JP3306283B2 - Infrared measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of periodically applying a load to a subject, detecting and integrating a temperature change on the surface of the subject based on heat generation and heat absorption by an infrared camera, and obtaining a distribution of the temperature change. The present invention relates to an infrared measuring device configured to detect a stress distribution based on the information.

[0002]

2. Description of the Related Art Measuring the magnitude of a stress generated in each part of an object is a complete and accurate method for designing a machine or a structure by selecting the shape of each part, the dimensions of the material used, the material, and the like. It is crucial to enable economical design. Therefore, conventionally, a strain gauge is attached to a subject, and a strain generated in the subject is detected to measure a stress distribution.

[0003] However, there is a problem that it is troublesome to attach the strain gauge to the subject, and it takes a lot of time for the measurement. On the other hand, there has been proposed a stress distribution measuring method capable of measuring quickly and easily in a non-contact manner as compared with a conventional measuring method using a strain gauge or the like (for example, Japanese Patent Publication No. Sho 62-1204 and Japanese Patent Publication No. Sho No. Sho 62-1204). No. 62-1205,
JP-B-63-7333, JP-A-6-26947, JP-A-7-110272 and JP-A-7-190909. This stress distribution measurement method compresses
It focuses on the fact that when a tensile load is repeatedly applied, a heat-generating / endothermic effect appears. In other words, if this heat generation and heat absorption are repeated in a relatively short cycle, the surface temperature of the stress concentration portion changes in an adiabatic state where heat diffusion to the surroundings or heat inflow from the surroundings is cut off. Since there is a proportional relationship between the stress distribution and the stress change, the stress distribution is measured using this.

FIG. 3 is a time chart for explaining an example of a conventional infrared stress imaging system. By utilizing the above-described principle, an image of an infrared detector is periodically applied to a subject to which a load is applied. FIG. 6 is a timing chart for obtaining a stress distribution based on temperature data obtained by scanning a spot horizontally and vertically. To the subject
Camera HB overheating, endothermic effect and by the vibration excitation signal f _in applying the cyclic loading of the compression appeared subject surface
Signal: A (camera scan infrared data acquisition signal signals of one scan line of the infrared images), a maximum, although not achieved synchronization because there is a gap when a minimum, where the excitation signal f _in, The description will be made on the assumption that the phases of the temperature signals generated by the vibration are in phase.

[0005] In the stress distribution measurement, as shown in FIG. 3, stress to the excitation signal f _in is generated a positive trigger near the phase of maximum, the negative trigger in the vicinity of the phase which stress is minimized appear. In response to the positive trigger, a temperature signal is captured as positive data at the position of the first camera HB signal, and a temperature signal is captured as negative data at the position of the first camera HB signal in response to the minus trigger. When detecting a temperature signal, in order to detect a minute temperature difference such as 1/1000 ° C., S / N is improved by using a method such as line integration or frame integration. The example shown in FIG. 3 shows an example of line integration in which three data are fetched and added in each half cycle on the plus side and the minus side. Then, by taking the difference between the plus data and minus data thus obtained for the entire screen, temperature change distribution data is obtained and can be used as stress distribution data.

[0006]

In the stress measurement as described above, the stress distribution can be measured by repeatedly applying a tensile / compression load to the test object and detecting a temperature change on the surface. Can often crack. In such a case, the stress at the time of the crack,
There is a need to know the change in the stress state during repeated loading. However, in the above-described conventional stress measurement device, only continuous addition of the measurement data can be performed. Therefore, even if a crack occurs during the measurement, only the stress state until the end of the measurement can be known. If you want to know the state of stress when a crack occurs, you must detect the occurrence of the crack by some means, temporarily stop the device (measurement) at that moment, and drop the measurement data in a file. You must set the file name and start taking measurement data. Therefore, there is a problem that only discontinuous measurement data can be taken into the apparatus with respect to the progress of the crack.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to enable continuous measurement data to be taken into an apparatus even when a crack progresses. For this purpose, the present invention applies a load to the subject periodically, detects and integrates the temperature change of the subject surface due to heat generation and heat absorption by an infrared camera, and detects the stress distribution based on the distribution of the temperature change. In the infrared measuring device, the number of intermittent integration times or time and the total number of integration times or time are set, and the set integration data of the number of intermittent integration times or time and the total number of integration times or time are accumulated in a file. The present invention is characterized in that it is possible to detect a stress distribution based on integrated data at each intermittent integration frequency or time and overall integration frequency or time.

