Thermal parameter identification method based on optimum matching image of affine transformation

Abstract

The invention discloses a thermal parameter identification method based on an optimum matching image of affine transformation. The thermal parameter identification method comprises the following steps: preparing a high-temperature speckle test piece, fixing a to-be-tested piece on a three-point bending test machine, and collecting a speckle image before deformation of the test piece; applying a heat load, and collecting the speckle image after deformation of the test piece; selecting a calibration area on the speckle image before deformation, and finishing the practical length calibration of a unit pixel; selecting a calculating area on the speckle image before deformation, and setting an iteration initial value by taking to-be-tested thermal parameters as to-be-optimized vectors; performing affine transformation on the speckle image after deformation, thereby acquiring an image before tectonic deformation; matching the image before tectonic deformation with the speckle image before deformation, and performing continuous iterative optimization on the to-be-tested thermal parameters; setting a termination iteration threshold value, terminating the iteration according to the termination iteration threshold value, and realizing the optimal matching of the image before tectonic deformation and the speckle image before deformation; measuring and eliminating the translation and rotation of a rigid body; and meanwhile, identifying the thermal parameters including elasticity modulus, Poisson ratio and thermal expansion coefficient.

Description

technical field [0001] The present application relates to the technical field of high temperature measurement in experimental mechanics, in particular to a thermal parameter identification method based on an affine transformation best matching image. Background technique [0002] At present, the determination of elastic modulus and Poisson's ratio of high-temperature materials is mainly done through high-temperature tensile experiments. Raise the temperature to a predetermined value to stretch the sample uniaxially, record the load and measure the tensile direction and transverse strain of the material to obtain the elastic modulus and Poisson's ratio. The coefficient of thermal expansion is mainly measured by recording the strain by raising the temperature to a predetermined value. The thermal parameters of the traditional method must be measured separately, requiring repeated heating, the process is cumbersome, and the cost is high [0003] The patent CN103018111A invent...

AI Technical Summary

Problems solved by technology

However, this method requires the support of third-party digital image related software to obtain the displacement field and strain field before and after material deformation; it needs professional knowledge personnel to construct the virtual displacement field for the next step of processing; considering that there is rigid body motion in actual operation, rigid body translation is not excluded In some cases, errors will be introduced; the calculation process is cumbersome and time-consuming

Therefore, it is easy to operate, does not require third-party software support, and considers the possible rigid body translation in actual operation, and the simultaneous measurement technology of thermal parameters with fast processing speed (<10s) needs to be proposed urgently

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