CN112067147B - Method and device for synchronously measuring temperature and deformation - Google Patents
Method and device for synchronously measuring temperature and deformation Download PDFInfo
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- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/16—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge
Abstract
The utility model relates to a synchronous measuring method and device of temperature and deformation, wherein, the method comprises the steps of obtaining an initial image of the surface of a measured object when not heated, a reference image of the surface of the measured object in the heating process and the reference point temperature of the surface of the measured object; obtaining a temperature field of the surface of the measured object according to the light intensity of the initial image, the temperature of the reference point and the light intensity of the reference image; obtaining a deformation field of the surface of the measured object according to the initial image and the reference image; the reference image and the initial image are monochrome images shot by a monochrome camera; the reference point temperature is the single point temperature of the surface of the measured object when the reference image is shot. In this disclosure, only need monochromatic camera can measure full field temperature, remedied the not enough of unable full field temperature of measurement through monochromatic camera, simultaneously, realized temperature and deformation synchronous measurement under the high temperature environment, and measurement accuracy and efficiency all have showing and promote, promoted the application development of monochromatic camera in temperature and deformation synchronous measurement field greatly.
Description
Technical Field
The disclosure relates to the technical field of optical measurement, in particular to a method and a device for synchronously measuring temperature and deformation in the field of high-temperature test.
Background
In the aerospace field, critical structural components of aircraft need to face high temperature complex environments in service. Taking a high-speed aircraft as an example, with the further improvement of the cruising speed and the prevention capability, when the aircraft is cruising at a high speed and reenters, the extreme environments of key structural components such as engine turbine blades, a nose cone, a front edge and the like are accompanied with a plurality of physicochemical processes such as thermochemical ablation, aerodynamic heat effect, boundary layer transition, aerodynamic shape evolution and the like. In order to ensure the integrity of key structural components and the stability of functions of the key structural components, the ground test and verification of the comprehensive thermal and mechanical properties of the materials of the key structural components are carried out before service, and the method has important significance for the stable and safe service of a high-speed aircraft.
The characterization and testing of materials of key structural components in a high-temperature environment are always hot problems concerned in engineering and are also difficult points of relevant research; in the related art, when a high-temperature environment test is performed, an optical test mode based on non-contact measurement is generally adopted, but the test mode is subjected to the influence of a plurality of high-temperature extreme environments, wherein the influence of strong light radiation is the most important. In order to eliminate or reduce the above-mentioned influence, a narrow-band Digital filtering technology is gradually developed, and a deformation process of a material of a key structural component can be effectively analyzed by combining a traditional Digital Image Correlation (DIC) test.
Since the mechanical properties (such as elastic modulus, hardness, fracture toughness, etc.) of the material in the high temperature environment are all related to temperature, and the strain at the high temperature is often the coupling of thermal strain and stress strain, it is necessary to obtain the temperature field of the material to achieve the decoupling of the thermal strain and the stress strain. In the related art, a non-contact test method based on the blackbody radiation law is generally adopted, and an image and a colorimetric thermometry method are acquired through an industrial color Charge Coupled Device (CCD) camera, so as to acquire a temperature field of a material.
With the development of the technology, recently, high temperature testing technology based on an ultraviolet camera, ultraviolet band illumination and ultraviolet band digital filtering has come to receive wide attention. A large number of researches show that compared with the traditional narrow-band blue light source, the narrow-band blue light source has the advantages that the wavelength of an ultraviolet band is shorter, so that the filtering effect is better, and the precision of deformation testing is well improved. However, because the ultraviolet camera is a typical monochromatic camera, the current colorimetric temperature measurement method commonly used in engineering is not applicable any more, which greatly limits the development of the technology in the field of synchronous measurement of temperature and deformation.
Disclosure of Invention
In view of this, the present disclosure provides a method and an apparatus for synchronously measuring temperature and deformation.
According to an aspect of the present disclosure, there is provided a method for synchronously measuring temperature and deformation, including:
acquiring an initial image of the surface of a measured object when the measured object is not heated, a reference image of the surface of the measured object in the heating process and a reference point temperature of the surface of the measured object;
obtaining a temperature field of the surface of the measured object according to the light intensity of the initial image, the temperature of the reference point and the light intensity of the reference image;
obtaining a deformation field of the surface of the measured object according to the initial image and the reference image;
the reference image and the initial image are both monochrome images of the surface of the measured object shot by a monochrome camera; the reference point temperature is the single point temperature of the surface of the measured object when the reference image is shot.
In one possible implementation, the monochrome camera includes an ultraviolet camera.
In a possible implementation manner, the obtaining a deformation field of the surface of the measured object according to the initial image and the reference image includes: determining the size of a sub-area of each point to be measured in the initial image by using Gradient Magnitude Similarity Deviation (GMSD) as an evaluation index, wherein the sub-area of any point to be measured takes the point to be measured as a central point;
and obtaining the deformation field of the surface of the measured object by a digital image correlation method according to the size of the sub-area of each point to be measured.
In a possible implementation manner, the temperature field of the surface of the measured object is obtained according to the light intensity of the initial image, the temperature of the reference point and the light intensity of the reference image; the method comprises the following steps:
correcting the light intensity of the reference point in the reference image according to the light intensity of the initial image to obtain first light intensity;
correcting the light intensity of a non-reference point in the reference image according to the light intensity of the initial image to obtain second light intensity;
and obtaining the temperature field of the surface of the measured object according to the first light intensity, the second light intensity, the reference point temperature and the wavelength of the monochromatic camera.
In a possible implementation manner, the obtaining a temperature field of the surface of the measured object according to the first light intensity, the second light intensity, the reference point temperature, and the wavelength of the monochromatic camera includes:
calculating the difference between the natural logarithm of the first light intensity and the natural logarithm of the second light intensity;
calculating the product of the wavelength of the monochromatic camera and the difference value;
and obtaining the temperature field of the surface of the measured object according to the product, the reference point temperature and the Planck second radiation constant.
In a possible implementation manner, the determining, by using GMSD as an evaluation indicator, a size of a sub-region of each point to be measured in the initial image includes:
determining a selection interval according to the global GMSD of the initial image and a preset threshold;
and adjusting the size of the subarea of each point to be measured according to a preset rule until the GMSD of the subarea of each point to be measured is in the selection interval.
In a possible implementation manner, the adjusting the size of the sub-area of each point to be measured according to a preset rule until the GMSD of the sub-area of each point to be measured is within the selection interval includes:
if the GMSD of the sub-area of the point to be measured is larger than any numerical value in the selection interval, enlarging the size of the sub-area of the point to be measured until the GMSD of the sub-area of the point to be measured is in the selection interval;
and if the GMSD of the sub-area of the point to be measured is smaller than any numerical value in the selection interval, reducing the size of the sub-area of the point to be measured until the GMSD of the sub-area of the point to be measured is in the selection interval.
In a possible implementation manner, the obtaining a deformation field of the surface of the measured object by a digital image correlation method according to the size of the sub-region of each point to be measured includes:
and according to the size of the sub-area of each point to be measured, iteratively solving an extreme value of a correlation function in a digital image correlation method through Newton-Raphson (NR) to obtain a deformation field of the surface of the measured object.
