JP5893337B2 - Fatigue level detection strain gauge - Google Patents

Description

  The present invention relates to a fatigue level detecting strain gauge capable of measuring strain of a structural material and predicting in advance signs of fatigue failure occurring in the structural material.

  For example, a strain gauge that can measure the strain of a structural material and can predict in advance signs of fatigue failure of the structural material is generally known (see Patent Document 1). This strain gauge configuration has a stretchable base and a resistance wire with a notch, and the resistance wire that plays the role of the strain gauge breaks in advance to predict signs of fatigue failure of the structural material in advance. It is like that.

JP 7-218214 A

  Strain gauges generally have sufficient mechanical properties equivalent to mechanical structural materials. Therefore, in general structural materials such as beams, columns, piers, steel towers, bridges, etc., whose mechanical strength and fatigue strength are lower than those of mechanical structural materials, a single strain gauge is used at the base, welded portion, and notched portion of a beam that is particularly susceptible to fatigue failure. Is used as a strain sensor for fatigue detection, strain output trends must be collected over a long period of time via a data logger, etc., and the amount of data for accumulating the detected data becomes enormous. And processing is difficult.

  In addition, even when trying to use a single strain gauge for a part where a stress concentration is likely to occur due to a sudden change in the cross-sectional shape of a welded part or a structural material having a relatively low fatigue strength of a mechanical structural material used in an industrial machine, for example. Problems similar to those of the general structural material described above arise.

  On the other hand, the strain gauge described in Patent Document 1 described above is capable of detecting a strain and predicting in advance signs of fatigue failure of a structural material without requiring management of enormous data.

  However, this strain gauge does not function as a strain gauge once the resistance wire is disconnected. Therefore, in order to predict the degree of fatigue of the structural material step by step from the initial fatigue stage to the final fatigue stage, a plurality of strain gauges having different fatigue fracture strengths are required. If there is no space in the structural material for attaching such a plurality of strain gauges, it must be dealt with by a single strain gauge. In this case, if it is attempted to predict this by disconnecting the strain gauge fairly early with respect to the fatigue fracture of the structure, the degree of progress of fatigue of the structural material after that cannot be grasped, resulting in a problem. On the other hand, if the strain gauge is disconnected just before the fatigue failure of the structure and an attempt is made to detect signs of fatigue failure, it will not be possible to secure a sufficient period until the structure material actually breaks, and effective measures will be taken. Can not be.

  In addition, this strain gauge is provided with notches from the side of the resistance wire at a plurality of locations of the resistance wire having a very narrow line width. Therefore, the width of the resistance line in the notch is further narrower than the line width of the other part. If a large number of such narrow width resistance portions are formed by notches, it is practically difficult to arrange the resistance pattern so that all the cuts can be broken by a certain degree of fatigue. In addition, when the strain gauge is attached, there is a possibility that an inadvertent force acts on the cut portion having a narrow line width and breaks. As described above, the fatigue strength of this strain gauge is substantially different depending on the location where the resistance wire breaks, so that it is difficult to predict fatigue failure. This strain gauge lacks reliability regarding the prediction of fatigue failure of structural materials.

  Therefore, in order to avoid such a problem, a fatigue level detection strain gauge 500 related to the present invention as shown in FIG. 7 has been proposed, which is not yet known at the time of filing of the present invention. The strain gauge 500 includes a strain detection unit 530, a conduction unit 540 connected in series with the strain detection unit 530, and a fatigue level detection unit 550 connected in parallel with the conduction unit 540. The resistance of the strain gauge 500 is increased by breaking due to fatigue, and the fatigue is detected stepwise by outputting it to the outside via the terminal portions 521, 522 (520). .

  However, this fatigue level detection strain gauge 500 has two connecting points between the folded tabs and the strands constituting the fatigue level detecting unit 550, and the number of the connecting points between the lower side and the upper side in FIG. There may be a case where the fatigue level detection unit 550 does not break even if the structure reaches a predetermined fatigue level due to variations in processing accuracy of the portions. Therefore, there is a need for a fatigue level detection strain gauge that reliably breaks the fatigue level detection unit when the structural material reaches a predetermined level of fatigue.

  An object of the present invention is to provide a fatigue degree detecting strain gauge capable of measuring strain of a structural material and predicting signs of fatigue fracture occurring in the structural material in advance and accurately.

