JP3430006B2 - Fatigue detector - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention detects the fatigue state of an elasto-plastic member that deforms in response to the deformation of an object to be detected,
About the fatigue detector for estimating a fatigue state of the object.

[0002]

2. Description of the Related Art Conventionally, as a known technique of this type of a fatigue detector for detecting a fatigue state of a structure, there are those disclosed in, for example, JP-A-6-74875 and JP-A-4-50634. Japanese Unexamined Patent Publication No. 6-74875 discloses a fatigue detector having a structure in which a stress detecting portion is provided between a pair of fixing portions provided at both ends via a variable cross section. By providing this fatigue detector in the vicinity of a stress concentration position such as a welded portion of a structure, the stress generated at that position is transmitted to the stress detection unit made of an elasto-plastic member. Then, the fatigue state of the structure is estimated based on the fatigue state of the stress detection unit. Japanese Patent Laid-Open No. 4-50634 discloses a fatigue detector having a structure in which a pair of notches facing each other is formed in a connecting portion that connects between a pair of fixing portions provided at both ends. This fatigue detector is provided in the vicinity of the stress concentration occurrence position in the same manner as described above, and the stress generated at that position is transmitted to the connecting portion made of an elasto-plastic member. At this time,
The fatigue state of the structure is estimated by measuring the resistance of the crack gauge attached between the pair of notches of the fatigue detector with a tester every predetermined time, and the transition of the resistance value.

[0003]

However, the above-mentioned conventional techniques have the following problems. JP-A-6-748
The fatigue detector disclosed in Japanese Patent Publication No. 75 is designed to be provided near the stress concentration generation position. Therefore, both the position where the stress concentration occurs and the magnitude of the maximum stress generated at that time are required for the installation. Must be predicted in advance by analysis (for example, FEM analysis). Then, the fatigue detector is designed so that a predetermined fatigue state (for example, a fractured state) is generated in the stress detection unit when a predetermined repeated stress is generated at the stress concentration occurrence position. Usually, the fatigue characteristics of a material under the same load and load condition are represented by a single fatigue curve in which the vertical axis represents stress and the horizontal axis represents the number of repeated cycles, and the same stress with a certain value on the vertical axis repeatedly occurred. Sometimes the number of repetitions until breakage is shown on the horizontal axis. Even if different stresses occur during this repetition, a known conversion method (for example, Miner's rule) that corrects the number of repetitions small when a large amount of stress occurs and modifies the number of repetitions when a small amount of stress occurs By using this, it is possible to obtain the number of repetitions until fracture based on this one fatigue curve. Therefore, when designing the fatigue detector, the fatigue curve of the stress detector of the fatigue detector is designed to be lower than the fatigue curve of the member to be detected. As a result, the number of repeated fractures for the same deformation amount is always smaller in the stress detection part of the fatigue detector than in the detection target member, so the detection target member will not break at least until the stress detection part breaks. . Therefore, whether or not the stress detecting portion is broken can be used as an index of the remaining life of the detection target member, and the remaining life can be estimated. By the way, when the above-described analysis is performed, the magnitude of the maximum stress obtained by the analysis almost exactly matches the magnitude of the maximum stress actually generated.
However, on the other hand, regarding whether or not the maximum stress actually occurs at the position where the maximum stress occurs in the stress concentration obtained by the analysis, the error in the manufacturing stage of the member shape (for example, what is analyzed as a perfect circle is actually Actually, due to factors such as non-circularity) and structural non-uniformity of the material (for example, when non-uniformity occurs in the base metal itself due to welding),
Fatigue fracture often occurs at a position slightly deviated from the position obtained by analysis. In such a case, in the above-mentioned known technique, the position where the fatigue detector is provided is different from the actual maximum stress generation position, so that the detection accuracy is significantly reduced. That is, for example, at the position where maximum stress is actually generated due to stress concentration, even though fatigue is progressing considerably due to large stress, the stress generated due to the installation position of the fatigue detector deviating from this position. Becomes smaller and fatigue is detected to be in a state where it has not progressed so much yet. In order to prevent this, it is necessary to provide fatigue detectors at all positions where stress concentration may occur to some extent, which is not realistic. Further, providing another member in the vicinity of the stress concentration generating position itself causes another stress concentration or a defect, which impairs the fatigue characteristics of the detection target, which is not preferable.

The fatigue detector disclosed in Japanese Patent Laid-Open No. 4-50634 has the same problem as above because it is provided near the stress concentration position.

An object of the present invention is to provide a fatigue detector which can improve the detection accuracy without damaging the fatigue characteristics of the object to be detected.

[0006]

(1) In order to achieve the above object, the present invention provides a fatigue detector for detecting fatigue of one member or a combination of a plurality of members. In the first member and the second member, which exist so as to sandwich the fatigue occurrence site, at a position other than the fatigue occurrence site where fatigue to be detected is predicted to occur, The connecting means and the second connecting means are respectively connected, and between the first connecting means and the second connecting means,
One of the first connecting means and the second connecting means
It is inserted into the provided insertion part with a predetermined gap and fixed to the other.
And a substantially plate as a fatigue evaluation means that is elastically plastically deformed according to the relative displacement between the first part and the second part.
Connect with a strip member . When detecting fatigue due to stress concentration in one member or a combination of multiple members, first analyze in advance both the position where the stress concentration occurs and the magnitude of the maximum stress that occurs at that time. Predict by experiment. At this time, the magnitude of the maximum stress obtained by analysis, experiment, etc. almost exactly matches the magnitude of the maximum stress actually generated. However, on the other hand, regarding whether the maximum stress actually occurs at the position where the maximum stress occurs among the stress concentrations obtained by analysis and experiment, the error in the manufacturing stage of the member shape and the structural non-uniformity of the material etc. Due to the above factor, in many cases, fatigue fracture often occurs at a position slightly deviated from the position obtained by analysis, experiment, or the like. Therefore, in the present invention, stress transmission to the substantially plate-shaped member that undergoes elastic-plastic deformation is performed from a position other than the fatigue occurrence site where fatigue is predicted to occur due to stress concentration. That is, when one member or a combination of a plurality of members is momentarily deformed due to vibration or the like, the deformation is caused by a first portion which is apart from the fatigue occurrence portion and which exists so as to sandwich the fatigue occurrence portion, and The second portion is transmitted to the first connecting means and the second connecting means connected to them in the form of being replaced with the relative displacement of the second portion, and further, as a fatigue evaluation means, via the first and second connecting means. Plate-shaped part
Transfer to wood . As a result, the substantially plate-shaped member is elastically plastically deformed according to the stress due to the relative displacement transmitted at this time.
At this time, for example, when designing a substantially plate-shaped member , the number of repetitions until one member or a combined body of a plurality of members undergoes fatigue fracture and breaks due to elastic-plastic deformation, and the substantially plate-shaped member corresponds to the deformation. The latter is smaller in the number of repetitions until fatigue fracture due to deformation and fracture.
As a result, the substantially plate-shaped member is always fatigued and broken before the one member or the combined body of the plurality of members is broken. Therefore, at least until the substantially plate-shaped member is broken, the one member or the plurality of members is broken. The bonded body of 1 does not break. Therefore, whether or not the substantially plate-shaped member is broken can be used as an index of the remaining life of one member or a combination of a plurality of members, and the remaining life can be estimated. As described above, by performing stress transmission to the elasto-plastically deformable plate-shaped member from a position other than the fatigue occurrence site, maximum stress is generated at a position slightly deviated from the maximum stress occurrence position obtained by analysis, experiment, etc. Even if fatigue progresses, the fatigue can be accurately detected regardless of this. Further, at this time, unlike the conventional structure in which another member is provided in the vicinity of the stress concentration generation position, the fatigue characteristics of one member or a combination of a plurality of members, which is the object to be detected, are not impaired.