According to another aspect of the present disclosure, there is provided a temperature and deformation synchronous measuring device, including:
the data acquisition module is used for acquiring an initial image of the surface of the measured object when the measured object is not heated, a reference image of the surface of the measured object in the heating process and the reference point temperature of the surface of the measured object;
the temperature field solving module is used for obtaining the temperature field of the surface of the measured object according to the light intensity of the initial image, the temperature of the reference point and the light intensity of the reference image;
the deformation field obtaining module is used for obtaining a deformation field of the surface of the measured object according to the initial image and the reference image;
the reference image and the initial image are both monochrome images of the surface of the measured object shot by a monochrome camera; the reference point temperature is the single point temperature of the surface of the measured object when the reference image is shot.
According to another aspect of the present disclosure, there is provided a temperature and deformation synchronous measuring device, including: a processor; a memory for storing processor-executable instructions; wherein the processor is configured to perform the above method.
According to another aspect of the present disclosure, there is provided a non-transitory computer readable storage medium having computer program instructions stored thereon, wherein the computer program instructions, when executed by a processor, implement the above-described method.
In the embodiment of the disclosure, the temperature field of the surface of the measured object is obtained through the light intensity of the initial image of the surface of the measured object when the surface is not heated, which is shot by the monochromatic camera, the light intensity of the reference image of the surface of the measured object in the heating process, which is shot by the monochromatic camera, and the reference point temperature of the surface of the measured object when the reference image is shot; obtaining a deformation field of the surface of the measured object according to the initial image and the reference image; therefore, the full-field temperature can be measured only by the monochrome image collected by the monochrome camera and the reference point temperature, the defect that the full-field temperature cannot be measured by the monochrome camera is overcome, meanwhile, the temperature and deformation of the measured object under the high-temperature environment are synchronously measured, the measurement precision and efficiency are remarkably improved, and the application development of the monochrome camera in the field of temperature and deformation synchronous measurement is greatly promoted.
Other features and aspects of the present disclosure will become apparent from the following detailed description of exemplary embodiments, which proceeds with reference to the accompanying drawings.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate exemplary embodiments, features, and aspects of the disclosure and, together with the description, serve to explain the principles of the disclosure.
FIG. 1 shows a block diagram of a simultaneous temperature and deformation measurement device according to an embodiment of the present disclosure;
FIG. 2 illustrates a flow chart of a method of simultaneous temperature and deformation measurement according to an embodiment of the present disclosure;
FIG. 3 shows a schematic diagram of spectral radiant intensity versus wavelength according to an embodiment of the present disclosure;
FIG. 4 illustrates a digital image correlation method first principles diagram according to an embodiment of the present disclosure;
FIG. 5 illustrates a flow diagram of adaptive sub-region selection according to an embodiment of the present disclosure;
FIG. 6 shows a flow chart of a method of simultaneous temperature and deformation measurement according to an embodiment of the present disclosure;
FIG. 7 shows a block diagram of a simultaneous temperature and deformation measurement device according to an embodiment of the present disclosure;
FIG. 8 shows a block diagram of an apparatus for simultaneous measurement of temperature and deformation, according to an embodiment of the present disclosure.
Detailed Description
Various exemplary embodiments, features and aspects of the present disclosure will be described in detail below with reference to the accompanying drawings. In the drawings, like reference numbers can indicate functionally identical or similar elements. While the various aspects of the embodiments are presented in drawings, the drawings are not necessarily drawn to scale unless specifically indicated.
The word "exemplary" is used exclusively herein to mean "serving as an example, embodiment, or illustration. Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.
Furthermore, in the following detailed description, numerous specific details are set forth in order to provide a better understanding of the present disclosure. It will be understood by those skilled in the art that the present disclosure may be practiced without some of these specific details. In some instances, methods, means, elements and circuits that are well known to those skilled in the art have not been described in detail so as not to obscure the present disclosure.
Fig. 1 shows a block diagram of a simultaneous temperature and deformation measuring device according to an embodiment of the present disclosure. As shown in fig. 1, the apparatus may include: the device comprises a test cabin 101, a fixing clamp 102, an observation window 103, a heating device 104, a heat exchange device 105, a fixing support 106, a movable slide rail support 107, a monochromatic light source (such as an ultraviolet light source) 108, a monochromatic camera (such as an ultraviolet camera) 109, a monochromatic filter (such as an ultraviolet filter) 110, an infrared thermometer 111, a signal synchronization control device 112, a processing terminal 113 and the like. The test chamber is an environment chamber for examining the performance of a tested object in a high-temperature environment, and is generally a closed space (part of the test chamber can be in a vacuum environment); the fixed clamp is positioned in the test chamber and used for clamping a measured object 114, and a reference temperature measuring point (namely a reference point) 115 is marked on the measured object; the test cabin is provided with a plurality of observation windows, and the observation windows can be made of high-temperature-resistant quartz glass and are used for non-contact optical test data acquisition; the heating equipment provides a heat source for the test chamber, is used for generating a high-temperature environment and heating a tested object, and can generate high-temperature heat flow with local temperature exceeding 3000K under the high-temperature arc wind tunnel environment; the heat exchange equipment is used for exchanging heat with the external environment to ensure the temperature in the test cabin to be stable; the fixed bracket is positioned outside the test chamber, and a slide rail is arranged on the bracket; the movable slide rail support is used for fixing equipment such as a monochromatic camera, an infrared thermometer, a monochromatic light source and the like, and can be matched with the slide rail for use, so that the directions of the monochromatic camera, the infrared thermometer and the monochromatic light source can be adjusted in multiple angles and multiple postures; the monochromatic camera is used for shooting monochromatic images on the surface of a measured object, and a monochromatic filter is additionally arranged at the front end of a lens of the monochromatic camera and is matched with a monochromatic light source of a corresponding waveband for use so as to filter strong light radiation; the monochromatic light source is used for compensating the ambient light in the test chamber and is matched with the monochromatic filter plate of the corresponding wave band for use, so that the influence of strong light radiation can be eliminated; the infrared thermometer is used for measuring the single-point (reference point) temperature data of the surface of the measured object; the signal synchronous control equipment can be connected with the monochromatic camera, the monochromatic light source and the infrared thermometer through high-speed data lines, and controls the monochromatic camera, the monochromatic light source and the infrared thermometer to synchronously work by transmitting synchronous control signals to the monochromatic camera, the monochromatic light source and the infrared thermometer, so that the synchronous measurement of temperature and deformation is realized; the signal synchronous control equipment is also connected with the processing terminal, receives a signal instruction of the processing terminal and can feed back signal data to the processing terminal in real time; the processing terminal is connected with the signal synchronous control equipment, sends a control signal to the processing terminal in real time, and is connected with the monochromatic camera and the infrared thermometer respectively, so that monochromatic images of the surface of the measured object collected by the monochromatic camera and reference point temperature data of the surface of the measured object collected by the infrared thermometer are obtained, and the monochromatic images and the temperature data are subjected to related calculation and analysis to obtain a temperature field and deformation field information of the surface of the measured object.
