An effective Dynamic Moire method was presented to determine the critical time of crack instable propagation in rock dynamic fracture. Two pieces of grating were installed near the notch of Short Rod specimen to form ...An effective Dynamic Moire method was presented to determine the critical time of crack instable propagation in rock dynamic fracture. Two pieces of grating were installed near the notch of Short Rod specimen to form the Moire fringes, then the COD versus time could be monitored from the movement of the Moire fringes, and finally the critical time could be determined from the velocity of COD. This method was also compared with another one.It could be concluded that the critical time determined by Dynamic Moire method corresponds with that of the Transmitted Wave method at the loading rates from 103 to 104 MPa·m(1/2)·S(-1).展开更多
Moire interferometry method is introduced to study the feasibilities of J integral as a plastic singularity parameter at the tip of the notch in the welded joints. The results show that J dominance in most studied cas...Moire interferometry method is introduced to study the feasibilities of J integral as a plastic singularity parameter at the tip of the notch in the welded joints. The results show that J dominance in most studied cases is not validated in v and u displacement fields. Therefore, it can be concluded that J-integral as controlling parameter used to estimate the safety of welded structures is not always valid.展开更多
This paper makes use of the method of testing and measuring the human body tibia by using2-D moire interferometry of sticking film. hased on the J'--y direction moire patterns recorded synchronously by 2-D optical...This paper makes use of the method of testing and measuring the human body tibia by using2-D moire interferometry of sticking film. hased on the J'--y direction moire patterns recorded synchronously by 2-D optical path,the elastic constant,strain and displacement of the tibia are measured.Compared with the electric measuring method the error is samll and the sensitivity is high.展开更多
Phase Shifting And Logical Moire (PSALM) is a kind of computer image processing method which can be used in phase measurement and to obtain the shape, deformation and strain distribution of an object.This paper presen...Phase Shifting And Logical Moire (PSALM) is a kind of computer image processing method which can be used in phase measurement and to obtain the shape, deformation and strain distribution of an object.This paper presents the structure and working procedure of a 2D phase measurement PSALM2D program and its application. When analyzing moire interferometric fringes,we can obtain 2D distribution of displacement and strain.When it is used in reflection moire we can measure the slope of a specimen.Satisfactory visualization and quantitative results are given by PSALM2D.展开更多
The authors found equations for complex coordinates of spectral peaks and trajectories in the case of two superposed layers, each consisting of two orthogonal gratings. The number of geometric elements in spectra was ...The authors found equations for complex coordinates of spectral peaks and trajectories in the case of two superposed layers, each consisting of two orthogonal gratings. The number of geometric elements in spectra was found for four running parameters and different number of gratings by layers. The shape of trajectories was determined in the corresponding cases. The relationships between parameters were found which could help in reducing the intervals of parameters, in particular the relationship between the inverse aspect ratios. The numerical simulation and the physical experiment were in a good agreement with the theory. The proposed technique seems to be helpful in estimation of occurrence of moir6 patterns in visual displays which makes possible the minimization in the spectral domain without calculation of spectra.展开更多
The hole-drilling method is one of the most wellknown methods for measuring residual stresses. To identify unknown plane stresses in a specimen, a circular hole is first drilled in the infinite plate under plane stres...The hole-drilling method is one of the most wellknown methods for measuring residual stresses. To identify unknown plane stresses in a specimen, a circular hole is first drilled in the infinite plate under plane stress, then the strains resulting from the hole drilling is measured. The strains may be acquired from interpreting the Moire signature around the hole. In crossed grating Moire interferometry, the horizontal and vertical displacement fields (u and v) can be obtained to determinate two strain fields and one shearing strain field. In this paper, by means of Moire interferometry and three directions grating (grating rosette) developed by the authors, three displacement fields (u, v and s) are obtained to acquire three strain fields. As a practical application, the hole-drilling method is adopted to measure the relief strains for aluminum and fiber reinforced composite. It is a step by step method; in each step a single laminate or equivalent depth is drilled to find some relationships between the drilling depth and the residual strains relieved in the fiber reinforced composite materials.展开更多
In this paper, a novel interferometric method with a wide range of sensitivities, called holography quasi projection moire, is proposed. It combines the features of the variated double projection moire method and the ...In this paper, a novel interferometric method with a wide range of sensitivities, called holography quasi projection moire, is proposed. It combines the features of the variated double projection moire method and the holographic interferometry method. This technique is used to study the failure modes of microelectronic packaging modules.展开更多
In this paper, we demonstrate a new optical method for tiny strain measurements based on the principle of carrier fringes of moire interferometry. A cross-line grating with frequency of 1200 lp/mm is replicated on the...In this paper, we demonstrate a new optical method for tiny strain measurements based on the principle of carrier fringes of moire interferometry. A cross-line grating with frequency of 1200 lp/mm is replicated on the specimen surface, and the strain can be deduced from the changes in carrier fringes before and after the deformation of an object. Four coherent laser beams are used to obtain the carrier fringe patterns of field U and V. Both theoretical analysis and numerical simulation indicate that the ideal accuracy of strain can be controlled within a range of ±1με. Case study of a plane extension experiment shows that the measurement accuracy of strain can be controlled within the range of ±10με. The average strain values of every row of field U and every column of field V can be obtained by using this method, and approximated strain of every pixel in the whole-field can be further acquired, and thus it is possible to measure tiny strains occurred in a micro-field. The technology in this paper can provide comprehensive information for analyzing related mechanical content in the field of MEMS.展开更多
In order to investigate the survivable specimen gratings, the crossed-line300 lines/mm gratings were chemically etched directly into the surface of the specimens.In order to obtain high diffraction efficiency and to m...In order to investigate the survivable specimen gratings, the crossed-line300 lines/mm gratings were chemically etched directly into the surface of the specimens.In order to obtain high diffraction efficiency and to minimize the shear lag, the etcheddepth of the gratings was one fourth the wave length of coherent light. The influence ofthe uneven window on the high temperature moire interferometry was preliminarily analyzed. The quartz and inconel 718 specimens were tested up to 1200℃ and 900℃. Thecrack tip deformation singular field as well as load-induced and thermal expansion displacement fields were measured by means of high temperature moire interferometry.展开更多
文摘An effective Dynamic Moire method was presented to determine the critical time of crack instable propagation in rock dynamic fracture. Two pieces of grating were installed near the notch of Short Rod specimen to form the Moire fringes, then the COD versus time could be monitored from the movement of the Moire fringes, and finally the critical time could be determined from the velocity of COD. This method was also compared with another one.It could be concluded that the critical time determined by Dynamic Moire method corresponds with that of the Transmitted Wave method at the loading rates from 103 to 104 MPa·m(1/2)·S(-1).