(2) Further, in order to achieve the above object, the present invention is provided in a fixing structure in which a first portion of one member is connected and fixed to a second portion of another member. In a fatigue detector for detecting a fatigue state of a body, a first connecting means locked to a third portion of the one member other than the first portion, and a second connecting member of the other members. and second connecting means which is engaged with the fourth part of the other portion, connects between these first connecting means and second connecting means, before
Provided on one of the first connecting means and the second connecting means.
Inserted into the beam insertion part with a predetermined gap and fixed to the other
And a substantially plate-shaped member that elastically-plastically deforms in accordance with the relative displacement between the third portion and the fourth portion.

(3) In order to achieve the above object, the present invention is provided in a fixed structure in which a first portion of one pipe is connected and fixed to another pipe or a second portion of a structure, In the fatigue detector that detects the fatigue state of this fixed structure,
First connecting means locked to a third portion of the one pipe other than the first portion, and a fourth portion other than the second portion of the other pipe or structure. The locked second connecting means and the first connecting means and the second connecting means are connected to each other, and the first connecting means and the second connecting means are connected.
Insert it into the insertion part provided on one of the
The third portion and the fourth portion , which are inserted and fixed to the other .
Plate shape that undergoes elasto-plastic deformation according to the relative displacement between the
And a member .

[0009]

(4) In order to achieve the above object,
The invention, in a fatigue detector for detecting fatigue of one member, exists so as to sandwich the fatigue occurrence site at a position other than the fatigue occurrence site predicted to cause fatigue as a detection target in the one member. To the first part and the second part,
Connecting the first connecting means and the second connecting means respectively,
Between the first connecting means and the second connecting means, the first connecting means and the second connecting means are inserted into an inserting portion provided in one of the first connecting means and the second connecting means with a predetermined gap and fixed to the other. Is provided with a notch in the middle, and the first portion and the second portion
They are connected by a substantially round bar-shaped member that is elastically plastically deformed according to the relative displacement with the part.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a first embodiment of the present invention.
This will be described with reference to FIG. FIG. 1 is a front view showing the structure of the fatigue detector according to the present embodiment, and FIG. 2 is a transverse sectional view taken along the line II-II in FIG. 1 and 2, in the fatigue detector 1 of the present embodiment, an intermediate portion (a portion other than the end portion) 2a of one pipe 2 is formed into a substantially T-shape at the end portion 3a of the other pipe 3. It is provided on the fixed structure 4 that is connected and fixed, and detects the fatigue state of the fixed structure 4. That is, in the fatigue detector 1, the connecting member 5 fixed to the fixing position 2b of the pipe 2 away from the vicinity of the intermediate portion 2a and the connecting member 5 fixed to the fixing position 3b of the pipe 3 away from the vicinity of the end 3a. A member 6 and a connecting member 8 that connects between the connecting member 5 and the connecting member 6 and that is elastically plastically deformed according to the relative displacement between the fixing position 2b and the fixing position 3b are provided.

The pipe 2 and the pipe 3 belong to a pipe system having a large number of pipes including them, and FIG. 1 shows a branch portion 7 where the pipe 3 branches from the pipe 2 which is a part of the pipe system.
The vicinity is illustrated. At this time, the fixed position 2b of the pipe 2 and the fixed position 3b of the pipe 3 are present at positions where there is little change in shape in the longitudinal direction of the pipe where maximum stress does not occur, and the maximum stress occurs. Therefore, the intermediate portion 2a and the end portion 3a, which are predicted to cause fatigue of the detection target, exist so as to sandwich the vicinity of the connection fixing position (that is, the branch portion 7).

The connecting member 8 is a substantially plate-like member, and one end side (the right end side in FIG. 2) is inserted into the through hole 5a provided in the connecting member 5 with a predetermined gap and the other end side ( The left end side in FIG. 2) is fixed to the connecting member 6. This allows
The connecting member 8 is adapted to deform in the normal direction of the contact surface with the through hole 5a according to the relative displacement between the fixing position 2b and the fixing position 3b. That is, the connecting member 8 is
Regarding the deformation (in-plane bending deformation) of the pipe 2 or the pipe 3 parallel to the plane of FIG. 1, the deformation of the pipe 2 or the pipe 3 perpendicular to the plane of the paper of FIG. Regarding the (torsional deformation), only the component of the deformation amount in the in-plane bending deformation direction (direction parallel to the paper surface of FIG. 1) is deformed. Therefore, the deformation corresponding to the in-plane bending deformation is dominant in the connecting member 8. As described above, since the deformation of the connecting member 8 corresponding to the in-plane bending deformation of the pipe 2 or the pipe 2 is dominant, the connecting member 8 is the in-plane bending of the deformation of the target fixed structure 4. Designed with attention to deformation. The method of designing the connecting member 8 will be described in detail below. (1) Calculation of Relative Displacement First, under the input conditions to be considered in design (for example, vibration when an earthquake is applied), the magnitude of the maximum stress generated in the bifurcation 7 and the three-dimensional deformation are experimentally or analyzed Ask. Then, of the three-dimensional deformation, a component in the corresponding in-plane bending direction is obtained. Further, the component is converted into a relative displacement amount when viewed between the fixing position 2b of the pipe 2 which is the fixing position of the connecting member 5 and the fixing position 3b of the pipe 3 which is the fixing position of the connecting member 6.

