JP2724805B2 - Method and apparatus for detecting cracks and dislocations by magnetism - 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 and an apparatus for detecting cracks and dislocations by magnetic measurement and enabling measurement and prediction of fatigue fracture.

[0002]

2. Description of the Related Art As shown in FIG. 5, a conventional crack measuring method is to attach a crack gauge 20, which is a kind of a strain gauge, on a position where a crack 21 is expected to occur in an object to be measured.
A crack is measured by measuring a change in resistance value due to a displacement caused by the crack 21. In this case, only large cracks can be detected, and it is difficult to detect fine cracks and dislocations. Also, it was difficult to calculate the direction of the crack and the crack propagation speed, and it was difficult to measure and predict the fatigue fracture. The results were also inaccurate. Furthermore, since the crack gauge 20 is stuck on the crack 21, there is a problem that the crack gauge is broken by the crack, cannot be reused, and costs increase.

[0003]

SUMMARY OF THE INVENTION The problem to be solved by the present invention is to solve these problems of the prior art, to detect fine cracks and dislocations and to measure and predict fatigue fracture. An object of the present invention is to provide a crack and dislocation detection method and device.

[0004]

The gist of the present invention to solve the above problems is as follows: 1) A magnetic sensor using a Hall element is provided two-dimensionally or three-dimensionally around a crack or dislocation measurement point of an object to be measured. The magnetic intensity of the same magnetic sensor is measured over time, and the position and intensity of magnetic generation are calculated from the magnetic intensity of each magnetic sensor and its change over time. Method for detecting cracks and dislocations by magnetism, characterized by using the moving speed and magnetic strength of cracks as indices of the size and traveling speed of cracks and dislocations 2) Two-dimensional Alternatively, a magnetic sensor using three-dimensionally arranged Hall elements and recording the magnetic strength of the magnetic sensor over time
And a position / velocity calculating means for calculating a position where the magnetism is generated and a moving speed thereof based on a change over time of the magnetism of each magnetic sensor of the recording unit, and the progress calculated by the position / speed calculating means. An apparatus for detecting cracks and dislocations is characterized in that the velocity and the magnetic strength are output as indices of the moving speed and size of the cracks and dislocations.

[0005]

According to the present invention, the magnetism of an object to be measured is measured by magnetic sensors arranged two-dimensionally or three-dimensionally. When cracks and dislocations occur, magnetism is generated at the cracks and dislocations. This magnetism is sensed by a magnetic sensor, and the strength of the sensed magnetism of the plurality of magnetic sensors is recorded with time in a recording unit, and the position and speed calculation unit stores the stored magnetic intensity of the recording unit and the position of the magnetic sensor. Then, the position and intensity of the magnetic generation are calculated from the above, and the moving speed of the position of the magnetic generation is calculated from the temporal change of the magnetic generation position. The moving speed of the magnetizing position calculated by the position / speed calculating unit is output as an index of the progress speed of cracks / dislocations. Predict repair and replacement time.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. The magnetic sensor of the crack / dislocation detection device of this embodiment uses a Hall element, and the storage means is a computer CP.
U and memory, and the position / velocity calculation means is CPU
Is operated using the program software. FIG. 1 is an explanatory diagram showing the arrangement of the magnetic sensors of the embodiment, FIG. 2 is a hardware configuration diagram showing a crack / dislocation detection device of the embodiment, and FIG. 3 shows a processing flow of the crack / dislocation detection device of the embodiment. FIG. 4 is an explanatory view showing a state of a crack. In the figure, reference numeral 1 denotes an object to be measured which is a test piece which can be pulled right and left
Is a crack generated in the measured object, 3 is a magnetic sensor using a Hall element, 4 is a sensor support for mounting a magnetic sensor, 5 is a differential amplifier and a level shifter, 6 is a sample hold and an A / D converter, 7 is an interface I / O,
Reference numeral 8 denotes a CPU that performs operations such as calculation, storage command, and display of a magnetic generation position, a magnetic intensity, and a traveling speed of the magnetic generation position.
CH2, CH3 Memory with time, 10 CRT display, 11 interface, 12 printer, 13 printed matter, 14 clock for generating date signal.

