RU2665323C1 - Sample at the high-temperature impact thereon geometrical parameters and / or deformations measurement method and system for its implementation - Google Patents

Abstract

FIELD: measuring equipment.SUBSTANCE: invention relates to the measuring equipment, in particular to the objects deformation parameters measuring contactless means and methods. Claimed sample under high-temperature exposure geometric parameters and / or deformations measuring system includes the high-temperature chamber made with possibility of the sample placement therein, sight glass located in the chamber wall with possibility of visual observation over it, installed inside the chamber sample illumination system, mounted on the chamber outer side photo-recording device to ensure that the sample is placed in the frame, associated with the photo-recording device computing device. Photo-recording device performs image processing, the processing results visualization and the sample three-dimensional numerical image construction, by which the geometric and deformation parameters measurement and calculation are performed by the sample boundaries in the image in pixel form coordinates calculation with their subsequent approximation by straight lines or polynomial curves, marks coordinates in the pixel form obtaining and the boundaries coordinates and the sample marks conversion into the metric form.EFFECT: possibility of the loaded sample deformations and its shape at high temperatures non-contact measurement.15 cl, 12 dwg

Description

FIELD OF TECHNOLOGY

The invention relates to measuring equipment, in particular to non-contact means and methods for measuring the parameters of deformation of objects, for example, when testing for strength, in conditions of elevated temperatures (for example, up to 700 ° C), as well as in complex stress conditions, and can be used for diagnosing destruction of the sample and estimates of the time after which the destruction will occur. The invention will find application in scientific research laboratories conducting high-temperature studies of loaded samples or structures, and in industry where it is necessary to remotely measure the shape and / or deformation of a sample during high-temperature deformation.

BACKGROUND

Existing analogues for measuring strains at elevated temperatures can be divided into two groups: methods for measuring strains at individual points on the body and methods that measure strains continuously throughout the body under study (or continuously over a selected area of the body). Strain measurement methods with various types of sensors and transducers used in them can be classified as methods for measuring deformations at individual points on the body. The second group includes optical-geometric (the method of dividing and moire nets), interference-optical, polarization-optical methods, etc.

In the first group, the closest non-contact method is the TRViewX video extensometer (e.g. TRViewX 240S) manufactured by Shimadzu (http://www.ssi.shimadzu.com/products/literature/Testing/C224-E052.pdf), designed for non-contact measurement longitudinal and transverse deformations at elevated temperature. It allows you to register on the surface of the samples the movement of specially applied optical marks.

However, this video extensometer does not allow measuring the displacements of randomly selected points on the sample and does not fully control the shape change of samples and materials during deformation (in particular, it is not possible to measure the shape of the sample during the entire deformation time). A video extensometer also requires high-contrast markers and strong external lighting, which is difficult to implement at elevated temperatures (above 200 ° C), and the mechanism for using this video extensometer at elevated temperatures is not described.

In the second group of strain gauges at elevated temperatures, the closest analogues can be divided into the following subgroups:

1. methods requiring the application of special characters on the sample,

2. methods requiring the application of films on a sample (limited at elevated temperatures),

3. methods using line lighting,

4. shadow method,

5. methods using structured light.

1. Drawing special characters on a sample.

A device is known “A method for determining the coordinates of points and the orientation of surface sections of a body of complex shape” (RU 2162591), in which special marker symbols are placed on controlled sections of the surface of a body of complex shape proportional to the size of this surface. As symbols, flat elements of the same shape and size are used. The perception of the image of the body surface of complex shape is carried out by an optical fixing device, for example, a video camera. Comparing the images of the symbol and the reference symbol, located in such a way that the coordinates of all the points of the symbol are known, they judge the coordinates of the points on the surface of the body of complex shape, as well as the orientation of the surface area on which the symbol is located, taking into account the angle of its inclination.

However, this method does not allow to determine the shape of the object, is not applicable for measuring deformations in arbitrary directions and is not applicable for measuring the deformation of small parts. And also the use of this method at high temperatures is doubtful.

2. Application of films to the sample

The well-known "Method for the determination of microdeformations of a sample" (RU 2011160). A photographic layer is applied to the surface of the sample, which is used as a photosensitive layer of photographic film, for example, a dry film photoresist, which is previously exposed through a template with a coordinate grid. A sample with a coordinate grid photographed on its surface is loaded. At the same time, the sizes of the cells of the coordinate grid before and after loading are measured using a microscope, and the microdeformation of the sample with a curved surface is determined from the measurement results.

However, the use of this method at elevated temperature is impossible, because the applied photoresist burns out, and it is also impossible to measure changes in the sample at the time of deformation.

3. Linear lighting.

This class is different in that a bright contrast line is projected onto the surface to be measured using a source of a flat ray of light, followed by registration with a digital matrix.

The well-known "Method of measuring the shape of an object and a device for its implementation" (RU 2256878), "Optical radius gauge" (US 5,090,811) including the formation on the surface of an object using a light emitting system of a light line lying in a given section of the object, obtaining an image of the light line, its processing and determining the coordinates of the profile section of the object.

It is known "Device for controlling the linear dimensions of three-dimensional objects" (RU 125335), containing a projector for projecting onto an object under study an image having at least two disjoint lines along one of the longitudinal axes and at least two cameras for recording the position of the image placed at different distances from a projector with the formation of different triangulation angles, with the ability to connect a computer processor for measuring and determining coordinates and a monitor to form a 3D image of the object.

There are also varieties of this method that differ in some details: “Scanning arrangement and method” (US 5,912,739), “Method of non-contact measurement of three-dimensional objects” (RU 2365876), “Method of triangulation measurement of the surface of objects and a device for its implementation” (RU 2315949) .

However, these methods require rotation of the object to determine its shape or rotation of the camera around the object (depending on the method), do not allow determining surface deformations and, in addition to visual access for the photorecorder to the sample, require another (one or more, depending on the method) visual access for linear laser or other mechanism for the formation of special illumination on the sample.

