published_or_final_version / Mechanical Engineering / Master / Master of Philosophy

Orientador: Inácio Maria Dal Fabbro / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agrícola / Made available in DSpace on 2018-08-23T11:41:51Z (GMT). No. of bitstreams: 1 Gazzola_Jonathan_D.pdf: 4193064 bytes, checksum: cfa66521e595db19afcd4c8f16250515 (MD5) Previous issue date: 2013 / Resumo: A distribuição de tensões em corpos dá suporte à engenharia de projetos visando à melhoria da qualidade e segurança de produtos e atualmente são determinados por métodos analíticos e experimentais. A vantagem dos métodos experimentais em relação aos métodos analíticos está em analisar a distribuição de tensões e deformações independentemente das condições do material e de sua geometria. Entre os métodos experimentais, as técnicas ópticas que tem se demonstrado propícias são holografia, speckle interferométrico e as técnicas de moiré. As técnicas ópticas interferométricas permitem determinar campos de deslocamento, porém, quando combinados com métodos híbridos se tornam passíveis de determinação do componente de tensões e deformações específicas e são comumente conhecidas como técnicas fotomecânicas. As técnicas de moiré são conhecidas por sua habilidade em determinar topografia de objetos, porém, pesquisas recentes têm mostrado muito útil em determinar campo de deslocamento. A técnica de moiré é baseada na fenomenologia moiré, na qual, duas grades superpostas produzem franjas padrões e, por meio de tratamento de imagem adequado permite deduzir qualitativamente o mapa de distribuição de tensões e deformações. Os principais tipos de técnicas de moiré são de sombra e por phase-shifting e seu arranjo experimental consiste no uso de equipamentos de baixo custo, o que o torna altamente viável, frente às outras técnicas ópticas. A proposta deste trabalho de pesquisa se identifica em analisar o uso da técnica de moiré por phase-shifting para determinação de tensões e deformações de forma qualitativa e quantitativa a partir do campo de deslocamento determinado experimentalmente. Para validação, os resultados gerados pela técnica de moiré foram comparados com os resultados obtidos por ensaio experimental de extensometria elétrica e simulação computacional. Os resultados mostraram que qualitativamente, a técnica de moiré foi hábil em determinar campo de deslocamento, enquanto que, quantitativamente a técnica foi hábil em determinar campo de deslocamento, deformações e tensões / Abstract: Stress distribution in specimens supports the design engineering objectiving quality and insurance products improvement and actually are determined through analytical and experimental analyses. Analyzes of stress and strain distribution independently of material conditions and its geometry becomes advantage of experimental methods, in relation to analytical methods. Among experimental methods, optical techniques have demonstrated to be favorable are holography, interferometrical speckle and moiré techniques. Interferometrical optical techniques allow to determine displacement fields, but, when associated to hybrid methods, they become able to stress and strain components determination and they are usually named as photomechanical technique. Moiré technique is known for its hability to determine shape surface, but, researches have demonstrated to be usefull to determine displacement field. Moiré technique is based about moiré phenomenology, which, two superposed grids produces pattern fringes and, applying an adequated image treatment is possible to deduce qualitatively the stress and strain distribution mapping. The main kind of moiré technique are shadow and phase-shifting and its setup is based in use of low cost equipments, which becomes highly feasible, when compared to other optical techniques. This research work objectives to analyze the use of phase-shifting moiré technique to stress and strain determination qualitative and quantitatively using datas of displacement field determined experimentally. Results obtained through moiré technique were validated comparing results obtained through etectrical extensometry experimental tests and computational simulation. Results showed that qualitatively, moiré technique was able to determine displacement field, while quantitatively moiré was able to determine displacement, strain and stress / Doutorado / Maquinas Agricolas / Doutor em Engenharia Agrícola

