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Error caused by borehole in residual stress detection and its correction
In the blind hole method residual stress detection , such as the error caused by the test process, it can be reduced to a low level of Zui by careful operation during the test. The test error caused by the drilling requires necessary corrections to the relevant test data.
Plastic strain caused by borehole stress concentration and its correction: When blind hole method is used to detect welding residual stress, it must be drilled in it, which will inevitably lead to stress concentration, especially at the measuring point in the weld and its vicinity, the residual stress in this area It is close to or reaches the yield limit of the material itself. Therefore, a certain amount of plastic strain is inevitably generated around the blind hole. At this time, the strain felt by the strain flower stuck around the blind hole is actually the sum of the plastic strain and the elastic strain, so that the measured residual stress greatly exceeds the material. bow to extremes. Therefore, the measurement error must be corrected. The correction method generally includes the experimental curve correction method, the A and B coefficient classification using the correction method and the error iterative calculation correction method.
Drilling additional strain and its correction: When drilling with a drilling device, the drill bit causes the material of the hole wall to undergo elastic deformation, plastic deformation and cutting process, thus creating an additional stress field around the hole wall due to local plastic deformation. The strain gage attached to this area senses the additional strain of the drill, its size and aperture, hole depth, drilling speed, bit type, bit sharpness, resistance strain gauge size and its distance to the center of the blind hole, and material properties. In addition, in practice, in addition to paying attention to controlling the geometric dimensions and keeping the bit sharp, it is necessary to make necessary measurements and corrections. The measurement of additional strain for drilling is generally carried out by a drilling test of a stress-free test piece.
JH-30 residual stress detector and residual stress drilling device related content, Nanjing Juhang Technology Co., Ltd. for consultation.