(2) Calculation of Fatigue Curve Generally, when a material having the same property undergoes elasto-plastic deformation under the same load and load condition, the stress applied to the material and the number of repetitions until fracture due to fatigue are one curve (fatigue curve). expressed. In this fatigue curve, the vertical axis represents stress and the horizontal axis represents the number of repetitions until fatigue failure and fracture. The fatigue curve usually has a downward sloping line during this period because the number of repetitions until fracture gradually increases as the stress applied to the material decreases. When the stress decreases to a certain extent and reaches the fatigue limit, the number of repetitions until rupture becomes almost infinite, and finite number of elasto-plastic deformations make it almost impossible to rupture. Becomes After the above (1), such fatigue curves are obtained for the connecting member 8 and the constituent material of the branch portion 7 of the fixed structure 4, respectively.

(3) Conversion of vertical axis of fatigue curve In FIG. 1, between the fixing position 2b of the pipe 2 which is the fixing position of the connecting member 5 and the fixing position 3b of the pipe 3 which is the fixing position of the connecting member 6. When the relative displacement amount x in 1 occurs, the stress corresponding to this occurs in the branch portion 7 of the fixed structure 4.
That is, there is a certain correlation between the stress generated in the branch portion 7 and the relative displacement amount x between the fixing position 2b and the fixing position 3b. Therefore, the vertical axis of the fatigue curve of the branched portion 7 of the fixed structure 4 calculated in (2) above is converted from the stress into the relative displacement amount x and replaced to create a converted fatigue curve of the branched portion 7. Similarly, based on the correlation between the stress generated in the connecting member 8 and the relative displacement amount x, the vertical axis of the fatigue curve of the connecting member 8 calculated in (2) above is replaced with the relative displacement amount x, and the connecting member 8 is replaced. Create a reduced fatigue curve for.

(4) Comparison of Two Converted Fatigue Curves FIG. 3 shows an example of the converted fatigue curve B of the branch portion 7 and the converted fatigue curve B of the connecting member 8 created in the above (3). The vertical axis represents the relative displacement amount x when viewed between the fixed position 2b and the fixed position 3b, and the horizontal axis represents the number of repetitions n until the fracture. In the present embodiment, as shown in FIG. 3, the material and shape of the connecting member 8 are appropriately selected so that the converted fatigue curve B of the connecting member 8 is below the converted fatigue curve B of the branch portion 7. As a result, at the same deformation amount xo under the input condition calculated in (1) above, the branch portion 7 of the fixed structure 4 is
The number of repetitions nb of the connecting member 8 is smaller than the number of repetitions na until the fracture.

In the above designs (1) to (4), it is preferable to consider the characteristic change due to the temperature of the material when the change in operating temperature is large or when the operating temperature is high or low. That is, it is preferable to design in consideration of the difference in fatigue characteristics due to the difference in operating temperature between the fixed structure 4 and the connecting member 8 and the change in fatigue characteristics due to the temperature of each material. Although the connecting member 8 is a substantially plate-shaped member in FIG. 1, it may have another shape, for example, a substantially rod shape. Further, a groove, a constriction or a hole may be formed in a substantially flat plate or a substantially rod shape. Further, the through hole 5a is not limited to this and may be a groove.

Next, the operation and action of the present embodiment having the above configuration will be described. When the piping system vibrates with respect to the wall surface of the building or the fixed structure due to an earthquake or the like, the vibration is transmitted to each part of the piping system. Thereby, for example, the fixed structure 4
The branch portion 7 undergoes elasto-plastic deformation, but if the elasto-plastic deformation is repeated a predetermined number of times, the branch portion 7 undergoes fatigue fracture and breaks, so maintenance must be performed before the fracture. In the present embodiment, as described above with reference to FIG. 3, the converted fatigue curve B of the connecting member 8 is below the converted fatigue curve B of the branch portion 7, and the same deformation amount xo
In the above, the connecting member 8 is more than the repeating number na of the branch portion 7.
The number nb of repetitions of is smaller. As a result, the number of repetitions nb until the connecting member 8 is broken is calculated as follows:
Is always smaller than the number of repetitions na, the connecting member 8 will always undergo fatigue fracture and break before the branch portion 7 if the deformation history experienced by both is the same. Therefore, since the branch portion 7 of the fixed structure 4 is not broken at least until the connecting member 8 is broken, the function of the fixed structure 4 is guaranteed at least until the connecting member 8 is broken, and Whether or not the member 8 is broken can be used as an index of the remaining life of the fixed structure 4. Therefore,
Always only monitor whether the connecting member 8 is broken,
When the breakage of the connecting member 8 is found, it can be estimated that the remaining life of the fixed structure 4 is not long and the time for maintenance is not long, so the fixed structure 4 may be repaired or replaced. Here, the breakage of the connecting member 8 at this time may be visually confirmed, but an electrical detecting means may be used. The detection by this electric detection means is shown in FIG. That is, as shown in FIG. 4, a conducting wire 9 that is deformable together with the joining member 8 is fixed to the side surface of the joining member 8, and the resistance of the conducting wire 9 is measured by an electric resistance measuring device (not shown). At the same time that the connecting member 8 breaks, the conducting wire 9 also breaks, and the resistance measurement value by the electric resistance measuring device becomes infinite. Thereby, the breakage of the connecting member 8 can be confirmed even from a distant place. Therefore, when the measured value of the electric resistance measuring device shows infinity, the fixed structure 4 may be repaired or replaced. The conductor 9 and the electric resistance measuring device are an example of means for detecting breakage of the connecting member 8, and the breakage of the connecting member 8 is detected by using other electrical detecting means or other non-electrical detecting means. It may be detected.