Orientadores: Inácio Maria Dal Fabbro, Antonio Carlos Loureiro Lino / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agrícola / Made available in DSpace on 2018-08-26T12:42:52Z (GMT). No. of bitstreams: 1 Silva_MarcosValerioGebrada_D.pdf: 4641823 bytes, checksum: ad2a00015d9cecbe7670eac31c98b827 (MD5) Previous issue date: 2014 / Resumo: A medição estática de sólidos tridimensionais tem recebido uma grande atenção da comunidade científica. Porém, há também a possibilidade de serem feitas essas medições em condições dinâmicas, que ainda são pouco exploradas, mas que apresentam ampla gama de aplicações. Como exemplo, o estudo do fenômeno de vibração, geralmente associado a estruturas mecânicas tais como elementos de máquinas. Estudo sobre as tensões e deformações sofridas por corpos vegetais sob condições dinâmicas também são necessárias. Tendo em vista tais deficiências técnicas na área. Nota-se a importância de estudos específico, os quais podem ser levados a cabo com o suporte técnico de métodos ópticos, os quais permitem a medição de deformações, movimentos e posições relativas de elementos de máquinas em ensaios dinâmicos não destrutivos dentre outros. Entre os métodos perfilométricos mostrados na literatura, a Técnica de Moiré se mostra como uma ferramenta científica confiável, considerada rápida, de baixo custo e exequível, motivo pelo qual esse método foi selecionado para conduzir este trabalho, especificamente o método conhecido como "Moiré de Projeção com Deslocamento de Fase". Softwares específicos de uso gratuito foram empregados nas análises das imagens para alcançar o objetivo do presente trabalho, identificado como a determinação do deslocamento transversal da linha elástica de uma lâmina engastada, excitada por um solenoide com controle de oscilação. Os princípios de medição e o modelamento matemático do sistema foram detalhados e apresentados no trabalho. Uma sistemática de calibração do sistema também foi apresentada e modelada juntamente com os aspectos relativos à implementação computacional do sistema os quais foram discutidos / Abstract: Three dimensional coordinates survey of solids in static conditions has received major attention from the scientific community. However, the broad applications of three dimensional measures of solids under dynamic conditions is closely associated to structure, machine elements, subjected to a variety of dynamic loading which forcibly includes vibrational impositions. Agricultural science exhibits a major variety of examples, including farm machinery, plant-machine mechanical relations, rural buildings and bridges, etc. This research work is devoted to the application of optical techniques to capture the three dimensional measures of bodies under vibrational loadings, which permit measuring deformation patterns, motion, relative positions, etc. Optical methods can be easily associated to mechanical tests as well as to stress-strain distribution. The selected optical method is identified as Phase Shift Projection Moiré which is included in the moiré family of optical methods. The selected structural member was identified as cantilever beam, more precisely a steel blade clamped at one of its end which is excited by a solenoid to vibrate. Frequency as well as amplitude can be controlled. Images captured from the vibrating body were processed by means of specific software. Measuring principles and the mathematical modeling, the calibration procedure and the computational implementation were detailed as well / Doutorado / Maquinas Agricolas / Doutor em Engenharia Agrícola

Digital heterodyne methods are employed in conjunction with periodic fringe projection to produce a fast automated surface relief measurement technique. A method of sampling the image with a solid state detector array which produces a moire fringe image free of the noise terms normally present with moire techniques is presented along with an extension to Whittaker-Shannon sampling theory to cover the moire aliasing phenomena. The limitations imposed on the surface slopes by the requirement that the properly moire sampled image spectra must be confined to a moire interval are given. Moire sampling allows an optical processing step (removal of the reference surface tilt), while classical nonaliased sampling produces the same information with respect to a tilted surface. General additive noise is analyzed as regards both integrating bucket and phase stepping algorithms and yields a signal to noise ratio dependent error with twice the frequency of the fringes for some algorithms. A phase averaging technique which eliminates these oscillatory errors as well as those caused by reference phase shift errors in all the algorithms is demonstrated. Both parallel and divergent geometries are discussed. The feasibility is experimentally demonstrated with results for the parallel case based on a system composed of commercially obtainable components.

published_or_final_version / Mechanical Engineering / Master / Master of Philosophy

