JPH11211644A - Two-dimensional crack gauge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically and continuously detect the position of a crack tip two-dimensionally by providing an insulator for maintaining the insulation between planar resistors between first and second planar resistors. SOLUTION: An insulator base 2 comprising an insulation material, and a first planar resistor 14a where a plurality of first resistance lines 13a-13e are arranged in parallel between a pair of first gauge lead line connection part being arranged while they oppose each other on the insulator base 2 are constituted. Also, a plurality of second resistance lines 13f-13j are arranged in parallel in a direction that orthogonally crosses the direction of the first resistance lines 13a-13e of the first planar resistor 14a between a pair of second gauge lead line connection parts being arranged while they oppose each other, thus constituting a second planar resistor 14b. An insulator 15 for maintaining insulation is provided between planar resistors is provided between the first and second planar resistors 14a and 14b. Therefore, when a two-dimensional crack gauge 10 is stuck to an area near a point where a crack is generated, only the resistance of a planar resistor where the resistance line is cut changes out of two planar resistors being provided in directions that orthogonally cross each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crack gauge for detecting crack growth, and more particularly to a two-dimensional crack gauge capable of automatically and continuously detecting crack growth two-dimensionally.

[0002]

2. Description of the Related Art Conventionally, as a method of detecting crack growth in a fatigue test, detection using a crack gauge or visual observation using a magnifying glass or the like has been generally used.
As a crack gauge, a gauge using a readily breakable foil or the like in a grid portion of a strain gauge has been used.

FIG. 5 is a plan view showing a configuration example of a conventional general crack gauge of this kind. As shown in FIG. 5, a crack gauge 1 includes a plurality of resistance wires 4 between a pair of gauge lead wire connection portions (hereinafter, referred to as tabs) 3 on an insulator base 2 made of an insulating material such as a resin. It is composed of resistors arranged in parallel with each other.

When such a crack gauge 1 is used, a lead wire (not shown) is connected to the tab 3 of the crack gauge 1 by a method such as spot welding or the like, and is attached on a path where crack growth is predicted. By doing so, the resistance wire 4 is sequentially cut along with the growth of the crack, and the resistance value between the tabs 3 changes, so that the growth of the crack can be electrically detected.

However, in such a crack gauge 1, when the growth direction of a crack cannot be specified, for example, in a spot welded portion, not only must a plurality of gauges be attached, but also cracks generated between the gauges. Cannot be detected.

Therefore, recently, as a solution to such a problem, a multi-round crack gauge has been proposed. FIG. 6 is a plan view showing a configuration example of this type of conventional multiple round crack gauge.

As shown in FIG. 6, a multiple round crack gauge 5 is provided with a double or more concentric resistance wire 7 on a circular insulator base 6 made of an insulating material such as resin. A lead wire 8 is connected to the end of the wire 7.

By attaching such a central portion of the multiple round crack gauge 5 so as to correspond to a position where a crack is expected to occur, the resistance wire 7 substantially surrounds the periphery of the crack occurrence portion. Therefore, cracks in any direction can be detected simply by attaching one gauge.

[0009]

However, when the structure becomes complicated, the stress state changes with the growth of the crack, so that the crack often grows while changing its direction. In such a case, the conventional multi-round crack gauge described above can detect only a linear distance from the crack occurrence point by cutting the concentric resistance wire. The length and the two-dimensional position of the crack tip cannot be specified.

In the above-described visual observation, since the measurement must be continuously performed at regular time intervals, not only a great deal of labor is required but also a reading error is large. SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a two-dimensional crack gauge capable of automatically and continuously detecting the position of a crack tip two-dimensionally and continuously. Is to do.

[0011]

According to a first aspect of the present invention, there is provided a crack gauge for detecting a crack, comprising: an insulator base made of an insulating material; A first planar resistor having a plurality of first resistance wires disposed in parallel between a pair of first gauge lead wire connection portions disposed on the base and facing each other; A plurality of second resistance wires are arranged in parallel in a direction orthogonal to the direction of the first resistance wires of the first planar resistor between the pair of second gauge lead wire connection portions arranged in the same manner. A second planar resistor provided, and an insulator disposed between the first planar resistor and the second planar resistor to maintain insulation between the respective planar resistors. And

Therefore, in the two-dimensional crack gauge according to the first aspect of the present invention, when the two-dimensional crack gauge is attached near the crack generation point, the resistance lines of the planar resistor are sequentially cut as the crack grows, and are orthogonal to each other. Of the two sheet resistors arranged in the same direction, only the resistance of the sheet resistor whose resistance wire has been cut changes.

Thus, the position of the tip of the crack can be automatically and continuously detected two-dimensionally. A two-dimensional crack gauge according to a second aspect of the present invention is the two-dimensional crack gauge according to the first aspect of the present invention, wherein the first resistance wire of the first planar resistor is radially arranged, Or the first resistance wire of the first planar resistor is arranged in an arc, and the second resistance wire of the second planar resistor is arranged in an arc. The second resistance wire is arranged radially.

