). The applicability of the RKPM is examined and extended by systematical studies for laminated composite plates. The enforcement of essential boundary conditions is a difficult task for the analysis of meshless approximations. Because the basic RKPM shape function does not possess Kronecker delta properties, usually some transformations are needed to obtain the nodal displacements or other quantities. In this thesis, the full transformation method and the singular kernel method have been used to enforce the boundary conditions. These two methods modify the RKPM shape function to satisfy the Kronecker delta properties; the boundary conditions can then be easily treated as in finite element analysis. The singular kernel method is the first application for RKPM analysis. Doctor of Philosophy (MPE)

This report present a numerical model for rapidly computing the critical loads of beams with multiple delaminations and to analysis the buckling behaviour of laminated composite beam under in-place compression. This study is focused on beam has two unequal length parallel delaminations with one enveloping the other. Master of Science (Mechanics & Processing of Materials)

The thermal-induced distortions in three simple-shaped solids that are a cube, a short cylinder and a sphere loaded with temperature boundary conditons are studied. Lastly focus is made on our main concern for a slider head. Master of Science (Mechanics & Processing of Materials)

This report contains the results of a study on the interaction between cracks and inclusion. Such studies are of particular importance in the micro-mechanics of composite materials. Master of Science (Mechanics & Processing of Materials)

The main objective of present research is to develop a new unified constitutive model, taking into account of macrostructure factors such as phase size. Doctor of Philosophy (MPE)

This dissertation studies a specific process “Optimization of geometric reconstruction” in the problem of converting a 2D line drawing in to a 3D model. The solution being offered consists of two parts: identifying the circuits of edges in the drawing that form true faces of the 3D models, and then reconstruct the geometry using these faces as a basic. Master of Science (Computer Integrated Manufacturing)

In this research, extensive works were carried out to study the mechanics of the bi-leaflet mechanical heart valve (MHV) through both numerical and experimental studies.

The development and validation of one form of meshless methods, the Element-Free Galerkin (EFG) method, were presented in this thesis for the studies of bending and free vibration analysis of Mindlin-Reissner plates and finally the static and dynamic analysis of piezolaminated composite plates. Master of Engineering (MPE)

158 p. Artificial Heart Valves with the bi-leaflet design was introduced clinically around 1977. This design has proven to be an effective alternative to other valve designs. Many surgeons who were skeptical of this bi-leaflet design concept have since switched to using this ever popular valve design. The bi-leaflet valve design offers lower profile and improved haemodynamics. However due to the complex hinge design, there were cases of valve leaflet rendered immobile due to blood clotting in the narrow flow channel in the hinge region. In the early 1990s, there were cases of reported valve leaflet failure and further investigation led to a new research areas relating to cavitation in mechanical heart valve. Despite the so claimed improved bi-leaflet valve design, these valves are not problem free. Many problems related to haemodynamics of the valve remains a challenge for researchers to address. RG 75/98

This projects studies ways of modifying the 3D models so that all the faces are planar. Given that there is an infinite number of a possibility for the planar object, one key issue is to find the optimum-an object with planar faces that deviates from the original objects as little as possible. Master of Science (Computer Integrated Manufacturing)

This project was funded originally to develop a parallel manipulator for light machining operations such as final polishing. RG 16/95

This report describes the development of a 3-dimension (3D) computer simulation software to simulate parts feeding in a vibratory bowl feeder. Master of Engineering (MPE)

Currently, an automatic system for full-field photoelastic stress analysis still remains susceptible due to the ambiguity problem in phase-shifting digital photoelasticity. The project therefore studies the important problem and some new techniques have been developed with the aim of building up a unified tool for photoelastic stress analysis. Master of Engineering (MPE)

This project concerns the developlment of a window-based program to design planar four bar linkages for motion, path and function generation with three prescribed positions. Master of Science (Smart Product Design)

In this dissertation, the gear stress/strength rating is performed using the analytical method and the Finite Element Analysis (FEA) respectively. A gear error analysis and minimization technique is also introduced and discussed through the interpretation for the measured error curve and data. Master of Science (Precision Engineering)

The present work develops an improved theoretical model with the effect of inertia included. Master of Engineering (MPE)

This project presents the analysis of structure-borne noise in computer tower structure by statistical energy using the AutoSEA software, and followed by experimental verification. Optimization of noise and vibration transmission by damping application and plate geometry change, and development of optimal design modification technique by statistical energy analysis have also been carried out following the analysis. Master of Engineering (MPE)

In this project, stress investigation for a micro-crack initiated near various notches in an infinite plate (two-dimensional aspect) is analyzed. To study the fracture and failure mechanism due to stress concentrations near various notches of the tw-dimensional element. Master of Science (Mechanics & Processing of Materials)

An investigation was conducted on the degraded austenitic stainless plate. Master of Science (Mechanics & Processing of Materials)

This report presents the simulation study on the blast contour caused by the explosion of high explosive charge. Master of Engineering (MPE)

This work explores instrumented indentation methodology, both theoretically and experimentally, for mechanical properties of ductile metals and alloys including shape memory alloys. The objective is to conduct instrumented indention experiments with both spherical and sharp indenters on commonly available ductile metals. Master of Engineering (MPE)

This project aims to design, fabricate and assemble a computerized test rig.

