13th International Conference on Fracture June 16–21, 2013, Beijing, China -1- Paper Template for Digital Speckle Interferometry Method for Research of Dynamic Processes Michael N. Osipov1, Anton N. Chekmenev1, Yury D. Sheglov1 1 Department of mathematic and mechanic, Samara State University, 443011, Ac. Pavlova str., 1, Russia osipov@samsu.ru Abstract The new digital speckle interferometry method for research of processes in mechanics of fracture, fatigue and strength of solid materials and structures in real time is considered. The new method is based on simultaneous registration of information by the standard digital speckle interferometry method and registration of distribution of intensity in the single speckle. Such decision allows to investigate fracture processes in real time; to increase sensitivity and accuracy of measurements; to expand a range of measured displacements. Besides, an offered method of the analysis of distribution of intensity in the single speckle allows will get rid of own noise inherent of interferometric methods of coherent optics. In work theoretical and experimental results on realization of an offered method are presented. The optoelectronic scheme the digital speckle interferometer for registration at the same time speckle interferograms and intensity distribution in the single speckle is presented. The algorithm of processing of speckle interferograms on an offered method is presented. It is shown that dynamic displacements can be measured with high resolution, in large range of measured value of displacements and in the large frequency range and in real time by this new method. Keywords Experimental mechanics, Dynamic processes, Optical methods, Digital speckle interferometry, Processing and analysis of images and signals 1. Introduction One of the main problems of solid mechanics, both fundamental, and the applied character, in many respects of a strength and durability of elements of designs, research of dynamic tasks is defining. Development of technique sets a task of increase of reliability of created and already working elements of designs subjecting to dynamic loadings. Existing mathematical models of the mechanics of fracture and settlement methods of forecasting don't allow to consider all real service conditions of designs fully. Experimental researches are necessary for confirmation of mathematical models of the mechanics of fracture and ensuring demanded parameters of designs at dynamic and static loadings. It demands development of the experimental measuring means, allowing to receive both qualitative, and quantitative data at dynamic and static loadings. Optical contactless methods of researches gain now the increasing scientific and applied importance. Contactless methods have no impact on research elements of designs when carrying out experimental measurements that leads to increase of accuracy and reliability of received results. Considerable interest causes application of nondestructive interferometric methods for research of dynamic processes, both fundamental, and applied character. Optical, including laser interferometers, demand performance of a number of conditions which limit their practical application: the reflecting studied surface has to be optically smooth; the rigid mutual adjustment and fixing of elements of optical system is required. It should be noted also that interferometric methods, at practical application, demand use of lasers with a large spatial and time coherence that imposes additional restrictions when using data of systems in actual practice. At the present stage it is necessary first of all to allocate from interferometric methods the digital holographic and speckle interferometry [1-4]. However, it is well known that at application of the
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