In terms of the operating principle of its visual system, the test piece is first subjected to painting and speckling treatment and the target to be measured is marked the edge features of the cracks in the plane are then obtained using image matching and processing. The digital image correlation (DIC) technique has been successfully applied to non-contact measurement for surface displacement, deformation, and cracks in material and structure.
These methods should be applied to medical, chemical, agricultural, civil engineering, transportation, and several other fields, ,,. There is an urgent demand for new methods of non-contact measurement and the corresponding visual systems. Traditional contact measurement is also expensive, and its consumables are not reusable. Using traditional methods, maintenance personnel may struggle to check structural surfaces for deformation when they consist of complex components in dangerous environments.
The entire descending section of the full-field strain curve in certain mechanical tests cannot be obtained using a strain gauge, and thus, no data is available for that section. It is difficult for a limited number of strain gauges or sensors to record the deformation and destruction of the entire component. Uncertainty in the test destruction position renders the strain gauge generally unsuitable for recording the maximum strain data and reduces its overall accuracy. These methods have inherent limitations–for example, changes in external environment humidity and temperature or user errors could lead to inaccurate or incomplete data, or even failure of the strain gauge. This method can be used as a reasonable alternative to traditional contact measuring methods.Ĭontact measuring methods such as the use of strain gauges and mechanical sensors are traditionally used to collect strain and deformation data in a laboratory.
#BINOCULAR MEASUREMENTS ISO#
The test results showed that the mean relative errors of the maximum convex diameter in the visual static and dynamic measurements were 0.19% and 0.33%, respectively, and the mean relative error in the full-field strain in the visual measurement was between 0.20% and 0.49%, which shows that the proposed visual method comprehensively reflects the deformation process and full-field strain values of the components under engineering ISO Tolerance (IT7) accuracy requirements. Three-dimensional reconstruction was performed, and the results obtained were compared with those of a contact measuring tool. Based on the proposed image-processing algorithm and the principle of 3D deformation measurement, the least-square-based circle-fitting algorithm was presented in this article and was applied to binocular vision systems for the static and dynamic collection of full-field 3D deformation data in concrete-filled steel tubular columns. The proposed method was tested in the determination of the deformation and strain of concrete-filled steel tubes. This paper presents a non-contact 3D deformation measurement method based on binocular vision.
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