In order to solve the above-described problem, a fatigue degree detection strain gauge according to claim 1 of the present invention is provided.
A strain detection strain cage, a conduction portion, a fatigue detection portion, and a fatigue detection strain cage provided with a terminal portion on a film-like member,
The strain detection unit and the conduction unit are connected to the terminal unit, and the strain detection unit and the fatigue level detection unit are also connected to the terminal unit,
The fatigue level detection unit is configured by connecting a strand and an adjacent strand with a fatigue level detection folded tab in order to detect the fatigue strength of the structure ,
When the length ratio of the fatigue detecting flaps tab for the line widths of the plurality of the strands and the end-tab ratio, the said strands wrapping number of fatigue detection folding tabs in the same fatigue detecting unit of the end-tab ratio A plurality of film-like members are formed at both ends in the longitudinal direction , respectively.

  When the fatigue level detection strain gauge according to claim 1 has such a configuration, it is possible to increase the number of connecting portions between the folded tab and the strand of the fatigue level detection unit that breaks with the same level of fatigue. That is, the number of fractured parts increases according to a predetermined degree of fatigue. Here, since it is sufficient that at least one portion of the connecting portion breaks when predicting fatigue fracture, the possibility of fracture at a predetermined fatigue degree is improved, and fatigue fracture of a structural material can be predicted more appropriately. it can. In addition, the metal foil having a narrow line width as in the prior art is not cut into the side, and the connecting portion is determined by the relationship between the size of the end tab, that is, the length L of the folded tab and the width W of the strand. Since it determines the degree of fatigue at which fracture occurs, it is easy to manage the degree of fatigue at which fracture occurs.

  In addition, since a plurality of connecting portions between the folded tab and the strand that breaks with the same degree of fatigue are formed, even if the processing accuracy of each part varies somewhat, it is less affected. For example, if there is only one connecting portion between the folded tab and the strand, the length L of the folded tab is increased due to variations in processing accuracy, or the width W of the strand is widened to reach a predetermined degree of fatigue. However, it may not break. However, since a plurality of connection portions between the folded tabs and the strands are provided, the possibility of inconvenience such as failure does not occur even when the prescribed value is reached due to the influence of variation in pattern formation can be reduced as much as possible.

Moreover, the fatigue degree detection strain gauge according to claim 2 of the present invention is the fatigue degree detection strain gauge according to claim 1,
The fatigue level detection folded tab is characterized in that the corners of the inner side of the plurality of fatigue level detection folded tabs have an acute angle shape.

  The fatigue level detecting strain gauge according to claim 2 has such a configuration, and coupled with the function of claim 1, breakage of the folded portion and the strand from the corner portion of the inner portion of the folded tab formed in an acute angle shape. It becomes easy to become a starting point.

Moreover, the fatigue degree detection strain gauge according to claim 3 of the present invention is the fatigue degree detection strain gauge according to claim 2,
The acute angle shape is characterized in that at least one of the folded tab side end portion of the inner edge portion on the strand side or the inner edge portion of the folded tab sandwiched between the strands is formed in an R shape.

  With the fatigue level detecting strain gauge according to claim 3 having such a configuration, coupled with the action of claim 1, the folded portion and the strand break from the corner portion of the inner portion of the folded tab formed in an R shape. It becomes easy to become a starting point. In addition, since the metal foil is generally patterned on the film-like member by etching, the acute angle of the inner portion can be more easily managed by managing the size of R.

Further, the fatigue level detection strain gauge according to claim 4 of the present invention is the fatigue level detection strain gauge according to claim 1 to claim 3,
A cut is provided in the vicinity of the inner portion of the folded back of the folded tab for detecting the degree of fatigue.

  When the fatigue degree detecting strain gauge according to claim 4 is provided with a notch in the vicinity of the inner part of the turn, if a predetermined degree of fatigue acts, the part also breaks. Therefore, even if it is the structure provided with the folding tab of shorter length, it becomes easy to fracture | rupture according to a predetermined fatigue degree.

  ADVANTAGE OF THE INVENTION According to this invention, while being able to measure the distortion | strain of a structural material, the fatigue degree detection strain gauge which can predict the sign of the fatigue fracture which arises in a structural material in advance and exactly can be provided.

It is a top view which shows the fatigue degree detection strain gauge which concerns on this embodiment. It is a perspective view showing roughly the state where the fatigue degree detection strain gauge concerning this embodiment was attached to a structural material. It is a top view which expands and shows the folding tab for fatigue degree detection of the fatigue degree detection strain gauge shown in FIG. 1, and the strand connected to this. FIG. 4A is a plan view showing a first modification of the fatigue detection folded tab of the fatigue degree detection strain gauge shown in FIG. 1 and a strand connected thereto, and FIG. 4B is a plan view showing a second modification. FIG. 4B is a plan view showing a third modification (FIG. 4C). FIG. 5A is a plan view showing a fourth modification of the folded tab for detecting the fatigue degree of the fatigue degree detecting strain gauge shown in FIG. 1 and the strand connected thereto, and FIG. 5B is a plan view showing the fifth modification (FIG. 5). (B)). FIG. 6A is a plan view showing a sixth modification of the folded tab for detecting the fatigue degree of the strain detecting strain gauge shown in FIG. 1 and the strand connected thereto, and FIG. 6 is a plan view showing the seventh modification. (B)). It is a top view which shows the fatigue degree detection strain gauge relevant to this invention.