Here, by appropriately setting the material and shape of the connecting member 8, it is possible to more accurately estimate the maintenance time. This will be explained below. That is, in the present embodiment, in FIG. 3, the reduced fatigue curve B of the connecting member 8 is set lower than the reduced fatigue curve of the branching portion 7 to make the connecting member 8 and the branching portion 7 easier to break. However, by appropriately setting the shape and material, the degree of stress concentration and the maximum stress value can be controlled to adjust the difference in easiness of breakage. This means that with this setting, the fatigue state of the branch portion 7 when the connecting member 8 breaks can be set in advance. In other words, the vibration energy that can be absorbed by the branch portion 7 after the connecting member 8 breaks. The amount can be preset. As a result, only whether or not the connecting member 8 is broken is constantly monitored, and when the breaking of the connecting member 8 is found, the vibration energy that can be absorbed by the branch portion 7 of the fixed structure 4 thereafter is already clear. Therefore, the remaining life of the fixed structure 4 can be a period until it is considered that a disturbance exceeding the vibration energy is generated. Therefore, it is possible to more accurately estimate the period length until the time when maintenance should be performed after the connecting member 8 is broken.

Further, if the vibration energy amount to be set is set based on the relationship with the break inspection cycle, more rational maintenance can be performed. This will be explained below. That is, the amount of vibration energy that can be absorbed by the branch portion 7 of the fixed structure 4 after the breakage of the connecting member 8 is larger than the maximum amount of vibration energy that is generated by a vibration disturbance such as an earthquake that can be considered in the cycle of performing the breaking inspection of the connecting member 8. Just set it. By doing so, even if the connecting member 8 breaks immediately after the previous inspection and remains in the broken state until the current inspection, the branch portion 7 of the fixed structure 4 has the maximum amount of vibration energy that can occur during this period. Since it can be absorbed, the function of the fixed structure 4 is maintained. Therefore, at each inspection cycle, it is checked only whether the branch portion 7 is broken, and when the break is found, the fixed structure 4 is repaired.
If the replacement is performed, the function of the fixed structure 4 can always be maintained. Accordingly, the connecting member 8 can manage the inspection time and the maintenance time of the fixed structure 4 together.

The effects of the present embodiment described above will be described below. That is, as described in (1) above, when trying to detect fatigue due to stress concentration in a combination of a plurality of members such as the fixed structure 4, first, the position where the stress concentration occurs is first determined. Both the magnitude of the maximum stress generated at that time is predicted in advance by analysis and experiment.
At this time, the magnitude of the maximum stress obtained by analysis and experiment is
It almost exactly matches the magnitude of the maximum stress that actually occurs. However, on the other hand, whether or not the maximum stress actually occurs at the maximum stress generation position obtained by analysis and experiment depends on factors such as errors in the manufacturing stage of the member shape and structural non-uniformity of the material. In reality, fatigue fracture often occurs at a position slightly deviated from the position obtained by analysis or experiment. Therefore, in the present embodiment, the stress transmission to the elastically plastically deformed connecting member 8 is fixed at a fixing position 2b, which is far from the branch portion 7 where fatigue is expected to occur due to stress concentration.
Perform from 3b. That is, the deformation of the fixed structure 4 is replaced by the relative displacement of the fixing position 2b and the fixing position 3b far from the branch portion 7, and the connecting member 5 connected to them is connected.
And to the connecting member 6, and further to the connecting member 8 via these, to cause elastic-plastic deformation. And the fixed position 2
The connecting member 8 is broken first by setting the reduced fatigue curve (b) of the connecting member 8 between b and the fixed position 3b to be lower than the reduced fatigue curve (a) of the branch portion 7. With such a stress transmission path, even if maximum stress occurs at a position slightly deviated from the maximum stress occurrence position obtained by analysis, experiment, etc. and fatigue progresses, regardless of this, the stress can be accurately measured. The fatigue state of the fixed structure 4 can be detected. Further, at this time, unlike the conventional structure in which another member is provided in the vicinity of the stress concentration generation position, the fatigue characteristics of the fixed structure 4, which is the detection target, are not impaired.

Further, in the fatigue detector 1 of the present embodiment, as described in (1) above, the connecting member 8 moves in the in-plane bending direction, which is the dominant component of the three-dimensional deformation. The structure focuses only on the components and allows other components to escape as much as possible. This is for the following reason.
That is, in the structure in which the connecting members 5 and 6 are fixed to the position away from the fatigue occurrence position and the deformation is transmitted to the connecting member 8 as in the present embodiment, the amount of displacement in the connecting member 8 is corresponding to the distance. Grows larger. Therefore, JP-A-6-
Similar to Japanese Patent Publication No. 74875 and Japanese Patent Application Laid-Open No. 4-50634, for example, when the connection member 8 is fixed to both the connection members 5 and 6, the deformation in all three-dimensional directions is detected, the connection member 8 The displacement constraint is too large, which hinders the free deformation of the fixed structure 4 itself, and the effective function of the detector cannot be expected so much. Therefore, such inconvenience is prevented by selecting and detecting only the dominant component of the three-dimensional deformation and letting the other components escape as much as possible. Further, by narrowing down the target components in this way, it is possible to easily adjust the number of repetitions at the time of fatigue failure, as compared with the case of designing in all directions.

In the first embodiment described above, the fatigue detector 1 is applied to a structure in which the pipe 3 branches from the pipe 2, but the pipe shape is not limited to the branched shape. . That is, it may be applied to an elbow portion in which one pipe is bent, instead of the branched structure. Also in this case, the same effect is obtained.

Further, in the first embodiment, the connecting members 5 and 6 are fixed to the fixing positions 2b and 3b of the pipes 2 and 3, respectively, but the present invention is not limited to this. Such a modified example will be described with reference to FIGS. FIG. 5 is a front view showing the structure of the fatigue detector according to this modification, and FIG. 6 is a transverse sectional view taken along the line VI-VI in FIG. As shown in these FIGS. 5 and 6, the connecting member 5 connected to the connecting member 8
The shape of A and the connecting member 6A expands into a substantially triangular shape. The connecting member 5A includes the strip-shaped members 10, 10 wound around the outer periphery of the pipe 2 and the bolt 1 for fastening them.
It is locked to the pipe 2 via 1, 11, and the connecting member 6
A is locked to the pipe 3 via strip-shaped members 12 and 12 wound around the outer periphery of the pipe 3 and bolts 13 and 13 for fastening them. Note that it is not necessary to provide two strip-shaped members 10 and two strip-shaped members 12, and at least one strip-shaped member 10 is sufficient. According to this modification, the same effect as that of the first embodiment can be obtained.

