JPH05296735A - High precision non-contact strain measurement method and device therefor - Google Patents

Abstract

PURPOSE:To measure strain by saving a distance between points for measurement on a measurement object, enlarging and photographing the vicinity of the measurement points, applying temperature and/or pressure to the object and then measuring the change of the measurement points on an enlarged pickup image. CONSTITUTION:A distance between two marks (a) and (b) on the surface of an accumulator 2 is accurately measured, and saved in an arithmetic processing device 6. The marks (a) and (b) are first illuminated with a lighting device 3. As a result, visual fields A and B are respectively incident on magnifying glass via the reflector of an optical device 4, and further incident on an image pickup device 5. In this device 5, enlarged photographing visual fields A' and B' become available from the visual fields A and B. After the accumulator 2 is heated up to high temperature, visual fields A and B near the marks (a) and (b) are similarly enlarged through the optical device 4 and then photographed. The positions of the marks (a) and (b) available from the photographed image are read, and a mark shift distance is obtained from a relationship between an original mark position and a mark position after a change. Then, generated strain is obtained from the mark shift distance and a distance between the marks (a) and (b). The magnifying power of the optical device 4 is taken at approximately at 25, and the resolution of the image pickup device is taken at 1/493. As a result, strain can be measured with accuracy of about 1/10000.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention, such as a heat accumulator in a space heat engine power generation system, has a measurement object housed in a vacuum container and emits strong light at a high temperature of 1000 ° C. or higher during operation. The present invention relates to a non-contact strain measuring method and an apparatus therefor capable of continuously measuring with high accuracy even in such a case.

[0002]

2. Description of the Related Art Artificial satellites are equipped with a space heat engine power generation system that uses sunlight as a heat source. However, in artificial satellites that fly at low altitudes, sunlight enters when they enter the shadow of the earth. Therefore, in order to operate the power generation system continuously, it is necessary to install a heat storage device and supply a higher temperature fluid to the gas turbine to continue power generation when the satellite enters the shadow of the earth. is there.

The performance of the heat accumulator used for such purposes is an important factor that determines the performance of the power generation system. In principle, the higher the heat storage temperature of the regenerator, the better the system performance, but in practice, a heat storage temperature of at least 1000 ° C or higher is required.

However, in these heat accumulators, since the artificial satellites intermittently pass through the portion exposed to sunlight, the outer surface is intermittently heated. For this reason, thermal strain is likely to occur, and unless sufficient consideration is given to design and manufacturing, the heat accumulator may be destroyed by the stress associated with this thermal strain.

It is important to properly design and manufacture the regenerator so as not to be destroyed by the stress caused by the thermal strain. However, in order to verify that the design and manufacture are appropriate, the operation of the regenerator is performed. Under the conditions, it is necessary to measure the thermal strain of the regenerator with sufficient accuracy.

However, since the heat accumulator is housed in a vacuum container, the strain measurement cannot be calibrated during measurement, and moreover, it is heated at a high temperature of 1000 ° C. or more during operation, and its surface is in a strong light emitting state. In particular, it is extremely difficult to perform the measurement with the conventional strain measurement method with sufficient accuracy and such that the measurement accuracy does not change even if the measurement is continuously performed for several tens of hours.

As an example of a high temperature thermal strain measuring device, there is a method of adhering a strain gauge made of a material capable of withstanding high temperature to a measuring object and estimating the strain of the measuring object by the change of its electric resistance.

Further, in an example of a non-contact measurement method of strain using light, two points of a measuring object are captured by one optical measuring device, the distance between them is measured, and the measured value is compared with the size of the object. , There is a way to calculate the distortion.

In addition, there is a method of achieving the object by measuring the displacement of a measuring point by utilizing the interference of light and converting the displacement into a strain.

[0010]

However, in the method using the above-mentioned high temperature thermal strain measuring device, the characteristics of the strain gauge change with temperature, and the change state varies depending on the individual strain gauge. Since the gauge changes over time, it is necessary to adjust compensation for each measurement.

In particular, at a high temperature of 1000 ° C. or higher, in many cases, the strain gauge undergoes a non-negligible change in characteristics during measurement, so that the reliability of accuracy is poor.

Further, as shown in the above-mentioned field of use, when the object to be measured is enclosed in a vacuum container, adjustment is particularly difficult and practically impossible.