[0008]

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a view for explaining an embodiment of an infrared measuring device according to the present invention. The infrared measuring device according to the present invention applies a compressive / tensile load repeatedly to the subject periodically, generates heat, detects and integrates a temperature change on the surface of the subject based on an endothermic effect by an infrared camera, and integrates the temperature change. When detecting the stress distribution based on the distribution, not only the total number of integrations (hours) but also the number of intermittent integrations (hours) while applying the load repeatedly as the timing of taking in the measurement data can be set for each number of intermittent integrations The measurement data is dropped to a file so that the stress state in the process of crack generation can be known.

In the infrared measuring apparatus according to the present invention, when performing infrared stress measurement in the continuous capturing mode, first, as shown in FIG. 1, a file name _mi is set as i = 1 as a measurement condition (step S11). Further, the total number of additions (integration) A and the number of intermittent additions (integration) B are set as the timing of taking in the measurement data (steps S12 and S13). Thereafter, the compression / tensile load is repeatedly applied to the subject periodically to start the stress measurement (step S14). When the stress measurement starts, the number of intermittent additions and the total number of additions are counted and the measurement data is added (step S15), and it is checked whether or not the total number of additions has reached the previously set A number (step S16). A
If not, it is checked whether the number of intermittent additions has reached the previously set B times (step S17).
Or intermittent addition count total number of additions reaches A times repeatedly executes addition processing of the measured data of step S15 until the B times reaches the B times, dropping the measurement data obtained by adding process to the file m _i (step S18). And
Update i to i + 1 (step S19), clear the number of intermittent additions, return to step S15, start counting the number of intermittent additions again, and repeat the same processing (step S20). When the entire number of additions reaches A times, dropping the measurement data obtained by adding process to the file m _i (step S
18), end the process.

FIG. 2 is a block diagram showing an example of the system configuration of the infrared stress measuring device according to the present invention. In FIG. 2, a vibrator 1 vibrates the subject S by repeatedly applying a compression / tensile load, and an infrared camera 2 captures an image of the subject S that is repeatedly loaded by the vibrator 1. It is. The frequency detection circuit 5 outputs the vibration signal f
_in a circuit for detecting the input to the frequency of the excitation signal f _in the positive trigger generating circuit 3, a positive trigger generated in phase position near that maximizes the stress to input excitation signal f _in negative trigger generating circuit 4 is a circuit for generating a negative trigger at smallest phase position near the stress to input excitation signal f _in. The plus data memory 6 and minus data memory 7 repeatedly input a camera HB signal for a horizontal scanning line at a predetermined vertical position from the infrared camera 2, and the plus data memory 6 corresponds to a plus trigger generated by the plus trigger generation circuit 3. Then, a predetermined number of plus temperature data is taken in and added, and the minus data memory 7 takes in and adds a given number of minus temperature data corresponding to the minus trigger generated by the minus trigger generating circuit 4. The arithmetic and control unit 9 inputs the data relating to horizontal scan frequency from the infrared camera 2, and inputs the frequency detection signal of the vibration signal f _in the frequency detecting circuit 5, taken in the positive data memory 6 and the minus data memory 7 The difference between the obtained plus temperature data and minus temperature data is obtained, the difference data is corrected, and the corrected difference data is integrated. For example, each time the number of times of integration by the counter reaches a predetermined number of intermittent integrations B set in a register in advance, the measurement data integrated at that time is stored in the measurement data file 8 and the predetermined total number of integrations A is stored. When it reaches, the stress measurement ends. The display device 10 displays a stress image based on data accumulated in the measurement data file 8, for example.