A second embodiment of the present invention will be described with reference to FIGS. FIG. 7 is a front view showing the structure of the fatigue detector according to the present embodiment, and the fatigue detector 20 according to the present embodiment.
1 is provided in the fixed structure 204 in which the intermediate portion 203a of the pipe 203 is connected and fixed to the surface vicinity portion 214a of the wall 214, and the fatigue state of the fixed structure 204 is detected. That is, in the fatigue detector 201, the connection member 206 fixed to the fixing position 203b of the pipe 203, which is separated from the vicinity of the intermediate portion 203a, and the bolt 215 are fixed to the fixing position 214b of the wall 214, which is separated from the vicinity of the front surface portion 214a. A connecting member 205 fixed through the connecting member 206 and a connecting member 208 connecting between the connecting member 206 and the connecting member 205 and elastically and plastically deformed according to the relative displacement between the fixed position 203b and the fixed position 214b. ing.

The fixed structure 204 is basically a structure in which the pipe 2 of the fixed structure 4 of the first embodiment is replaced with a wall 214, and the fatigue detector 201 is also the fatigue of the first embodiment. This is a structure in which the detector 1 is modified according to this replacement. That is, the pipe 203 belongs to a pipe system including a large number of pipes including the pipe 203, and FIG. 7 illustrates the vicinity of the drawer portion 207 where the pipe 203, which is a part of the pipe system, is pulled out from the wall 214. Is. The connecting member 205 has substantially the same structure as the connecting member 5A shown in FIGS. 5 and 6, and the connecting member 206 has substantially the same structure as the connecting member 6 shown in FIGS. 1 and 2. Further, the connecting member 208 has substantially the same structure as the connecting member 8 shown in FIGS. 1 and 2 or FIGS. 5 and 6, and one end thereof is inserted into the through hole 205a provided in the connecting member 205 via a predetermined gap. At the same time, the other end is fixed to the connecting member 206. The design method is the same as that of the connecting member 8.

As with the first embodiment, the fatigue detector 201 of this embodiment also detects the fatigue of the lead portion 207 with high accuracy without impairing the fatigue characteristics of the fixed structure 204, which is the object to be detected. be able to.

In the second embodiment, the fatigue detector 201 is provided within the range that can be illustrated although it is separated from the lead-out portion 207 to some extent, but the invention is not limited to this, and the fatigue detector 201 is not limited thereto. A fatigue detector may be provided at a position significantly apart from the drawer portion 207. This modification will be described with reference to FIG.

FIG. 8 shows a fatigue detector 25 according to this modification.
1 is a front view showing the structure of FIG. 1, and a fatigue detector 251 detects the fatigue state of the lead-out portion 207 of the fixed structure 204 similarly to the fatigue detector 201 of FIG.
The other of 03, which is significantly separated from the vicinity of the intermediate portion 203a
A connecting member 256 fixed to one fixing position 203c;
A connecting member 255 fixed to a fixing position 214c far apart from the vicinity of the surface 214a of the wall 214;
The connecting member 256 and the connecting member 255 are connected to each other, and a connecting member 258 that is elastically plastically deformed according to the relative displacement between the fixed position 203c and the fixed position 214c is provided. The connecting member 258 has a structure similar to that of FIG. 7, one end side is inserted into the through hole 255a provided in the connecting member 255 with a predetermined gap, and the other end side is fixed to the connecting member 256. It is similar to the connecting member 208.

According to this modification, as in the same manner as the second embodiment, the fatigue of the branch portion 7 can be detected with high accuracy without impairing the fatigue characteristics of the fixed structure 204.

A third embodiment of the present invention will be described with reference to FIGS. FIG. 9 shows a front view showing the structure of the fatigue detector according to the present embodiment, and FIG. 10 shows a transverse sectional view taken along line XX in FIG. The same parts as those in the first embodiment are designated by the same reference numerals. 9 and 10, the fatigue detector 301 of the present embodiment is similar to the fatigue detector 1 of the first embodiment in that the middle portion 2a of one pipe 2 is substantially the same as the end portion 3a of the other pipe 3. The fatigue state of the fixed structure 4 connected and fixed so as to form a T shape is detected. That is, the fatigue detector 301 includes the connecting member 305 fixed to the fixing position 2b of the pipe 2 which is separated from the vicinity of the intermediate portion 2a, and the pipe 3
A connecting member 306 fixed to a fixing position 3b apart from the vicinity of the end portion 3a and a connecting member 305 and the connecting member 306 are connected to each other, and a relative displacement between the fixing position 2b and the fixing position 3b is achieved. A connecting member 308 that is elastically plastically deformed accordingly
It has and.

The connecting member 308 is a substantially plate-shaped member,
The groove 3 provided on the connecting member 306 on one end side (the upper right side in FIG. 9)
06a through a predetermined gap, and the other end side (lower left side in FIG. 9) is fixed to the connecting member 305, and the groove 30
6a is deformed in the normal direction of the contact surface. At this time, the groove 306a is parallel to the straight line connecting the fixing position 2b and the fixing position 3b. As a result, similarly to the connecting member 8 of the first and second embodiments, the connecting member 308 also deforms in the in-plane bending deformation parallel to the paper surface of FIG. 9 corresponding to almost all the deformation amounts. However, regarding the torsional deformation perpendicular to the paper surface of FIG. 9, since the deformation occurs only in the in-plane bending deformation direction component (direction parallel to the paper surface of FIG. 9) of the deformation amount, the in-plane bending deformation Corresponding deformations dominate. Further, the connecting member 308 is provided close to the fixed position 3b side, as shown in FIG. 9, not at a substantially intermediate position between the fixed position 2b and the fixed position 3b as in the first embodiment.

The method of designing the connecting member 308 is substantially the same as that of the first and second embodiments except for the portion related to thermal deformation (described later), and thus detailed description thereof will be omitted.

According to the present embodiment as well, as in the first embodiment, the fatigue of the branch portion 7 can be detected with high accuracy without impairing the fatigue characteristics of the fixed structure 4, which is the object to be detected. In addition to these, the following effects are obtained.