  In order to detect the fatigue strength of a structure, the fatigue detection strain gauge according to this embodiment includes a plurality of fatigue detection units configured by connecting a strand and an adjacent strand with a return tab for fatigue detection. It is a strain gauge for detecting fatigue. Further, the fatigue level detection strain gauge is configured so that the fatigue level detection folded tab of the fatigue level detection unit having the same end tab ratio is defined as the ratio of the length of the fatigue level detection folded tab to the line width of the plurality of strands. A plurality of folding numbers are formed on both ends of the strand.

  Hereinafter, a fatigue level detection strain gauge according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a plan view showing a fatigue level detecting strain gauge according to the present embodiment. In the following description, the vertical direction of the film-like member in FIG. 1 is the longitudinal direction, and the horizontal direction is the width direction. Moreover, let the upper side of the film-like member in FIG. 1 be a front end side, and let the lower side be a base end side.

  The fatigue level detection strain gauge 100 according to the present embodiment is used to detect the fatigue level of general structural materials such as beams, columns, piers, steel towers, bridges, etc. of buildings, and is a flexible insulator. A film-like member 110 made of a resin material and an electric resistor made of a metal foil patterned on the film-like member 110 are used. The electrical resistor includes terminal portions 121 and 122 (120), a strain detection unit 130, a conduction unit 140, and a fatigue level detection unit 150.

  The film-like member 110 is made of a resin member, has flexibility, and has a rectangular shape. It should be noted that an adhesive is applied to the back side of the film-like member 110 and is attached to the structural material. However, what attaches the film-like member 110 to a structural material is not limited to an adhesive material, What is necessary is just to show a double-sided tape and other similar effects.

  The terminal portion 120 is formed on the base end side of the film-like member 110 and in the vicinity of both ends in the width direction. An electric wire (not shown) is soldered to the terminal portion 120, and a change in the resistance value of the electric resistor composed of the strain detection portion 130, the conduction portion 140, and the fatigue level detection portion 150 is output to the outside, and calculation control (not shown) is performed. The strain and fatigue level of the structural material to which the fatigue level detection strain gauge 100 is attached are detected by means.

  The strain detection unit 130 has a width of about 1/3 from the vicinity of the end of one side in the width direction of the film-like member 110 (left side in FIG. 1), and is one terminal portion from the vicinity of the tip of the film-like member 110. It is formed in a region extending in the vicinity of 121.

  In the present embodiment, the strain detection unit 130 is a metal foil having a thin line width and is folded back in the same direction many times on the end side, and the extension portions of the constant length are slightly spaced. They are so-called zigzag folded shapes (hereinafter simply referred to as “zigzag folded” shapes) arranged in parallel with each other. In addition, each extending part of the strain detection unit 130 extends in the longitudinal direction of the film-like member 110.

  In addition, one end of the strain detection unit 130 is connected to one terminal unit 121, and the other end is connected to the conduction unit 140 and the fatigue level detection unit 150.

  More specifically, the strain detection unit 130 includes a plurality of strands (gauge sensing units) 131 (the above-described extension portion) and a folding tab 132 (the above-described folding unit), and the strain detection unit 130 has a tensile strain. As a result, the resistance value of the strain detector 130 increases and the resistance value of the entire electrical resistor increases. In addition, the shape of the inner part of the folding tab 132 of the portion where the folding tab 132 and the strand 131 of the strain detection unit 130 are connected has a curved shape in which the curvature gradually and continuously breaks due to fatigue. The shape is difficult to occur.

  The conducting portion 140 has a width of about 2/3 from the vicinity of the other end in the width direction of the film-like member 110 (right side in FIG. 1) to the vicinity of the tip end portion of the film-like member 110.

  The conductive portion 140 also has a zigzag shape in which the length of each extending portion between the folded portions is short, and one end portion (the left end portion in FIG. 1) of the folded portion is the strain detecting portion 130 and the fatigue degree detecting portion 150. One strand 151 a is connected, and the other end (the right end in the width direction in FIG. 1) is connected to the other strand 151 d ′ and the other terminal portion 122 of the fatigue detection unit 150.