The operation will be described. File name for storing stress measurement data from a setting device such as a keyboard (not shown) in the arithmetic and control unit 9, the total number of additions A and the number of intermittent additions B
Is set in a register, for example, and the start of stress measurement is instructed, and the subject S is vibrated by repeatedly applying a compressive / tensile load by the vibrator 1. Excitation signal f _in the frequency detecting circuit 5 of the measurement start vibrator 1, plus the trigger generating circuit 3, since the input to the negative trigger generating circuit 4, the detection frequency of the frequency detection circuit 5 excitation signal f _in Then, a plus trigger is generated in the vicinity of the phase position where the stress becomes maximum in the plus trigger generation circuit 3, and a minus trigger is generated in the vicinity of the phase position where the stress becomes minimum in the minus trigger generation circuit 4. Then, the data by the plus trigger is input to the plus data memory 6, and the data by the minus trigger is input to the minus data memory 7. On the other hand, a camera HB signal is repeatedly input from the infrared camera 2 to the plus data memory 6 and the minus data memory 7 for a horizontal scanning line at a predetermined vertical position. With these inputs, the plus data memory 6 stores a predetermined number of cameras HB as plus temperature data corresponding to the plus trigger.
The signals are fetched, and the minus data memory 7 fetches a predetermined number of camera HB signals as minus temperature data corresponding to the minus trigger, and adds them.

The arithmetic and control unit 9 obtains difference data between the plus temperature data and minus temperature data taken into the plus data memory 6 and minus data memory 7, and further obtains information on the vibration frequency and the camera horizontal scan frequency. And the difference data after the correction is integrated. Conventionally, when measurement data of a predetermined integration count (total integration count) A is obtained, the measurement data is dropped into the measurement data file 8 and the measurement is terminated.
In the present invention, by performing the processing described with reference to FIG. 1, the measurement data integrated for each preset intermittent integration count B is dropped to the measurement data file 8. Therefore, after the measurement is completed, the stress image data can be displayed on the display device 10 based on the measurement data dropped in the measurement data file 8 for each intermittent integration count B.

Note that the present invention is not limited to the above-described embodiment, and various modifications are possible. For example, in the above embodiment, the stress image was output to the display device.
It may be configured to print out to a printer or the like. In addition, only one intermittent integration count is set, and the measurement data integrated for each count is taken in. However, immediately after the measurement is started, the count is increased, and the count in the middle is reduced. The number of times may not be fixed and may be changed stepwise or continuously, or may be applied only to a part of the measurement period. Although the number of integrations was set to take in the intermediate measurement data, it may be set by the elapsed time from the start of the measurement, or a trigger signal from the outside, for example, a trigger obtained from a means for detecting crack generation and its progression, etc. A signal may be used. Even when a trigger signal is used, the number of files can be limited to a certain number and updated with the latest measurement data, and only the files before and after that can be saved by the trigger signal. Data may be dropped to a file. As described above, from the configuration in which the change in the surface temperature at an arbitrary point is detected and captured, the speed and magnitude of the change in the surface temperature and the stress can be detected and used for controlling the change in the temperature and the stress. .

[0015]

As is clear from the above description, according to the present invention, not only the total number of times of integration but also the number of intermittent integration times is set as the timing of taking in a plurality of measurement data, and the measurement data integrated at each number of times is set. Into a file, it is possible to detect not only the final measurement data but also a continuous stress state and its change at an arbitrary point in the middle. Therefore, when a crack occurs, a change in the stress state before and after the crack can be detected without resetting the stress measurement.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining an embodiment of an infrared measuring device according to the present invention.

FIG. 2 is a block diagram illustrating a system configuration example of an infrared stress measurement device according to the present invention.

FIG. 3 is a time chart for explaining an example of a conventional infrared stress imaging system.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Exciter, 2 ... Infrared camera, 3 ... Positive trigger generation circuit, 4 ... Negative trigger generation circuit, 5 ... Frequency detection circuit, 6 ... Positive data memory, 7 ... Negative data memory, 8 ... Measurement data file, 9 ... arithmetic and control unit, 10
… Display device

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-66640 (JP, A) JP-A-59-4098 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01L 1/00 G01J 1/02

Claims (1)

(57) [Claims] 1. A method in which a load is periodically applied to a subject to generate heat,
Infrared measuring device that detects and integrates the temperature change of the surface of the subject based on the endothermic action by the infrared camera and detects the stress distribution based on the distribution of the temperature change, the number of intermittent integration or the time and the total number of integration or By setting the time, the set intermittent integration frequency or time and the integration data of the total integration frequency or time are accumulated in a file, and the stress based on the integration data at each intermittent integration frequency or time and the total integration frequency or time is stored. An infrared measuring device characterized in that the distribution can be detected.