Computerized method of determining surface strain distributions in a deformed body
First Claim
1. A method of measuring strain distribution on a deformed surface, comprising:
- applying a grid pattern having grid points to the surface, which pattern is deformed by deformation of the surface;
taking two different images of the deformed surface from two different orientations, there being a geometric relationship between the two images;
digitizing the grid points of the deformed grid pattern for each image to obtain two sets of two-dimensional coordinates for the grid points;
correlating the points of one set of coordinates with the corresponding points of the other set of coordinates;
calculating one set of three-dimensional coordinates for the grid points as a function of the geometric relationship between the two images and of the two sets of two-dimensional coordinates of the correlated grid points; and
calculating strain distribution over the surface as a function of the three-dimensional coordinates for the grid points, taken in groups of multiple grid points.
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Abstract
A method and apparatus for measuring strain distribution on a deformed surface utilizes a video or photographic camera for taking two images of the surface which are taken at an angle to each other. The surface carries a deformed grid which has grid points that are digitized using images from the camera. The digitized points each form one set of two-dimensional coordinates. Each point of the one set of coordinates is correlated with a corresponding point of the other set. The two sets of two-dimensional coordinates are then used in conjunction with the geometrical relationship between the images to calculate a single set of three-dimensional coordinates for the grid points. The three-dimensional coordinates are then used in groups of three adjacent points to calculate strain over the surface.
60 Citations
21 Claims
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1. A method of measuring strain distribution on a deformed surface, comprising:
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applying a grid pattern having grid points to the surface, which pattern is deformed by deformation of the surface; taking two different images of the deformed surface from two different orientations, there being a geometric relationship between the two images; digitizing the grid points of the deformed grid pattern for each image to obtain two sets of two-dimensional coordinates for the grid points; correlating the points of one set of coordinates with the corresponding points of the other set of coordinates; calculating one set of three-dimensional coordinates for the grid points as a function of the geometric relationship between the two images and of the two sets of two-dimensional coordinates of the correlated grid points; and calculating strain distribution over the surface as a function of the three-dimensional coordinates for the grid points, taken in groups of multiple grid points. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. An apparatus for measuring strain distribution over a deformed surface carrying a deformed grid pattern having grid points, comprising:
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means for taking two different images of the deformed surface with the deformed grid pattern thereon from two different orientations, there being a known geometrical relationship between the images; means for digitizing the grid points of the deformed grid pattern for each image to obtain two sets of two-dimensional coordinates for the grid points; means for calculating one set of three-dimensional coordinates for the grid points of the grid pattern as a function of the two sets of two-dimensional coordinates and the geometrical relationship between the two images; and means for calculating the strain distribution over the deformed surface as a function of local groups of plural grid points over the deformed surface. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21)
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Specification