  These configurations will be described in more detail with reference to FIG. In FIG. 1, the conducting portion 140 is composed of a plurality of strands 141 and folded tabs 142a, 142b, 142c, and 142d. Even if the conducting portion 140 is distorted, the resistance value of the conducting portion 140 does not change. The resistance value of the entire resistor is not changed. Moreover, the shape of the inner part of the folding tabs 142a, 142b, 142c, 142d where the folding tab of the conducting part 140 and the strand 141 are connected has a curved shape in which the curvature gradually changes continuously, and fatigue. It has a shape in which breakage due to is difficult to occur. As a result, when the fatigue level detection unit 150 breaks, no current flows through the fatigue level detection unit 150 and current flows only through the conduction unit 140, so that the resistance value of the entire electrical resistor increases. It has become.

  The fatigue degree detection unit 150 has a width of about 2/3 from the vicinity of one side (right side in FIG. 1) end of the film-like member 110 in the width direction of the film-like member 110, similar to the conduction part 140. In FIG. 5, the conductive portion 140 is formed in parallel to the conductive portion 140 in a region closer to the base end than the conductive portion 140. In addition, each extension part which makes the strand 151 of the fatigue degree detection part 150 is extended in the longitudinal direction of the film-like member 110.

  In this embodiment, the fatigue level detection unit 150 is made of a metal foil having a thin line width, and is composed of a plurality of strands 151 and folded tabs 152, which have a zigzag folded shape that extends in the longitudinal direction of the film-like member 110. There is no. The fatigue level detection unit 150 detects the four fatigue levels of the first fatigue level detection element 150A, the second fatigue level detection element 150B, the third fatigue level detection element 150C, and the fourth fatigue level detection element 150D. Each fatigue degree detecting element is provided with four folding tabs 152a, 152b, 152c, 152d on the base end side and three folding tabs (not shown in FIG. 1) on the distal end side. The proximal-side folding tabs 152a, 152b, 152c, 152d and the distal-side folding tabs have the same configuration in each element, and hence the proximal-side folding tabs 152a, 152b, 152c, 152d are hereinafter referred to. The configuration will be described, and this will be replaced with the description of the folded tab on the front end side.

  Here, the folding tabs 152a, 152b, 152c, and 152d for detecting the degree of fatigue are the length L of the folding tab 152 for detecting the degree of fatigue with respect to the line width W (see FIG. 3A) of the plurality of strands 151 (see FIG. 3). 3 (a)) is defined as the end tab ratio, the end tab ratio differs for each fatigue level detection element. If the length dimension L in the longitudinal direction of the folded tab 152a (see FIG. 3A) and the length dimension W in the width direction of the strand 151 (see FIG. 3A) are set, the dimension L is long and the dimension W is long. The shorter it is, the easier it is for the fatigue level detector 150 to break.

More specifically, in FIG. 1 , the fatigue detection element 150A located on the leftmost side of the fatigue detection unit 150 has the longest fatigue detection loop tab 152a (that is, the ETR is the largest). . And it breaks even by slight fatigue. Thereafter, the lengths of the return tabs 152b, 152c, and 152d for detecting the fatigue level provided in the fatigue level detection elements 150B, 150C, and 150D are gradually reduced toward the right side in the width direction of the fatigue level detection unit 150. The degree of fatigue when the gap between the tab 152 and the strand 151 is broken also increases toward the end in the width direction of the film-like member 110.

  The adjacent strands 151a ′ and 151b extending from the adjacent folded tabs 152a and 152b are electrically connected to the folded tab 142a ′ of the conducting portion 140, and the adjacent strands 151b ′ extending from the adjacent folded tabs 152b and 152c. , 151c are electrically connected to the folded tab 142b ′ of the conductive portion 140, and the adjacent strands 151c ′, 151d extending from the adjacent folded tabs 152c, 152d are electrically connected to the folded tab 142c ′ of the conductive portion 140, and end portions thereof. The strand 151 d ′ extending from the side folding tab 152 d is electrically connected to the folding tab 142 d ′ of the conducting portion 140.

  Further, in the present embodiment, the strands 151 a and 151 d ′ at both ends of the fatigue degree detection unit 150 further extend to the tip side of the film-like member 110. One strand 151 a is electrically connected to the strand 131 of the strain detector 130. Further, the other strand 151 d ′ of the fatigue level detection unit 150 is electrically connected to the terminal part 122 via the folded tab 142 d ′ of the conduction part 140.

  In the present embodiment, the fatigue level detecting strain gauge 100 is attached to the structural material so that the folded tab 152a is positioned at or near the stress concentration portion generated in the structural material. A current always flows through the strain detection unit 130 and the conduction unit 140, but depending on the degree of fatigue of the structure, the strand 151 of the fatigue detection element corresponding to the degree of fatigue and the folded tabs 152a, 152b, 152c, 152d By breaking the gaps one after another, the current does not flow to the fatigue level detection unit 150 step by step. As a result, the resistance value of the entire electric resistor increases stepwise, and it is possible to accurately predict the fatigue failure of the structural material.

