JPH0363698B2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) This invention measures metals in infrared rays and processes the temperature data captured by a computer to image the fatigue status of metals that have exceeded their fatigue limits. Regarding how to.

(Prior Art) When a load is repeatedly applied to a metal such as steel, the metal will not break if the load is below the fatigue limit, but if the fatigue limit is exceeded, the metal will break a number of times corresponding to the load.

FIG. 4 shows a so-called SN curve showing the relationship between the load (unit: Kg/mm ² ) and the number of times the load is applied.
This figure shows the fatigue limit load, which means, for example, if we consider point A on the curve, the target metal will break if this amount of load is applied about 10 ⁶ times.

Therefore, it would be extremely meaningful to easily and accurately know the fatigue status of metals that have exceeded their fatigue limits, for example, which parts exceed their fatigue limits and to what extent. Measuring the limits is an extremely difficult task, takes a long time, and the information obtained is not accurate.

At present, no method has been proposed for easily, quickly, and accurately imaging such metal fatigue conditions.

Therefore, in another application previously filed by the inventor of this application (Japanese Patent Application No. 143308/1989), we have developed a new metal A method for imaging fatigue status is proposed. The principle of this proposed method will be briefly explained.

This heat generation includes heat generation and heat absorption due to thermoelastic effects, as well as drift due to changes in room temperature. Furthermore, it has been known for a long time that the metal material being tested generates heat when it exceeds its fatigue limit, and this amount of heat corresponds to the amount that exceeds its fatigue limit. Therefore, by detecting only the portion where the temperature has increased due to heat generation due to fatigue, it is possible to know the state and size of the fatigue distribution.

However, since metal has good thermal conductivity, the temperature increase in the heat-generating portion propagates rapidly, resulting in an increase in the temperature of the entire subject.

Therefore, the following method may be used to detect the increased temperature of the heated portion from the increased temperature of the entire subject.

Now, as shown in FIG. 5, a load pulse group is intermittently applied to the subject 1 using the load shaker 2. In this case, the repetitive load pulse is a sine wave pulse, and the load pulse group consisting of these pulses is set at a constant period S, for example, as shown in FIG. 6A.
It is assumed that the subject 1 is loaded at a cycle of about 1 second. Depending on the positive or negative direction of each load pulse, the specimen 1 is stretched or compressed, and as a result, the thermoelastic effect of tension and compression and the heat generation in the part that exceeds the fatigue limit cause the specimen 1 to be stretched or compressed. The temperature rise is shown in Figure 6B.
As shown in , it rises and falls approximately corresponding to the magnitude of the load pulse, and increases in an integrated manner according to the loading time of the load pulse group.

Next, as shown in Figure 6C, computer processing averages the rising temperature over one to several cycles immediately before the load of the load pulse group is stopped. The temperature average value during that cycle is determined, and this average value is set as the temperature under load _T1 . At the same time, as shown in FIG. 6D, the temperature _T2 at the time of no load immediately before the start of loading of the load pulse group of the next cycle is taken out. The temperature under load T ₁ and the temperature under no load T ₂ are determined for each load cycle of the load pulse group.

And these temperature under load T ₁ and temperature under no load
The difference from T ₂ △T = T ₁ - _{T 2} represents the amount of heat generated by the metal of the object 1 due to fatigue, so measure this by performing infrared scanning over the entire surface of the object 1. For example, it is possible to know the distribution and degree of metal fatigue.

(Problem to be Solved by the Invention) However, in the imaging method of metal fatigue status based on such a principle, the temperature average value over one to several cycles immediately before stopping the loading of the load pulse group, that is, temperature data. However, when a load exceeding the fatigue limit is applied to the test object using a metal fatigue tester, if the test object deforms due to elongation, bending, etc., or misaligns, the load Since positional deviation occurs in the scanning points of temperature data measurement during the loading period, the difference between the temperature under load T ₁ and the temperature under no load T ₂ on different scan points △T = T ₁ − _{T 2}
Therefore, there was a risk that accurate data could not be obtained.

In order to avoid this fear and obtain more accurate temperature data, if deformation or positional shift occurs due to load, it is recommended to shift the timing of detecting temperature data of the subject using an infrared detector. good.