4. The shadow method.

The well-known "Method for monitoring the diameters of the part" RU 2301968 and "Photoelectric device for measuring the diameter of the product" RU 2173833, which can be used for non-contact measurement of the diameter of the products and / or shape of the object. The device includes rotating the part, scanning it in the transverse plane by the radiation beam of the laser source, fixing the surface of the part along the boundaries of the shadow portion of the points of contact with the radiation beam, and determining the diameter from the distance between these points of contact. The diameters are measured in each of two predetermined cross-sections of the part in mutually perpendicular longitudinal planes of the part.

However, this method does not allow measuring surface deformations and is not applicable for large objects, because It requires a receiving matrix corresponding to the size of the object (the Apparatus and method for measuring an object is known, US 4,198,165, which allows the use of matrices of significantly smaller sizes), and also requires rotation of the object.

Also known is the “Device for measuring the linear deformations of articles or samples under loading and heating” (SU 181824), containing a radiation source, curtains located on the beam path and mounted on the deformable object or formed by its edges, a focusing device, a device for moving the beam, radiation receiver, electrical converting, measuring and recording devices. In order to increase the temperature limit of the object’s heating and reduce errors due to the influence of the background of the glow of the curtains during heating, the source of ultraviolet rays was used as a radiation source, and a concave mirror swinging or rotating relative to an axis perpendicular to its optical axis was used as a focusing and deploying device axis.

The disadvantages of this device are the complex camera mount system suspended on the grips of the testing machine, the need for ultraviolet light and high-temperature windows that are transparent to ultraviolet rays.

5. Structured backlight.

A distinctive feature of this method is the design on the surface of an object of structured light (spatially and / or in intensity).

By the type of light structuring, methods can be distinguished into: methods in which a set of strips with a sinusoidal intensity distribution is projected (for example, RU 2148793 “Method for measuring the shape and spatial position of an object’s surface” and “Structured-light, triangulation-based three-dimensional digitizer” WO9958930 ), methods in which a set of images is projected with a given luminous flux structure (in the given linear example) (for example, RU 2448323 “Method for optical measurement of the surface shape”), methods using the principle of interferometry (for example, EP1117973), method s that use optical radiation spatially modulated in intensity (for example, RU 2185598 “Non-contact control method for the linear dimensions of three-dimensional objects”), methods that use a laser emitter matrix (for example, RU 2296947 “Non-contact measurement of bodies with a complex surface shape”) or in which an array of point images is formed on the surface of an object (for example, RU 2304760 “Method for determining coordinates”), methods using the formation of collimated beams of optical radiation with two the set perpendicular directions (e.g., RU 2491503 "Method of recognizing three-dimensional shapes of objects"), and others. Subsequent registration image distorted by a surface relief of the controlled object and the determination using the digital electronic calculator surface shape of the controlled object according to the degree of distortion of the radiated illumination structure on a computing device. The main purpose of these methods is to calculate the shape of the object.

However, the application of all these technologies at high temperatures has a number of significant difficulties: when using infrared illumination, the method is impossible, because Infrared radiation of heaters and / or a heated sample occurs. When using the visible range backlight, it is impossible to obtain an image of the entire sample, this requires external illumination, which in turn illuminates (completely or partially reduces contrast) structural illumination. These methods do not allow measuring surface deformation on the test sample.

A close analogue is also a method based on the moire effect (for example, "Method for remote measurement of displacements" RU 93042088). However, this method is associated with the great difficulty of applying a raster on the surface of the product during its manufacture, consisting of parallel strips and the difficulty in measuring uniform deformations throughout the volume.

A device is known for low-temperature non-contact measurement of deformations of samples by applied reference points (Pavlenkova E.V., Zhegalov D.V. “Numerical methods for experimental-theoretical analysis of large deformations of structural elements and determination of parameters of mathematical models of elastoplastic materials.” Teaching aid. Nizhny Novgorod: Nizhny Novgorod State University, 2012. - 35-40 p.). The experimental complex includes a testing machine equipped with appropriate sensors for force measurement and deformation, a digital camera, lighting equipment, a personal computer with a package of application programs for processing photo images. “Canon EOS 5D Mark II”, a software package manufactured by National Instruments, was used as a photographic recorder. The principle of operation consists in periodically photographing the sample, followed by recognition of the pictures in the “Vision Builder for Automated Inspection”, from which the elongation of the sample, narrowing and radius of the neck were determined. The method and equipment is designed to measure the strains of loaded samples only at room temperature.

However, in this device there is no means for measuring strain at high temperatures (up to 700 ° C). And the assumption used “the working (measuring) part of the sample remains cylindrical until the formation of macrocracks, and changing the wall thickness evenly over the specified length” (see page 43 of this book) does not allow measuring the non-uniform distribution of deformations in the sample. This solution does not describe the possibility of adaptive recognition recognition during operation, which is necessary at high temperatures on the sample.

The closest analogue in the second group is the digital image correlation method (http://ru.wikipedia.org/wiki/Digital_Image Correlation) in particular, some improvement of the method is known ("Multiple-Scale Digital Image Correlation Pattern and Measurement" US2014160279). The essence of the method is as follows: 1. Preparation - a stochastic texture is applied to the surface of the sample, usually in the form of small spots of contrasting paint. 2. Photoregistration - at the time of deformation, the sample is continuously photographed. 3. Processing - consists in maximizing the correlation coefficient, which is determined by the intensity of the array of pixels in question in 2 or more relevant images and by extracting the projection function of the deformations on these related images. The method allows one to obtain deformation fields on the sample surface.