  Further, the fatigue level detection strain gauge according to the present embodiment is provided for each of the fatigue level detection elements 150A, 150B, 150C, and 150D that break at the same fatigue level as compared to the fatigue level detection strain gauge related to the present invention described above. The number of connecting portions between the folded tab 152 and the strand 151 is increased. In other words, the number of fractured parts in the element is increased in accordance with the fatigue level predetermined for each of the fatigue level detection elements 150A, 150B, 150C, and 150D. Here, since it is sufficient that at least one portion of the connecting portion breaks when predicting fatigue fracture, the possibility of fracture at a predetermined fatigue degree is improved, and fatigue fracture of a structural material can be predicted more appropriately. become able to. Moreover, the structure which cut | disconnects the side of the metal foil with narrow line | wire width as described in patent document 1 is not taken, but the magnitude | size of ETR, ie, the length L of a folding tab, and the width W of a strand Since the fatigue level at which the connecting portion breaks is determined by the relationship, it is easy to manage the fatigue level at which the fracture occurs.

  In addition, since a plurality of connecting portions between the folded tabs 152 and the strands 151 that break with the same degree of fatigue are formed for each of the fatigue level detection elements 150A, 150B, 150C, and 150D, even if each processing accuracy varies slightly, Less affected. For example, if there is only one connecting portion between the folding tab 152 and the strand 151, the length L of the folding tab is shortened due to variations in processing accuracy, or the width W of the strand is widened, resulting in a predetermined structural material. Even if the degree of fatigue is reached, it may not break. However, in the present embodiment, since a plurality of connecting portions between the folding tab 152 and the strand 151 are provided for each of the fatigue detection elements 150A, 150B, 150C, and 150D, a predetermined value is reached due to the influence of variation in pattern formation. However, the occurrence of inconvenience such as no breakage can be reduced as much as possible.

  The fatigue level detection strain gauge 100 according to the present embodiment is an electrical resistance type fatigue level detection strain gauge that can detect the fatigue level by using the fatigue level detection unit 150, but has the structure described above. It is not only specialized in detecting the fatigue level of the material, but when the strain is detected in the strain detector 130, the resistance value of the strain detector 130 changes, and the strain of the structural material can be detected from the changed value. It is possible.

  Then, the specific usage method of the fatigue degree detection strain gauge 100 mentioned above is demonstrated. FIG. 2 is a perspective view schematically showing a state in which the fatigue level detection strain gauge 100 according to the present embodiment is attached to a structural material. In FIG. 2, two fatigue degree detection strain gauges 100 </ b> A and 100 </ b> B are affixed to a connecting portion between a column 11 and a beam 12 as a general structural material.

  Since the two strain level detecting strain gauges 100A and 100B are attached to the column 11 and the beam 12 in this way, a bending load or a tensile load acts on the column 11 or the beam 12 of the structural material, and the degree of fatigue is previously determined. When the assumed initial fatigue level is reached, at least one of the folded tabs 152a and the strands 151 in the first fatigue level detection element 150A breaks. Then, by measuring the resistance value of the electrical resistor, it can be seen that the fatigue of the structural material has reached the first stage of fatigue, which can be used for prediction of fatigue failure. Further, when a stronger bending load or tensile load acts on the column 11 or the beam 12 of the structural material and the degree of fatigue reaches the second level of fatigue assumed in advance, the second fatigue level detection element 150B at least The connecting portion between any one folded tab 152b and the strand 151 is broken. In this case, the first fatigue level detection element 150A has already been broken at some place. By measuring the resistance value of the electrical resistor, it can be seen that the fatigue level of the structural material has advanced to the second stage, which can be used for prediction of fatigue failure. Similarly, when the stress acting on the structural material increases and the fatigue level of the structural material reaches the third level fatigue level and the fourth level fatigue level in order, the third fatigue level detection element 150C, The fatigue level detection element 150D will break correspondingly in that order. Then, by measuring the resistance value of the electric resistor, it can be seen that the fatigue level of the structural material has advanced to the third stage, and then has advanced to the fourth stage.

  Since the fatigue level detection strain gauge according to the present embodiment described above has both the fatigue level detection unit 150 and the strain detection unit 130, the following usage method unique to the present invention is possible. Specifically, for example, when the fatigue level detection strain gauge 100 according to the present embodiment is provided in a general structural material of a pier that passes a lot of vehicles, for a while from the completion of the pier, the strain detection unit 130 detects the structural material. The trend of the degree of strain can be collected, and the tendency of the degree of strain accompanying the vehicle traffic of the structural material constituting the pier can be detected.