A new hybrid method combining moire interferometry, high resolution data-reduction technique, two-dimensional datasmoothing method, and Finite Element Method (FEM) has been successfully developed. This hybrid method has been applied to residual strain analyses of composite panels, strain concentrations around optical fibers embedded in composites, and cruciform composite shear test. This hybrid method allows moire data to be collected with higher precision and accuracy by digitizing overexposed moire patterns (U & V fields) with appropriate carrier fringes. The resolution of the data is ± 20 nm. The data extracted from the moire patterns are interfaced to an FEM package through an automatic mesh generator. This mesh generator produces a nonuniform FEM mesh by connecting the digitized data points into triangles. The mesh, which uses digitized displacement data as boundary conditions, is then fed to and processed by a commercial FEM package. Due to the natural scatter of the displacement data digitized from moire patterns, the accuracy of strain values is significantly affected. A modified finite-element model with linear spring elements is introduced so data-smoothing can be done easily in two dimensional space. The results of the data smoothing are controlled by limiting the stretch of those springs to be less than the resolution of the experimental method. With the full-field hybrid method, the strain contours from moire interferometry can be easily obtained with good accuracy. If the properties of the material are known, the stress patterns can also be obtained. In addition, this method can be used to analyze any two-dimensional displacement data, including the grid method and holography. / Ph. D.

Moiré interferometry is a relatively new branch of photomechanics that utilizes a diffraction grating on the specimen to determine surface displacements. To date, it has been used primarily to determine in-plane displacements of the specimen surface. The objective of this work is to demonstrate that the technique is capable of determining out-of-plane displacements as well. A high-frequency phase grating on a specimen surface is illuminated by oblique beams; two diffracted beams are recorded by holographic interferometry. If the wavefront warpages of the two diffracted beams are characterized by fringe orders, Nₐ and N_b, it is demonstrated that the in-plane displacements are proportional to Nₐ - N_b, while out-of-plane displacements are proportional to Nₐ + N_b. Initially, these subtractive and additive parameters are determined numerically, and the resulting displacements are compared to displacements measured by well-accepted prior experimental methods. Excellent agreement with these proven methods is shown. Using this remarkably simple relationship between wavefront warpages, an experimental procedure is developed which is capable of simultaneously determining the in-plane and out-of-plane displacements of a specimen surface. The method requires only one photographic exposure of the deformed specimen, with displacement information being extracted through the use of optical filtering. The fact that the information required to yield these patterns can be obtained from a single photographic recording not only makes this an experimentally simple technique to use, but provides the capability of analyzing dynamic events as well. The sensitivity of measurements made by utilizing this technique are directly proportional to the frequency of the specimen grating. Therefore, it is desirable to obtain specimen gratings with frequencies on the order of 500-2000 lines/mm ( 12, 700 - 50,800 lines/in.). A technique is developed whereby high frequency moire gratings with highly reflective surfaces can be transferred to workpieces made from most engineering materials. Specimen gratings with frequencies as high as 2000 lines/mm (50,800 lines/in.) and exhibiting 10 percent diffraction efficiency in the first diffraction order have been applied to numerous specimens using simple laboratory techniques. / Ph. D.

The objective of this study was to provide an optical technique allowing full-field in-plane deformation measurements at high temperature by using high-sensitivity moiré interferometry. This was achieved by a new approach of performing deformation measurements at high temperatures in a vacuum oven using an achromatic interferometer. The moiré system setup was designed with particular consideration for the stability, compactness, flexibility, and ease of control. A vacuum testing environment was provided to minimize the instability of the patterns by protecting the optical instruments from the thermal convection currents. Also, a preparation procedure for the high-temperature specimen grating was developed with the use of the plasma-etched technique. Gold was used as a metallic layer in this procedure. This method was demonstrated on a ceramic block, metal/matrix composite, and quartz. Thermal deformation of a quartz specimen was successfully measured in vacuum at 980 degrees Celsius, with the sensitivity of 417 nm per fringe. The stable and well-defined interference patterns confirmed the feasibility of the developments, including the high-temperature moiré system and high-temperature specimen grating. The moiré system was demonstrated to be vibration-insensitive. Also, the contrast of interference fringes at high temperature was enhanced by means of a spatial filter and a narrow band interference filter to minimize the background noise from the glow of the specimen and heater. The system was verified by a free thermal expansion test of an aluminum block. Good agreement demonstrated the validity of the optical design. The measurements of thermal deformation mismatch were performed on a graphite/epoxy composite, a metal/matrix composite equipped with an optical fiber, and a cutting tool bit. A high-resolution data-reduction technique was used to measure the Strain distribution of the cutting tool bit. / Ph. D.

