A role of fringe pattern catalogue in the course of interferometrically based determination of residual stresses by the hole-drilling method

Писарев, В. С.; Balalov, V. V.

doi:10.1016/s0143-8166(02)00203-8

Cited by 13 publications

(30 citation statements)

References 3 publications

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“…Such an approximation is derived from the interference between fringe patterns by means of the relations so called initial transition model (PISAREV& BALALOV, 2004) By employing the whole field subtracting method as defined by POST (1994), an isostrain field could be defined which would indicate the occurrence of stress concentration.…”

Section: Methodsmentioning

confidence: 99%

Moiré Inteferometry Applied to Soil Dynamic Studies

Maciel

Albiero

Fabbro

2008

Revista Brasileira De Engenharia De Biossistemas

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This research work reports the application of a shadow moiré technique as a photoelastic method to support a qualitative stress distribution study on soil samples. The knowledge of stress distribution on undisturbed soil is of unquestionable value to tillage purposes as well as to the civil construction field. The name moiré has its origin in the French language, referring to wave like pattern. When screens of same mesh density are superposed, fringes are generated which move when its relative positions are displaced, it was reported that moiré fringes can be used to magnify displacements, being also suitable as a photoelastic method. The experimental setup for this work included a digital camera to capture the moiré patterns generated for the Ronchi grid and a light source. The images were processed by the softwares named IrfanView, and Idrizi. Five images were taken the sample of clay and they were submitted to varying axial loads kept under the failure stress. Undisturbed samples cylindrical were prepared at the dimensions of 60 mm of height and 60 mm of diameter. Results included the stress distribution maps for each case. It is concluded that the technique get to determine qualitatively the principal stress in soil cylindrical testing specimens. Keywords RESUMOEste trabalho de pesquisa trata da aplicação da técnica de moiré de sombra como um método fotoelástico para auxiliar em estudos qualitativos na distribuição de tensões em amostras de solo. O conhecimento da distribuição da tensão sobre solos não perturbados é de grande importância para o trabalhos de preparo de solo, assim como na área da construção civil. A palavra moiré tem origem francesa e se refere a um padrão de onda, quando grades de mesma densidade de linhas são superpostas são formadas franjas que se movem quando as posições relativas dos deslocamentos mudam, sendo que as franjas de moiré podem ser usadas para aumentar a percepção do deslocamento, representando um método fotoelástico. O arranjo experimental adotado neste trabalho inclui uma câmera digital para capturar os padrões moiré gerados por uma grade Ronchi e uma fonte de luz. As imagens foram processadas pelos softwares IrfanView e Idrizi. Cinco imagens foram obtidas de amostras de latossolo vermelho distroférrico que foram submetidas a cargas axiais variáveis até o falha por tensão. As amostras de solo não perturbado foram preparadas com dimensões de 60 mm de altura e 60 mm de diâmetro. Como resultados foram obtidos os mapas de isodeformação das amostras, dos quais se conclui que a técnica conseguiu determinar qualitativamente a distribuição de tensões principais das amostras cilíndricas.Palavras Chaves: Comportamento do Solo; Interferência Óptica; "Brazilian Test".

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Section: Methodsmentioning

confidence: 99%

Moiré Inteferometry Applied to Soil Dynamic Studies

Maciel

Albiero

Fabbro

2008

Revista Brasileira De Engenharia De Biossistemas

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“…Fue utilizado el método de procesamiento Substracción de Campo Entero, definido por Post et al (1994), donde se efectuó la substracción píxel a píxel de una foto con un nivel de carga X i de una otra foto de nivel X i+1 . Este método es usado para determinar la deformación sufrida por la muestra que ocurre entre dos diferentes niveles de carga.…”

Section: Tabla 1 Dimensiones De Los Probetas De Ensayo De G Angustiunclassified

“…Así, cuando la imagen es obtenida y procesada se cometen errores y este efecto es llamado efecto gap. Según Post et al 1994, para evitar este efecto es preciso que la distancia entre la cámara y la fuente de luz sea la misma en relación al plano de referencia del objeto. Para la optimización del sistema en el montaje experimental y la adopción de una geometría apropiada, se torna necesaria la adopción de una fuente de luz coherente y colimada, que posibilite una mejor homogeneidad en la intensidad luminosa y una mejor definición de las franjas generadas.…”

Section: Tallos Saturadosunclassified

Técnica De Moiré Aplicada Al Análisis De Esfuerzos De Compresión en El Bambú Guadua

Beraldo

Albiero

Maciel

et al. 2007

Maderas, Cienc. tecnol.

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RESUMENEl bambú es considerado como una materia prima muy importante para los países en vías de desarrollo, pues combina levedad con una elevada resistencia mecánica. Hasta ahora no se conoce adecuadamente el comportamiento del material cuando es sometido a los ensayos de caracterización mecánica. En este trabajo se buscó evaluar probetas de bambú (Guadua angustifolia) sometidas al ensayo de compresión simple. Se utilizó la técnica de moiré de sombra para mapear las deformaciones de las probetas en función de la cantidad de nudos presentes en ella (0, 1 ó 2). Los resultados obtenidos evidenciaron la adecuación de la técnica utilizada, permitiendo observar la distribución de las líneas de iso-deformación en el bambú. Palabras claves: bambú, guadua, moiré ABSTRACTBamboo is considered an important raw material in developing countries because its physical characteristics associate lightness with high mechanical resistance. However its behavior obtained from mechanical tests is not yet well defined. This research work had the objective of evaluating bamboo (Guadua angustifolia) testing specimens under simple uniaxial compression loading. Shadow moiré optical methods had been employed to generate deformation mapping as function of knots (0, 1 or 2). Obtained results indicate that the technique is well adequate in generating iso-deformation contour lines in bamboo specimens.

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“…Remarkable properties of reflection hologram interferometry with respect to residual stresses determination in plane structures by through or blind hole drilling have been previously established and comprehensively demonstrated [40][41][42]. Among them the unique capability of recognising principal strain directions at a stage of fringe patterns reconstruction is of great importance.…”

Section: Introductionmentioning

confidence: 99%

“…The third way for a choice and verification of the transition model is based on a constructing so-called reference fringe patterns of the second kind [43,44]. A fine coincidence between actual and reference interferograms takes place when the transition model involved corresponds to the type of residual stress field of interest [32][33][34][40][41][42]. If such a correlation is not achieved, the question on the accuracy of determination of residual stress components remains open.…”

Section: Introductionmentioning

confidence: 99%