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On-Line Strain Measurement by Sheet Metal Forming Using Computer Vision
|關鍵字:||Computer Vision;電腦視覺;Strain Measurement;Grid Analysis;Sheet Metal Forming;應變量測;網格分析;金屬薄板成形||出版社:||機械工程學系||摘要:||
The strain path of sheet metal influences its forming limit diagram. However, by measuring the strain on the sheet metal, the forming process must be interrupted, then the strain path can not correctly be described and consequently the forming limit can not properly be defined. In order to measure the forming limit and strain path, this study presents apply computer vision to set up On-Line Non-contact measuring the strain on the sheet metal system. The main processing sheet metal is initially printed with square grids pattern by an electrochemical etching method. During the forming process the sheet metal is sequentially photographed with two CCD (Charge Couple Device) cameras mounted on the forming machine. We can use a pair of two-dimensional images to reconstruct a three-dimensional image. When images processed, the coordinates for each node of the grids can be determined, the skeleton of the part can also then be constructed with the topology identification, and then the strain at the node can be calculated under the postulation of homogeneous deformation. The developed on-line measurement technique can catch the sheet metal images during the forming process, which can be used not only to illustrate its geometry but also to display its strain distribution, especially to follow the strain path at the grids. This study presents the Non-contact On-Line strain measuring method applying to sheet metal forming by the following experiments: uniaxial tension sheet metal in tension strain state, uniaxial tension sheet metal in plane strain state, and stretching sheet metal in plane strain state.
|Appears in Collections:||機械工程學系所|
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