However, the application of the method at elevated temperatures (above 200 ° C) is difficult, which causes great difficulties with the applied coating, methods for applying a stochastic structure (for example, a small size of black spots on a white background) on the surface of the sample are quite complicated, and the accuracy of the method substantially depends on quality (random uniform distribution) and size (the smaller, the more accurate) the contrasting spots. The method is not applicable for autonomous thin films. Also, when processing the resulting photo data, the processing technology used is more complicated than in the proposed method, and requires a large number of computer calculations.

SUMMARY OF THE INVENTION

The technical problem to be solved by the claimed group of solutions is the creation of a method and system that provides strain measurements on samples by the non-contact method, at elevated temperatures (up to 700 ° C) and / or in a difficult stress state.

In addition to measuring deformations (for example, the general deformation of a sample, deformation of elements on the surface of a sample, etc.), the invention also provides measurement of geometric dimensions (for example, length, width in various sections, coordinates of reference points, etc.).

 The method is characterized by simplicity and allows to obtain results in the process of deformation. Through the use of processing technology, a qualitative increase in efficiency appears (namely, an increase in the strain measurement range, an increase in the accuracy of measurements and coordinates of points on the surface of the sample in substantially large volumes, for example, for sediment testing, the value of the diameter of the sample in any longitudinal or cross section at any time ) and the ease of quantitative assessment of deformations of the sample under high-temperature exposure to it, including in the case of a complex stress state.

The technical result to which the invention is directed is the possibility of non-contact measurement of deformations of a loaded sample (including when the stress state is complex) and its shape at high temperatures (up to 700 ° C, to a glow temperature) by creating and processing (including its forms, deformations in different zones and coordinates of points) of the numerical image of the object under study while reducing the complexity of the measurements and achieving high accuracy of the obtained parameters of the deformation of the object.

The achievement of the technical result is possible due to the fact that the present invention builds a numerical image of the deforming sample, according to which measurements are made. The measuring equipment is located outside the high-temperature zone and does not require complicated settings, which eliminates the complexity of measurements at elevated temperatures and reduces the complexity of measurements, and the use of the proposed processing technology provides high-precision strain calculations.

The invention is implemented by a method for measuring geometric parameters and / or deformations of a sample under high-temperature impact on it, which includes the steps at which

- carry out the application on the surface of the sample of reference points;

- install the sample in a high-temperature chamber with the provision of its lighting and visual access to it from outside;

- carry out photo registration of the images of the sample before the deformation of the sample and in the process of deformation of the sample under high temperature exposure with fixing the time of the obtained images, with sequential processing of the resulting images, each image being processed by constructing a three-dimensional numerical image of the sample, and the numerical image of the sample is constructed using

- determination of the coordinates of the boundaries of the sample on the photo image in pixel form with the subsequent construction of an approximating curve;

- determination on the photo image of the coordinates of the reference points in pixel form;

- transformation of coordinates of borders and reference points of an object from a pixel form to a metric form;

- and then using three-dimensional (volumetric) numerical image of the sample using the data characterizing the axis of symmetry of the sample;

- calculate the geometric and deformation parameters based on the obtained three-dimensional numerical image of the sample as parameters for the deformation of the sample, use the time from the beginning of deformation until the fracture of the sample, and / or the coordinates of the side points and / or the shape of the boundaries of the sample, and / or the coordinates of the reference points, and / or the displacement values of the reference points, and / or the displacement speeds of the reference points, and / or the height / length / width of the sample in arbitrary vertical / horizontal sections, and / or the maximum size and position minimal and lateral displacement / thinning, and / or asymmetry of deformation, and / or barrel-shaped / narrowing and / or deformation of elements on the surface and / or height / width of the specimen and / or radius of the longitudinal tangent to the lateral border of the specimen at the point of greatest narrowing.

In one particular embodiment of the method, the registration of sample images is carried out at regular intervals or through a predetermined value of elongation and / or contraction of the sample in a selected direction.

In one particular embodiment of the method, the points of intersection of lines in the grid deposited on the surface of the sample are used as reference points.

In one particular embodiment of the method, the grid consists of rectangular cells 1-3 mm in size.

In one particular embodiment of the method for photographic recording, the sample is placed in the center of the frame, and the size of the sample in the frame is one third of the frame in width and / or length ± 10%.

In one particular embodiment of the method, the approximating curve is a straight line or a polynomial curve.

The claimed invention is also implemented by a system for measuring geometric parameters and / or deformations of a sample under high-temperature exposure, including a high-temperature chamber configured to place a sample in it, a viewing window located in the chamber wall with the possibility of visual observation of it, and a sample lighting system installed inside the camera, a photo-recording device mounted on the outside of the camera to ensure placement of the sample in the frame, a computing device associated with the photo-recording device and performing image processing, visualization of the processing results, and the construction of a three-dimensional numerical image of the sample, which measure and calculate geometric and deformation parameters by calculating the coordinates of the boundaries of the sample on the image in pixel form, followed by approximation by straight lines or polynomial curves, obtaining the coordinates of the labels in pixel form and converting the coordinates of the borders, and the labels of the sample in metric form.

In one of the private options for implementing the system, the inspection window is made of high-temperature optical quartz glass.

In one particular embodiment of the system, the lighting system is one or more lamps located in the furnace, each of which can be equipped with a reflector on ceramic holders that are connected to a nichrome wire for supplying electricity,

In one of the private options for implementing the system, the photo-recording device is rigidly fixed on the window using a connecting flange between the viewing window and the lens of the photoregistrator.

In one of the private options for implementing the system, a camera or a video camera is selected as a photo-recording device.

In one particular embodiment of the system, the parameters from the deformation of the sample to the time of destruction of the sample, and / or the coordinates of the side points and / or the shape of the boundaries of the sample, and / or the coordinates of the reference points, and / or the offset values of the reference points, are used as parameters for the deformation of the sample, and / or the displacement speeds of the reference points, and / or the height / length / width of the sample in arbitrary vertical / horizontal sections, and / or the magnitude and position of the maximum and minimum lateral displacement / thinning, and / or the asymmetry of deformation I, and / or barrel-like / narrowing and / or deformation of elements on the surface and / or height / width of the sample and / or radius of the longitudinal tangent circle to the side border of the sample at the point of greatest narrowing.

