CN104457603A - Object deformation measurement method under high-temperature environment - Google Patents

Abstract

The invention discloses an object deformation measurement method under a high-temperature environment and relates to the fields of materials, optical experiments, solid mechanics and the like. According to the method, through a device for measuring deformation of an object in the high-temperature environment, the measured object is placed on a high-temperature loading platform, a reflective mirror is arranged on each of the two sides of the measured object, background speckle images reflected by the object and the reflective mirrors are collected by a CCD camera before and after heating, the collected images are analyzed through a digital image related algorithm, speckle displacement fields of the measured object and the reflective mirrors are obtained, the interpolation values of the displacement fields reflected by the reflective mirrors on the two sides are removed from the displacement field reflected by the measured object, then, the displacement fields reflected by deformation after air disturbance is removed can be obtained, and the surface appearance of the object can be obtained through calculation under high temperature. According to the method, the flexibility of an optical device is made full use of, implementation is easy, and the surface appearance change of the object in the high-temperature environment and in the whole field can be measured in real time online.

Description

Deformation of body measuring method under a kind of hot environment

Technical field

The present invention relates to a kind of digital correlation image technique that utilizes and measure object distortion in high temperature environments, belong to solid mechanics, material science, Experiments of Optics technical field.

Background technology

In the field such as Aero-Space, microelectronics, often have thin-slab construction work situation in high temperature environments, whether the surface deformation of thin-slab construction is for investigating the performance change of thin plate and losing efficacy significant.

Method such as the electrical measuring method of conventional measurement body surface distortion pastes foil gauge at body surface to survey strain, then integration obtains displacement, the method can only measure in-plane deformation, and non-measurement of full field, although the flash spotting of Later development meets deformation measurement outside face to a certain extent, but also do not have the method for complete measurement of full field, and cannot revise for the impact of air refraction change under high temperature, so under high temperature, the measuring method accurately of body surface distortion is a vacancy always.

Digital Image Correlation Method achieves non-cpntact measurement generally, utilize body surface natural texture or spraying speckle, with the speckle image before and after cameras record distortion, go out displacement field by digital correlation Algorithm for Solving, a kind of method as amount of the noncontact whole audience is extensively promoted.But under high temperature complex environment, owing to there is the unfavorable factors such as air refraction change, make image record and out of true, the displacement field directly recorded exists very big error, need to revise and improve.

Summary of the invention:

The invention provides a kind of object deformation of body measuring method in high temperature environments, the method can carry out noncontact, measurement of full field to the surface deformation of object under hot environment, eliminates air refraction and changes the impact brought, improve the accuracy of measurement.

Technical solution of the present invention is as follows:

Deformation of body measuring method under a kind of hot environment, is characterized in that the method adopts following steps:

A). under hot environment, deformation of body measurement mechanism and method adopt object deformation of body measurement mechanism in high temperature environments, and this device comprises this device and comprises background speckle, high temperature weighted platform, spectroscope, catoptron, support, CCD camera and the computing machine containing calculation procedure;

Testee is placed on the catoptron on high temperature weighted platform, and background speckle is the stochastic distribution black spots point diagram of hand spray, light illuminating hot spot during experiment, the background speckle reflected through body surface and catoptron with CCD camera shooting;

Be placed in by testee on the catoptron on high temperature weighted platform, the background speckle of CCD camera shooting after two secondary reflections, CCD camera is L apart from the light path of background speckle, and testee and background speckle distance are D, and testee is b, and such testee and catoptron are considered as at grade;

B). utilize and load at high temperature weighted platform, record temperature T, load p, electric field strength E, magnetic field intensity H in high temperature environments, the background speckle image before and after loading with CCD camera shooting;

C). the background speckle image before and after loading is inputted computing machine, and set up coordinate system: testee place plane is OXY plane, background speckle place plane is OX _oy _oplane, calculates the background speckle displacement field (u loading front and back testee and catoptron reflection respectively by Digital Image Correlation Method _o, v _o) and (u _k, v _k), wherein u _o, v _o) produced by testee surface deformation and testee upper air variations in refractive index, (u _k, v _k) only produced, by (u by catoptron upper air variations in refractive index _k, v _k) two-dimentional matching obtain only being caused by object upper air variations in refractive index displacement field (u ' _o, v ' _o), by (u _o, v _o) correspondence deduct (u ' _o, v ' _o), namely obtain the displacement field (u, v) removing air refraction variable effect;

