Cascas cilíndricas circulares com uma pequena variação de espessura ao longo de seu comprimento, quando submetidas à rotação, apresentam em alguns casos, deslocamentos elásticos de sua superfície externa, tendendo a uma forma de um oval. O objetivo deste trabalho é estabelecer a relação entre a variação de espessura das cascas cilíndricas com a sua deformação devida às forças centrífugas medida durante a rotação utilizando-se dois enfoques, um experimental e outro numérico, no caso o método de elementos finitos (MEF). As cascas cilíndricas estudadas tiveram sua espessura de parede medidas por meio de aparelho de ultra-som, mas por serem fabricadas em ferro fundido cinzento, as suas lamelas de grafita atuam como refletores, o que torna a medição imprecisa. Os resultados da análise numérica encontrados se relacionam bem com os experimentais de maneira qualitativa, mas divergem na forma quantitativa. Modelos de cascas com variação de espessura imposta também foram criados e analisados usando-se o método de elementos finitos de forma a se avaliar o comportamento da casca cilíndrica sob diversas configurações de distribuição da variação da espessura. Sugere-se a pesquisa de novas tecnologias para medições por ultra-som de peças fabricadas de ferro fundido com grafita lamelar. Neste trabalho, a medição da forma oval foi feita utilizando-se sensores de proximidade do tipo \"eddy-current\". / Circular cylindrical shells with small thickness variations along their body, when submitted to rotation, present, in some cases, elastic displacements of their outside surface induced by centrifugal forces leading to final oval like shapes. The main purpose of this study is to establish relationships between thickness variation of the cylindrical shells with their measured deformation during the rotation, due to centrifugal forces, using two approaches, one experimental and the other one numerical, in the latter case the finite element method (FEM). The studied cylindrical shells had their wall thickness measured by means of an ultrasound device. The used material is flake graphite cast iron (gray cast iron). The graphite flakes act as reflectors, what makes such measurements imprecise. The numerical results found are satisfactory in a qualitative way, but they disagree in the quantitative form. Shell models with theoretical imperfections also were created and analyzed using the finite element method in order to evaluate the behavior of the cylindrical shell under several configurations of distribution of the shell thickness variation. Further research is necessary on new technologies to measure the thickness of pieces manufactured of flake graphite cast iron. In this research, the oval shape measurements were done by means of eddy-current proximity sensors.

Injection moulding using the process of Shear Controlled Orientation Injection Moulding (SCORIM) to enhance the aesthetic characteristics of plastics was investigated. Unsightly surface weld lines were successfully removed from highly reflective aluminium flake pigmented plastics by the application of a single macroscopic SCORIM shear when used in series with Bright Surface Moulding (BSM). A gonio spectrophotometer (GSP) was used for the quantitative characterisation of the Al flake pigmented mouldings as a measure of surface reflectivity and preferred angle of reflection. The different directional properties of surface reflectivities to either side of a conventional weld line are unacceptable, but were successfully reoriented approximately uniformly with the use of SCORIM and BSM moulding (i. e. SBM) used in series. SBM therefore provided an acceptable quality of surface finish for mouldings originally containing a weld line, without deterioration of mechanical properties. Indeed, some improvements in mechanical properties were observed. Translucent two-colour mouldings were used to successfully demonstrate the flow paths taken by sheared material during the application of macroscopic shears. The use of intermittent shearing to encapsulate shear oriented material in the solidifying layers, manifested original and profound aesthetic effects. This resulted from mixing the two colours and was reproducible and widely variable. The morphology of isotactic polypropylene (iPP) processed in this way and examined by light and electron microscopy revealed how only one or two intermittent shears were required to orient a large volume of the moulding in the shear direction. Moreover, U-shaped flow paths demonstrated that the easiest shear route was close to the mouldings edges, an observation supported by x-ray analysis. The addition of Al flake pigment was found to act as a heterogeneous nucleant for ß-spherulites. This acted as a suitable marker for the clear identification of the displaced weld interface using polarised light microscopy, of filled and unfilled iPP. y-phase was identified with the use of only one or two intermittent shears which reflects an increase in molecular alignment and consequent improved mechanical properties. The intensity of the y-phase increased with the volume of material sheared. Strong evidence was also obtained of a linear relationship between the logarithm of the time lapse between two intermittent shears and the corresponding values of a-phase index, crystallinity index and percentage crystallinity. The values of each increasing proportionally with the length of time used. Microhardness characterisation revealed anisotropy within SCORIM samples consistent with preferred orientation and increased modulus in the shear direction. The skin layers were characterised as the softest region through the thickness of SCORIM mouldings. The results of this work were used to provide the basis of a computer simulation of the SCORIM process under development at the University of Wales Swansea.

This study of lithic analysis shifts attention from typological studies to explicitly behavioral analyses, complimenting studies of both intrasite and intersite patterns of variability and change. Analysis of several assemblages from the Placitas Arroyo site complex reveals changing patterns of raw material procurement and selection, core reduction strategies, as well as tool production and discard. The most striking result thus far is the quite uniform emphasis on flake production from well-prepared cores, and the near absence of manufacture or maintenance of bifacial tools, especially projectile points. Associated with common ground stone artifacts, the flaked stone materials may well represent intensive food processing. Regardless, the technological patterns being revealed by this approach illustrate a productive new means to gain insights into changing behaviors in the Jornada Mogollon cultural tradition.

Using flake dimensions and attributes commonly agreed are associated with site use, occupation age, and occupation duration, it was argued that relative estimations of site function and occupation age could be determined using debitage. This is particularly beneficial for assemblages that have little to no diagnostics that could provide a general cultural period for one or more occupations at a site. The results of this study suggest that, although certain attributes are generally associated with lithic production stage, relative age, and duration indicators, they were not all applicable within this study. The methods employed were relatively successful; however, reducing the number of classes, removing of a dimension, and more sites that meet the definition of lithic scatter is needed. Furthermore, testing occupation duration using the number of breaks on a flake is not possible unless it is proven a single occupation site.