FIG. 2 shows a flow chart of a method for simultaneous measurement of temperature and deformation according to an embodiment of the present disclosure. The method may be applied to the processing terminal in fig. 1, and as shown in fig. 2, the method may include:
In the step, the processing terminal can obtain a monochrome image of the surface of the measured object shot by the monochrome camera during the high-temperature test; the monochrome camera can obtain a monochrome image with the best imaging quality through the optimization control of multiple parameters (such as focal length, exposure time, gain function and the like); meanwhile, the monochrome camera can work in cooperation with the monochrome light source and the monochrome filter plate, namely monochrome image collection is combined with narrow-band filtering and monochrome band illumination of monochrome bands, and clear monochrome images of the surface of a measured object are obtained on the basis of eliminating interference of high-temperature strong light radiation and the like. Before the heating device does not heat the surface of the measured object, acquiring a monochrome image of the surface of the measured object by a monochrome camera, wherein the monochrome image is an initial image; after the surface of the object to be measured is heated by the heating equipment, monochrome images of the surface of the object to be measured at different moments are collected by a monochrome camera, and the monochrome images are reference images; illustratively, the monochromatic camera may be an ultraviolet camera, the monochromatic light source may be an ultraviolet light source, and the monochromatic filter may be an ultraviolet filter.
The processing terminal can also acquire the reference point temperature of the surface of the measured object acquired by the infrared thermometer, wherein the reference point is a reference position calibrated in advance on the surface of the measured object, after the heating device heats the surface of the measured object, the monochromatic camera and the infrared thermometer are synchronously started, and the infrared thermometer acquires the reference point temperature of the surface of the measured object at different moments in real time.
in the step, after the processing terminal acquires the initial image, the reference images and the reference point temperatures at different moments, the light intensity (i.e. the gray value) of the initial image and the light intensity (i.e. the gray value) of the reference images at different moments can be extracted, and the temperature field of the surface of the measured object can be obtained according to the light intensity and the reference point temperatures of the reference images at the same moment and the light intensity of the initial image.
In the related art, a non-contact temperature measurement method based on a colorimetric method is widely applied to the whole-field temperature measurement of a measured object in a high-temperature environment, and the basic principle of the colorimetric temperature measurement method is as follows: the method comprises the steps of acquiring an image of a measured object by using a color CCD camera, extracting red light and green light information of the image, acquiring a single-point reference temperature of the surface of the measured object by using an infrared thermometer, and calculating according to the following formula (1) to obtain the full-field temperature.
Wherein T represents the temperature at any point on the surface of the object to be measured, and T0Indicating the reference point temperature, C, measured by an infrared thermometer2Denotes the Planck second radiation constant, λRAnd λGRespectively representing the wavelengths of the light fields corresponding to the R channel and the G channel of the color CCD camera, IRAnd IGRepresenting the gray value, I, obtained from an image taken by a color CCD cameraR0And IG0Representing the gray value of the reference point.
Because the monochrome camera can only acquire monochrome images during image acquisition, the colorimetric temperature measurement method is not applicable any more, and the application development of the monochrome camera in the field of synchronous measurement of temperature and deformation is greatly limited. In the embodiment of the disclosure, only the monochrome camera is needed to collect the monochrome image of the measured object, the full field temperature can be measured through the monochrome image and the reference point temperature, the monochromatic radiation temperature measurement is realized, the measurement precision is high, the defect that the full field temperature cannot be measured through the monochrome camera is overcome, meanwhile, the test cost is saved, and the application range of the monochrome camera for high temperature test is expanded.
In a possible implementation mode, based on the blackbody radiation law and the monochromatic radiation temperature measurement principle, the full-field temperature is calculated by using a monochromatic image acquired by a monochromatic camera and the reference point temperature measured by an infrared thermometer. In the embodiment of the disclosure, a scheme for simply calculating the full-field temperature is obtained by starting from the blackbody radiation law and combining with the imaging rule of a monochromatic camera.
FIG. 3 shows a schematic diagram of spectral radiant intensity versus wavelength according to an embodiment of the present disclosure; as shown in fig. 3, the relationship between the intensity of the radiated light and the emissivity, temperature and wavelength of the material is shown in the following formula (2) in combination with the blackbody radiation law:
where E (λ, T) denotes the spectral radiance (i.e. monochromatic radiation emitted in energy per unit area per unit time) at a given wavelength λ and a given temperature T, and ε (λ, T) denotes the given wavelength λ and a given temperature TMonochromatic emissivity at temperature T, C1And C2Respectively representing a planck first radiation constant and a planck second radiation constant.
When C is in the above formula (2)2/λT>>1, the above formula (2) can be simplified into the form of the following formula (3):
where E (λ, T) represents the spectral radiance at a given wavelength λ and a given temperature T, ε (λ, T) represents the monochromatic radiance at a given wavelength λ and a given temperature T, C1And C2Respectively representing a planck first radiation constant and a planck second radiation constant.
For a conventional CCD camera, after a filter is added to the front end of the camera, the light intensity that can be received by the light sensing unit is as shown in the following formula (4):
wherein I represents the light intensity receivable by the light-sensing unit of the CCD camera, A (C, T, a) represents the conversion coefficient related to the photoelectric characteristics C of the CCD camera, the exposure time T and the relative aperture a, k (λ) represents the transmittance of the optical system, h (λ) is the Spectral Response Function (SRF), ε (λ, T) represents the monochromatic emissivity at a given wavelength λ and a given temperature T, C (C, T, a) represents the spectral response function (SR1And C2Respectively representing a Planck first radiation constant and a Planck second radiation constant, λ1And λ2Respectively a minimum and a maximum of the wavelength lambda.
For a monochrome camera, after a filter is added at the front end of the monochrome camera, the light intensity which can be received by a light sensing unit is shown in the following formula (5):
in the formula IiDenotes the wavelength λiTime sheetLight intensity receivable by the light-sensitive unit of the color camera, Aλi(c, t, a) denotes a conversion coefficient, k (λ @), relating to the monochrome camera photoelectric characteristic c, the exposure time t, and the relative aperture ai) Denotes the transmittance of the optical system, h (λ)i) Denotes the spectral response function, ε (λ)i,Ti) Represents the wavelength lambdaiAnd temperature TiEmissivity of single color, λiDenotes the wavelength, T, of the monochromatic lightiDenotes the temperature, C, at any point1And C2Respectively representing a planck first radiation constant and a planck second radiation constant.
When the emissivity of the material of the object to be measured does not change significantly with temperature or is less affected by temperature, the above equation (5) can be rewritten into the form of the following equation (6):
in the formula IiDenotes the wavelength λiLight intensity receivable by the light-sensitive unit of a time-monochrome camera, Aλi(c, t, a) denotes a conversion coefficient, k (λ @), relating to the monochrome camera photoelectric characteristic c, the exposure time t, and the relative aperture ai) Denotes the transmittance of the optical system, h (λ)i) Denotes the spectral response function, ε (λ)i) Represents the wavelength lambdaiEmissivity of single color, λiDenotes the wavelength, T, of the monochromatic lightiDenotes the temperature, C, at any point1And C2Respectively representing a planck first radiation constant and a planck second radiation constant.
When the temperature and the deformation of the measured object are synchronously measured by the monochromatic camera, the temperature value T of the reference point acquired by the infrared thermometer0Then the light intensity value I of the position of the reference point at the momenti0As shown in the following equation (7):
in the formula Ii0Denotes the wavelength λiThe light intensity of the position of the reference point receivable by the light-sensitive unit of the monochrome camera, Aλi(c, t, a) denotes a conversion coefficient, k (λ @), relating to the monochrome camera photoelectric characteristic c, the exposure time t, and the relative aperture ai) Denotes the transmittance of the optical system, h (λ)i) Denotes the spectral response function, ε (λ)i) Represents the wavelength lambdaiEmissivity of single color, λiDenotes the wavelength, T, of the monochromatic light0Denotes the reference point temperature, C1And C2Respectively representing a planck first radiation constant and a planck second radiation constant.
