Thesis (M.S.)--Marquette University, 2009. / Robert J. Stango, Raymond A. Fournelle, Vikram Cariapa, Advisors.

Nowadays technology development places increasing demands on miniature and micro components and products, and micro-milling is one of the most flexible machining processes in manufacturing 3D structures and complex structured surfaces. A thorough and scientific understanding on fundamentals of the micro-milling process is essential for applying it in an industrial scale. Therefore, in-depth scientific understanding of the micro-cutting mechanics is critical, particularly on size effect, minimum chip thickness, chip formation, tool wear and cutting temperature, etc. so as to fulfil the gap between fundamentals and industrial scale applications. Therefore, three key fundamental research topics are determined for this research, and a comprehensive study on those topics is conducted by means of modeling, simulation, experiments. The topics include chip formation process in micro-milling, novel cutting force modeling in multiscale and study on the tool wear and process monitoring. The investigation into chip formation process in micro-milling consists of three stages; the micro-cutting process is firstly simulated by means of FEA with a primary focus on finding the minimum chip thickness for different tool/material pair and explaining the size effect; the simulation results are then validated by conducting micro-cutting experiment on the ultra-precision lathe. Experiments are carried out on aluminium 6082-T6 with both natural diamond and tungsten carbide tool. By knowing the minimum chip thickness for different tool/material pair, the chip formation process is investigated by performing comparative study by using the diamond and tungsten carbide micro-milling tools. As the minimum chip thickness for diamond micro-milling tool is smaller than that for tungsten carbide tool compared to nominal chip thickness, MCT is ignored in diamond micro-milling. Thus the comparative study is conducted by utilizing both tools with perfectly sharpened cutting edge and tools with the rounded cutting edge in micro-milling. The chips are inspected and associated with cutting force variations in the micro-milling process. The findings are further consolidated by comparing with research results by other researchers. The cutting force modeling is developed in three different aspects, e.g. cutting force on the unit length or area and cutting force on the unit volume in order to better understand the micro-cutting mechanics in aspects of size effect, tool wear mechanism and the cutting energy consumption. The mathematical modeling firstly starts with a novel instantaneous chip thickness algorithm, in which the instantaneous chip thickness is computed by taking account of the change of tool geometry brought about by the tool runout; then the collected cutting forces are utilized to calibrate the model coefficients. For accurate measurement on cutting forces, the Kalman Filter technique is employed to compensate the distortion of the measured cutting force. Model calibration is implemented using least-square method. The proposed cutting force model is then applied in micro-milling to represent the conditions of tool wear and the cutting energy consumption. Further study on the surface generation simulation is based on force model and its comparison with the machined surface is also performed. Cutting experiments using the new tungsten carbide tool are carried out and the tool wear is monitored offline at different machining stages. The dominant tool wear types are characterised. Tool wear is investigated by mainly analysing cutting force at different tool wear status. Frequency analysis by Fourier Transform and Wavelet Transform are carried out on the force signals, and features closely related to the tool wear status are identified and extracted. The potential of applying these features to monitoring the tool wear process is then discussed. Experimental studies to machine the structured surface and nano-metric level surface roughness are presented, the machining efficiency, dimensional accuracy and tool-path strategies are optimised so as to achieve the desired outcomes. Moreover, investigation on cutting temperature in micro-cutting is also studied to some extent by means of simulation; the influence of cutting edge radius on cutting temperature is particularly investigated. Investigation on above aspects provides systematic exploration into the micro-milling process and can contribute substantially to future micro-milling applications.

The ultimate goal of this research is to develop a method, from the designers point of view, for using the embodied specialized knowledge of Finite Element Analysis [FEA] software to study the behavior of materials, geometries, and configurations in order to create an iterative design feedback loop that uses structural performance as a primary evaluation criteria and point of departure for generating and refining complex formo-techtonic configurations while ensuring constructability, improved structural performance, and syntactic consistency. Syntactic consistency meaning that there would not be a loss in translation from concept to construct. Instead of the 2-dimensional [planar] manual technology which drove modernist analysis towards the structural hyper-rationality of the trabeated system, this new process should compile and synthesize computational speed, mathematic principles, mechanical knowledge, and material logics within a digital 3-dimensional [spatial] analytical environment in order to realize a new paradigm of constructible spatialized sensuality. The research will focus on the development of interoperability techniques and protocols between advanced parametric CAD systems and advanced structural analysis systems towards the creation of a fluid design + analysis process of creating and engineering complex forms and dynamic systems. Rapid prototyping will be integrated as a secondary feedback and verification loop, and as a precursor to the production of full scale construction machine readable files. In other words, the research focuses on the development of intricately designed, geometrically complex, and materially sophisticated structural skins that can be produced through advanced CAD/CAM techniques.