(1) Reduction of Influence of Thermal Deformation Generally, a structure such as a pipe causes thermal deformation due to temperature. However, in the fatigue detector 1 of the first embodiment shown in FIGS. Unless all of the pipes 2, 3 and the connecting members 5, 6 have the same linear expansion coefficient or there is no temperature change, the pipes 2, 3 and the connecting members 5, 6 expand and contract in their respective longitudinal directions to form the connecting member 5. Since the connecting member 6 is relatively displaced in the longitudinal direction, the connecting member 8 is deformed. When the influence of this thermal deformation is great, the connecting member 8 may break regardless of the fatigue of the branch portion 7 of the fixed structure 4. On the other hand, in the fatigue detector 301 of this embodiment,
Since the connecting member 308 is inserted into the groove 306a parallel to the straight line connecting the fixing positions 2b and 3b, the connecting member 3
Even if 05 and the connecting member 306 are displaced relative to each other, the connecting member 308 does not deform. As a result, it is possible to reduce the effects of thermal deformation as described above. However, the connecting member 30
By the relative displacement of 5,306, as shown in FIG.
Since the length a of the portion of the connecting member 308 exposed to the outside of the groove 306a changes, the stress of the connecting member 308 that changes in response to the deformation of the fixed structure 4 changes. Therefore, when designing the connecting member 308, the change in the length a is taken into consideration as an effect of thermal deformation, and the effect of this thermal deformation is taken into consideration for the reduced fatigue curve of the connecting member 308 as shown in FIG. It is necessary to add a correction.

(2) Improvement of detection sensitivity The connecting member 308 has the same fixing position 2 as in the first embodiment.
It is provided not near the intermediate position between b and the fixing position 3b but close to the fixing position 3b side as shown in FIG. Thereby, the detection sensitivity of the fatigue detector 301 can be improved. This will be described with reference to FIGS. 12 and 13. FIG. 12 is a diagram showing an example of a case where bending deformation of the pipe 3 with respect to the pipe 2 occurs in the fatigue detector 301 of the present embodiment, and FIG. 13 shows a connecting member as a comparative example to the present embodiment. Fatigue detector 301 'arranged at an intermediate position
FIG. 13 is a diagram showing a case where bending deformation occurs at the same angle as in FIG. 12 in FIG. 12 and 13, the connection member is not shown for clarity. As can be seen by comparing FIGS. 12 and 13, in the deformation of the same angle,
The connecting member 30 in the fatigue detector 301 of the present embodiment shown in FIG. 12 is more than the connecting members 305 ′ and 306 ′ in the fatigue detector 301 ′ of the comparative example shown in FIG.
It can be seen that 5 and the connecting member 306 are displaced to positions greatly different from each other. That is, in the case of deformation at the same angle, the normal direction detected by the connecting member (direction b in the figure)
The displacement between the connecting members that occurs in FIG. 12 is larger in FIG. Thereby, even with the same modification, the detection value of the fatigue detector 301 of the present embodiment is amplified and becomes larger, so that the detection sensitivity can be improved.

In the third embodiment, as described above in (1) with reference to FIG. 11, the connecting member 3 is used.
When designing 08, it was necessary to consider the change in the length a as an effect of thermal deformation, but the structures of the connecting member 308 and the groove 306a may be modified so that such consideration is unnecessary. . This modification is shown in FIG. 14
FIG. 12A is a view showing a structure of a connecting member 308A and a groove according to the present modification, and is a view corresponding to FIG. 11. That is, a plate-shaped portion 308Aa substantially equal to the connecting member 308 of FIG.
A columnar portion 308Ab having a substantially columnar shape is provided at the tip of the connecting member 3
In addition, the connecting member 306A is provided with a groove 306Aa having a slightly higher height, and the column portion 308Ab is slid in the groove 306Aa. That is, since the connecting member 308A contacts the groove 306Aa only at the cylindrical portion 308Ab, the connecting members 305 and 306 due to thermal deformation.
Even if the distance a from the connecting member 305 to the connecting member 306 changes due to the relative displacement of the connecting member 305 to the connecting member 30.
The distance L to the position where 8A contacts the connecting member 306A is always constant. Therefore, unlike FIG. 11, since the stress of the connecting member 308A generated in response to the deformation of the fixed structure 4 does not change, it is not necessary to consider the influence of thermal deformation when designing the connecting member 308A. That is, 1
Since it suffices to design by using the converted fatigue curve of the book connecting member 308 as it is, there is an effect that the design becomes extremely easy.

The third embodiment described above can also be applied to a structure for pulling out a buried pipe, as in the second embodiment shown in FIG. This modified example is shown in FIGS.
Will be described. FIG. 15 is a front view showing the structure of the fatigue detector according to the present modification, and FIG. 16 is a side view seen from the direction A in FIG. As shown in FIGS. 15 and 16, in the fatigue detector 301B of the present modification, the intermediate portion 303a of the pipe 303 is connected to the wall 31 as in the second embodiment.
Fixing structure 3 connected and fixed to the surface vicinity portion 314a of No. 4
This is for detecting the 04 fatigue state. That is, the fatigue detector 301B includes the connecting member 3 fixed to the fixing position 303b of the pipe 303, which is separated from the vicinity of the intermediate portion 303a.
06B and the connecting member 305 fixed to the fixing position 314b apart from the vicinity of the surface 314a of the wall 314.
B, a connecting member 308B that connects between the connecting member 306B and the connecting member 305B and that is elastically plastically deformed according to the relative displacement between the fixing position 303b and the fixing position 314b.
It has and. The connecting member 308B is the connecting member 308.
The structure is almost similar to that of the first embodiment, and one end side is inserted into the groove 306Ba provided in the connection member 306B.

According to this modification, as in the second embodiment, the fatigue of the lead portion 307 can be detected with high accuracy without impairing the fatigue characteristics of the fixed structure 304 which is the object to be detected. In addition to this, the influence of thermal deformation at this time can be reduced. A fourth embodiment of the present invention will be described with reference to FIGS. In this embodiment,
Different from the first to third embodiments, this is an embodiment in which the main object is to detect so-called torsional deformation. FIG. 17 is a front view showing the structure of the fatigue detector according to the present embodiment, and FIG. 18 is a transverse sectional view taken along the line XVIII-XVIII in FIG. The same parts as those in the third embodiment are designated by the same reference numerals. 17 and 18, the fatigue detector 401 of the present embodiment is the fatigue detector 301 of the third embodiment.
Similarly to the above, the fatigue state of the fixed structure 4 is detected, and the connecting member 405 fixed to the fixing position 2b, the connecting member 406 fixed to the fixing position 3b, and the fixing position 2b.
And a connecting member 408 that is elastically plastically deformed according to the relative displacement between the fixing position 3b and the fixing position 3b.