  Further, the fatigue degree of the fatigue failure of the structural material can be accurately determined based on which element of the fatigue degree detection elements 150A, 150B, 150C, and 150D of the fatigue degree detection unit 150 is broken. In addition, by collecting from the strain detector 130 for a while from the trend of the strain degree of the structural material immediately after the progress of the fatigue degree, it is possible to grasp what kind of phenomenon the fatigue fracture of the structural material is approaching Can do. On the other hand, even if the fatigue detection unit 150 does not break, for example, when the traffic amount of a vehicle passing through a bridge pier rapidly increases, the structure from the strain detection unit 130 for a while immediately after the increase of the traffic amount. By collecting the trend of the degree of strain of the material, it is possible to analyze the influence of the increase in traffic on the structural material.

  Such a method of use is not limited to the case where a general structural material is used for a pier, and may be applied to a general structural material that forms the framework of a multi-story building, for example. Thereby, for a while immediately after the building is completed, the strain detection unit 130 detects the trend of the degree of distortion of the structural material, whereby the change in the degree of distortion of the structural material after the building is completed can be analyzed.

  In addition, when a fatigue failure of a structural material is predicted due to the breakage of the fatigue level detection unit 150, by collecting a trend of the degree of strain of the structural material from the strain detection unit 130 for a while immediately after that, by what phenomenon It is possible to grasp whether the fatigue failure of the structural material is approaching. On the other hand, even if the fatigue detection unit 150 does not break, for example, when a heavy object such as an industrial machine is installed on the upper floor of a building, the distortion of the structural material for a while immediately after the installation of the heavy object. By collecting the trend of the degree from the strain detection unit 130, it is possible to analyze the influence of the installation of heavy objects on the structural material.

  Next, various modifications of the fatigue level detection strain gauge will be described. These various modifications are obtained by partially deforming the folded tab and the strand in each fatigue level detection element of the fatigue level detection unit of the fatigue level detection strain gauge. Specifically, the shapes of the connecting portions of the strand and the folded tab are different in various modifications.

  Initially, the 1st modification of the fatigue detection part which concerns on embodiment mentioned above is demonstrated. In addition, about the structure equivalent to embodiment mentioned above and the structure which is common in each fatigue degree detection element, a corresponding code | symbol is attached | subjected and detailed description is abbreviate | omitted. Fig.4 (a) is a top view which shows the 1st modification of the fatigue degree detection part which concerns on this embodiment.

  In the fatigue degree detection unit 910 according to the first modified example, the shape of the inner edge portion 912p of the folded tab 912 sandwiched by the inner edge portions 911n of the two strands 911 connected to the folded tab 912 as shown in FIG. In addition, it has an R shape (arc shape) protruding toward the region sandwiched between the strands extending from the folded tab 912 (downward in FIG. 4A). As a result, when the connecting portion between the inner edge portion 911n of each strand 911 and the inner edge portion 912p of the folded tab 912 (that is, the corner portion of the folded tab 912 inside) cuts into an acute angle and reaches a certain degree of fatigue. The crack is sure to enter from that part.

  Next, a second modification of the fatigue level detection unit according to the above-described embodiment will be described. In addition, about the structure equivalent to embodiment mentioned above and the structure which is common in each fatigue degree detection element, a corresponding code | symbol is attached | subjected and detailed description is abbreviate | omitted. FIG. 4B is a plan view showing a second modification of the fatigue level detection unit according to the present embodiment.

  As shown in FIG. 4B, the fatigue degree detection unit 920 according to the second modification includes an inner edge portion 921n of two strands 921 connected to the folded tab 922 and an inner edge portion of the folded tab 922 sandwiched between the inner edge portions. A triangular notch 921t is formed between 922p and 922p so as to narrow the width of the connecting portion between the strand 921 and the folded tab 922. As a result, the connection portion between the inner edge portion 921n of each strand 921 and the inner edge portion 922p of the folded tab 922 (that is, the corner portion of the folded tab 922 inside) cuts into an acute angle, and reaches a certain degree of fatigue. The crack is sure to enter from that part.

  Next, a third modification of the fatigue level detection unit according to the above-described embodiment will be described. In addition, about the structure equivalent to embodiment mentioned above and the structure which is common in each fatigue degree detection element, a corresponding code | symbol is attached | subjected and detailed description is abbreviate | omitted. FIG.4 (c) is a top view which shows the 3rd modification of the fatigue detection part which concerns on this embodiment.