Natural surfaces are usually associated with feature graphs, such as the cortical surface with anatomical atlas structure. Such a feature graph subdivides the whole surface into meaningful sub-regions. Existing brain mapping and registration methods did not integrate anatomical atlas structures. As a result, with existing brain mappings, it is difficult to visualize and compare the atlas structures. And also existing brain registration methods can not guarantee the best possible alignment of the cortical regions which can help computing more accurate shape similarity metrics for neurodegenerative disease analysis, e.g., Alzheimer’s disease (AD) classification. Also, not much attention has been paid to tackle surface parameterization and registration with graph constraints in a rigorous way which have many applications in graphics, e.g., surface and image morphing. This dissertation explores structural mappings for shape analysis of surfaces using the feature graphs as constraints. (1) First, we propose structural brain mapping which maps the brain cortical surface onto a planar convex domain using Tutte embedding of a novel atlas graph and harmonic map with atlas graph constraints to facilitate visualization and comparison between the atlas structures. (2) Next, we propose a novel brain registration technique based on an intrinsic atlas-constrained harmonic map which provides the best possible alignment of the cortical regions. (3) After that, the proposed brain registration technique has been applied to compute shape similarity metrics for AD classification. (4) Finally, we propose techniques to compute intrinsic graph-constrained parameterization and registration for general genus-0 surfaces which have been used in surface and image morphing applications.

M. Tech. (Department of Mechanical Engineering, Faculty of Engineering and Technology), Vaal University of Technology. / The purpose of this study was to develop a design synthesis approach that can be used to reach an optimal design solution (in terms of the strength, stiffness and weight) of automotive body structures during the conceptual stages of the design process. Two conceptual model variants; standard sedan and open-top unitary body structures that were made from the same platform were analysed for their maximum bending moment, stresses, deflections and their maximum load carrying capacity. Topology optimization was also undertaken in order to find a lightweight design of the body structures. The body structures were modelled using three different modelling techniques, namely; the simple beam model, the simple structural surface (SSS) method and the finite element (FE) method. The simple beam model was used to determine the axle reaction forces and the maximum bending moment of a body structure that was subjected to static and dynamic loading conditions. Dynamic load factors and an extra safety factor were used to simulate the dynamic bending loads. The factors were varied from 1.0 to 4.5 with a step of 0.5. It was found that the maximum bending moment under dynamic loading is simply a multiple of the static maximum bending moment and they both occur at a position that is close to the rear part of the front seats. The effects of different geometries on the strength, stiffness and the weight of body structures were studied using the finite element method. The two conceptual models were made into four different plane FE models with each concept having two different FE models. The panels of these models were constructed as simple structural surfaces and were based on the SSS analysis of the standard sedan. The models were subjected to bending and torsion load cases. Each load case was varied similarly for 19 different iterations until the yield point was reached for each FE model. It was also found that the load-displacement graphs were linear for loading within the elastic range, even if there are subassemblies that are missing. However, it was found that this relationship ceases to apply once the body structures are subjected to the torsion loads that are above the yield load. It was also found that the qualitative response to torsion loads was similar for all four body structures. However, the quantitative response was quite observable. It was found that the stiffness can be reduced by at least 37% by omitting subassemblies for the same platform and almost the same mass of the body structure. In addition, the effects of different materials on the strength, stiffness and the weight of body structures were also studied. It was found that lightweight designs can be achieved by using lightweight materials. However, both the bending and torsion stiffness were observed to be reduced or increased in proportion to the Young’s modulus or modulus of elasticity of the material that was used to construct the models. It was also noted that, the stiffness to weight ratio remained almost the same for the same models made from different materials. Topology optimization was undertaken in order to determine alternative load paths of the body structures. The two conceptual models were made into four different solid FE models. It was observed that the load paths remain similar for different volume fraction constraints for similar models under similar loading conditions. It was also noted that at least 20% in weight savings and at least 5% in torsion stiffness improvement can be achieved when topology optimization is used to determine the alternative load paths for a standard sedan model. Besides, the load carrying capacity was found to remain similar. However, the bending stiffness was noted to have reduced due to the reduction in the mass of the structure. In contrast, it was found that for an open-top model, both the bending and torsion stiffnesses were reduced in proportion to the reduction in the mass of the body structure. In addition, it was observed that a further reduction in the mass of the open-top body structure can also significantly reduce its load carrying capacity. Although the stiffness of the optimized open-top model was noted to have reduced due to the reduction in the mass of the structure. The stiffness to weight ratio of the optimized body structure was higher than that of the non-optimal structure.

Principal message of this thesis is to introduce designer Pavel Pánek putting him into proper historical context and to reveal some of his unpublished designs or sketches which are hidden to the eye of wider audience. First chapter is fully devoted to the concise history of technique of pressing glass and mention is made of so called pressing ring playing important role in it. One of the sections contains in brief Pavel Pánek's biography where some moments of crucial importance are underlined. Most important part is that, which provides with account of Pánek's works that I found either interesting or crucial for the development of pressed glass. At the beginning of the description of each piece brief description of used technology is added. I am striving to emphasize Pánek's inexhaustible inventiveness and knowledge of techniques that eventually gave rise to some of his best pieces ever. It appears that in some way Pánek was to a certain extent predestined to grow into a sculptor of great providence especially for the sake of his vocational education. Due to the fact Pánek's personality faces false accusation of plagiarism and theft of foreign invention nowadays I had to include apologetic chapter in it. At the end of the thesis I conclude that Pánek, embodied one of the most experimentally -...