Os erros cíclicos nas escalas das máquinas de medir a três coordenadas (MM3Cs) exercem influência significativa nos resultados das medições efetuadas em comprimentos pequenos. Um dos fatores que contribuem para a ocorrência dos erros cíclicos é a acuracidade limitada dos métodos utilizados na fabricação de escalas. As MM3Cs utilizam escalas desenhadas e fabricadas por métodos fotográficos ou riscadas em máquinas tipo \"step and repeat\". Ambos os métodos produzem um erro sistemático entre traços sucessivos. Desta forma, a medida que o número de traços aumenta as parcelas do erro sistemático somam-se e quando atingem um determinado valor este erro é compensado. Esta correção é feita a cada distância cujo valor corresponde ao de um período cíclico de baixa freqüência e o processo repete-se até que toda a escala seja riscada. Outro fator que contribui para a existência dos erros cíclicos origina-se da resolução exigida pela MM3C, que é sempre bastante alta e ultrapassa as capacidades existentes atualmente para fabricação de escalas. O que se faz para lidar com o problema da resolução é subdividir eletronicamente o espaço entre traços consecutivos da escala. Esta divisão eletrônica está associada a um sinal seno gerado pelas franjas de Moiré. A digitalização e subdivisão deste sinal geram erros periódicos, também conhecidos como erros cíclicos de alta freqüência. Embora diversos erros das MM3Cs tenham sido largamente estudados, ainda hoje, não foi realizada uma observação sistemática para que se tenha a exata medida da influência dos erros cíclicos, na medição a três coordenadas. Para suprir essa necessidade e contribuir na busca de novos métodos de avaliação, este trabalho apresenta os procedimentos de medição dos erros cíclicos de baixa e de alta freqüência, bem como a aplicação de Análise de Fourier aos conjuntos de dados obtidos. A medição da distância entre as linhas consecutivas da régua móvel da MM3C também foi realizada e os resultados comprovaram a existência dos erros de fabricação, a ocorrência de compensação periódica e também sugeriram os erros de subdivisão eletrônica. Além disso, no levantamento dos erros cíclicos de baixa freqüência foi confirmada a existência de um período cíclico de quatro milímetros. / Cyclic errors in scales of Coordinate Measuring Machines (CMMs) have a significant influence in measuring results on a very small displacement hindering most of the measuring tasks. One of the factors that contribute to the appearance of the cyclic errors is the limited accuracy of the used manufacturing methods of the scales. CMMs use scales drawn and manufactured by photographic methods or marked in step and repeat machines. In both methods the distances between succeeding lines are prone to systematic errors and therefore, with the increasing of the number of lines systematic errors are added up. Error compensation is provided when the amount of errors reaches a predetermined value. The error correction made at predetermined lengths defines a period what one can call the low frequency cyclic error. This process must be repeated all along the scale. Another factor that contributes to the existence of cyclic errors originates from high resolution required by CMM that goes beyond the existent manufacturing capacities of scales. This problem is somewhat solved by means of an electronic signals splitting up. The electronic sign obtained as two consecutive lines on the scale is probed can be associated to a sine signal what is generated by Moiré type fringes. Digital conversion and electronic division of these signals also generate periodic errors and can be called high frequency cyclic error. Although several types of errors in CMMs have been largely studied,there is a lack regarding the cyclic errors. A huge need for a systematic study and observation of these errors is needed to permit an exact measure of its influence on coordinate measurements. To cope with the urgent need and to contribute in the search for new evaluation methods of the cyclic errors, this work presents a measuring procedure of low and high frequency cyclic errors and the application of Fourier Analysis to the testing data. Measurements of distances between consecutive lines of the scale were also obtained and the results have shown the existent manufacturing errors and suggested frequencies and period of errors of electronic division. A cyclic period of four millimeters was confirmed in the low frequency tests.