文摘Moire interferometry method is introduced to study the feasibilities of J integral as a plastic singularity parameter at the tip of the notch in the welded joints. The results show that J dominance in most studied cases is not validated in v and u displacement fields. Therefore, it can be concluded that J-integral as controlling parameter used to estimate the safety of welded structures is not always valid.
文摘This paper makes use of the method of testing and measuring the human body tibia by using2-D moire interferometry of sticking film. hased on the J'--y direction moire patterns recorded synchronously by 2-D optical path,the elastic constant,strain and displacement of the tibia are measured.Compared with the electric measuring method the error is samll and the sensitivity is high.
文摘Phase Shifting And Logical Moire (PSALM) is a kind of computer image processing method which can be used in phase measurement and to obtain the shape, deformation and strain distribution of an object.This paper presents the structure and working procedure of a 2D phase measurement PSALM2D program and its application. When analyzing moire interferometric fringes,we can obtain 2D distribution of displacement and strain.When it is used in reflection moire we can measure the slope of a specimen.Satisfactory visualization and quantitative results are given by PSALM2D.
文摘The authors found equations for complex coordinates of spectral peaks and trajectories in the case of two superposed layers, each consisting of two orthogonal gratings. The number of geometric elements in spectra was found for four running parameters and different number of gratings by layers. The shape of trajectories was determined in the corresponding cases. The relationships between parameters were found which could help in reducing the intervals of parameters, in particular the relationship between the inverse aspect ratios. The numerical simulation and the physical experiment were in a good agreement with the theory. The proposed technique seems to be helpful in estimation of occurrence of moir6 patterns in visual displays which makes possible the minimization in the spectral domain without calculation of spectra.
基金the National Natural Science Foundation of China (10772117, 10572089)
文摘The hole-drilling method is one of the most wellknown methods for measuring residual stresses. To identify unknown plane stresses in a specimen, a circular hole is first drilled in the infinite plate under plane stress, then the strains resulting from the hole drilling is measured. The strains may be acquired from interpreting the Moire signature around the hole. In crossed grating Moire interferometry, the horizontal and vertical displacement fields (u and v) can be obtained to determinate two strain fields and one shearing strain field. In this paper, by means of Moire interferometry and three directions grating (grating rosette) developed by the authors, three displacement fields (u, v and s) are obtained to acquire three strain fields. As a practical application, the hole-drilling method is adopted to measure the relief strains for aluminum and fiber reinforced composite. It is a step by step method; in each step a single laminate or equivalent depth is drilled to find some relationships between the drilling depth and the residual strains relieved in the fiber reinforced composite materials.
基金The project supported by the National Natural Science Foundation of China
文摘In this paper, a novel interferometric method with a wide range of sensitivities, called holography quasi projection moire, is proposed. It combines the features of the variated double projection moire method and the holographic interferometry method. This technique is used to study the failure modes of microelectronic packaging modules.
基金the Basal Research Funds of National Defence Science and Technology
文摘In this paper, we demonstrate a new optical method for tiny strain measurements based on the principle of carrier fringes of moire interferometry. A cross-line grating with frequency of 1200 lp/mm is replicated on the specimen surface, and the strain can be deduced from the changes in carrier fringes before and after the deformation of an object. Four coherent laser beams are used to obtain the carrier fringe patterns of field U and V. Both theoretical analysis and numerical simulation indicate that the ideal accuracy of strain can be controlled within a range of ±1με. Case study of a plane extension experiment shows that the measurement accuracy of strain can be controlled within the range of ±10με. The average strain values of every row of field U and every column of field V can be obtained by using this method, and approximated strain of every pixel in the whole-field can be further acquired, and thus it is possible to measure tiny strains occurred in a micro-field. The technology in this paper can provide comprehensive information for analyzing related mechanical content in the field of MEMS.
文摘In order to investigate the survivable specimen gratings, the crossed-line300 lines/mm gratings were chemically etched directly into the surface of the specimens.In order to obtain high diffraction efficiency and to minimize the shear lag, the etcheddepth of the gratings was one fourth the wave length of coherent light. The influence ofthe uneven window on the high temperature moire interferometry was preliminarily analyzed. The quartz and inconel 718 specimens were tested up to 1200℃ and 900℃. Thecrack tip deformation singular field as well as load-induced and thermal expansion displacement fields were measured by means of high temperature moire interferometry.