The connecting member 408 is a substantially plate-like member similar to the connecting member 308 of the third embodiment, but its arrangement direction is a direction rotated by 90 ° around the axial direction.
That is, the plate surface of the connecting member 408 faces in the front direction shown in FIG. 17, and the connecting member 40 faces in the side direction shown in FIG.
8 narrow width faces. Correspondingly, the groove 406a of the connecting member 406 is also in the direction rotated by 90 ° from the groove 306a of the third embodiment. Thus, unlike the first to third embodiments, the connecting member 408 corresponds to almost all the deformation amounts of the deformation (torsion deformation) of the pipe 2 or the pipe 3 perpendicular to the paper surface of FIG. However, the deformation of the pipe 2 or 3 parallel to the paper surface of FIG. 17 (in-plane bending deformation) corresponds only to the torsional deformation direction component (direction perpendicular to the paper surface of FIG. 17) of the amount of deformation. And transform. Therefore, the deformation corresponding to the torsional deformation of the connecting member 408 is dominant. Also,
Unlike the connecting member 308, the connecting member 408 is provided at a substantially intermediate position between the fixed position 2b and the fixed position 3b.

The designing method of the connecting member 408 includes a portion related to thermal deformation, and the designing method of the third embodiment is applied from bending deformation to torsional deformation, and therefore detailed description will be omitted.

According to the present embodiment, as in the third embodiment, the fatigue of the branch portion 7 can be detected with high accuracy without impairing the fatigue characteristics of the fixed structure 4 which is the object to be detected, and The influence of thermal deformation at that time can be reduced.

FIG. 19 and FIG. 2 show the fifth embodiment of the present invention.
This will be described with reference to 0. The present embodiment is an embodiment in which the fatigue of one member is targeted instead of the fixed structure of a plurality of members. FIG. 19 shows a front view showing the structure of the fatigue detector according to the present embodiment, and FIG. 20 shows a transverse sectional view taken along the line XX-XX in FIG. 19 and 20, the fatigue detector 501 of the present embodiment is provided in one pipe 502, and detects the fatigue state of the fatigue occurrence part 502a in which the fatigue is likely to occur in the pipe 502. Is. In the pipe 502, the first position 502b, 502b and the second position 502c, so as to sandwich the fatigue generating part 502a.
502c is present, and the fatigue detector 501 uses the strip-shaped members 503, 503 and the bolts 504, 504 for the first
Member 505 locked at positions 502b and 502b
And band members 508, 508 and bolts 509, 509
Connection member 506 locked to the second positions 502c and 502c via the connection member 505 and the connection member 506.
And a first position 502b and a second position 50
2c and a connecting member 508 that is elastically plastically deformed according to the relative displacement.

The connecting member 508 has a notch 508 in the middle.
20 is a substantially round bar-shaped member having one end side (the right end side in FIG. 20) inserted into a through hole 505a provided in the connecting member 505 with a predetermined gap, and the other end side (the left end in FIG. 20). Side) is fixed to the connecting member 506. As a result, the connecting member 508 is deformed in the direction normal to the contact surface with the through hole 505a. That is, regarding the bending deformation of the pipe 502a, the connecting member 508 is deformed corresponding to almost all the deformation amounts of the bending deformation.
Regarding the torsional deformation of 2a, only the torsional deformation direction component of the deformation amount is deformed. Therefore, the deformation corresponding to the bending deformation of the connecting member 508 is dominant. With respect to the design of the connecting member 508, the design method of the connecting member 8 of the first embodiment is simply applied to the bending deformation direction of one pipe 502, and thus detailed description thereof will be omitted.

According to the present embodiment, according to the same principle as that of the first embodiment, it is possible to detect the fatigue of the fatigue generating portion 502a with high accuracy without impairing the fatigue characteristics of the pipe 502 which is the object to be detected. it can.

In the fifth embodiment, as in the first embodiment, the influence of thermal deformation is not taken into consideration, but the deformation can be made to reduce the influence of thermal deformation. This modification will be described with reference to FIGS. 21 and 22. FIG. 21 is a front view showing the structure of the fatigue detector according to this modification.
22 shows a cross-sectional view taken along the line XXII-XXII in FIG. The same parts as those in the fifth embodiment are designated by the same reference numerals. In these FIG. 21 and FIG. 22, the present modification is the fifth example.
What is different from the embodiment is that the connecting member 508A connecting the connecting member 505A and the connecting member 506A is arranged in the pipe axis direction rotated by 90 °, not in the direction perpendicular to the pipe axis as in the fifth embodiment. That is what is being done. That is, one end (left end) of the connecting member 508A is fixed to the connecting member 505A, and the connecting member 508A is inserted into the axial hole 506Aa formed in the connecting member 506A. As a result, the connecting member 508A enables deformation in response to torsional deformation in addition to bending deformation of the connecting member 508 of the fifth embodiment, and also reduces the effect of thermal deformation of the pipe 502 that expands and contracts in the axial direction. It can be reduced.

The first to fifth embodiments described above are not limited to the individual implementations, and the fatigue detectors of the respective embodiments can be used in combination. For example, FIG. 23 shows an example in which the fatigue detector 301 of the third embodiment shown in FIG. 9 and the fatigue detector 401 of the fourth embodiment shown in FIG. 17 are used in combination. In this case, fatigue of the branch portion 7 due to in-plane bending deformation and torsional deformation of the branch portion 7 can be detected together while reducing the influence of thermal deformation.

[0048]

According to the present invention, the detection accuracy can be improved without impairing the fatigue characteristics of the object to be detected.

[Brief description of drawings]

FIG. 1 is a front view showing the structure of a fatigue detector according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along the line II-II in FIG.

FIG. 3 is a diagram showing an example of a converted fatigue curve of a branched portion and a converted fatigue curve of a connecting member.

FIG. 4 is a diagram showing detection by an electrical detection means.

FIG. 5 is a front view showing a structure of a fatigue detector according to a modified example of the first embodiment.

6 is a cross-sectional view taken along the line VI-VI in FIG.

FIG. 7 is a front view showing the structure of a fatigue detector according to a second embodiment of the present invention.

FIG. 8 is a front view showing a structure of a fatigue detector according to a modified example of the second embodiment.

FIG. 9 is a front view showing the structure of a fatigue detector according to a third embodiment of the present invention.