Reinforced concrete (RC) Structures are frequently subjected to repeated loads, also called cyclic loads, and the resulting cyclic stresses can lead to microscopic physical damage to the materials involved. Even at stresses well below a given material's ultimate strength, this damage can accumulate with continued cycling until it develops into a crack that leads to brittle fracture failure of the structure. Brittle fracture does not have any telltale sign such as yielding of material before failure, which is extremely dangerous, if it is not well taken care. Master of Engineering (MPE)

This project aims at gaining a better understanding of the mechanics of precision grinding of brittle materials. Indentation and scribing experiments on brittle materials were carried out to study crack initiation and propagation, brittle-ductile transition and material removal mechanism. The results of indentation and scribing tests show that brittle materials can be machined in a ductile manner when penetration depth is less than a critical value. Single point diamond turning of brittle materials, both as an alternative machining technique in its own right and as a model for certain parameters involved in grinding, was performed. Experimental results show that the properties of the workpiece material have a considerable influence on the critical depth of cut. Mirror surfaces are more prone to be generated on single crystal silicon than glasses. A smooth surface with a roughness in nano-scale was produced on silicon by properly controlling machining parameters. Tool wear mechanism in diamond cutting of glasses was investigated.

The nonlinear interaction of finite-amplitude sound waves is a phenomenon that is encountered both in air and underwater. In this thesis, nonlinear interactions of acoustic plane waves in an air-filled duct as well as ultrasonic beams in air are studied. The final goal of the present study is to apply the nonlinear interaction of ultrasonic beams in air to sound reproduction. Doctor of Philosophy (MPE)

Default probabilities are important to the credit markets. Changes in default probabilities of a borrowing firm may predict the occurrence of financial distress or default in the firm. Knowing a firm's default likelihood is important to financial lenders as it allows them to estimate their resulting credit exposure to the firm. In this dissertation, we examine the likelihood of default of a group of local companies listed on the Singapore Exchange using the default prediction framework of the KMV Corporation of San Francisco. Although a variety of default risk models are available in the market, we have chosen the KMV approach for several reasons. First, it is relatively simple to implement. Second, by being based on stock market data rather than "historic" book value accounting data, it is forward-looking. Third, it has strong theoretical underpinnings, having its basis on the modern theory of corporate finance and options. Based on our study, there appears to be significant leading information about credit events in the expected default frequencies (EDFs) generated using the KMV framework. Master of Science (Financial Engineering)

This thesis describes work done to study structural vibration in the medium to high frequency range. Attention is focused on Statistical Energy Analysis (SEA), which is the primary high frequency analysis method at present. The principal aim of this thesis is to study the sensitivity of the coupling loss factor (CLF, which is a central parameter in SEA) to variation in the system properties, e.g. damping. An efficient method to measure the CLF is also proposed. The thesis also looks into the method of images. Considering its potential contributions to high frequency vibration analysis in general, and the development of SEA in particular, the theory is extended and the potential for its application is discussed. Doctor of Philosophy (MPE)

Investigation on piezoelectric inhomogeneity-crack interaction, contact model for bi-material interface strength study, and residual stress analysis for shot-peened materials. RG 61/95

This project investigates the interaction problem of a fiber-shaped piezoelectric inhomogeneity embedded in a non-piezoelectric elastic matrix which contains a crack. The matrix is assumed to be infinite in all directions and the crack is near the piezoelectric fiber. The body is subjected to a far-field in-plane tension and a far-field anti-plane electric field. Master of Engineering (MPE)

The differential quadrature (DQ)method displays potential to become an accurate numerical tool for mathematical approximation. Recently the solution capability of the DQ method has been aggressively explored especially in the field of computational mechanics. In this thesis, the DQ method is employed to solve three major categories of structural mechanics problems pertaining to plate. They are namely the bending, buckling, and free vibration of plates. The three-dimensional elasticity theory is adopted for the analysis of these plate problems as there is no DQ solution of this class in the open literature. In this study, various edge and lateral surface boundary conditions, and their combinations are considered. Master of Engineering (MPE)