In one particular embodiment, the system comprises a control unit associated with the photo-recording device and configured to generate the response signals of the photo-recording device generated when the elongation and / or narrowing of the sample changes in the selected direction. at a given value or at regular intervals.

In one particular embodiment of the system, the control unit includes a linear displacement sensor mounted on a plate arranged in such a way that allows to measure elongation and / or contraction of the sample in a selected direction, an electronic signal processing system from the sensor resulting from sample deformations, a button control module descent of the photo-recording device, as well as a module for indicating measured and controlled parameters.

In one particular embodiment of the system, the high-temperature chamber has a range of operating temperatures of up to 900 ° C.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an installation plan for carrying out the invention.

FIG. 2 illustrates a flowchart of a photographic data processing algorithm.

FIG. 3 illustrates examples of physical implementation of an indoor lighting system.

FIG. 4 illustrates examples of samples.

FIG. 5 illustrates a manufactured control unit of a photorecorder.

FIG. 6 illustrates a real sample (b) in an oven at 400 ° C and its numerical image (a).

FIG. 7 illustrates an image of a computer window showing the processing of data obtained in the process of measuring the deformation of cylindrical samples.

FIG. 8 - FIG. 9 illustrate graphs of the distribution of sample diameter along its longitudinal coordinate x at various points in time.

FIG. 10 illustrates graphs of the trajectories of points in the XY plane in millimeters on the surface of the sample.

FIG. 11 illustrates plots of the maximum stress σ _max (t) in a sample.

FIG. 12 illustrates curves of changes in sample elongation versus time for various experiments.

The positions in the figures indicated:

1 - the investigated object,

2 - lighting lamp,

3 - high-temperature (heating) chamber / furnace,

4 - optical glasses, for example quartz,

5 - photo recorder, for example, a camera,

6 - reflective and focusing system,

7 - computing device

8 - connecting flange,

9 - control unit,

10 - reference marks (for example, lines) on the surface of the investigated object,

11 - block storage of input photo data,

12 - block allocation of borders,

13 is a block changing the boundaries recognition parameters,

14 - block recognition quality control boundaries,

15 - block allocation of reference points,

16 - block changes the recognition parameters of reference points,

17 - block quality control recognition of fixed points,

18 is a block recognition control of the entire image,

19 - block storage "pixel" geometry

20 is a block conversion of “pixel” to “metric” geometry,

21 is a block forming a numerical image of the sample,

22 - unit for the formation of measured data,

23 - block generating requests

24 - block storage of measured data,

25, 26, 27 - curves of the values of σ _max (t) of the current maximum voltage in the sample, measured using this invention,

28, 29, 30 - curves of σ _max (t) of the current maximum stress in the sample, measured by the direct method (change in the distance between the loading rods, outside the furnace zone) with the assumption of uniform deformation,

31, 32, 33 - the points of difference of the curves 25 and 28, 26 and 29, 27 and 30, respectively,

34, 35, 36 - curves of changes in elongation of the sample from time to time for various experiments, measured using this invention,

37, 38, 39 - curves of changes in elongation of the sample from time to time for the same experiments as the corresponding curves 34, 35, 36, but measured by the direct method,

40 - TEN-s (thermal heating elements) of the furnace,

41 - the main image (example, when the deformation of the cylinder),

42 - settings menu,

43 - graphs of color (red, green, blue) and brightness (brightness, contrast, color) of the selected horizontal section,

44 is a graph of a selected vertical section (similar to 43),

45 - thumbnail of the entire frame for quick navigation,

46 - automatic and manual editor,

47 - calculator,

48 - post-processor.

The system for measuring deformations of a sample under high-temperature exposure includes a high-temperature chamber (furnace) 3 with a window 4 made in the wall of the chamber to provide visual (optical) access to the test sample 1, a lighting system 2 and 6, installed inside the furnace to ensure maximum lighting efficiency of the studied the working area of the sample, a photorecorder 5, mounted on the outside of the camera using a connecting flange, a control unit 9 and a computing unit (computing device) 7, Example computer-related photorecorder 5. As computing device may also use a smart phone, a tablet and any other device capable of computing processing of the data.

The test sample 1 is located inside the chamber (see figure 1). The lighting system is one or more lamps 2, for example, quartz lamps, with a reflector 6 on ceramic holders, with a nichrome wire connected to supply electricity (see Fig. 3). To prevent the penetration of cold air into the furnace through the window, as well as to protect against lateral flare of the photorecorder matrix, the window is closed on the outside and inside of the furnace by optical glasses 4, for example, quartz. In this case, the photoregistrator 5 is mounted on the outer side of the heating chamber along the axis connecting the sample 1 and window 4. so that the sample falls into the frame of the photorecorder and its location on the frame is in the center, and the size of the sample on the frame is one third of the frame width along the length of ± 10%. A connecting flange 8 is fixed on the lens of the photoregistrator; the other side of the flange is attached to the window of the heating chamber through a thermally insulated gasket. The photorecorder 5 is connected to the processing unit 7 and the control device 9 cables. A camera was used as a photo recorder (a video camera can also be used) that meets the following requirements.

1. High resolution matrix. For example, to obtain a resolution on a 0.1 mm frame with a sample in a frame occupying 1/3 of the frame, it is necessary that the resolution of the matrix be 6 MP (Megapixels).

2. Shooting at an accurate time interval.

Optical System Requirements:

1. Weak geometric distortion (RMS geometric distortion less than 1%).

2. High resolution optics.

3. High depth of field (more than 1 cm for flat samples). The sample during the experiment will be shifted from the focusing plane, which should not affect the clarity of the resulting images.