Comparing the above equation (6) and equation (7) yields the following equation (8):
in the formula IiDenotes the wavelength λiLight intensity, I, receivable by the light-sensitive unit of a time-monochrome camerai0Denotes the wavelength λiThe light intensity of the position of the reference point receivable by the light-sensitive unit of the monochrome camera, Aλi(c, t, a) denotes a conversion coefficient, k (λ @), relating to the monochrome camera photoelectric characteristic c, the exposure time t, and the relative aperture ai) Denotes the transmittance of the optical system, h (λ)i) Denotes the spectral response function, ε (λ)i) Represents the wavelength lambdaiEmissivity of single color, λiDenotes the wavelength, T, of the monochromatic lightiIndicating the temperature, T, of any point0Denotes the reference point temperature, C1And C2Respectively representing a planck first radiation constant and a planck second radiation constant.
The following formula (9) can be obtained by simplifying the above formula (8):
where, (x, y) represents the pixel coordinates of any point in the reference image; lambda [ alpha ]iDenotes the wavelength, T, of the monochromatic lighti(x, y) and Ii(x, y) respectively represent coordinatesThe position is the temperature value and the light intensity value, T, at (x, y)0And I0Respectively representing the temperature value and the light intensity value at a reference point (the temperature measuring point of the infrared thermometer), C2Representing the planck second radiation constant. In one possible implementation, step 22 may include: correcting the light intensity of the reference point in the reference image according to the light intensity of the initial image to obtain first light intensity; correcting the light intensity of a non-reference point in the reference image according to the light intensity of the initial image to obtain second light intensity; and obtaining the temperature field of the surface of the measured object according to the first light intensity, the second light intensity, the reference point temperature and the wavelength of the monochromatic camera.
By analyzing the formula (9), the light intensity of the image can influence the precision of temperature field calculation, and the effective information is the high-temperature radiation light intensity when the temperature field calculation is carried out, and the light intensity of the monochromatic light source can bring interference; in order to obtain an accurate temperature field, in the embodiment of the disclosure, the light intensity value of the reference image is further optimized and corrected through the light intensity of the initial image, so as to obtain a first light intensity of a reference point in the reference image and a second light intensity of a non-reference point (i.e. other pixel points except the reference point in the reference image) in the reference image, wherein the first light intensity and the second light intensity eliminate the interference of the environmental light intensity; and calculating to obtain the temperature field of the surface of the measured object according to the first light intensity, the second light intensity, the reference point temperature and the monochromatic light wavelength of the monochromatic camera. Therefore, the influence of the light intensity of environments such as a monochromatic light source and the like is eliminated by optimizing the light intensity value of the reference image, so that more accurate full-field temperature is obtained.
In a possible implementation manner, the obtaining a temperature field of the surface of the measured object according to the first light intensity, the second light intensity, the reference point temperature, and the wavelength of the monochromatic camera includes: calculating the difference between the natural logarithm of the first light intensity and the natural logarithm of the second light intensity; calculating the product of the wavelength of the monochromatic camera and the difference value; and obtaining the temperature field of the surface of the measured object according to the product, the reference point temperature and the Planck second radiation constant.
Illustratively, if the extracted initial image has a light intensity value of IinitialThe initial light intensity is filtered on the basis of the above equation (9), so as to obtain a temperature field calculation equation as shown in the following equation (10):
where, (x, y) represents the pixel coordinates of any point in the reference image; lambda [ alpha ]iDenotes the wavelength, T, of the monochromatic lighti(x, y) and Ii(x, y) respectively represent the temperature value and the light intensity value at the coordinate position of (x, y), T0And I0Respectively representing the temperature value and the light intensity value, I, at the reference pointinitialRepresenting the intensity value of the initial image, C2Representing the planck second radiation constant.
Referring to the above formula (10), the light intensity value I is referenced by the reference point0With the light intensity value I of the initial imageinitialMaking difference to obtain first light intensity, and obtaining the first light intensity by using light intensity value I of non-reference point in reference imageiThe light intensity value of (x, y) and the initial image is IinitialMaking difference to obtain second light intensity, calculating the difference value of natural logarithm of first light intensity and natural logarithm of second light intensity, and further making monochromatic light wavelength lambda of monochromatic camera according to said difference valueiReference point temperature T0And Planck's second radiation constant C2And obtaining the temperature field of the surface of the measured object. Therefore, the temperature measuring step is simplified by introducing the reference point temperature, and meanwhile, the accuracy of temperature measurement is improved by eliminating the initial radiation light intensity and exposure control.
Compared with the calculation formula (1) of the colorimetric thermometry, the full-field temperature measurement formula (10) based on the principle of monochromatic radiation in the embodiment of the disclosure is simpler in form, the full-field temperature can be calculated in a monochromatic band, and the calculation precision is high; therefore, the defect that the full-field temperature cannot be measured by the monochrome camera in the related technology is overcome, the test cost is saved, the calculation efficiency of the temperature field is improved, and the application range of the monochrome camera for high-temperature test is expanded.
In one possible implementation, the monochrome camera includes an ultraviolet camera. The monochromatic camera can be an ultraviolet camera, when the surface image of the measured object is acquired by the ultraviolet camera, the monochromatic light is ultraviolet light of a corresponding optical waveband, and the wavelength of the ultraviolet light can be 10-400 nm; the light intensity values of different coordinate positions in the monochromatic image are extracted by the monochromatic image acquired by the ultraviolet camera, and the full-field temperature can be calculated by the formula (10) by using the light intensity values and the reference point temperature measured by the infrared thermometer. Therefore, for the limitation of the existing high-temperature test, the temperature field measurement is realized based on the ultraviolet camera, the ultraviolet light source and the ultraviolet filtering technology and by combining the radiation temperature measurement principle, and the problem that the existing ultraviolet camera can only acquire images and cannot process the temperature field is solved; and the temperature field calculation formula is more concise, the calculation efficiency is effectively improved while the calculation precision is maintained, and the application range of the ultraviolet camera for high-temperature test is expanded.
And 23, obtaining a deformation field of the surface of the measured object according to the initial image and the reference image.
In the step, the processing terminal can obtain the deformation field (including a displacement field and a strain field) of the surface of the measured object by a digital image correlation method according to the initial image and the reference image, so that the synchronous measurement of the temperature and the deformation of the measured object in a high-temperature environment is realized, and the application development of the monochrome camera in the field of synchronous measurement of the temperature and the deformation is greatly promoted.
In one possible implementation, the monochrome camera includes an ultraviolet camera.
When temperature and deformation synchronous measurement are carried out in the related technology, a narrow-band blue light source is generally adopted, compared with the blue light wavelength, the wavelength of an ultraviolet band is shorter, the filtering effect is better, and the testing precision of the deformation of a tested object can be well improved. Therefore, the full-field temperature and deformation synchronous measurement can be realized by combining the image acquisition, the ultraviolet filtering and the ultraviolet illumination of the ultraviolet camera, and meanwhile, compared with the temperature and deformation synchronous measurement mode in the current engineering, the measurement precision and efficiency are obviously improved, and the application range of the ultraviolet camera in high-temperature testing is expanded.