On the other hand, in the above-described non-contact strain measurement method using light, since the entire object is captured by the photographing device at one time, it is not possible to improve the distortion measurement accuracy beyond the disassembling performance of the photographing device. However, its resolution is about 1/1000,
It is extremely difficult to increase this resolution by one digit.

Further, in the above-mentioned method utilizing the interference of light, the interference light is sensitive to the influence of the passage, and in the strain measurement of the heat accumulator housed in the above-mentioned vacuum container, the temperature inside and outside the container is measured. The influence of the difference and the material of the peep window has a great influence on the interference state, and the measurement is practically impossible.

Therefore, according to the present invention, even when the object to be measured is housed in a container and the calibration cannot be performed during the measurement, such as the heat accumulator of the space heat engine power generation system, the present invention has sufficient accuracy. Moreover, it is an object of the present invention to develop a non-contact strain measurement method that does not change the measurement accuracy even when continuously measuring for several tens of hours.

[0016]

Therefore, in the present invention, in the non-contact strain measuring method for measuring the strain of the measuring object housed in the container from the outside of the container, the two points defined on the measuring object are measured. Mark the measurement points, store the distance between the measurement points in the arithmetic processing unit, first magnify and photograph the vicinity of each of the marked measurement points, and calculate the first position of each mark from the photographing surface. The first mark of the mark stored in the processor is stored in the processing device, and then the vicinity of the marked measurement point when the temperature and / or pressure is applied to the measurement object is magnified and photographed in the same manner as above. And the change in the position of each mark on the shooting surface enlarged from the position of the mark on the shooting surface, and based on the change in the mark position, the temperature and / or pressure is calculated by the arithmetic processing unit. Giving It proposes a non-contact strain measurement method for performing a strain measurement distance movement measured by the between time points after.

Further, in the present invention, as a device for carrying out the measuring method of the present invention, a measuring mark for reflecting light of a wavelength in a predetermined region for marking two measuring points defined on the object to be measured, An illumination device that allows light of a wavelength in a predetermined region to enter through a viewing window, an optical device that has the function of magnifying the image from the measurement point, and a photographing device that captures the image sent through this optical device. The present invention proposes a non-contact strain device including a calculation processing device that calculates strain from the moving distance of a measurement point.

[0018]

That is, in the present invention, before the measurement is started, the distances between the two marks on the object to be measured are accurately measured and stored in the arithmetic processing unit.

Then, first, each mark is illuminated with light having a wavelength in a predetermined region by an illuminating device, each mark reflects this light, and a field of view in the vicinity of each mark is drawn out through a viewing window. Is magnified and photographed through an optical device, and the initial position of each mark obtained from this photographing surface is stored in the arithmetic processing unit.

As the illuminating device, an ultra-high pressure mercury lamp that emits light in the high wavelength region of visible light is used to distinguish it from, for example, light in the low wavelength region of visible light emitted from a heated object to be measured. To be done.

Next, after giving a physical change such as high temperature heating, the field of view near each mark is similarly enlarged and photographed through an optical device, and the position of each mark obtained from this photographing surface is calculated. From the relationship between each mark position that was read by the processing device and initially stored and the changed mark position, use the processing program of the arithmetic processing device to find the moving distance of each mark From the distance, by the processing program of the arithmetic processing unit,
Calculate the change in the distance between two marks. From the change in the distance and the distance between the marks initially stored, the generated distortion is calculated and obtained using the processing program of the arithmetic processing unit.

The measurement accuracy is, in principle, a value obtained by dividing the resolution of the photographing device by the magnification of the optical device. For example, if the resolution of the imaging device is 1/1000 and the magnification of the optical device is 100, strain measurement with high accuracy of 1/10000 can be performed.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on the illustrated embodiments. This example shows an example in which the strain of the heat accumulator is continuously measured for a long time in a test device of an energy storage system for heat engine power generation for space use. In FIG. 1, 1 is a vacuum container, and a vacuum container. 1 has a peephole 1a, and a heat storage device 2 as a measurement object is housed inside.

The outer wall of the regenerator 1 is made of Inconel, the thickness is 1 mm, the inside of the regenerator is filled with lithium fluoride, and the maximum temperature of the regenerator is about 1000 ° C. during operation.
Rise to. Two measurement points are defined on the surface of the heat storage device 2 at a position facing the observation window 1a, and the mark a is set at this measurement point.
And b are added.