$\left\{\begin{array}{c}u=u_o-u_o^{\′}\\ v=v_o-v_o^{\′}\end{array}\right.$

D). the deflection angle (φ after the light reflection caused only is out of shape by body surface _x, φ _y) calculated by following formula:

$\left\{\begin{array}{c}{\mathrm{\φ}}_x=\frac{u}{D}\\ {\mathrm{\φ}}_y=\frac{v}{D}\end{array}\right.$

Wherein u and v is only out of shape the speckle x of reflection and the displacement in y direction by body surface before and after being respectively and loading, φ _xand φ _yfor the reflection ray after the surface incidence of light vertical object is along the deflection angle in x and y direction, the coordinate (x, y) on testee plane OXY and speckle plane OX _oy _oon coordinate (x _o, y _o) between pass be:

$\left\{\begin{array}{c}x=\frac{L}{L+D}{x}_o\\ y=\frac{L}{L+D}{y}_o\end{array}\right.$

E). when deformation of body is less, the full-field distribution of now object loading rear surface pattern gradient is calculated by following formula:

$\left\{\begin{array}{c}2\frac{\∂z}{\∂x}\·{\mathrm{\φ}}_x=\frac{u}{D}\\ 2\frac{\∂z}{\∂y}\·{\mathrm{\φ}}_y=\frac{v}{D}\end{array}\right.$

Try to achieve real topography z after deformation of body by surface topography gradient, calculated by following formula:

$z=\underset{0}{\overset{X}{\∫}}\frac{\mathrm{uL}}{2D(L+D)}\mathrm{dx}+\underset{0}{\overset{Y}{\∫}}(v-\frac{\∂\underset{0}{\overset{X}{\∫}}\frac{\mathrm{uL}}{2D(L+D)}\mathrm{dx}}{\∂y})\mathrm{dy}$

Curvature κ after deformation of body _xx, κ _yycalculated by following formula:

$\left\{\begin{array}{c}{\mathrm{\κ}}_{\mathrm{xx}}=\frac{{\∂}^{2}z}{\∂x^2}=\frac{\frac{1}{D}\∂u}{\∂x^2}\\ {\mathrm{\κ}}_{\mathrm{yy}}=\frac{{\∂}^{2}z}{\∂y^2}=\frac{\frac{1}{D}\∂v}{\∂y^2}\end{array}\right.$

The present invention compared with prior art, has the following advantages and the technique effect of high-lighting:

The present invention can when there is flow perturbation in hot environment, and remove by interpolation the impact that flow perturbation causes variations in refractive index, measure the information such as the true strain of testee, commonsense method can not remove the impact of air refraction change.

Accompanying drawing explanation

Fig. 1 is deformation of body measurement mechanism schematic diagram under hot environment provided by the invention.

In accompanying drawing: 1-background speckle; 2-light source; 3-spectroscope; 4-testee; 5-catoptron; 6-high temperature weighted platform; 7-CCD camera; 8-computing machine; 9-support; 10-light path.

Fig. 2 is the process flow diagram of deformation of body measuring method under hot environment provided by the invention.

embodiment:

Below in conjunction with accompanying drawing, the present invention will be further described, but should not limit the scope of the invention with this.

Fig. 1 is deformation of body measurement mechanism schematic diagram under hot environment provided by the invention.This device comprises background speckle, high temperature weighted platform, spectroscope, catoptron, support, CCD camera and the computing machine containing calculation procedure.

Testee is placed on the catoptron on high temperature weighted platform, and background speckle is the stochastic distribution black spots point diagram of hand spray, and light illuminating hot spot during experiment, is followed successively by the spectroscope at the angle at 45 ° with ground, background speckle directly over testee.As shown in light path in figure, first background speckle glazed thread reaches mirror surface through spectroscope and is reflected, and reflection ray reaches spectroscope lower surface and again reflected, and horizontally, enters CCD camera, completes the shooting to background speckle; High temperature weighted platform is utilized to load.Object produces in face, is out of shape outside face, and shooting loads contexts speckle image, calculates object and catoptron speckle displacement respectively, and then calculate testee distortion in high temperature environments by Digital Image Correlation Method.

