System and method for measuring residual stress in real time

Abstract

The invention relates to a system and a method for measuring residual stress in real time. The method comprises the following steps of: performing three-dimensional surface coordinate reconstruction on a test piece by three-dimensional digital image correlation, performing related research on a speckle image at the periphery of a hole before and after drilling the test piece, and calculating a three-dimensional displacement field before and after drilling; automatically feeding an electric spindle precisely through control over a stepping motor by a stepping motor controller and the translation of a worm gear and worm mechanism according to the drilling depth of the test piece; and calculating the residual stress of the test piece according to planar assumption of a drilling area of a curved surface by combining a theoretical formula for measuring the residual stress during drilling. The system can drill the hole precisely in real time, and measures the residual stress of the test piece with depth change in a stepping mode. The system and the method for measuring the residual stress have the advantages of real-time property, high precision, non-contact, whole-field displacement measurement, flexibility and convenience of operation, and the like.

Description

technical field [0001] The invention relates to a system for real-time drilling to measure residual stress and uses three-dimensional digital image correlation technology to measure residual stress. The invention belongs to the fields of optical measurement experiment mechanics, engineering materials, component deformation, three-dimensional reconstruction and drilling residual stress measurement. Background technique [0002] Residual stress refers to the stress that still exists inside the material after the removal of various external factors that generate stress, and maintains balance by itself. There are many external factors that produce residual stress, such as temperature changes, material processing, shot peening, surface treatment, phase change, precipitation, etc. Residual stress directly affects the performance of the structure. Especially in engineering pipelines, welding residual stress directly affects the safe performance of the structure. It can promote stre...

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Problems solved by technology

[0003] Residual stress is often measured in engineering by using the drilling method combined with the measurement method of strain gauges. There are also many technologies for residual stress by drilling methods, such as a welding residual stress measurement method (Chinese invention patent application publication specification 200910014661.1), The residual stress testing device (Chinese Invention Patent Application Publication No. 200820090081.9), combined with strain gauges and drilling methods can satisfy most engineering measurements, but because the strain gauges are sensitive to temperature, the accuracy of strain measurement depends on the bonding technology, and the drill Hole centering is very demanding, and the measurement process is greatly affected by environmental electromagnetic radiation, etc., which is not suitable for measurement in complex environments

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