Reference numeral 3 denotes an illuminating device for irradiating the above-mentioned two measuring points with light necessary for measurement. As the illuminating device 3, an ultrahigh pressure mercury lamp is used. Reference numeral 4 denotes an optical device having a function of enlarging the field of view. In front of the optical device 4, an optical filter 4a for passing only the light emitted from the measurement point is provided, and the optical device 4 has a reflecting mirror 4b ... And a magnifying glass 4c.

Further, 5 is a photographing device for photographing the field of view near the mark enlarged by the optical device 4, and 6 is an arithmetic processing device.

In order to prevent the light from the illuminating device 3 from being reflected by the observation window 1a and entering the optical device 4, the illuminating device 3,
The peep window 1a and the optical device 4 are coated.

In the measurement of strain using this apparatus, the distance between the two marks a and b on the surface of the heat accumulator 2 is accurately measured and stored in the arithmetic processing unit 6.

First, the illuminating device 3 illuminates the respective marks a and b, and the marks a and b are passed through the observation window.
A visual field A in the vicinity and a visual field B in the vicinity of the mark b are drawn out, and these visual fields A and B are made incident on the magnifying mirror 4c through the reflecting mirrors 4b ... Enlarged photographic fields A ′ and B ′ of A and B are obtained (see FIG. 2). The initial positions of the marks a and b are stored in the arithmetic processing unit 6.

Next, after the heat accumulator 2 is heated to a high temperature, the visual fields A and B near the marks a and b are similarly enlarged and photographed through the optical device 4, and the respective marks a obtained from this photographing surface are obtained. The positions of b and b are read by the arithmetic processing unit 6,
The moving distance of each mark is obtained from the relationship between the initially stored position of each mark and the changed position of the mark using the processing program of the arithmetic processing unit 6, and the calculated moving distance is used to calculate The processing program of the processing device calculates the change in the distance between the two marks. The generated distortion was calculated from the change in the distance and the distance between the marks initially stored by using the processing program of the arithmetic processing unit.

In this case, as a result of setting the magnification of the optical device 4 to about 25 times and the resolution of the photographing device 5 to 1/493, the distortion could be measured with an accuracy of about 1/10000.

[0032]

According to the present invention, the thermal strain of the regenerator in the space heat engine power generation system, which has been extremely difficult to measure in the high temperature atmosphere of 1000 ° C. or higher, is highly accurate to 1/10000 or more. Can be measured.

[Brief description of drawings]

FIG. 1 is a system conceptual diagram of the present invention.

FIG. 2 is a diagram showing the measurement principle of the present invention.

FIG. 3 is a diagram showing the principle of a method of enlarging two measurement points in the vicinity of the measurement point according to the present invention.

[Explanation of symbols]

 1 Vacuum container 2 Heat storage device 3 Illumination device 4 Optical device 5 Imaging device 6 Arithmetic processing device a and b Marks of measurement points A and B Field of view near marks a and b Fields A'and B'fields of view A and B

Claims (3)

[Claims] 1. A non-contact strain measuring method for measuring the strain of a measuring object housed in a container from outside the container, by marking two measuring points defined on the measuring object, and between the measuring points. The distances of the marks are stored in the arithmetic processing unit, and first, the vicinity of the marked measurement points are magnified and photographed, and the first position of each mark on the photographing surface is stored in the arithmetic processing unit, and then the measurement is performed. The vicinity of the marked measurement point when temperature and / or pressure is applied to the object is magnified and photographed in the same manner as above, and the first position of the mark stored in the arithmetic processing unit and the mark on this photographing surface are recorded. The change in the position of each mark on the shooting surface enlarged from the position of is measured, and the distance between the measurement points after the temperature and / or pressure is applied by the arithmetic processing unit based on the change in the mark position is measured. Distortion by measuring movement A non-contact strain measuring method characterized by performing. 2. The method according to claim 1, wherein the measuring object is a heat accumulator in a space heat engine power generation system. 3. A non-contact strain measuring device for measuring strain of a measuring object housed in a container through a peep window provided in the container, wherein two measuring points defined on the measuring object are marked. A measuring mark for reflecting light of a wavelength in a predetermined region, an illuminating device for injecting light of a wavelength in the predetermined region through a viewing window, an optical device having a function of enlarging an image from a measuring point, and this optical device. A non-contact distortion device comprising: a photographing device for photographing an image sent through the device and an arithmetic processing device for calculating distortion from a moving distance of each measurement point.