In a possible implementation manner, the obtaining a deformation field of the surface of the measured object according to the initial image and the reference image in step 23 may include: determining the size of a sub-area of each point to be measured in the initial image by using GMSD as an evaluation index, wherein the sub-area of any point to be measured takes the point to be measured as a central point; and obtaining the deformation field of the surface of the measured object by a digital image correlation method according to the size of the sub-area of each point to be measured.
In the embodiment of the disclosure, the existing deformation measurement mode of the digital image correlation method is improved, GMSD is used as an evaluation index, and the optimization selection of the sizes of the sub-regions of the points to be measured in the initial image is realized, so that the full-field deformation measurement is performed through the self-adaptive sub-region selection, and the calculation efficiency of the deformation field is effectively improved.
Fig. 4 is a schematic diagram illustrating a basic principle of a digital image correlation method according to an embodiment of the present disclosure, and as shown in fig. 4, a basic principle of a typical digital image correlation method is shown in the following formula (11):
in the formula, f (x)i,yi) And g (x'i,y′i) Respectively representing pixel points (x) in the reference sub-regioni,yi) Gray level of (c) and pixel point (x ') in target sub-region'i,y′i) Of (d), u ═ x'i-xi,v＝y′i-yiRepresenting the displacement of the reference sub-area to the target sub-area in the x and y directions, respectively, fmAnd gmRespectively representing the gray level average value of the reference sub-area and the gray level average value of the target sub-area, and N representing the number of pixels in the reference sub-area and the target sub-area.
As can be seen from the analysis of the above equation (11), the selection and quality of the sub-regions (reference sub-region and target sub-region) affect the accuracy and efficiency of the subsequent digital image correlation calculation. In the embodiment of the disclosure, based on the digital image correlation method, the intrinsic feature points of the material surface of the object to be measured are used as the feature points of the sub-region matching, and the size of the sub-region is determined by introducing the gradient amplitude similarity deviation (GMSD), which is an evaluation index, and the image gradient field of the evaluation index is sensitive to image degradation, so that the efficiency of digital image correlation calculation of a high-temperature image can be ensured, and the calculation efficiency is high.
The basic calculation flow of GMSD is as follows: firstly, gradient information of a subregion to be selected is obtained by using a prewitt operator (edge detection of a first-order differential operator), wherein a standard 3 × 3 prewitt operator can be selected, as shown in the following formula (12):
in the formula, hx、hyRepresenting the components of the prewitt operator in the x, y directions, respectively.
Performing convolution operation on the image by using the operator in the formula (12) to obtain the gradient amplitude m of the image in the horizontal directionrAnd gradient amplitude m in the vertical directiondAs shown in the following formula (13),
in the formula, hx、hyRespectively representing the components of the prewitt operator in the x direction and the y direction; and r and d respectively represent the coordinate values of the pixel point i in the horizontal direction and the vertical direction.
Further, Gradient Magnitude Similarity (GMS) is found by the following formula (14):
wherein i represents the position of a pixel point in the image, c is a constant, GMS (i) represents the gradient amplitude similarity of the pixel point i, and mr(i) Represents the gradient amplitude m of the pixel point i in the horizontal directiond(i) Representing a pixelThe gradient magnitude of point i in the vertical direction.
The deviation of the gradient amplitude similarity GMS, i.e. GMSD, is calculated by the following equation (15):
in the formula, N represents the number of pixel points in the region, gms (i) represents the gradient amplitude similarity of the pixel point i, and GMSD represents the average value of the gradient amplitude similarity of the region; the larger the GMSD, the worse the quality of the image representing the region.
In the embodiment of the present disclosure, the GMSD of the above formula (15) is used as an evaluation index, and an influence of the size of the sub-region of each point to be measured in the initial image on the image matching quality is determined, so as to effectively improve the quality and efficiency of sub-region selection. After the size of the sub-area of the point to be measured is determined, namely the sub-area is selected, the full-field displacement field and the strain field of the surface of the measured object are calculated by a digital image correlation method.
In a possible implementation manner, the determining, by using GMSD as an evaluation indicator, a size of a sub-region of each point to be measured in the initial image includes: determining a selection interval according to the global GMSD of the initial image and a preset threshold; and adjusting the size of the subarea of each point to be measured according to a preset rule until the GMSD of the subarea of each point to be measured is in the selection interval.
In the embodiment of the disclosure, a global GMSD of an initial image is first calculated, which is denoted as [ GMSD ], and a selection interval is determined by [ GMSD ] and a preset threshold, where the preset threshold may be set according to requirements such as actual calculation accuracy and speed, and is not limited herein, and a boundary of the selection interval may be determined according to the global GMSD of the initial image and the preset threshold, so as to determine the selection interval. Illustratively, if the preset threshold is 0.1, the selection interval is [ GMSD ] -0.1 to [ GMSD ] +0.1, and then the size of the sub-area of each point to be measured is continuously adjusted according to the preset rule, that is, when the GMSD of the sub-area of a certain point to be measured falls within the selection interval, the size of the fixed sub-area is not adjusted, and at this time, the sub-area is the final corresponding sub-area of the point to be measured. By the self-adaptive sub-area selection mode, the calculation efficiency is effectively improved.
In a possible implementation manner, the adjusting the size of the sub-area of each point to be measured according to a preset rule until the GMSD of the sub-area of each point to be measured is within the selection interval includes: if the GMSD of the sub-area of the point to be measured is larger than any numerical value in the selection interval, enlarging the size of the sub-area of the point to be measured until the GMSD of the sub-area of the point to be measured is in the selection interval; and if the GMSD of the sub-area of the point to be measured is smaller than any numerical value in the selection interval, reducing the size of the sub-area of the point to be measured until the GMSD of the sub-area of the point to be measured is in the selection interval.
In the embodiment of the disclosure, for any point to be measured, calculating GMSD values corresponding to sub-areas of different sizes, and comparing the GMSD values with the set selection interval, if the GMSD values are greater than any numerical value in the selection interval, enlarging the size of the sub-areas; if the GMSD value is smaller than any numerical value in the selection interval, the size of the sub-area is reduced, in this way, the size of the sub-area is continuously adjusted, the GMSD value of the sub-area is calculated in real time, and the size of the sub-area is fixed and is not adjusted until the GMSD value falls in the selection interval, so that the sub-area of the point to be measured is selected.
For example, the size of the sub-region may be represented as (2N +1) × (2N +1), the GMSD value of the sub-region is represented as GMSD (N), that is, the sub-region is a square pixel matrix with a side length of 2N +1 pixels, the point to be measured is located at the center of the square pixel matrix, when the size of the sub-region is selected, the initial sub-region size of the sub-region may be set, and for example, the initial value of N may be N0When the pixel point is 8, the size of the initial sub-area of the sub-area is 17 × 17 pixel points; the initial value may be set as required, and is not limited herein; further, GMSD of the initial sub-region is calculated and recorded as GMSD (8), and whether or not [ GMSD ] is satisfied is determined]-0.1<GMSD(8)<[GMSD]+0.1, if satisfied, the size of the sub-area is selected to be 17 × 17 pixels, if GMSD (8) is greater than or equal to [ GMSD ≧ GMSD]+0.1, the sub-area size is adjusted to 19 × 19 pixels, and the GMSD (9) at this time is obtained and continuesPerforming the above judgment; if GMSD (8) < GMSD ≦ []-0.1, adjusting the size of the sub-area to 15 × 15 pixels, obtaining the GMSD (7) at the moment, and continuing the judgment; repeating the sub-region size adjusting step until the [ GMSD ] is satisfied]-0.1<GMSD(N)<[GMSD]+0.1, fix the value of N at this time, i.e. the selected sub-region size.