Testee is placed on the catoptron of high temperature weighted platform, after loading, object produces in face, is out of shape outside face, the speckle displacement field of such testee reflection is relevant with air refraction and self-deformation, and the speckle displacement field of catoptron reflection is only relevant with air refraction.Testee is loaded, with the image that CCD camera shooting is reflected through object and catoptron before and after loading, calculates the background speckle displacement field (u of testee and catoptron reflection before and after loading respectively by Digital Image Correlation Method _o, v _o) and (u _k, v _k), wherein u _o, v _o) produced by testee surface deformation and testee upper air variations in refractive index, (u _k, v _k) only produced, by (u by catoptron upper air variations in refractive index _k, v _k) adopt least-squres camber fitting to obtain only being caused by object upper air variations in refractive index displacement field (u ' _o, v ' _o), concrete operations are as follows:

By horizontal displacement field u, and the surface fitting function of vertical displacement field v is expressed as follows respectively:

$\left\{\begin{array}{c}{f}_u(x,y)=\underset{i=0}{\overset{n}{\mathrm{\Σ}}}\underset{j=0}{\overset{n}{\mathrm{\Σ}}}{a}_{\mathrm{ij}}{x}^i{y}^i\\ f_v(x,y)=\underset{i=0}{\overset{n}{\mathrm{\Σ}}}\underset{j=0}{\overset{n}{\mathrm{\Σ}}}{b}_{\mathrm{ij}}{x}^i{y}^i\end{array}\right.---\left(1\right)$

Wherein, n is (u _k, v _k) in get the number of match point, a _ij, b _ijbe respectively the coefficient of polynomial fitting, f _u(x, y), f _v(x, y) is respectively the fitting function of u field, v field;

Error function is:

$\left\{\begin{array}{c}E\left(a_{\mathrm{ij}}\right)=\underset{i=0}{\overset{n}{\mathrm{\Σ}}}{[{\left(u_k\right)}_i-f_u(x_i,y_i)]}^2\\ E\left(b_{\mathrm{ij}}\right)=\underset{i=0}{\overset{n}{\mathrm{\Σ}}}{[{\left(v_k\right)}_i-f_v(x_i,y_i)]}^2\end{array}\right.---\left(2\right)$

Get extreme value by error function, determine coefficient a _ij, b _ijvalue:

$\left\{\begin{array}{c}\frac{\∂E\left(a_{\mathrm{ij}}\right)}{{\∂a}_{\mathrm{ij}}}=0\\ \frac{\∂E\left(b_{\mathrm{ij}}\right)}{{\∂b}_{\mathrm{ij}}}=0\end{array}\right.---\left(3\right)$

The displacement field that finally obtains only being caused by object upper air variations in refractive index (u ' _o, v ' _o), by (u _o, v _o) correspondence deduct (u ' _o, v ' _o), namely obtain the displacement field (u, v) removing air refraction variable effect;

$\left\{\begin{array}{c}u=u_o-u_o^{\′}\\ v=v_o-v_o^{\′}\end{array}\right.---\left(4\right)$

D). the deflection angle (φ after the light reflection caused only is out of shape by body surface _x, φ _y) calculated by following formula:

$\left\{\begin{array}{c}{\mathrm{\φ}}_x=\frac{u}{D}\\ {\mathrm{\φ}}_y=\frac{v}{D}\end{array}\right.---\left(5\right)$

Wherein D is testee and background speckle distance, u and v is only out of shape the speckle x of reflection and the displacement in y direction by body surface before and after being respectively and loading, φ _xand φ _yfor the reflection ray after the surface incidence of light vertical object is along the deflection angle in x and y direction.Coordinate (x, y) on object (catoptron) plane OXY and speckle plane OX _oy _oon coordinate (x _o, y _o) between pass be:

$\left\{\begin{array}{c}x=\frac{L}{L+D}{x}_o\\ y=\frac{L}{L+D}{y}_o\end{array}\right.---\left(6\right)$

Wherein L is the optical path length between CCD camera and testee, from geometric relationship, and φ _xand φ _yfollowing relation is had with the surface graded of testee:

$\left\{\begin{array}{c}\tan {\mathrm{\φ}}_x=2\frac{\∂z}{\∂x}\\ \tan {\mathrm{\φ}}_y=2\frac{\∂z}{\∂y}\end{array}\right.---\left(7\right)$

When being out of shape less, can turn to:

$\left\{\begin{array}{c}{\mathrm{\φ}}_x=2\frac{\∂z}{\∂x}\\ {\mathrm{\φ}}_y=2\frac{\∂z}{\∂y}\end{array}\right.---\left(8\right)$

Wherein z is that object is from face height.