The object of the present invention is to provide a test object that can be used in a metal fatigue testing machine to deform the test object due to elongation, bending, etc., or to shift its position when a load exceeding the fatigue limit is applied to the test object using a metal fatigue testing machine. The object of the present invention is to provide a method for more accurately imaging metal fatigue conditions.

(Means for Solving the Problems) In order to achieve this object, according to the present invention, a group of load pulses are intermittently applied to a metal object at a constant period, and the object is placed under an infrared detector. The temperature data immediately after stopping the load application and just before the start of the next load application to this test object is scanned using Determine the temperature under load and the temperature under no load, calculate the difference between the temperature under load and the temperature under no load to determine temperature information including information on the position exceeding the metal fatigue limit and the degree of fatigue, A feature is that an image is displayed based on this temperature information.

(Function) With this configuration, the temperature data remaining in the test object immediately after the stop of load application is inputted into the computer as the temperature under load, and the temperature data immediately before the start of load application is input into the computer as the temperature under no load. , it is possible to capture temperature data on the same scanning point without positional deviation, and therefore it is possible to more accurately image the state of metal fatigue.

(Embodiments) Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 3.

In Fig. 1, A indicates a repeated sinusoidal load pulse applied to the subject, B indicates the temperature change state of the subject, and C indicates a timing pulse for detecting the temperature when the subject is loaded. , D indicates a timing pulse for detecting the temperature of the subject when no load is applied, E is the position of metal fatigue obtained by calculating the difference between the temperature of the subject when the subject is loaded and the temperature when no load is applied, It shows temperature information including size information.

By the way, there is a positional shift in the test object during the last cycle of loading, but immediately after the load is stopped, there is no positional shift because no load is being applied, and the temperature has hardly dropped since the load has stopped. do not have.

Therefore, in this embodiment, we focused on this point and set the timing for taking temperature data during loading as shown in Fig. 1B.
As shown in Figure 2, the temperature data of the test object is shifted to the point immediately after the load stops and the load becomes zero, and the temperature data of the test object is imported into the computer at this timing, and the temperature at the time of loading is calculated from the imported temperature data. The processing may be performed by performing imaging using, for example, the apparatus shown in FIG. 2 or 3, as described below.

Therefore, first, with reference to FIGS. 1A to 1E and FIG. 2, we will explain a method for imaging the state of metal fatigue by performing infrared measurement by scanning each point of the object 1. .

FIG. 2 is a diagram showing the equipment system used to implement this method. 3 is a scanner, and as shown in FIG. , for example, for a duration of about 1 second and at intervals of about 1 second. For this point detection,
While these load pulse groups are being applied, it does not scan, but stays at one point, for example, the first point, and reads the temperature data of this first point, and when the next load pulse group is applied, the temperature data of the next point is read. Move to the second point, stop at this point, and read the temperature data of the second point. In this way, the infrared detector 4 is configured to read analog temperature data at each point while stopping scanning at each point. As in the case of Fig. 6A described above, this analog temperature data increases while fluctuating in response to each pulse while the load pulse group is applied, and decreases when the load pulse group is stopped. .

5 is an amplifier that amplifies this analog temperature data, and 6 is an A/D converter that converts the analog temperature data into digital temperature data and sends it to the computer 7 at the next stage.

Reference numeral 8 denotes a timing circuit which takes the timing of the load pulse of the load shaker 2 and also supplies timing pulses to the A/D converter 6 and computer 7, respectively, as shown in FIG. 1C and D. 1st
The timing pulse shown in Figure C determines the timing for importing the digital temperature data into the computer 7 immediately after the final pulse of the load pulse group is applied, that is, immediately after the vibration of the object 1 has stopped. take. Further, digital temperature data immediately before the start of loading of the next load pulse group is input into the computer 7 for each point using the timing pulse shown in FIG. 1D.

After each temperature data taken in this way is averaged for each point by computer processing, the temperature under load similar to that described above is calculated.
T ₁ and no-load temperature T ₂ are obtained, respectively, and then,
By calculating the difference between the temperature T ₁ under load and the temperature T ₂ under no load, temperature information corresponding to each point is obtained, for example, as shown in FIG. 1E. The position of this temperature information represents the portion exceeding the metal fatigue limit, and the magnitude of this information represents the degree of fatigue in terms of brightness. Therefore, the temperature information obtained in this way can be supplied to a display device 9 such as a CRT to display an image of the portion exceeding the metal fatigue limit and the extent thereof.