Therefore, in the two-dimensional crack gauge according to the second aspect of the present invention, the resistance wires of the two sheet resistors are arranged radially and arcuately. By combining them, it is possible to automatically and continuously detect the growth state of the cracks two-dimensionally in the same manner as described above even when the crack generation point is an arc, such as a spot weld or a corner turning weld. it can.

[0015]

Embodiments of the present invention will be described below in detail with reference to the drawings. (First Embodiment) FIG. 1 is a plan view showing a configuration example of a two-dimensional crack gauge according to the present embodiment, and FIG. 2 is a side view showing a configuration example of the two-dimensional crack gauge.

As shown in FIGS. 1 and 2, a two-dimensional crack gauge 10 according to the present embodiment has a rectangular insulator base 11 made of an insulating material such as a resin film, and a gap formed on the insulator base 11. A plurality of (five in this example) made of a resistive wire or a metal foil is provided between a pair of first gauge lead wire connecting portions (hereinafter, referred to as tabs) 12a and 12c arranged to face each other with a gap. Of the first resistance lines 13a, 13
b, 13c, 13d, and 13e are arranged in parallel so that each tab 1
A first planar resistor 14a integrally connected to the first planar resistor 2a, 12c and a first planar resistor 14a between a pair of second tabs 12b, 12d disposed to face each other with a space therebetween. Resistor 1
4a, the first resistance lines 13a, 13b, 13c, 13d,
13e, a plurality (five in this example) of second resistance wires 13 made of a resistance element wire or a metal foil are arranged in a direction orthogonal to the direction of 13e.
f, 13g, 13h, 13i, and 13j are arranged in parallel, and are integrally connected to the tabs 12b and 12d; a second planar resistor 14b; a first planar resistor 14a; And each of the planar resistors 14b is disposed between the planar resistors 14b.
a and an insulator 15 made of an insulating material such as a resin film for maintaining insulation between the a and b.

A lead 16 is connected to each of the tabs 12a, 12b, 12c, 12d of the two-dimensional crack gauge 10. That is, the two lead wires 16a and 16e are connected to the outermost sides of the tab 12a at the portion where the crack first enters. Furthermore, only one lead wire 16b, 16c, 16d is connected to each of the remaining tabs 12b, 12c, 12d.

Next, the operation of the two-dimensional crack gauge 10 according to the present embodiment configured as described above will be described.
When using the two-dimensional crack gauge 10 of the present embodiment, if the two-dimensional crack gauge 10 is attached near the crack occurrence point, the resistance wires 13 of the planar resistor 14 are sequentially cut as the crack grows, and Of the two sheet resistors 14 arranged in the direction orthogonal to each other, only the resistance of the sheet resistor 14 from which the resistance wire 13 has been cut changes.

Thus, the position of the crack tip can be automatically and continuously detected two-dimensionally. This point will be described more specifically with reference to a partially enlarged plan view shown in FIG.

The two-dimensional crack gauge 10 is inserted into the two lead wires 16a, 16a at positions where cracks are expected to occur.
e is attached to the test piece so that the tab 12a to which e is connected comes, and the resistance between the tabs is determined by the lead wires 16a, 16c and 16c.
e and 16c, and 16d and 16b, respectively.

As the crack 17 grows, the tab 12a, the second resistance line 13f, the first resistance line 13c,
The second resistance line 13g, the second resistance line 13h, and the first resistance line 13d are cut in this order.

At this time, since the first planar resistor 14a and the second planar resistor 14b are insulated from each other, the tabs,
The change in the resistance value due to the disconnection of the resistance wire does not affect other planar resistors.

That is, first, the cutting of the tab 12a changes the resistance value between the lead wires 16a and 16c and between the lead wires 16e and 16c, so that the X coordinate of the crack 17 is specified, and the range of the Y coordinate is limited.

Next, when the second resistance wire 13f is cut, the resistance value between the lead wires 16d and 16b changes, the X coordinate of the crack 17 is specified, and the range of the Y coordinate is limited. Next, when the first resistance wire 13c is cut, the resistance value between the lead wires 16e and 16c changes, and the crack 1
7, the Y coordinate is specified, and the range of the X coordinate is limited.

By repeating the above, the detected positions of the tips of the cracks 17 are smoothly connected to each other,
The growth state of the dimensional crack 17 can be specified. When the crack 17 grows toward the first resistance wire 13b, the resistance value between the lead wires 16a and 16c changes, so that the position of the tip of the crack 17 can be detected in the same manner as described above. it can.

As described above, the two-dimensional crack gauge 10 according to the present embodiment can electrically detect the two-dimensional growth state of the crack 17. Thereby, the growth state of the crack 17 can be automatically and continuously detected without using the above-described conventional visual operation, so that the efficiency of the fatigue test is greatly improved, and there is no reading error and accurate reading. Detection can be performed.