  In the fatigue degree detection unit 930 according to the third modified example, the shape of the inner edge portion 932p of the folded tab 932 sandwiched between the inner edge portions 931n of the two strands 931 connected to the folded tab 932 as shown in FIG. It has an R shape (arc shape) recessed in a direction away from the region sandwiched between the strands extending from the folded tab 932 (upward in FIG. 4C). Further, the distance between both ends of the inner edge 932p of the folded tab 932 is larger than the width of both ends of the inner edge 931n of the strand 931. A notch 931t is formed at the end of the inner edge portion 931n of the strand 931 so as to taper in the direction of narrowing the width of the connecting portion between the strand 931 and the folded tab 932. As a result, when the connecting portion between the inner edge portion 931n of each strand 931 and the inner edge portion 932p of the folded tab 932 (that is, the corner portion of the folded tab 932 inner portion) cuts into an acute angle, and reaches a certain degree of fatigue. The crack is sure to enter from that part.

  Next, the 4th modification of the fatigue detection part which concerns on embodiment mentioned above is demonstrated. In addition, about the structure equivalent to embodiment mentioned above and the structure which is common in each fatigue degree detection element, a corresponding code | symbol is attached | subjected and detailed description is abbreviate | omitted. Fig.5 (a) is a top view which shows the 4th modification of the fatigue degree detection part which concerns on this embodiment.

  As shown in FIG. 5A, the fatigue degree detection unit 940 according to the fourth modification is the length of the inner edge portion 942p of the folded tab 942 sandwiched by the inner edge portions 941n of the two strands 941 connected to the folded tab 942. Is larger than the width between the inner edges of each strand 941. Then, an R shape (arc shape) protruding from the strand side toward the folding tab 942 between each end portion of the inner edge portion 941n of each strand 941 and each end portion of the inner edge portion 942p of the folding tab 942 is partially used. A notch 941t is formed. As a result, the connection portion between the inner edge portion 941n of each strand 941 and the inner edge portion 942p of the folded tab 942 (that is, the corner portion of the folded inner portion of the folded tab 942) cuts into an acute angle, and reaches a certain degree of fatigue. The crack is sure to enter from that part.

  Next, a fifth modification of the fatigue detection unit according to the above-described embodiment will be described. In addition, about the structure equivalent to embodiment mentioned above and the structure which is common in each fatigue degree detection element, a corresponding code | symbol is attached | subjected and detailed description is abbreviate | omitted. FIG. 5B is a plan view illustrating a fifth modification of the fatigue level detection unit according to the present embodiment.

  As shown in FIG. 5 (b), the fatigue detection unit 950 according to the fifth modification has the shape of the inner edge portion 952 p of the folded tab 952 sandwiched between the inner edge portions 951 n of the two strands 951 connected to the folded tab 952. It has an R shape (arc shape) recessed in a direction away from the region sandwiched between the strands extending from the folded tab 912 (upward direction in FIG. 5B). Further, the distance between both ends of the inner edge portion 952p of the folded tab 952 is larger than the width of both ends of the inner edge portion 951n of the strand 951. Then, an R shape (arc shape) protruding from the strand side toward the folded tab 952 between each end portion of the inner edge portion 951n of each strand 951 and each end portion of the inner edge portion 952p of the folded tab 952 is partially formed. A notch 951t is formed. As a result, when the connecting portion between the inner edge portion 951n of each strand 951 and the inner edge portion 952p of the folded tab 952 (that is, the corner portion of the folded inner portion of the folded tab 952) cuts into an acute angle, and reaches a certain degree of fatigue. The crack is sure to enter from that part.

  Next, a sixth modification of the fatigue level detection unit according to the above-described embodiment will be described. In addition, about the structure equivalent to embodiment mentioned above and the structure which is common in each fatigue degree detection element, a corresponding code | symbol is attached | subjected and detailed description is abbreviate | omitted. Fig.6 (a) is a top view which shows the 6th modification of the fatigue degree detection part which concerns on this embodiment.

  In the fatigue level detection unit 960 according to the sixth modified example, the shape of the inner edge portion 962p of the folded tab 962 sandwiched between the inner edge portions 961n of the two strands 961 connected to the folded tab 962 as shown in FIG. It forms an R shape (arc shape) protruding toward the region sandwiched between the strands extending from the folded tab 912 (downward in FIG. 6A). As a result, the connecting portion between the inner edge 961n of each strand 961 and the inner edge 962p of the folded tab 962 (that is, the corner of the folded inner portion of the folded tab 962) is cut at an acute angle. Further, a triangular notch 963 is formed in the connecting portion between the outer edge portion 962m of the folded tab 962 and the outer edge portion 961m of the strand 961 so as to narrow the width of the connecting portion between the strand 961 and the folded tab 962. By having such a configuration, when a certain degree of fatigue is reached, cracks are surely entered from the front ends of these cuts.