10 is a cross-sectional view taken along the line XX in FIG.

FIG. 11 is a diagram showing how the length a of the exposed portion of the connecting member changes due to relative displacement of the connecting member.

12 is a diagram showing an example of a case where bending deformation occurs in the fatigue detector shown in FIG.

FIG. 13 is a diagram showing a case where the same bending deformation as in FIG. 12 occurs in the comparative example.

FIG. 14 is a diagram showing a structure of a connecting member and a groove according to a modification of the third embodiment.

FIG. 15 is a front view showing the structure of a fatigue detector according to another modification of the third embodiment.

16 is a side view seen from the direction A in FIG.

FIG. 17 is a front view showing the structure of the fatigue detector according to the fourth embodiment of the present invention.

FIG. 18 is a cross-sectional view taken along the line XVIII-XVIII in FIG.

FIG. 19 is a front view showing the structure of a fatigue detector according to a fifth embodiment of the present invention.

20 is a cross-sectional view taken along the line XX-XX in FIG.

FIG. 21 is a front view showing the structure of a fatigue detector according to a modified example of the fifth embodiment.

22 is a cross-sectional view taken along the line XXII-XXII in FIG.

23 is a diagram showing an example in which the fatigue detector shown in FIG. 9 and the fatigue detector shown in FIG. 17 are used in combination.

[Explanation of symbols]

1 Fatigue Detector 2 Piping (One Piping, One Member) 2a Intermediate Part (First Part) 2b Fixed Position (Locking Position, Third Part, First Part) 3 Piping (Other Piping, Other) Member 3a End portion (second portion) 3b Fixing position (locking position, fourth portion, second portion) 4 Fixing structure (combined body of a plurality of members) 5 Connection member (first connection) Means) 6 connection member (second connection means) 7 branch portion (fatigue occurrence site) 8 connection member (fatigue evaluation means) 201 fatigue detector 203 pipe (one pipe, one member) 203a middle part (first) Part, fatigue part) 203b fixing position (locking position, third part, first part) 203c fixing position (locking position, third part, first part) 204 fixing structure (plural members) 205 connecting member (second connecting means) 206 connecting member (first connecting hand) Step 207 Drawer (fatigue occurrence site) 208 Connection member (fatigue evaluation means) 214 Wall (other piping, other member) 214a Surface vicinity part (second part) 214b Fixed position (locking position, fourth position) Part, second part) 214c fixing position (locking position, fourth part, second part) 255 connecting member (second connecting means) 256 connecting member (first connecting means) 258 connecting member (fatigue) Evaluation means) 301 Fatigue detector 301B Fatigue detector 303 Pipe (one pipe, one member) 303a Intermediate part (first part) 303b Fixing position (locking position, third part, first part) 304 Fixed structure (combination of a plurality of members) 305 connection member (first connection means) 305B connection member (second connection means) 306 connection member (second connection means) 306B connection member (first connection means) 307 Drawout Part (Fatigue Occurring Site) 308 Connecting Member (Fatigue Evaluation Means) 308B Connecting Member (Fatigue Evaluation Means) 314 Wall (Other Pipe, Other Member) 314a Surface Near Part (Second Part) 314b Fixed Position (Part Stop position, fourth part, second part 405 Connection member (first connection means) 406 Connection member (second connection means) 408 Connection member (fatigue evaluation means) 501 Fatigue detector 502 Piping (one) Member) 502a Fatigue occurrence part (fatigue occurrence part) 502b First position (locking position, third part,
1st part) 502c 2nd position (locking position, 4th part,
Second part) 505 Connection member (first connection means) 506 Connection member (second connection means) 508 Connection member (fatigue evaluation means)

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Satoru Ono 3-1-1 Sachimachi, Hitachi City, Ibaraki Hitachi Ltd., Hitachi Works, Ltd. (56) Reference JP-A-9-268777 (JP, A) Actual Kai 61-163972 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01M 19/00

Claims (4)

(57) [Claims] 1. A fatigue detector for detecting fatigue of one member or a combination of a plurality of members, wherein fatigue to be detected is predicted to occur in the one member or a combination of a plurality of members. A first connecting means and a second connecting means are respectively connected to a first portion and a second portion existing at positions other than the fatigue occurrence portion so as to sandwich the fatigue occurrence portion, and these first connection means are connected. between the second connecting means, said
Provided to one of the first connecting means and the second connecting means
Inserted into the insertion part with a specified gap and fixed in the other part.
The fatigue detector is characterized in that the first portion and the second portion are connected by a substantially plate-shaped member that elastically-plastically deforms according to the relative displacement. 2. A fatigue detector which is provided in a fixed structure in which a first portion of one member is connected and fixed to a second portion of another member and which detects a fatigue state of the fixed structure, First connecting means locked to a third part of the member other than the first part, and a fourth connecting part locked to a fourth part of the other member other than the second part. One of the first connecting means and the second connecting means for connecting between the first connecting means and the second connecting means.
Is inserted into the insertion part provided on one side with a predetermined gap and the other side
And a substantially plate-shaped member which is fixed to the first part and elastically plastically deforms in accordance with the relative displacement between the third part and the fourth part. 3. A fixed structure in which a first portion of one pipe is connected and fixed to a second portion of another pipe or structure,
In a fatigue detector for detecting a fatigue state of this fixed structure, first connecting means locked to a third portion of the one pipe other than the first portion, and the other pipe or structure. The second connection means locked to the fourth portion of the object other than the second portion and the first connection means and the second connection means are connected to each other, and the first connection is made. Means and one of the second connecting means
Is inserted into the insertion part provided on one side with a predetermined gap and the other side
And a substantially plate-shaped member which is fixed to the first part and elastically plastically deforms in accordance with the relative displacement between the third part and the fourth part. 4. A fatigue detector for detecting fatigue of one member.
Then , if the fatigue to be detected occurs in the one member,
Place the fatigue occurrence site at a position other than the predicted fatigue occurrence site
The first part and the second part which are sandwiched between
Connecting means and second connecting means respectively, and between the first connecting means and the second connecting means,
Provided to one of the first connecting means and the second connecting means
Inserted into the insertion part with a specified gap and fixed in the other part.
A notch in the middle, and the first part and the second part
A round bar that undergoes elasto-plastic deformation in response to relative displacement between
A fatigue detector characterized by being connected by a strip-shaped member.