Non-contact and fast measurement of small roll angle using digital shearography

Wu, Sijin; Li, Xin; Li, Weixian; Si, Juanning

doi:10.1016/j.optlaseng.2021.106846

Cited by 5 publications

(2 citation statements)

References 21 publications

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“…Recently, a non-destructive testing method based on digital shear speckle interferometry has emerged. Compared with the above conventional non-destructive testing methods, it has the advantages of full-field, non-contact, pollution-free, high precision and high sensitivity, no special shockproof, no restrictions on the geometric dimensions of the workpiece, fast real-time and online detection, and has become a research focus in the field of testing [15][16][17][18] . In the digital speckle shearing interferometry, the first derivative of the out-of-plane displacement of a deformed object can be measured directly by using the shearing device.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Plane Displacement of Pressure Vessels with Defects

Feng

Bao²

2023

J. Phys.: Conf. Ser.

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Aiming at the problem that the internal defects of the pressure vessel are not easy to detect, the out-of-plane displacement method is used to study it. The out-of-plane displacement field of circular flat plate heads with defects is obtained by the method of elastic theory analysis and compared with the finite element method to verify the accuracy of the finite element method. Based on the finite element method, the effects of vessel material, pressure load, defect shape, and defect size on the first-order out-of-plane displacement derivative are studied. The results show that the material of the container has little effect on the out-of-plane displacement. The first derivative of out-of-plane displacement increases linearly with the increase of pressure, and this relationship will not change with the increase of pressure. With the increase of defect aspect ratio, the maximum value of the first derivative of out-of-plane displacement increases gradually. When δ ˃ 9, the defect is detectable. The research results lay a theoretical foundation for the internal defect detection of pressure vessels based on digital speckle shearing interferometry.

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Section: Introductionmentioning

confidence: 99%

Analysis of Plane Displacement of Pressure Vessels with Defects

Feng

Bao²

2023

J. Phys.: Conf. Ser.

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“…This enables precise and real-time capture of surface tension variations, providing valuable insights into material behavior. In their publication, Wu (2022), 9 developed a high-speed shear system that significantly surpasses traditional interferometric devices in measurement speed and anti-interference capability. Anti-interference refers to the use of methods to prevent reduce the formation of secondary fringes between optical elements in a device or system.…”

Section: Introductionmentioning

confidence: 99%

Simultaneous orthogonal shearography using two pairs of parallel slits and a tetra-split lens

Lima

Barrera

Gonçalves

2023

Optical Measurement Systems for Industrial Inspection XIII

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There are a growing number of industrial applications for shearography, especially in non-destructive testing of composite materials. Its tolerance to hostile environments is probably the most relevant success factor for industrial applications. The introduction of carrier fringes for phase recovery, replacing temporal phase shift techniques, allows measurements with a single exposure for each loading state, making shearography even more robust. Some defects are better evident when the shearing direction is horizontal. Others are best viewed with a vertical shearing direction. Thus, it is desirable to inspect in both directions. Fortunately, the literature reports some configurations capable of using carrier fringes to perform simultaneous measurements in more than one shearing direction. These systems work well, but since they use a mask with circular holes, they require a high amount of light. An alternative is the use of a pair of oblong slits, which increases the amount of light captured. This paper extends the use of oblong slit pairs for simultaneous measurement in two orthogonal shearing directions. Two pairs of parallel oblong slits are arranged orthogonally on the system mask. Although the Fourier transform of the resulting signal at the camera sensor contains the desired signals as well as a crosstalk between the slit pairs. However, the mask can be designed in such a way that the orthogonal signals are separable. To promote shearing in orthogonal directions, a polymeric lens was sectioned, forming four quadrants of 90°. The quadrants were radially displaced and arranged so that each oblong slit covers only one quadrant of the lens. As a result, four laterally shifted images are formed, two of them with horizontal shearing and the other two with vertical shearing. A proof-of-concept prototype was developed and the first results were evaluated by the authors in the laboratory environment and are presented in this article. The paper also shows details of the resulting Fourier spectrum and the strategy used to separate the orthogonal components and recover the phase using carrier fringes. The performance of the prototype met expectations and validated the concept. Future works involve miniaturization of the prototype and tests in industrial environments.

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