4. Exact selection of focal length. For maximum resolution, the image of the sample in the frame should be maximum, but it should also be taken into account that due to the imperfectness of optical systems, the image at the periphery of the frame has additional distortions that should be taken into account when composing the frame. The easiest way to select the focal length is to use a varifocal lens.

As a photorecorder, for example, a NIKON D300s camera equipped with a NIKKOR 80-200mm f / 2.8D AF lens with an extension ring of 12 mm can be used.

The control unit 9 is a linear displacement sensor mounted on a plate, an electronic system for processing signals from the sensor arising from deformations of the sample, a control module for the shutter button of the photographic recorder, and a measurement indication module (for example, elongation of the sample, time from the beginning of loading, exceeding the operating limit lengthening, battery discharge level) and controlled parameters (for example, the number of frames taken) (see Fig. 5), and is intended to form commands to the photorecorder 5, corresponding which change the length of the working area of the sample, for example, by 0.1 mm (adjustable parameter). This allows you to maintain the accuracy of the measurement and to eliminate the redundancy of frames from the experiment during serial shooting or timer shooting. Block 9 also allows you to generate commands to the DVR at regular intervals.

The proposed method is as follows.

Preparation of the test sample is carried out, for which reference marks 10 are applied on the surface mechanically (for example, by scratching, extruding, stamping, punching or knurling, or by any method known from the prior art) (marks can have any shape and size, the most advantageous is marks are made in the form of lines forming a grid with mesh sizes from 1 to 3 mm), which are used to calculate the surface deformations and the movement of reference points on the surface of the sample. To increase the accuracy of application and facilitate the recognition of deformation marks, the surface of the sample is pre-ground and polished (optional). As applied deformation marks, for example, points obtained by crossing the grid lines are used. An example of images of test samples coated with reference lines is shown in FIG. 4 (a) and (b).

Then the prepared sample is placed in the chamber, while providing illumination and visual access to it from the outside, heated to a predetermined temperature T ₀ , for example 500 ° C, and maintained at this temperature T ₀ for a time corresponding to the establishment of a constant temperature inside the chamber and in all elements of the furnace (about 1 hour). In the process of high temperature exposure, multiple photographing of the sample by the photorecorder 5 is carried out at regular intervals or at a predetermined value of the elongation of the sample. For photographing at regular intervals, the interval timer of the camera used was used (if the photorecorder is equipped with a timer, then block 9 is not used), and after the set extension value, the control unit 9. Then, data is input from the photorecorder 5 to the computing device 7, where they are processed . Information can be transmitted from the photorecorder 5 to the computing device 7 via a wired or wireless connection, for example, a USB connection, Wi-Fi, Bluetooth, IrDa, etc.

To transfer the photographed images of the object into numerical geometry and for subsequent calculations of various parameters, a method was used, a detailed description of which is presented below, a block diagram of the implementation of which is shown in FIG. 2.

The processing method is implemented due to three main modules: automatic and / or manual editor 46, calculator 47 and post-processor 48. In the process, these tools are linked through a common file structure that stores the source or calculated data.

Automatic and manual editor 46 are intended for automatic and / or manual recognition of borders and labels of the sample. If the automatic module does not correctly recognize the image, then the operator needs to fix the image recognition on their own and put reference points on the digital image using the manual editing module. The manual editing module allows you to use the mouse to put reference points on the image, and then calculate the geometry of the sample.

The recognition process is as follows (see Fig. 2). For each frame from block 11, an object is selected, its borders are fixed by block 12. They are controlled by block 14 and, in case of unsatisfactory result, the parameters are corrected in block 13 and the process is repeated. For the object (sample), the coordinates of the boundaries of the sample on the photo image in pixel form are determined, followed by the construction of an approximating curve. The boundaries of the object are approximated in the form of straight lines and / or in the form of polynomials (polynomial curve).

For each frame, an analysis of each horizontal line in the image in the vicinity of the right and left borders of the sample is performed separately. Each pixel of the image is displayed in the RGB and HSV color system, receiving the corresponding numerical values for each channel. One of the channels is selected: R, G, B, H, S or V. The criterion threshold is set. Considering the dependence of the value of the channel on the horizontal coordinate, if the threshold is overcome, then the horizontal coordinate of the place of overcoming is remembered - this is the place of the boundary of the sample. The operation is repeated along all horizontal lines intersecting the region of the sample boundary.

Then, reference points 10 on the surface of the sample are recognized using blocks 15, 16, and 17. After control by block 18, all the recognized geometry is saved in block 19 to a file in the coordinate system of the photograph in pixel scale (one pixel - one unit of length).

The calculator unit 20 uses the recognized image data by the editor of 19 to calculate the numerical metric image in block 21, which is used to calculate the parameters of the deforming object. A numerical image is constructed based on the calculated metric boundaries of the sample, the metric coordinates of the reference points and using the axisymmetry of the sample.

The first frame containing the initial geometry with known sizes, calibrate the scale of the image. Based on the numerical image and the calculated scale, all geometric parameters of the experiment are calculated. The process of translating recognized reference points from pixel to numerical form is performed as follows: The coordinate system on the photo frame is set, associated with the upper left corner of the photo image. On each frame, reference lines are tied to this coordinate system. The coordinates of the points of intersection of the reference lines are calculated - this is the future basis of points for calculating the kinematics of deformation. A second rectangular coordinate system associated with the sample is introduced; for definiteness and ease of use, the coordinate (0, 0) corresponds to the middle of the sample in height on its surface. The coordinates of the reference points from the first coordinate system are converted to the second using the calibration table. This table is compiled before the experiment. It should be noted that the sample and, accordingly, the reference points are located not on the same plane, but on the curved surface of the sample, while the photograph contains their image on the same plane, which is taken into account when calculating the coordinates of the reference points in the coordinate system associated with the sample.