Including: 3 parts. TiNi thin films have attracted much attention in recent years as intelligent and functional materials because of their unique properties. TiNi thin film based micro-actuators will become the actuator of choice in many aspects in the rapidly growing field of micro-electro-mechanical systems. In this report, TiNi and TiNiCu films were successfully prepared by co-sputtering of a TiNi target and a separate Ti or Cu targets. Some critical issues and problems in the successfully development of TiNi thin films were discussed, including preparation and characterization considerations, residual stress and adhesion, frequency improvement, fatigue and stability, patterning and modeling of behavior as well as functionally graded or composite thin films. Comparison was made of TiNi SMA microactuation with other microactuation methods. Different types of MEMS applications we have done so far (such as microgrippers, micropumps, micromirror, etc.) were reported and the prospects for future advances in fabrication process and device development were discussed.

Including: 3 parts. With greater demands for increasing data storage capacity, the flying height of the slider head has decreased to less than 50 nanometers, for example, to reach a storage density of 1 Tbig/in2 , a flying height of 3 nanometer is necessary [Wu & Bogy, 2001]. At this flying height, the topography of the surface of the disk and the slider head has to be taken into consideration. The extremely thin air-bearing beneath the slider head provides the necessary lifting force. However, at start-up and working conditions, contact is highly possible and two tribological problems arise: friction and wear. To protect the head and disk surface from these problems, a thin film lubricant is applied to the disk surface.

This work focuses on a numerical development of the differential quadrature method (DQM) for solving the bending and vibration of moderately thick plates with geometric complexity and various discontinuities, described by the Reissner/Mindlin first-order shear deformation theory. Doctor of Philosophy (MPE)

One of the commonly encountered types of defect in laminated composite structures is delamination. Delamination not only affects the strength and integrity of the structure by contributing to its final failure but also causes a reduction in stiffness, which affects its dynamic behavior. Master of Science

The present research addresses several important issues in structural dynamic modeling and relevant applications. Respective efforts are made to theoretical developments of time domain modal analysis, structural dynamic sensitivity analysis, structural modification prediction and structural damage detection. Doctor of Philosophy (MPE)

An emulsification system capable of producing water-in-disel emulsion; the emulsified fuel, was designed and fabricated.

Research has been concentrated on the evaluation of behaviour of frictional pairs in an attempt to improve their shelf life. Despite the efforts to obtain a better understanding of the behaviour of frictional systems, a convincing theory has yet to be established on the mechanism of scoring or scuffing. In-situ observation of frictional contacts was previously performed using either a scanning electron microscope or closed circuit digital camera and was restricted to the observation of leading and trailing edges of the contact. Recent work on in-situ observation of seizure facilitated use of idealized contact of sapphire disk. The present work was aimed at the in-situ observation of seizure by using an X-ray microscope (real time radiography), in practical contacts. This technique facilitates observation of interface during the testing which is not normally possible with the known techniques in case of non-idealized practical contacts. Doctor of Philosophy (MPE)

Including: 3 parts. System integration and miniaturization have become one of the most distinct trends of modern technological development where electro-mechanical devices are highly miniaturized and integrated into micro-systems to meet various challenging industrial and commercial applications. However, as these micro-systems are increasingly miniaturized to become smaller in size and lighter in weight, new structural mechanics related issues such as structural dynamics, kinematics, tribology, acoustics, mechanical properties of materials, fluid mechanics, thermal- mechanical interactions etc. become ever more acute and need to be carefully considered in micro-system designs, fabrication and assembly to optimize system performances. Most of these mechanics issues will assume different roles in different forms as compared with those involved in conventional system designs and even new mechanics/physics phenomena will emerge as the feature size of a micro-system becomes ever increasingly small. In order to improve design capabilities and hence performance of micro-systems, it is obvious that these various mechanics issues need to be rigorously studied and thoroughly understood to enable accurate modeling, characterization and control methodologies needed to be developed for micro-system applications.

In the offshore industry, a common operation problem is the last minute change of barge scheduled for transporting an offshore jacket to the designated location for installation while fabrication of the jacket is almost complete. Arising from this last minute alteration and/or addition of loading conditions, some of the tubular joints need to be reinforced in order to avoid punching shear failure due to axial compression. One of the convenient and less costly methods is to reinforce the joints with doubler plates. However, such reinforcements may have negative effects when the joints are subjected to different loading conditions. Thus the study of the behaviour of welded tubular joints reinforced with doubler plates is important, for which there is hardly any literature on such joint reinforcements Master of Engineering (MPE)