Orientadores: Inácio Maria Dal Fabbro, Julio Soriano / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agrícola / Made available in DSpace on 2018-08-18T01:26:15Z (GMT). No. of bitstreams: 1 Gazzola_Jonathan_M.pdf: 6105660 bytes, checksum: f01d4a2bd88ae142584872066c1b7532 (MD5) Previous issue date: 2011 / Resumo: A silvicultura ocupa a segunda posição no agronegócio brasileiro, exibindo grande importância econômica e social para o país. As atividades econômicas associadas ao reflorestamento enfrentam diversos obstáculos internos e externos, os quais se contrapõem ao crescimento desse setor no país. Nesse sentido, o transporte de madeira se torna um fator de grande concentração de custo. Toras de madeira, quando atuam em conjunto em forma de feixes apresentam maior rigidez a esforços do que atuando individualmente. As técnicas fotoelásticas podem determinar tensões e deformações em objetos independente da complexidade de sua geometria. A técnica óptica de moiré é considerada como uma técnica fotoelástica viável e de resultados confiáveis. A proposta deste trabalho foi de aplicar a técnica de moiré de sombra na determinação qualitativa e quantitativa da distribuição de tensões em modelos reduzidos de feixe de toras, doravante denominados MRFT. Foi utilizado neste trabalho de pesquisa, essência da espécie Eucalyptus saligna com corpos de prova divididos em três grupos distintos, de acordo com o diâmetro da tora. Uma simulação computacional, através do programa ABAQUS, foi realizada como forma de comparação dos dados qualitativos com o ensaio fotoelástico. Dados experimentais de tensão, obtidos pelos dados fornecidos por sensores acoplados à prensa eletrônica, foram comparados com os resultados de quantificação de tensão obtida pelo método de moiré de sombra. A comparação entre os resultados experimentais do ensaio de carregamento, bem como a simulação computacional associada ao comportamento para vigas atuantes em feixes determinado pela teoria da mecânica dos materiais indicou que a técnica de moiré de sombra foi adequada para a determinação de distribuição de tensão no MRFT. Os resultados mostraram inicialmente a possibilidade do uso do feixe de madeiras para otimização de forwarder. É concluído pelos resultados de qualificação da distribuição de tensão que os elementos que compunham o MRFT atuaram de forma unida. A análise dos resultados quantitativos mostra que, dadas as imperfeições nas superfícies que podem implicar em não efetividade do contato entre as toras, conclui-se que, as toras atuaram individualmente. Também é concluído que a técnica óptica de moiré é adequada para se determinar a distribuição de tensão em peça fletidas / Abstract: The silviculture figures as the second most important Brazilian agribusiness activity, exhibiting economical and social importance. Economical activities associated to reforestation face several internal and external obstacles which contrast with the development in this economical sector. Analyzing the costs related to wood exploration chain, the transportation figures the highest concentration. Wood logs, acting united as bundle logs, become more resistant to loading when compared with individual elements. Photoelastic techniques are able to determine stress and strain distribution on loaded specimens, independently of theirs geometrical shapes. Moiré optical techniques are considered as capable and reliable photoelastic techniques. This research work objectives the application of shadow moiré technique to qualitative and quantitative stress distribution determination reduced bundle log models, named as (RBLM). Wood specimens have been made by Eucalyptus saligna specie, and they were classified into three distinct groups, according their log diameter. Computational simulation, using ABAQUS software, has been carried on to compare qualitative results obtained by photoelastic test. Stress experimental dates, obtained through dates provided by electronical pressure machine sensors, have been compared to quantitative results obtained through shadow moiré technique. Comparison between loading test dates, as well as computational simulation associated to the supposed results determined by material mechanics theories to beam working in bundles showed that shadow moiré techniques were adequate to determine stress distribution on RBLM. Results obtained through shadow moiré technique showed a possibility of using bundle logs to forwarder design optimization. It is concluded that the stress distribution qualitative analysis showed individual pieces that composed BLRM worked as united element. Analyzing quantitative results obtained through shadow moiré technique, and considering surface imperfections, which is able to imply a not effective contact among wood logs, is concluded that, quantitatively, the logs acted individually. It is also concluded that shadow moiré optical technique is adequate to determine qualitative and quantitative stress distribution on bent pieces / Mestrado / Maquinas Agricolas / Mestre em Engenharia Agrícola