,

, продольная координата

):For objects of various shapes, the processing method allows calculating a different number of parameters, for example, for example 1, the sample is shown in FIG. 4 (a), obtain the values of 14 different parameters, for example, presented below. For examples 2 (Fig. 4 (b)) and 3 (Fig. 4 (c)) the number of parameters is less. For example 1, the calculator allows you to calculate the following parameters (all calculations of the parameters below are performed in the coordinate system associated with the sample, if possible, the parameters of the variables will be omitted, the superscript indicates a time step

,

, longitudinal coordinate

):

.1. Elapsed time since the beginning of the experiment. -

.

.2. Three coordinates of the points lying on the lateral border -

.

.3. Three coordinates of reference points -

.

.4. Four offset values of reference points

.

, для

,

for

,

.

.

.5. Four speeds of shift of reference points

.

.6. Sample height

.

.7. The diameter of the sample in various sections -

.

,

.8. The size and position of the maximum and minimum lateral displacement -

,

.

,9. The asymmetry of the ends -

,

.

.

,10. Barrel -

,

.

.

, где11. The approximation parameters of the barrel-shaped side surface of the parabola -

where

- параметры аппроксимации параболой

, Суммарная среднеквадратическая ошибка аппроксимации,

- Parabola approximation parameters

, Total mean square error of approximation,

- величина бокового радиуса, кривизны, и суммарная среднеквадратическая отклонение боковой поверхности от окружности.

- the value of the lateral radius, curvature, and the total standard deviation of the lateral surface from the circle.

.12. Two coordinates of elements composed of reference points -

.

.13. The height and width of the elements -

.

.14. The three values of the logarithmic deformation of the elements -

.

, например виде

.15. Time to destruction -

for example

.

,

,

) имеется возможность изображать в виде полей на графическом изображении образца (дополненная реальность).Block 22 of the post-processor 48 is endowed with the function of visualizing all the calculated parameters, using the calculator 47, from the obtained metric data, in the form of two-dimensional graphical dependencies (for example, Fig. 7), in the form of fields on the surface of the sample and in the video process of deformation with the possibility of applying deformation fields on a sample form of augmented reality. Also, the unit is endowed with the function to depict graphs of curves of various parameters depending on time, height, width, length and other values of the sample. Some options (e.g.

,

,

) it is possible to depict in the form of fields on the graphic image of the sample (augmented reality).

In FIG. 7 shows an example of a computer window, a fragment of the data processing process of example 1. Region 41 depicts a cylinder in high magnification (relative to the normal size) in accordance with the selected area in miniature 45. On region 41 there are two moving lines - vertical and horizontal, along which into 43 and 44 are graphs of chroma and brightness. Area 41 also contains images of four rectangles - two on the left, on the right, and two on the top, bottom. These rectangles should be located in the area of the corresponding boundaries of the cylinder. They search and highlight the boundaries of the cylinder (blocks 12 and 15). Field 42, containing the recognition parameters area, shows their current values and allows you to change them (blocks 13 and 16). Above region 41 and 42, there are information fields showing the name of the file being viewed, elapsed time since the start of the experiment, supporting information, and more.

Taking measurements. The prepared sample was installed in the chamber / furnace. The lighting was adjusted so that the image on the displays of the DVR was bright and clear. The photo recorder was adjusted so that the depth of field was more than 1 cm, for which the aperture was clamped to F8, the sensitivity was selected 1600-3200 ISO, the image mode was L + JPEG, and the maximum speed shooting mode (up to 7 frames / sec). A photo recorder was installed, the position of which and the shooting parameters remained unchanged during the entire measurement.

To increase the accuracy of the result, a checkered table was placed in place of the sample before the experiment. Several frames of the table were photographed, according to which the calculator was subsequently calibrated.

Example 1

The invention is tested on an experimental installation zdmxh-30t, which consisted of a hydraulic press with a maximum compression force of 300 kN and a heating chamber in which a temperature of up to 900 ° C can be maintained, the chamber volume is 0.42 m ³ . During the experiments, a uniform temperature field was maintained on the cylinder, pressure plates and feed rods. An additional photo recorder 5 was connected to the installation, connected by a cable to a computing device 7.

. Осаживание производилось до величины осевого укорочения

. На боковую поверхность цилиндров наносились продольные и поперечные линии глубиной 0.1 мм, образующие равномерную квадратную или прямоугольную сетку, имеющую размер одной ячейки 1.8 x 3.1 мм. Точки пересечения продольной и поперечной линий являлись реперными точками. Предварительно на торцы цилиндра наносилась высокотемпературная смазка Molykote P37. Для повышения контрастности реперных линий на боковой поверхности цилиндра, линии подкрашивались темной смазкой Molykote P1000, которая при высоких температурах становилась темно-коричневой и обеспечивала хороший контраст с серебристой боковой поверхностью цилиндра. Далее производился нагрев цилиндра, давящих плит и подводящих тяг. При достижении рабочей температуры печь переводилась на режим регулирования, и приблизительно в течение 30 минут производилось выдерживание цилиндра при этой температуре, после чего начиналось его осаживание. По достижению заданного уровня осадки процесс деформирования останавливался, а образец остужался.Precipitation was made (in accordance with GOST 8817-82) of a continuous cylinder with a height of 2H ₀ and radius R ₀ using two plates moving towards each other with a mutual speed of 2w along the longitudinal axis z. During the time t ₁ at the temperature T to a value precipitates cylinder height 2H cylinder _1. We used cylinders (see Fig. 4a) from an aluminum alloy D16T with a radius R ₀ = 19.5 mm and a height of 2H ₀ = 39 mm. The deformation parameters are as follows:

. Precipitation was carried out to the value of axial shortening

. On the lateral surface of the cylinders, longitudinal and transverse lines were 0.1 mm deep, forming a uniform square or rectangular grid with a single cell size of 1.8 x 3.1 mm. The points of intersection of the longitudinal and transverse lines were reference points. Previously, Molykote P37 high-temperature grease was applied to the ends of the cylinder. To increase the contrast of the reference lines on the lateral surface of the cylinder, the lines were tinted with Molykote P1000 dark grease, which became dark brown at high temperatures and provided good contrast with the silver side surface of the cylinder. Next, the cylinder, pressure plates and feed rods were heated. When the operating temperature was reached, the furnace was put into control mode, and the cylinder was kept at this temperature for approximately 30 minutes, after which it began to settle. Upon reaching a predetermined level of precipitation, the deformation process stopped, and the sample cooled.