However, this point measurement method requires time to measure temperature data point by point for the entire image and convert it into an image.

Therefore, next, with reference to FIGS. 1A to 1E and FIG. 3, a description will be given of measurement by line or single screen scanning, which can shorten the measurement time. In FIG. 3, detailed description of the same components as those shown in FIG. 2 will be omitted.

In this case, the scanner 3 and the infrared detector 4 may be used to apply a group of repetitive load pulses as shown in FIG. , and read part of the analog temperature data showing temperature changes as shown in FIG. 1B into the computer 7. This scanning may be one line scanning, several lines, or one field scanning. Then, 256 to 512 points are taken in one line, one line is scanned at high speed many times during the loading time of the load pulse group, and the temperature data at these points are collected by timing pulses from the timing circuit 8 (see Fig. 1). C and D) to the line memory 10a of the computer 7, and the temperature data when the load is stopped is also stored in the line memory 10a in the same way.
Take it into b. In each one line memory 10a and 10b, the captured temperature data is averaged to obtain an average value in the same way as explained in the embodiment of FIG. 1, and these average values are used as the temperature under load.
T ₁ and no-load temperature T ₂ .

Next, the computer 7 calculates these loading temperatures T ₁
and calculation of the difference between temperature _T2 at no load (indicated by 11 in the figure)
to find the temperature information △T, and this temperature information △T
is stored in the one-screen memory 12. After the temperature information per screen is stored, the computer 7 sends a signal to the display device to display the temperature distribution as an image. In this case, the portion displayed in the obtained temperature distribution image represents the position where the metal fatigue limit is exceeded, and the brightness of the image represents the extent to which the metal fatigue limit is exceeded.

When performing single-screen scanning, except for the fact that the subject 1 needs to be scanned at a scanning speed comparable to that of television scanning, the other points are processed in the same way as in the case of line scanning described above. It is possible to visualize metal fatigue conditions.

(Effects of the Invention) As is clear from the above explanation, according to the method of the present invention, the temperature data on the compression side is read immediately after the load is stopped on the test object, so the temperature data on the compression side is read. The present invention has the advantage that more accurate temperature data can be read that is independent of deformation or positional displacement of the specimen, and therefore metal fatigue conditions can be imaged more accurately.

[Brief explanation of drawings]

1A to 1E are waveform diagrams for explaining the embodiments of this invention, FIG. 2 is a diagram showing an apparatus system for explaining this invention, and FIG. 3 is a diagram for explaining other embodiments of this invention. A diagram showing the apparatus system, FIG. 4 is an SN curve diagram for explaining the method of this invention, FIG. 5 is a diagram showing the subject part for explaining the principle of this invention, and FIGS. D is a signal waveform diagram for explaining the principle of the invention. 1... Subject, 2... Load shaker, 3... Scanner, 4... Infrared detector, 5... Amplifier, 6...
A/D converter, 7... Computer, 8... Timing circuit, 9... Display device, 10a... One line memory, 10b... Line memory, 11...
...Difference operation, 12...One screen memory.

Claims (1)

[Scope of Claims] 1 A group of repeated load pulses is intermittently applied to a metal object at a fixed period, and the object is scanned using an infrared detector, immediately after and after the load application to the object stops. The temperature data immediately before the start of load application is imported into the computer, and based on the imported temperature data, the temperature at the time of loading and the temperature at the time of no load are determined for each cycle of the load pulse group, and the temperature at the time of loading and the temperature at the time of no load are determined. The method is characterized in that temperature information including information on the position exceeding the metal fatigue limit and the degree of fatigue is obtained by calculating the difference from the temperature when no load is applied, and an image is displayed based on the temperature information. A method for imaging metal fatigue conditions. 2. The method for imaging metal fatigue conditions as set forth in claim 1, characterized in that the scanning by the infrared detector is performed by point scanning, line scanning, or single screen scanning. Imaging method.