The mechanical properties of biomedical materials were determined and discussed in this study. The extension and tensile tests for aorta and coronary artery were carried out using tensile testing machine. Based on incompressibility of biological soft tissue, the stress-stretch curves of arteries were obtained. This study proposed a nonlinear Ogden material model for the numerical simulation of coronary artery extension during stent implantation. The corresponding Ogden model parameters were derived by the obtained stress-stretch curves from tensile tests. For validation, the proposed nonlinear Ogden material model for coronary artery was applied to a Palmaz type stent implantation process. The simulated stent deformation was found to be reasonable. It had a good correlation with the measured results. The microindentation experiments were used to measure the mechanical properties of enamel and dentine of human teeth in this study. To reveal the relation between the experimental parameters and measured mechanical properties, Young¡¦s moduli were investigated by varying experimental parameters. The parameter of maximum indentation load significantly influences measured values. Young¡¦s modulus varies very slightly when 10 to 100 mN of maximum indentation load applied. Young¡¦s modulus is not sensitive to the parameters of portion of unloading data and teeth age. The combination of finite element analysis and curve-fitting method is proposed to determine the mechanical properties of thin film deposited on substrate. The mechanical properties of thin film, i.e. Young¡¦s modulus, yield strength and strain-hardening exponent, were extracted by applying an iterative curve-fitting scheme to the experimental and simulated force-indentation depth curves during the microindentation loading and unloading processes. The variation of mechanical properties of TiN thin films with thicknesses ranging from 0.2 to 1.4 £gm was extracted. The results presented the film thickness effect makes the Young¡¦s modulus of TiN thin films reduces with reducing film thickness, particularly at thicknesses less than 0.8 £gm. Therefore, it can be inferred that a film thickness of 0.8 £gm possibly represents the upper bound when employing macroscopic mechanics with bulk material properties.

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Made available in DSpace on 2014-12-17T14:07:01Z (GMT). No. of bitstreams: 1 NataliaFD_DISSERT.pdf: 4136751 bytes, checksum: 47b384d6442f251d58542735c23ae300 (MD5) Previous issue date: 2012-02-27 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Titanium nitride films were grown on glass using the Cathodic Cage Plasma Deposition technique in order to verify the influence of process parameters in optical and structural properties of the films. The plasma atmosphere used was a mixture of Ar, N2 and H2, setting the Ar and N2 gas flows at 4 and 3 sccm, respectively and H2 gas flow varied from 0, 1 to 2 sccm. The deposition process was monitored by Optical Emission Spectroscopy (OES) to investigate the influence of the active species in plasma. It was observed that increasing the H2 gas flow into the plasma the luminescent intensities associated to the species changed. In this case, the luminescence of N2 (391,4nm) species was not proportional to the increasing of the H2 gas into the reactor. Other parameters investigated were diameter and number of holes in the cage. The analysis by Grazing Incidence X-Ray Diffraction (GIXRD) confirmed that the obtained films are composed by TiN and they may have variations in the nitrogen amount into the crystal and in the crystallite size. The optical microscopy images provided information about the homogeneity of the films. The atomic force microscopy (AFM) results revealed some microstructural characteristics and surface roughness. The thickness was measured by ellipsometry. The optical properties such as transmittance and reflectance (they were measured by spectrophotometry) are very sensitive to changes in the crystal lattice of the material, chemical composition and film thicknesses. Therefore, such properties are appropriate tools for verification of this process control. In general, films obtained at 0 sccm of H2 gas flow present a higher transmittance. It can be attributed to the smaller crystalline size due to a higher amount of nitrogen in the TiN lattice. The films obtained at 1 and 2 sccm of H2 gas flow have a golden appearance and XRD pattern showed peaks characteristics of TiN with higher intensity and smaller FWHM (Full Width at Half Maximum) parameter. It suggests that the hydrogen presence in the plasma makes the films more stoichiometric and becomes it more crystalline. It was observed that with higher number of holes in the lid of the cage, close to the region between the lid and the sample and the smaller diameter of the hole, the deposited film is thicker, which is justified by the most probability of plasma species reach effectively the sample and it promotes the growth of the film / Filmes finos de nitreto de tit?nio foram crescidos sobre vidro utilizando a t?cnica de deposi??o por descarga em gaiola cat?dica a fim de averiguar a influ?ncia das vari?veis de processo nas propriedades ?pticas e estruturais do filme. Como atmosfera do plasma foi utilizada a mistura de gases Ar, N2 e H2, fixando o fluxo de Ar e N2 em 4 e 3 sccm, respectivamente, e usando fluxos de 0, 1 e 2 sccm de H2. O processo de deposi??o foi monitorado por Espectroscopia de Emiss?o ?ptica (OES) para investiga??o das esp?cies ativas no plasma. Observou-se que com o aumento fluxo de H2 as intensidades das esp?cies luminescentes no plasma sofrem altera??es e que a esp?cie N2 (391,4 nm) n?o teve um crescimento proporcional ao fluxo de H2. Outros par?metros investigados foram o di?metro e o n?mero de furos da gaiola. As an?lises de difra??o de raios X com ?ngulo de incid?ncia rasante (GIXRD) comprovaram que os filmes obtidos s?o compostos por TiN, podendo ter varia??es quanto a quantidade de nitrog?nio na rede e o tamanho de cristalito; a microscopia ?ptica forneceu dados sobre a homogeneidade, a partir da microscopia de for?a at?mica (AFM) observou-se algumas caracter?sticas microestruturais do filme e a rugosidade. A espessura foi quantificada atrav?s das an?lises de elipsometria. As propriedades ?pticas como reflet?ncia e transmit?ncia (medidas por espectrofotometria) s?o bastante sens?veis a altera??es na rede cristalina do material, composi??o qu?mica e espessura, sendo, portanto, uma boa ferramenta para verifica??o do controle do processo. De maneira geral, os filmes obtidos com fluxo de 0 sccm de H2 possuem uma maior transmit?ncia atribu?da ao menor cristalinidade decorrente da maior quantidade de nitrog?nio na rede cristalina do TiN. Os filmes obtidos nos fluxos de 1 e 2 sccm de H2 obtiveram um aspecto dourado e o difratograma apresentou picos caracter?sticos do TiN com maior intensidade e menor largura a meia altura, sugerindo que com a presen?a de hidrog?nio na atmosfera do plasma os filmes s?o mais estequiom?tricos e com maior cristalinidade. Quanto ? configura??o da gaiola observou-se que com maior quantidade de furos na tampa, maior a proximidade da tampa com a amostra e menor o di?metro do furo, maior ? a espessura do filme, o que ? justificado pela maior probabilidade das esp?cies do plasma atingirem efetivamente o substrato e promoverem o crescimento do filme