For examples 2 and 3, the IMEH-5 installation was used, consisting of a small heating chamber up to 900 ° C, providing heating and tension by constant force of the sample in the furnace. The tests were carried out at 400 ° C in accordance with GOST 9651-84 according to the following scheme. A sample fixed in the rods of the installation was placed in a furnace and heated to a predetermined temperature. After the temperature reached the preset level, the photorecorder turned on. The sample was loaded to a given level of axial stress σ ₀ . Further deformation was performed under creep conditions with a constant tensile load up to fracture. Throughout the entire test period, the photographic recorder took pictures of the deformable cylinder at regular intervals or at a given elongation value controlled by block 9. On average, the deformation process is recorded by 300-500 photographs, in some tests the number of photographs reaches 1000.

In Example 2, tensile (according to ISO 783-89) of a flat sample (see Fig. 4b) of length L ₀ , width W ₀ and thickness D ₀ was carried out between two rods moving in opposite directions under the action of a constant load P ₀ . The deformation was carried out before the destruction of the sample, with a working length L ₀ = 48 mm, a width W ₀ = 5 mm and a thickness D ₀ = 1.3 mm.

In example 3, tensile (according to ISO 783-89) cylindrical specimen (see Fig. 4c) was made with a length L ₀ = 28 mm and a diameter D ₀ = 5 mm with a constant force P ₀ in time. Deformation was carried out before the destruction of the sample. Deformation parameters: P ₀ = 500 N, t * ~ 2000 sec.

The proposed technical solution allows you to build a numerical image of a real heated object (for example, a cylinder for example 1, see Fig. 6a or the image of a fillet-like sample (example 2) or a flat sample (example 3) or any other) in a furnace in almost real time Sound latches are associated with the processing speed of the next image, which makes it possible to eliminate the problems of measuring deformation at high temperature and to measure a large number of sample parameters during deformation. In this case, measurements of all geometric parameters can be performed in a numerical manner, which reduces the complexity of the measurements and increases the awareness of the object. An example of a graphic representation of a numerical image of a deformable cylinder is shown in FIG. 6 (a) obtained by a real cylinder (Fig. 6 (b)) located at a high temperature in the furnace. This method has significant advantages:

1. non-contact measurement

2. a greater number of measured parameters of the investigated object,

3. lack of high temperature measuring instruments.

This measurement system made it possible to understand the processes occurring in the contact zone of the side surface and the contact surface (for example 1). In the process of deformation of the cylinder, broadening of the sample in the contact zone occurs not due to the broadening of the contact area, but due to the flow of material from the side to the contact surface. The process of material flowing over the surface of the sample is uneven. In the central part, the material moves slowly to the center of the sample, closer to the end part of the sample, the speed increases. There was no movement of material on the contact surface.

The results obtained by this method.

This invention for example 3 made it possible to measure the distribution of the diameters of the sample along the working part at any time. Two experiments were conducted on samples geometrically and physically similar, with the same power and temperature conditions. These data are shown in FIG. 8 (experiment 1) and FIG. 9 (experiment 2). FIG. Figure 8 shows the evolutionary change in the working part of the sample — the process of thinning and extension, which was impossible to measure by other methods. A distinctive feature of the deformation process in FIG. 9 is a weak deformation most of the time, and then a rapid onset of fracture during localization of the deformation. The reasons for this behavior during high-temperature tests are either a relatively high temperature drop along the working part of the sample, which was excluded at the tuning stage, or structural imperfection of the sample in a given section. These samples must be recognized as defective, but without a preliminary x-ray study, this fact cannot be established. This invention eliminates the need for expensive x-ray equipment and reject such samples.

In FIG. 10 shows the trajectories of the points on the surface of the sample for example 2. The working area of the sample was {-4.5 <x <4.5 U -28 <y <28}. The figure shows 11 points on the surface, showing characteristic trajectories of movement.

In the problems of stretching, in which there is the possibility of localization of deformation, this measurement system allows you to find and show the localization of deformations long before it can be seen with the naked eye. In this area, the current stress rises sharply, the development of which entails destruction. The area of increased voltage is quite wide relative to the average sample. At the same time, the part of the sample occupied by the neck at t = 95% conditionally is 26% of the length, and at the time of destruction reaches 48%. Such a high part of the sample, affected by the developing neck, refutes the assumption of many authors that the localization of deformation does not affect most of the sample.

Thanks to the development, it became possible to compare the actually acting stress in the sample (task 3) with the stress obtained under the assumption of uniform deformation along the entire working part, as is usually done. In FIG. 11 shows three pairs of curves corresponding to three experiments, with the numbers 25, 26, 27 designating the curves corresponding to the actual maximum stress in the sample, curves 28, 29, 30, corresponding to the stress in the sample under the assumption that the deformation of the working part of the sample occurs uniformly without localization. The numbers 31, 32, 33 indicate the time points at which a significant divergence of the pair of curves begins. This graph clearly illustrates that the assumption of uniform deformation of the working part (as it does in similar experiments) is fulfilled on average only at the beginning of the process (at t <30-40%). The differences between the mentioned stresses reach 100%, which indicates the importance of taking into account the true stress distribution in the sample.

