Suppression Method of Airflow Disturbance Error in Non-contact Measurement of High Temperature Deformation

Abstract

The invention provides a method for suppressing an airflow disturbance error in high-temperature deformation non-contact measurement, and belongs to the technical field of measurement. The method comprises the following steps: uses a high-speed camera to obtain digital image sequences during the high-temperature deformation process of material components, calculating a sequence displacement fieldin the deformation process of the material components in every two sets of the digital image sequences; performing wavelet decomposition on the sequence displacement field to obtain the decomposed high-frequency coefficient matrix and low-frequency coefficient matrix; zero setting the high-frequency coefficient matrix, performing smoothing filtering on the low-frequency coefficient matrix, and calculating the all-zero high-frequency coefficient matrix and the smoothed low-frequency coefficient matrix; finally, obtaining a displacement field after wavelet average noise reduction of the sequencedisplacement field by using the wavelet reconstruction. The method provided by the invention obtains a smooth displacement field by performing wavelet de-noising processing on a displacement field containing noise disturbed by an air flow, which solves the influence of airflow disturbance on non-contact deformation measurement such as digital image correlation in a high temperature environment, and improves the accuracy of non-contact deformation measurement in a high temperature environment.

Description

technical field [0001] The invention relates to the field of measurement technology, in particular to a method for suppressing airflow disturbance errors in non-contact measurement of high-temperature deformation based on sequence displacement field wavelet averaging. Background technique [0002] In metallurgy, electric power, aerospace and many other fields, strain measurement technology in high temperature environment is one of the key technologies for evaluating the thermodynamic properties of high temperature material structures. There are two types of strain measurement: contact and non-contact. Because the traditional contact measurement method has difficulties such as strain element selection and connection, and error compensation when performing high-temperature strain measurement, non-contact high-temperature strain measurement technology has been paid more and more attention. Electronic speckle interferometry and electronic misalignment speckle interferometry are...

AI Technical Summary

Problems solved by technology

Some commonly used noise reduction methods include median filtering, mean filtering, etc., and median filtering is a nonlinear filtering algorithm, which has an obvious noise reduction effect on impulse noise, but the noise reduction effect on large areas of random bumps is not as good as the average value. Filtering, mean filtering is to use a given template to calculate the average value of the noisy displacement, which smoothes the displacement field to a certain extent, but it is easy to cause distortion of the displacement field

Scholars are also constantly researching new methods for smoothing and denoising the displacement field, mainly the overall smoothing method. The basic idea is to regard the noisy displacement field as a whole, and use the global basis function to fit the displacement field to achieve the effect of smoothing the displacement field. Such as: thin plate spline smoothing method, method combining least square method and finite element method, improved Hermite finite element smoothing method and method combining finite element and two-dimensional generalized crossover algorithm, the purpose of these surface fitting methods is to smooth At the same time, make the fitting surface as close as possible to the original displacement field. On the one hand, if it is a large-area noise with random bumps on the displacement field, and these noises are enough to cover up the real displacement field of the specimen, use the above surface The smooth displacement field fitted by the fitting method cannot represent the real deformation of the specimen. On the other hand, these smooth noise reduction methods are carried out on a single displacement field, which cannot solve the influence of the temporal randomness of the airflow field on the displacement field. Guarantees the accuracy of calculated strain values

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