  Next, a seventh modification of the fatigue level detection unit according to the above-described embodiment will be described. In addition, about the structure equivalent to embodiment mentioned above and the structure which is common in each fatigue degree detection element, a corresponding code | symbol is attached | subjected and detailed description is abbreviate | omitted. FIG.6 (b) is a top view which shows the 7th modification of the fatigue degree detection part which concerns on this embodiment.

  In the fatigue degree detection unit 970 according to the seventh modified example, the shape of the inner edge portion 972p of the folded tab 972 sandwiched between the inner edge portions 971n of the two strands 971 connected to the folded tab 972 as shown in FIG. It has an R shape (arc shape) that is recessed in a direction away from the region sandwiched between the strands extending from the folded tab 912 (upward direction in FIG. 6B). In addition, the space | interval of the both ends of the inner edge part 972p of the folding | turning tab 972 is larger than the width | variety of the both ends of the inner edge part 971n of each strand 971. And, between each end of the inner edge 972p of the folded tab 972 and each end of the inner edge 971n of the strand 971, an R shape (arc-shaped) protruding from the strand 971 toward the folded tab is partly formed. A notch 971t is formed. As a result, the connecting portion between the inner edge portion 971n of each strand 971 and the inner edge portion 972p of the folded tab 972 (that is, the corner portion of the folded portion of the folded tab 972) is cut at an acute angle. Further, a triangular notch 973 is formed in a connecting portion between the outer edge portion 972m of the folding tab 972 and the outer edge portion 971m of the strand 971 so as to narrow the width of the connecting portion between the strand 971 and the folding tab 972. By having such a configuration, when a certain degree of fatigue is reached, cracks are surely entered from the front ends of these cuts.

  The arrangement pattern of the metal foil according to the embodiment and each modification described above is merely an example, and it goes without saying that various modifications can be applied without departing from the present invention.

  Further, the film-like member of the fatigue level detection strain gauge may not necessarily be made of resin and has flexibility as long as the strain detection unit and the fatigue level detection unit formed thereon play a role. It does not have to be.

  In addition, as an application example of the fatigue detection strain gauge according to the above-described embodiment and its modifications, a general structural material composed of columns and beams has been introduced, but the application target is limited to such a thing. Instead, for example, the present invention can be applied to a portion where stress concentration is likely to occur locally, such as a welded portion of a general structural material or a portion where the shape changes abruptly (a shape factor changes rapidly). Similarly, the above-described embodiment and its modifications are included in parts where stress concentration is likely to occur locally, such as a welded part or a part whose shape changes suddenly even if it is a mechanical structural material having the same mechanical properties as a strain gauge. The fatigue degree detection strain gauge according to the present invention can be applied.

100 (100A, 100B) Fatigue degree detection strain gauge 110 Film-like member 121, 122 (120) Terminal part 130 Strain detection part 140 Conducting part 142a, 142b, 142c, 142d Folding tab 150 Fatigue degree detection part 150A First fatigue degree Detection element 150B Second fatigue level detection element 150C Third fatigue level detection element 150D Fourth fatigue level detection element 151 (151a, 151a ′, 151b, 151b ′, 151c, 151c ′, 151d, 151d ′) Strand 152 (152a, 152b, 152c, 152d) Folding tabs 910, 920, 930, 940, 950, 960, 970 Fatigue degree detection unit

Claims (4)

A strain detection strain cage, a conduction portion, a fatigue detection portion, and a fatigue detection strain cage provided with a terminal portion on a film-like member,
The strain detection unit and the conduction unit are connected to the terminal unit, and the strain detection unit and the fatigue level detection unit are also connected to the terminal unit,
The fatigue level detection unit is configured by connecting a strand and an adjacent strand with a fatigue level detection folded tab in order to detect the fatigue strength of the structure ,
When the length ratio of the fatigue detecting flaps tab for the line widths of the plurality of the strands and the end-tab ratio, the said strands wrapping number of fatigue detection folding tabs in the same fatigue detecting unit of the end-tab ratio A fatigue degree detecting strain gauge, wherein a plurality of film members are formed on both ends in the longitudinal direction .   2. The fatigue level detecting strain gauge according to claim 1, wherein the fatigue level detecting folded tab has a corner portion of an inner portion of the folded back of the plurality of fatigue level detecting folded tabs.   The acute angle shape is configured such that at least one of the folded tab side end portion of the inner edge portion on the strand side or the inner edge portion of the folded tab sandwiched between the strands has an R shape. Item 3. The fatigue level detection strain gauge according to Item 2.   4. The fatigue degree detecting strain gauge according to claim 1, wherein a cut is provided in the vicinity of the inner part of the folded back of the folded back tab for detecting the fatigue degree.

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