In this embodiment, three magnetic sensors 3 using a sensitive Hall element are arranged at a position slightly away from a position where a crack 2 of the DUT 1 is expected to be generated. If a crack 2 or a dislocation occurs in the DUT 1, magnetism is generated in the cracked portion, and the magnetism is sensed by three magnetic sensors 3 and the measured value of the magnetism is transmitted to a channel C.
H1, CH2, and CH3 signals are input to each differential amplifier and level shift 5, and the differential amplifier and level shift 5
The noise and the like are removed to make the data of significant magnetic strength, and the data is input to the sample-and-hold and A / D converter 6, and each magnetic measurement value is taken in at a required timing and converted into a digital value. I / O
The magnetic measurement values input to the CPU 8 via the CPU 7 and read in the processing flow as shown in FIG. 3 are processed.

First, the magnetic measurement value input to the CPU 8 is stored in the memory 9 in association with the date and time of the measurement (at the time of input) and the channel number of the magnetic sensor 3. Next, based on the position of each magnetic sensor 3 input and stored in advance, the magnetic measurement value stored in the memory of each magnetic sensor 3 and the characteristics of the magnetic sensor, the position of the magnetic generation and the magnetic The strength is calculated. This calculation is performed by a calculation method verified in advance according to the characteristics of the magnetic sensor 3. Next, the calculated position of the magnetic generation and the magnetic intensity thereof are stored in the temporary memory 9 together with the measured or input date / time data.

Thereafter, at the time of storage in the memory 9, or at a predetermined date and time or at predetermined time intervals, the position of the above-mentioned magnetism and the fluctuation of its magnetism are calculated, and The moving speed of the position is calculated, and the moving speed of the position at which the magnetism is generated is output as the progress (propagation) speed of the crack / dislocation, and the magnetic strength is output as an index of the size of the crack / dislocation. The position of the magnetism, the strength of the magnetism, the moving speed thereof, and the fluctuation of the magnetism are determined by the CRT display 10 and the printer 12.
Is output to In addition, the output data of the moving speed (progressing speed), the magnetic strength / fluctuation, and the material characteristics of the DUT 1
Predictions and estimations of the progress of fracture due to cracks and dislocations are made from the dimensions and load state, and output to the CRT display 10 and the printer 12.

[0010]

As described above, according to the present invention, the magnetic sensors are arranged two-dimensionally and three-dimensionally, the fluctuation of the magnetism is measured over time, the movement of the position where the magnetism is generated and the strength of the magnetism are measured. By calculating the crack and dislocation progression (propagation) speed and size, the state of minute cracks and dislocations can be measured, and prediction of fracture due to cracks and dislocations, replacement time of components, and life Can be predicted. In addition, since the magnetic sensor is used at a location away from the cracks and dislocations, the magnetic sensor can be reused without being destroyed, and can be measured at low cost.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an arrangement of a magnetic sensor according to an embodiment of the present invention.

FIG. 2 is a hardware configuration diagram showing a crack / dislocation detection apparatus according to an embodiment.

FIG. 3 is an explanatory diagram showing a processing flow of the crack / dislocation detection apparatus of the embodiment.

FIG. 4 is an explanatory diagram showing a state of a crack.

FIG. 5 is an explanatory view showing a conventional crack measuring method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 DUT 2 Crack 3 Magnetic sensor 4 Sensor support stand 5 Differential amplifier and level shift 6 Sample hold and A / D converter 7 Interface I / O 8 CPU 9 Memory 10 CRT display 11 Interface 12 Printer 13 Printed matter 14 Clock

Claims (2)

(57) [Claims] 1. A plurality of magnetic sensors using a Hall element are two-dimensionally or three-dimensionally arranged around a measurement point of a crack / dislocation of an object to be measured, and the magnetic strength of the magnetic sensor is measured over time. And the position and intensity of magnetism are calculated from the magnetic strength of each magnetic sensor and its change over time, and the movement speed and magnetism of the position of magnetism are calculated as the size of cracks and dislocations and the traveling speed. A method for detecting cracks and dislocations by magnetism, wherein the method is used as an index. 2. The method according to claim 1, wherein a plurality of two-dimensionally or three-dimensionally arranged Hall elements are used for measuring cracks and dislocations of the object to be measured.
Calculating a magnetic sensor, a recording unit for time stored in the recording unit of the magnetic strength of the magnetic sensor, the magnetic generation position from the magnetic time course of the magnetic sensor of the recording unit and the moving speed It consists of a position speed calculating means for position-speed
A crack / dislocation detection device, wherein the traveling speed and the magnetic strength calculated by the degree calculating means are output as indices of the moving speed and size of the crack / dislocation.