FIG. 5 illustrates a flow diagram of adaptive sub-region selection according to an embodiment of the present disclosure; as shown in fig. 5, after the processing terminal reads the initial image and the reference image, a global GMSD of the initial image is first calculated, denoted as GMSD]And setting a subregion selection interval of [ GMSD]-0.1～[GMSD]+ 0.1; obtaining a point P to be calculated of an initial imagei(i 1,2,3 … … n) so as to cover the entire area; setting the sub-region size to be (2N +1) × (2N +1), and setting the initial reference sub-region size to be N-N0-8 pixels; calculating GMSD (N) of the subregion, and judging whether [ GMSD ] is satisfied]-0.1<GMSD(N)<[GMSD]+0.1, if not, further judging whether GMSD (N) is satisfied or not]+0.1, if satisfied, updating N +1, if not, updating N-1, recalculating GMSD (N) for the sub-region, and repeating iterations until [ GMSD ] is satisfied]-0.1<GMSD(N)<[GMSD]+ 0.1; if it satisfies [ GMSD]-0.1<GMSD(N)<[GMSD]+0.1, the deformation field (P) is calculated on the basis of the determined size of the subarea, i.e. the determined value of N, using the principles of the existing DIC method (equation (11) above)i) Until all the points P to be measured are calculatedi(i ═ 1,2,3 … … n), full-field deformation information is obtained.
In a possible implementation manner, the obtaining a deformation field of the surface of the measured object by a digital image correlation method according to the size of the sub-region of each point to be measured includes: and according to the size of the sub-area of each point to be measured, solving the extreme value of the correlation function in the digital image correlation method through Newton-Laplacian iteration to obtain the deformation field of the surface of the measured object.
In the embodiment of the disclosure, when the deformation field is calculated by a digital image correlation method, a Newton-Laplacian iteration method is adopted to carry out numerical iteration solution, so that the calculation precision of a sub-pixel level can be achieved, and the deformation field information with higher precision can be obtained.
FIG. 6 shows a flow chart of a method for simultaneous measurement of temperature and deformation according to an embodiment of the present disclosure. As shown in fig. 6, the device in fig. 1 is used to collect a reference image, an initial image and a reference point temperature, and the temperature and deformation synchronous measurement method is used to realize the synchronous measurement of the temperature field and the deformation field of the object to be measured; the heating equipment can be high-temperature arc wind tunnel and other heating equipment, and can heat the local temperature of the surface of the measured object to more than 2000 ℃ to the maximum extent; the monochromatic camera is an ultraviolet camera, the monochromatic light source is an ultraviolet light source, an ultraviolet filter is additionally arranged at the front end of the ultraviolet camera, the wavelengths of the ultraviolet light source and the ultraviolet filter are 250nm (+ -10 nm), and a reference point of the infrared thermometer on the surface of the measured object is calibrated before the measurement; the slide rail support and the slide rail can be portable triangular supports, and the object to be measured can be carbon/silicon carbide (C/SiC) cylinder materials which are most commonly used in aerospace, and the size of the object to be measured can be phi 40mm multiplied by 50 mm. The specific implementation steps are as follows:
firstly, referring to fig. 1, a measured object is clamped by a fixing clamp, the postures of an ultraviolet camera, an ultraviolet light source and an infrared thermometer are adjusted to be proper positions, and a signal synchronous control device and a processing terminal are connected; calibrating the position of a reference point of an infrared thermometer, turning on an ultraviolet light source, adjusting the focal length, gain and aperture of an ultraviolet camera to ensure that the imaging quality of the ultraviolet camera is optimal, and acquiring an initial image of the surface of a measured object when the surface is not heated; then, starting the heating equipment to carry out thermal examination on the measured object, synchronously starting the ultraviolet camera and the infrared thermometer, and acquiring and recording the reference image and the reference point temperature data of the measured object in real time; after the thermal examination is finished, the heating equipment is closed, and the ultraviolet camera, the infrared thermometer and the ultraviolet light source are synchronously closed; finally, the processing terminal receives the recorded initial image, the recorded reference image and the recorded reference point temperature data, selects sub-regions according to the adaptive sub-region selection scheme according to the initial image and the reference images at different moments, and calculates the displacement field and the strain field of the digital image correlation method based on the sub-pixel Newton-Raphson method (refer to the step 23); meanwhile, the processing terminal extracts the light intensity of the initial image, the light intensity of the reference image at different moments and the reference point temperature, and performs full-field temperature calculation according to the monochromatic radiation temperature measurement mode (refer to the step 22), so that synchronous measurement of the temperature field and the deformation field of the measured object is completed.
It should be noted that, although the temperature and deformation synchronous measurement method is described above by taking the above-mentioned embodiment as an example, those skilled in the art can understand that the disclosure should not be limited thereto. In fact, each implementation mode can be flexibly set according to the actual application scene as long as the technical scheme of the present disclosure is met.
In this way, the technical scheme of full-field temperature-deformation synchronous measurement based on a monochromatic camera (such as an ultraviolet camera) provided in the embodiment of the disclosure obtains the temperature field of the surface of the measured object by the light intensity of the initial image of the surface of the measured object when the surface is not heated, the light intensity of the reference image of the surface of the measured object in the heating process and the reference point temperature of the surface of the measured object when the reference image is shot, wherein the initial image is shot by the monochromatic camera; obtaining a deformation field of the surface of the measured object according to the initial image and the reference image; therefore, the full-field temperature can be measured only by the monochrome image collected by the monochrome camera and the reference point temperature, the defect that the full-field temperature cannot be measured by the monochrome camera is overcome, meanwhile, the temperature and deformation of the measured object under the high-temperature environment are synchronously measured, the measurement precision and efficiency are remarkably improved, and the application development of the monochrome camera in the field of temperature and deformation synchronous measurement is greatly promoted.
FIG. 7 shows a block diagram of a simultaneous temperature and deformation measurement device according to an embodiment of the present disclosure. As shown in fig. 7, the apparatus may include: the data acquisition module 41 is used for acquiring an initial image of the surface of the measured object when the measured object is not heated, a reference image of the surface of the measured object in the heating process and a reference point temperature of the surface of the measured object; the temperature field solving module 42 is configured to obtain a temperature field of the surface of the measured object according to the light intensity of the initial image, the reference point temperature, and the light intensity of the reference image; a deformation field obtaining module 43, configured to obtain a deformation field of the surface of the measured object according to the initial image and the reference image; the reference image and the initial image are both monochrome images of the surface of the measured object shot by a monochrome camera; the reference point temperature is the single point temperature of the surface of the measured object when the reference image is shot.