Accuracy of measurements. In the described examples, NIKKOR low dispersion low aberration optics was used. An independent laboratory (http://www.photozone.de/Reviews/252-nikkor-af-80-200mm-f28d-ed-review--test-report) study showed a maximum distortion of 0.4% distortion at a focal length of 135 mm and 0.7% at 200 mm. The error in the obtained linear dimensions was estimated by comparing the sample lengths measured by the optical method and direct measurement (the only available parameter for contact measurement) between the rods of the machine during the experiment. In FIG. Figure 12 shows three pairs of time dependence of the elongation of the samples: curves 34, 35, 36 correspond to the elongation of the sample ΔL ₁ obtained by the optical method, and curves 37, 38, 39 correspond to the elongation of the sample ΔL ₂ obtained by direct measurements. Analysis of the data depicted in FIG. 12 shows that the discrepancy between the sample lengths measured by the optical method and direct measurement does not exceed (ΔL ₁ - ΔL ₂ ) / L ₀ = 3%.

Claims (23)

1. A method for measuring the geometric parameters and deformations of a sample under high-temperature exposure to it, including the steps at which - carry out the application on the surface of the sample of reference points; - install the sample in a high-temperature chamber with the provision of its lighting and visual access to it from outside; - carry out photo-registration of the images of the sample before the deformation of the sample and in the process of deformation of the sample under high-temperature exposure with fixing the time of the obtained images, with sequential processing of the resulting images, each image being processed by constructing a three-dimensional numerical image of the sample, and the numerical image of the sample is constructed using - determination of the coordinates of the boundaries of the sample on the photo image in pixel form with the subsequent construction of an approximating curve; - determination on the photo image of the coordinates of the reference points in pixel form; - transformation of coordinates of borders and reference points of an object from a pixel form to a metric form; - and then using three-dimensional (volumetric) numerical image of the sample using the data characterizing the axis of symmetry of the sample; - calculate the geometric and deformation parameters based on the obtained three-dimensional numerical image of the sample, as the parameters of deformation of the sample, use the time from the beginning of deformation until the fracture of the sample, and / or the coordinates of the side points, and / or the shape of the boundaries of the sample, and / or the coordinates of the reference points , and / or the values of the displacement of the reference points, and / or the speed of the displacement of the reference points, and / or the height / length / width of the sample in arbitrary vertical / horizontal sections, and / or the magnitude and position of the maximum minimum and lateral displacement / thinning, and / or asymmetry of deformation, and / or barrel-shaped / narrowing, and / or deformation of elements on the surface, and / or height / width of the sample, and / or radius of the longitudinal tangent circle to the side border of the sample in place greatest narrowing. 2. The method according to p. 1, characterized in that the registration of the photo images of the sample is carried out at regular intervals or at a predetermined value of the elongation and / or narrowing of the sample in the selected direction. 3. The method according to p. 1, characterized in that as the reference points use the point of intersection of lines in the grid deposited on the surface of the sample. 4. The method according to p. 3, characterized in that the grid consists of rectangular cells 1-3 mm in size. 5. The method according to p. 1, characterized in that when photographic recording the sample is placed in the center of the frame, and the size of the sample on the frame is one third of the frame in width and / or length ± 10%. 6. The method according to p. 1, characterized in that the approximating curve is a straight line or a polynomial curve. 7. A system for measuring geometric parameters and deformations of a sample under high temperature exposure, including a high temperature camera configured to place a sample in it, a viewing window located in the wall of the camera with the possibility of visual observation of it, a lighting system for the sample installed inside the camera, a photo-recording device, mounted on the outside of the camera to ensure placement of the sample in the frame, a computing device associated with a photo-recording device and image processing, visualization of the processing results and construction of a three-dimensional numerical image of the sample, which is used to measure and calculate geometric and deformation parameters by calculating the coordinates of the boundaries of the sample on the image in pixel form, followed by their approximation by straight lines or polynomial curves, obtaining the coordinates of the labels in the pixel shape and transformation of the coordinates of the borders and labels of the sample in metric form. 8. The system according to claim 7, characterized in that the viewing window is made of high-temperature optical quartz glass. 9. The system according to claim 7, characterized in that the lighting system is one or more lamps located in the furnace, each of which can be equipped with a reflector on ceramic holders that are connected to a nichrome wire for supplying electricity. 10. The system according to claim 7, characterized in that the photo-recording device is rigidly fixed to the window using a connecting flange between the viewing window and the lens of the photorecorder. 11. The system according to claim 7, characterized in that the camera or camcorder is selected as the photo-recording device. 12. The system according to claim 7, characterized in that as the parameters of the deformation of the sample, use the time from the beginning of deformation until the fracture of the sample, and / or the coordinates of the side points, and / or the shape of the boundaries of the sample, and / or the coordinates of the reference points, and / or the values of the displacement of the reference points, and / or the speed of the displacement of the reference points, and / or the height / length / width of the sample in arbitrary vertical / horizontal sections, and / or the magnitude and position of the maximum and minimum lateral displacement / thinning, and / or the asymmetry of deformation, and/ or barrel-shaped / narrowing, and / or deformation of elements on the surface, and / or height / width of the sample, and / or radius of the longitudinal tangent circle to the lateral border of the sample at the point of greatest narrowing. 13. The system according to p. 7, characterized in that it contains a control unit associated with the photo-recording device and configured to generate the response signals of the photo-recording device generated by changing the elongation and / or narrowing of the sample in the selected direction by a predetermined amount or at regular intervals . 14. The system according to p. 13, characterized in that the control unit includes a linear displacement sensor mounted on the plate, located in such a way that allows to measure the elongation and / or narrowing of the sample in the selected direction, the electronic system for processing signals from the sensor resulting from deformations sample, the control module for the shutter button of the photo-recording device, as well as a module for indicating measured and controlled parameters. 15. The system according to claim 7, characterized in that the high-temperature chamber has a range of operating temperatures up to 900 ° C.

Images