Simultaneous (4)-(8) formula, the partial derivative from face height z can be expressed as:

$\left\{\begin{array}{c}\frac{\∂z}{\∂x}=\frac{\mathrm{uL}}{2D(L+D)}\\ \frac{\∂z}{\∂y}=\frac{\mathrm{vL}}{2D(L+D)}\end{array}\right.---\left(9\right)$

Whole audience topographical information can be obtained to (9) formula integration:

$z=\underset{0}{\overset{X}{\∫}}\frac{\mathrm{uL}}{2D(L+D)}\mathrm{dx}+\underset{0}{\overset{Y}{\∫}}(\frac{\mathrm{vL}}{2D(L+D)}-\frac{\∂\underset{0}{\overset{X}{\∫}}\frac{\mathrm{uL}}{2D(L+D)}\mathrm{dx}}{\∂y})\mathrm{dy}---\left(10\right)$

Curvature κ after deformation of body _xx, κ _yycalculated by following formula:

$\left\{\begin{array}{c}{\mathrm{\κ}}_{\mathrm{xx}}=\frac{{\∂}^{2}z}{{\∂x}^2}=\frac{\frac{1}{D}\∂u}{{\∂x}^2}\\ {\mathrm{\κ}}_{\mathrm{yy}}=\frac{{\∂}^{2}z}{{\∂y}^2}=\frac{\frac{1}{D}\∂v}{{\∂y}^2}\end{array}\right..---\left(11\right)$ 。

Claims (1)

1. a deformation of body measuring method under hot environment, is characterized in that the method comprises the steps:

A). set up measuring system: this system comprises background speckle (1), high temperature weighted platform (6), spectroscope (3), catoptron (5), CCD camera (7) and the computing machine (8) containing calculation procedure; Described high temperature weighted platform places catoptron, testee placed by catoptron, testee put surface finish or be sprayed into minute surface;

CCD camera is L apart from the light path of background speckle, and testee and background speckle distance are D, and testee and catoptron thickness are much smaller than D, and such testee and catoptron are considered as at grade;

Background speckle lighting source illuminates, and testee and catoptron are through dichroic mirror background speckle, and CCD camera takes the background speckle pattern through testee and spectroscope two secondary reflection in spectroscopical horizontal direction;

B). utilize high temperature weighted platform to load testee, record temperature T, load p, electric field strength E and magnetic field intensity H respectively in high temperature environments, the background speckle image before and after loading with CCD camera shooting;

C). the background speckle image before and after loading is inputted computing machine, and set up coordinate system: testee place plane is OXY plane, background speckle place plane is OX _oy _oplane, calculates the background speckle displacement field (u loading front and back testee and catoptron reflection respectively by Digital Image Correlation Method _o, v _o) and (u _k, v _k),

Wherein, (u _o, v _o) produced by testee surface deformation and testee upper air variations in refractive index, (u _k, v _k) only produced, by (u by catoptron upper air variations in refractive index _k, v _k) adopt least-squres camber fitting to obtain only being caused by object upper air variations in refractive index displacement field (u ' _o, v ' _o), by (u _o, v _o) correspondence deduct (u ' _o, v ' _o), namely obtain the displacement field (u, v) removing air refraction variable effect;

D). set and be only out of shape the deflection angle after the light reflection caused as (φ by body surface _x, φ _y), calculated by following formula:

Wherein, u and v is only out of shape the displacement of speckle in x and y direction of reflection by body surface before and after being respectively and loading, φ _xand φ _yfor the reflection ray after the surface incidence of light vertical object is along the deflection angle in x and y direction, the coordinate (x, y) on testee plane OXY and speckle plane OX _oy _oon coordinate (x _o, y _o) between pass be:

E). when deformation of body is less, namely the full-field distribution that object loads rear surface pattern gradient is calculated by following formula:

Try to achieve real topography z after deformation of body by surface topography gradient, calculated by following formula:

Curvature κ after deformation of body _xx, κ _yycalculated by following formula:

。