(Second Embodiment) FIG. 4 is a partially enlarged plan view showing a configuration example of a two-dimensional crack gauge according to the present embodiment, and the same elements as those in FIGS. 1 to 3 are denoted by the same reference numerals. The description thereof is omitted, and only different portions will be described here.

That is, the two-dimensional crack gauge 10 according to the present embodiment is different from the two-dimensional crack gauge 10 according to the first embodiment in that the first resistance wires 13a, 13b, and 13c of the first planar resistor 14a are provided. , 13d, 13e are arranged radially, and the second resistance wires 13f, 13g, 13h, 13i, 13j of the second planar resistor 14b are arranged in an arc shape.

Therefore, in the two-dimensional crack gauge 10 according to the present embodiment configured as described above, the resistance wires 13a to 13j of the two sheet resistors 14a and 14b are arranged radially. By combining the above and the ones arranged in an arc shape, even when the point of occurrence of the crack 17 is in an arc shape, for example, in a spot welded portion or a corner-turned welded portion, in the same manner as described above, the crack Growth status 2
Continuous detection can be performed automatically and dimensionally.

(Other Embodiments) (a) The two-dimensional crack gauge 1 of the first embodiment.
0, the first resistance line 13 of the first planar resistor 14a
a, 13b, 13c, 13d, and 13e are arranged in an arc shape, and the second resistance wire 13 of the second planar resistor 14b is provided.
Even in a configuration in which f, 13g, 13h, 13i, and 13j are radially arranged, the crack growth state can be automatically and continuously detected two-dimensionally in the same manner as described above.

(B) In each of the above embodiments, the case where the number of resistance wires of the first planar resistor 14a and the second planar resistor 14b is five has been described. However, the present invention is not limited to this. First, the first planar resistor 14a, the second planar resistor 1
Needless to say, 4b may be constituted by a plurality of resistance wires other than five.

(C) In each of the above embodiments, the case where a resin film is used as the insulating material has been described. However, the present invention is not limited to this, and it goes without saying that other insulating materials may be used.

[0033]

As described above, according to the present invention, between an insulator base made of an insulating material and a pair of first gauge lead wire connecting portions disposed on the insulator base so as to face each other. , A plurality of first resistance wires being arranged in parallel.
And a pair of second resistors disposed opposite to each other.
Between the gauge lead wire connecting portions of the first planar resistor
A second planar resistor in which a plurality of second resistive wires are arranged in parallel in a direction orthogonal to the direction of the resistive wire, and a first planar resistor and a second planar resistor And an insulator that is provided between the sheet resistors and maintains insulation between the planar resistors, so that the position of the crack tip can be automatically and continuously detected two-dimensionally. A two-dimensional crack gauge can be provided.

[Brief description of the drawings]

FIG. 1 is a plan view showing a first embodiment of a two-dimensional crack gauge according to the present invention.

FIG. 2 is a side view showing the first embodiment of the two-dimensional crack gauge according to the present invention.

FIG. 3 is a partially enlarged plan view for explaining the operation of the two-dimensional crack gauge according to the first embodiment.

FIG. 4 is a partially enlarged plan view showing a two-dimensional crack gauge according to a second embodiment of the present invention.

FIG. 5 is a plan view showing a configuration example of a conventional general crack gauge.

FIG. 6 is a plan view showing a configuration example of a conventional multiple round crack gauge.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... crack gauge, 2 ... insulator base, 3 ... tab, 4 ... resistance wire, 5 ... multiple round crack gauge, 6 ... insulator base, 7 ... resistance wire, 8 ... lead wire, 10 ... two-dimensional crack gauge Reference numeral 11: Insulator base, 12a, 12c: First tab, 13a, 13b, 13c, 13d, 13e: First resistance wire, 14a: First planar resistor, 12b, 12d: Second tab 13f, 13g, 13h, 13i, 13j: second resistance wire, 14b: second planar resistor, 15: insulator, 16a, 16b, 16c, 16d, 16e: lead wire, 17: crack.

Claims (2)

[Claims] 1. A crack gauge for detecting cracks, comprising: an insulator base made of an insulating material; and a pair of first gauge lead wire connecting portions disposed on the insulator base so as to face each other. A first sheet-like resistor in which a plurality of first resistance wires are arranged in parallel, and a first surface between a pair of second gauge lead wire connection portions arranged to face each other. A second planar resistor in which a plurality of second resistive wires are arranged in parallel in a direction orthogonal to the direction of the first resistive wires of the planar resistive element; An insulator disposed between the second planar resistor and an insulator for maintaining insulation between the planar resistors, and a two-dimensional crack gauge. 2. The two-dimensional crack gauge according to claim 1, wherein the first resistance wire of the first planar resistor is radially arranged, and the first resistance wire of the second planar resistor is radially arranged. 2 is arranged in an arc shape, or the first resistance line of the first sheet resistor is arranged in an arc shape, and the second resistance of the second sheet resistor is A two-dimensional crack gauge, wherein the wires are arranged radially.