In a possible implementation manner, the deformation field obtaining module 43 is further configured to determine the size of a sub-region of each point to be measured in the initial image by using a gradient magnitude similarity deviation GMSD as an evaluation index, where the sub-region of any point to be measured takes the point to be measured as a central point; and obtaining the deformation field of the surface of the measured object by a digital image correlation method according to the size of the sub-area of each point to be measured.
In one possible implementation, the monochrome camera includes an ultraviolet camera.
In a possible implementation manner, the temperature field obtaining module 42 is further configured to correct the light intensity of the reference point in the reference image according to the light intensity of the initial image to obtain a first light intensity; correcting the light intensity of a non-reference point in the reference image according to the light intensity of the initial image to obtain second light intensity; and obtaining the temperature field of the surface of the measured object according to the first light intensity, the second light intensity, the reference point temperature and the wavelength of the monochromatic camera.
In a possible implementation manner, the temperature field obtaining module 42 is further configured to obtain a difference between a natural logarithm of the first light intensity and a natural logarithm of the second light intensity; calculating the product of the wavelength of the monochromatic camera and the difference value; and obtaining the temperature field of the surface of the measured object according to the product, the reference point temperature and the Planck second radiation constant.
In a possible implementation manner, the deformation field obtaining module 43 is further configured to determine a selection interval according to the global GMSD of the initial image and a preset threshold; and adjusting the size of the subarea of each point to be measured according to a preset rule until the GMSD of the subarea of each point to be measured is in the selection interval.
In a possible implementation manner, the deformation field obtaining module 43 is further configured to, if the GMSD of the sub-area of the point to be measured is greater than any numerical value in the selection interval, enlarge the size of the sub-area of the point to be measured until the GMSD of the sub-area of the point to be measured is within the selection interval; and if the GMSD of the sub-area of the point to be measured is smaller than any numerical value in the selection interval, reducing the size of the sub-area of the point to be measured until the GMSD of the sub-area of the point to be measured is in the selection interval.
In a possible implementation manner, the deformation field obtaining module 43 is further configured to iteratively solve an extreme value of a correlation function in a digital image correlation method through newton-Raphson (Netwon-Raphson) according to the size of the sub-region of each point to be measured, so as to obtain the deformation field of the surface of the object to be measured.
It should be noted that, although the temperature and deformation synchronous measuring device is described above by taking the above-mentioned embodiment as an example, those skilled in the art can understand that the disclosure should not be limited thereto. In fact, each implementation mode can be flexibly set according to the actual application scene as long as the technical scheme of the present disclosure is met.
In this way, the technical scheme of full-field temperature-deformation synchronous measurement based on a monochromatic camera (such as an ultraviolet camera) provided in the embodiment of the disclosure obtains the temperature field of the surface of the measured object by the light intensity of the initial image of the surface of the measured object when the surface is not heated, the light intensity of the reference image of the surface of the measured object in the heating process and the reference point temperature of the surface of the measured object when the reference image is shot, wherein the initial image is shot by the monochromatic camera; obtaining a deformation field of the surface of the measured object according to the initial image and the reference image; therefore, the full-field temperature can be measured only by the monochrome image collected by the monochrome camera and the reference point temperature, the measurement precision is high, the defect that the full-field temperature cannot be measured by the monochrome camera is overcome, meanwhile, the temperature and the deformation of the measured object under the high-temperature environment are synchronously measured, the measurement precision and the efficiency are obviously improved, and the application development of the monochrome camera in the field of temperature and deformation synchronous measurement is greatly promoted.
This embodiment also provides a temperature and deformation synchronous measurement device, includes: a processor; a memory for storing processor-executable instructions; wherein the processor is configured to perform the above method.
The present embodiments also provide a non-transitory computer readable storage medium having stored thereon computer program instructions, wherein the computer program instructions, when executed by a processor, implement the above-described method.
FIG. 8 shows a block diagram of an apparatus 1900 for simultaneous measurement of temperature and deformation, according to an embodiment of the present disclosure. For example, the apparatus 1900 may be provided as a server or a processing terminal. Referring to FIG. 8, the device 1900 includes a processing component 1922 further including one or more processors and memory resources, represented by memory 1932, for storing instructions, e.g., applications, executable by the processing component 1922. The application programs stored in memory 1932 may include one or more modules that each correspond to a set of instructions. Further, the processing component 1922 is configured to execute instructions to perform the above-described method.
The device 1900 may also include a power component 1926 configured to perform power management of the device 1900, a wired or wireless network interface 1950 configured to connect the device 1900 to a network, and an input/output (I/O) interface 1958. The device 1900 may operate based on an operating system stored in memory 1932, such as Windows Server, Mac OS XTM, UnixTM, LinuxTM, FreeBSDTM, or the like.
In an exemplary embodiment, a non-transitory computer readable storage medium, such as the memory 1932, is also provided that includes computer program instructions executable by the processing component 1922 of the apparatus 1900 to perform the above-described methods.
The present disclosure may be systems, methods, and/or computer program products. The computer program product may include a computer-readable storage medium having computer-readable program instructions embodied thereon for causing a processor to implement various aspects of the present disclosure.
The computer readable storage medium may be a tangible device that can hold and store the instructions for use by the instruction execution device. The computer readable storage medium may be, for example, but not limited to, an electronic memory device, a magnetic memory device, an optical memory device, an electromagnetic memory device, a semiconductor memory device, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of the computer readable storage medium would include the following: a portable computer diskette, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a Static Random Access Memory (SRAM), a portable compact disc read-only memory (CD-ROM), a Digital Versatile Disc (DVD), a memory stick, a floppy disk, a mechanical coding device, such as punch cards or in-groove projection structures having instructions stored thereon, and any suitable combination of the foregoing. Computer-readable storage media as used herein is not to be construed as transitory signals per se, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through a waveguide or other transmission medium (e.g., optical pulses through a fiber optic cable), or electrical signals transmitted through electrical wires.
The computer-readable program instructions described herein may be downloaded from a computer-readable storage medium to a respective computing/processing device, or to an external computer or external storage device via a network, such as the internet, a local area network, a wide area network, and/or a wireless network. The network may include copper transmission cables, fiber optic transmission, wireless transmission, routers, firewalls, switches, gateway computers and/or edge servers. The network adapter card or network interface in each computing/processing device receives computer-readable program instructions from the network and forwards the computer-readable program instructions for storage in a computer-readable storage medium in the respective computing/processing device.
The computer program instructions for carrying out operations of the present disclosure may be assembler instructions, Instruction Set Architecture (ISA) instructions, machine-related instructions, microcode, firmware instructions, state setting data, or source or object code written in any combination of one or more programming languages, including an object oriented programming language such as Smalltalk, C + + or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The computer-readable program instructions may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer through any type of network, including a Local Area Network (LAN) or a Wide Area Network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet service provider). In some embodiments, the electronic circuitry that can execute the computer-readable program instructions implements aspects of the present disclosure by utilizing the state information of the computer-readable program instructions to personalize the electronic circuitry, such as a programmable logic circuit, a Field Programmable Gate Array (FPGA), or a Programmable Logic Array (PLA).
Various aspects of the present disclosure are described herein with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the disclosure. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer-readable program instructions.
These computer-readable program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks. These computer-readable program instructions may also be stored in a computer-readable storage medium that can direct a computer, programmable data processing apparatus, and/or other devices to function in a particular manner, such that the computer-readable medium storing the instructions comprises an article of manufacture including instructions which implement the function/act specified in the flowchart and/or block diagram block or blocks.