This thesis work deals with the volume changes during the solidification of cast irons and peritectic steels. The volume changes in casting metals are related to the expansion and/or contraction of the molten metal during solidification. Often, different types of shrinkage, namely macro- and micro-shrinkage, affect the casting quality. In addition to that, exposure of the metal casting to higher contraction or expansion during the solidification might also be related to internal strain development in samples, which eventually leads to surface crack propagation in some types of steel alloys during continuous casting. In consequence, a deep understanding of the mechanisms and control of the solidification will improve casting quality and production. All of the experiments during the entire work were carried out on laboratory scale samples. Displacement changes during solidification were measured with the help of a Linear Variable Displacement Transformer (LVDT). All of the LVDT experiments were performed on samples inside a sand mould. Simultaneously, the cooling curves of the respective samples during solidification were recorded with a thermocouple. By combining the displacement and cooling curves, the volume changes was evaluated and later used to explain the influence of inoculants, carbon and cooling rates on volume shrinkages of the casting. Hypoeutectic grey cast iron (GCI) and nodular cast iron (NCI) with hypo-, hyper- and eutectic carbon compositions were considered in the experiments from cast iron group. High nickel alloy steel (Sandvik Sanbar 64) was also used from peritectic steel type. These materials were melted inside an induction furnace and treated with different types of inoculants before and during pouring in order to modify the composition. Samples that were taken from the LVDT experiments were investigated using a number of different  methods in order to support the observations from the displacement measurements:  Differential Thermal Analysis (DTA), to evaluate the different phase present; Dilatometry, to see the effect of cooling rates on contraction for the various types of alloys; metallographic studies with optical microscopy; Backscattered electrons (BSE) analysis on SEM S-3700N, to investigate the different types of oxide and sulphide nuclei; and bulk density measurements  by applying Archimedes' principle. Furthermore, the experimental volume expansion during solidification was compared with the theoretically calculated values for GCI and NCI. It was found that the casting shows hardly any shrinkage during early solidification in GCI, but in the eutectic region the casting expands until the end of solidification. The measured and the calculated volume changes are close to one another, but the former shows more expansion. The addition of MBZCAS (Si, Ca, Zr, Ba, Mn and Al) promotes more flake graphite, and ASSC (Si, Ca, Sr and Al) does not increase the number of eutectic cells by much. In addition to that, it lowers the primary austenite fraction, promotes more eutectic growth and decreases undercooled graphite and secondary dendritic arm spacing (SDAS). As a result, the volume expansion changes in the eutectic region. The expansion during the eutectic growth increase with an increase in the inoculant weight percentage. At the same time, the eutectic cells become smaller and increase in number. The effect of the inoculant and the superheat temperature shows a variation in the degree of expansion/contraction and the cooling rates for the experiments. Effective inoculation tends to homogenize the eutectic structure, reducing the undercooled and interdendritic graphite throughout the structure. In NCI experiments, it was found that the samples showed no expansion in the transversal direction due to higher micro-shrinkages in the centre, whereas in the longitudinal direction the samples shows expansion until solidification was complete.   The theoretical and measured volume changes agreed with each other. The austenite fraction and number of micro-shrinkage pores decreased with increase in carbon content. The nodule count and distribution changes with carbon content. The thermal contraction of NCI is not influenced by the variation in carbon content at lower cooling rates. The structural analysis and solidification simulation results for NCI show that the nodule size and count distribution along the cross-sections at various locations are different due to the variation in cooling rates and carbon concentration. Finer nodule graphite appears in the thinner sections and close to the mold walls. A coarser structure is distributed mostly in the last solidified location. The simulation result indicates that finer nodules are associated with higher cooling rate and a lower degree of microsegregation, whereas the coarser nodules are related to lower cooling rate and a higher degree of microsegregation. As a result, this structural variation influences the micro-shrinkage in different parts. The displacement change measurements show that the peritectic steel expands and/or contracts during the solidification. The primary austenite precipitation during the solidification in the metastable region is accompanied by gradual expansion on the casting sides. Primary δ-ferrite precipitation under stable phase diagram is complemented by a severe contraction during solidification. The microstructural analysis reveals that the only difference between the samples is grain refinement with Ti addition. Moreover, the severe contraction in solidification region might be the source for the crack formation due to strain development, and further theoretical analysis is required in the future to verify this observation. / <p>QC 20170228</p>

In this thesis, the structural and mechanical changes, which took place in flake graphite cast iron after electron beam surface melting and chrome-nickel surface alloying, were studied. Furthermore, the effect of set parameters on properties and depth of the melted and alloyed region is also analyzed. In the experimental part, the analyzed microstructures, micro-hardness and the distribution of elements after melting and alloying, were presented. Structural differences of material regions caused by melting were described based on microstructures. In the end of diploma thesis, the conclusions of using EB technology for surface melting and alloying were discussed.

This Master's thesis deals with history of Fractal geometry and describes the fractal science development. In the begining there are essential Fractal science terms explained. Then description of fractal types and typical or most known examples of them are mentioned. Fractal knowledge application besides computer graphics area is discussed. Thesis informs about fractal geometry practical usage. Few present software packages or more programs which can be used for making fractal pictures are described in this work. Some of theirs capabilities are described. Thesis' practical part consists of slides, demonstrational program and poster. Electronical slides represents brief scheme usable for fractal geometry realm lectures. Program generates selected fractal types. Thesis results are projected on poster.