The computer readable program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other devices to cause a series of operational steps to be performed on the computer, other programmable apparatus or other devices to produce a computer implemented process such that the instructions which execute on the computer, other programmable apparatus or other devices implement the functions/acts specified in the flowchart and/or block diagram block or blocks.
The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present disclosure. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of instructions, which comprises one or more executable instructions for implementing the specified logical function(s). In some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.
Having described embodiments of the present disclosure, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen in order to best explain the principles of the embodiments, the practical application, or improvements made to the technology in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.
Claims (7)
1. A method for simultaneous measurement of temperature and deformation, comprising:
acquiring an initial image of the surface of a measured object when the measured object is not heated, a reference image of the surface of the measured object in the heating process and a reference point temperature of the surface of the measured object;
obtaining a temperature field of the surface of the measured object according to the light intensity of the initial image, the temperature of the reference point and the light intensity of the reference image;
obtaining a deformation field of the surface of the measured object according to the initial image and the reference image;
the reference image and the initial image are both monochrome images of the surface of the measured object shot by a monochrome camera; the reference point temperature is the single-point temperature of the surface of the measured object when the reference image is shot;
obtaining a deformation field of the surface of the measured object according to the initial image and the reference image; the method comprises the following steps:
determining the size of each sub-area of the point to be measured in the initial image by using the GMSD as an evaluation index, wherein the sub-area of any point to be measured takes the point to be measured as a central point;
obtaining a deformation field of the surface of the measured object by a digital image correlation method according to the size of the sub-area of each point to be measured;
obtaining a temperature field of the surface of the measured object according to the light intensity of the initial image, the temperature of the reference point and the light intensity of the reference image; the method comprises the following steps:
correcting the light intensity of the reference point in the reference image according to the light intensity of the initial image to obtain first light intensity;
correcting the light intensity of a non-reference point in the reference image according to the light intensity of the initial image to obtain second light intensity;
obtaining a temperature field of the surface of the measured object according to the first light intensity, the second light intensity, the reference point temperature and the wavelength of the monochromatic camera;
wherein, the obtaining the temperature field of the surface of the measured object according to the first light intensity, the second light intensity, the reference point temperature and the wavelength of the monochromatic camera comprises:
calculating the difference between the natural logarithm of the first light intensity and the natural logarithm of the second light intensity;
calculating the product of the wavelength of the monochromatic camera and the difference value;
and obtaining the temperature field of the surface of the measured object according to the product, the reference point temperature and the Planck second radiation constant.
2. The method of claim 1, wherein the monochrome camera comprises an ultraviolet camera.
3. The method according to claim 1, wherein the determining the size of the sub-region of each point to be measured in the initial image by using GMSD as an evaluation index comprises:
determining a selection interval according to the global GMSD of the initial image and a preset threshold;
and adjusting the size of the subarea of each point to be measured according to a preset rule until the GMSD of the subarea of each point to be measured is in the selection interval.
4. The method according to claim 3, wherein the adjusting the size of the subregion of each point to be measured according to a preset rule until the GMSD of the subregion of each point to be measured is within the selection interval comprises:
if the GMSD of the sub-area of the point to be measured is larger than any numerical value in the selection interval, enlarging the size of the sub-area of the point to be measured until the GMSD of the sub-area of the point to be measured is in the selection interval;
and if the GMSD of the sub-area of the point to be measured is smaller than any numerical value in the selection interval, reducing the size of the sub-area of the point to be measured until the GMSD of the sub-area of the point to be measured is in the selection interval.
5. The method according to claim 1, wherein the obtaining of the deformation field of the surface of the measured object by a digital image correlation method according to the size of the sub-region of each point to be measured comprises:
and according to the size of the sub-area of each point to be measured, solving the extreme value of the correlation function in the digital image correlation method through Newton-Laplacian (NR) iteration to obtain the deformation field of the surface of the measured object.
6. A simultaneous temperature and deformation measuring device, comprising:
the data acquisition module is used for acquiring an initial image of the surface of the measured object when the measured object is not heated, a reference image of the surface of the measured object in the heating process and the reference point temperature of the surface of the measured object;
the temperature field solving module is used for obtaining the temperature field of the surface of the measured object according to the light intensity of the initial image, the temperature of the reference point and the light intensity of the reference image;
the deformation field obtaining module is used for obtaining a deformation field of the surface of the measured object according to the initial image and the reference image;
the reference image and the initial image are both monochrome images of the surface of the measured object shot by a monochrome camera; the reference point temperature is the single-point temperature of the surface of the measured object when the reference image is shot;
obtaining a deformation field of the surface of the measured object according to the initial image and the reference image; the method comprises the following steps:
determining the size of each sub-area of the point to be measured in the initial image by using the GMSD as an evaluation index, wherein the sub-area of any point to be measured takes the point to be measured as a central point;
obtaining a deformation field of the surface of the measured object by a digital image correlation method according to the size of the sub-area of each point to be measured;
obtaining a temperature field of the surface of the measured object according to the light intensity of the initial image, the temperature of the reference point and the light intensity of the reference image; the method comprises the following steps:
correcting the light intensity of the reference point in the reference image according to the light intensity of the initial image to obtain first light intensity;
correcting the light intensity of a non-reference point in the reference image according to the light intensity of the initial image to obtain second light intensity;
obtaining a temperature field of the surface of the measured object according to the first light intensity, the second light intensity, the reference point temperature and the wavelength of the monochromatic camera;
wherein, the obtaining the temperature field of the surface of the measured object according to the first light intensity, the second light intensity, the reference point temperature and the wavelength of the monochromatic camera comprises:
calculating the difference between the natural logarithm of the first light intensity and the natural logarithm of the second light intensity;
calculating the product of the wavelength of the monochromatic camera and the difference value;
and obtaining the temperature field of the surface of the measured object according to the product, the reference point temperature and the Planck second radiation constant.
7. A simultaneous temperature and deformation measuring device, comprising:
a processor;
a memory for storing processor-executable instructions;
wherein the processor is configured to implement the method of any one of claims 1 to 5 when executing the memory-stored executable instructions.
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| CN112884751B (en) * | 2021-03-09 | 2021-10-01 | 清华大学 | Device and method for synchronously measuring deformation and temperature by using ultraviolet fluorescent mark |
| CN113049589B (en) * | 2021-03-10 | 2021-12-03 | 清华大学 | Adjustable image acquisition method in high-temperature environment |
| CN113030174B (en) * | 2021-04-09 | 2022-03-25 | 清华大学 | Temperature deformation measurement method and system based on partition filtering |
| CN113483987B (en) * | 2021-07-19 | 2022-09-13 | 清华大学 | Device and method for synchronously measuring temperature deformation in high-temperature wind tunnel environment |
| CN113532548B (en) * | 2021-08-23 | 2022-04-08 | 清华大学 | System and method for synchronously measuring temperature deformation in high-temperature environment |
| CN114018324B (en) * | 2021-11-02 | 2022-08-19 | 清华大学 | Multi-parameter synchronous measurement method and device, electronic equipment and storage medium |
| CN114120895A (en) * | 2021-11-17 | 2022-03-01 | 湖南国天电子科技有限公司 | PWM-based rotary LED screen brightness correction method |
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