JP7155651B2 - Crack growth control method and crack growth control structure - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crack growth suppression construction method and a crack growth suppression structure used to suppress the growth of cracks generated in metal objects.

Metal objects such as bridges, harbor structures such as cranes, and various other steel structures may crack due to fatigue due to repeated loads and the like.

It is required to suppress the growth (propagation) of cracks generated in such metal objects. In particular, in infrastructures such as bridges, suppression of crack propagation is required also from the viewpoint of measures against aging.

As a method for suppressing the propagation of cracks generated in this type of metal object, for example, providing a stop hole at the tip of the crack is known (see, for example, Patent Document 1).

A crack caused by fatigue in a metallic object propagates by opening the tip of the sharpened crack. Therefore, in the configuration in which the stop hole is provided at the tip of the crack, it is possible to eliminate the sharp tip of the crack and suppress the propagation of the crack.

JP 2010-255195 A

By the way, in order to obtain the effect of suppressing crack propagation, it is important to process the stop hole so that the sharp tip of the crack disappears.

However, in the case of a crack that changes intricately in the plate thickness direction, it is difficult to identify where the tip of the crack is by visual observation.

Therefore, for example, in a plate material that constitutes a metal object, if a crack inside the plate material has propagated beyond the position of the tip of the crack on the surface, the tip of the crack on the surface of the plate material is included. Even if a stop hole is provided by machining a circular hole in this way, there is a possibility that a crack inside the plate remains at the periphery of the formed stop hole. In the unlikely event that the tip of the crack remains at the periphery of the stop hole, it will be difficult to obtain the effect of suppressing the growth of the crack at the stop hole.

Therefore, the present invention can suppress the propagation of a crack generated in a metal object by a stop hole, and furthermore, even if the tip of the crack remains on the periphery of the formed stop hole, the propagation of the crack can be prevented. An object of the present invention is to provide a method for suppressing crack growth and a structure for suppressing crack growth.

In order to solve the above-mentioned problems, the present invention provides a process of providing a stop hole at a position corresponding to the tip of the crack at the location where the metal object is cracked, and and providing a pair of mounting grooves extending outward from a position along the direction of the diameter of the stop hole that intersects the direction in which the crack extends in the peripheral wall of the stop hole, wherein each of the mounting grooves is , the groove width of the opening opening in the peripheral wall of the stop hole is set to be smaller than the diameter of the stop hole, and each of the mounting grooves is located outside the peripheral wall of the stop hole, It is formed in a shape having a widened portion having a groove width larger than the groove width of the opening, and the plate thickness of the portion near both ends attached to each of the mounting grooves is larger than the plate thickness of the central portion. The end portion of the insertion member having a shape of The portions near both ends of the insertion member are attached to the respective locking portions of the mounting grooves in a state in which the portions near the ends of the insertion member are inserted into the respective mounting grooves. Crack growth restraint method is used.

The insertion member may have curved outer surfaces on both sides of the central portion.

Each of the mounting grooves may be provided along a diametrical direction that perpendicularly intersects the crack in the stop hole.

The stop holes and the mounting grooves are provided so as to penetrate the metal object, and the dimensions in the direction along which the insertion member is inserted into the mounting grooves are equal to the stop holes and the respective mounting grooves in the metal object. The thickness may be greater than or equal to the thickness of the portion where the mounting groove is provided.

In addition, a stop hole provided at a position corresponding to the tip of the crack at the place where the crack occurred in the metal object, and a diameter of the stop hole that intersects the direction in which the crack extends in the peripheral wall of the stop hole A pair of mounting grooves extending outward from a position along the direction of , and an insertion member having a shape in which the plate thickness of portions near both ends attached to each of the mounting grooves is larger than the plate thickness of the central portion , wherein the portions near both ends of the insertion member are inside the respective mounting grooves,
It is fixed by bonding, and the groove width of each mounting groove monotonically decreases from the widened portion located outside the peripheral wall of the stop hole toward the opening opening to the peripheral wall of the stop hole. The portions near both ends of the insertion member are locked to the locking portions of the mounting grooves in a state in which the portions near the ends of the insertion member are inserted into the mounting grooves. A crack growth restraint structure is adopted.

According to the crack growth suppression construction method and the crack growth suppression structure of the present invention, it is possible to suppress the growth of the crack generated in the metal object by the stop hole, and furthermore, the peripheral edge of the stop hole formed by the tip of the crack Crack propagation can be suppressed even when the crack remains in the crack.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows 1st Embodiment of the crack propagation suppression method. It is a figure which expands and shows the insertion member used by a crack propagation suppression construction method. It is a figure which shows the procedure of the crack propagation suppression construction method of 1st Embodiment. It is a figure which shows 2nd Embodiment of the crack propagation suppression method. It is a figure which shows the procedure of the crack propagation suppression construction method of 2nd Embodiment.

A method for suppressing crack growth and a structure for suppressing crack growth according to the present invention will be described with reference to the drawings.

[First embodiment]
FIG. 1 shows a first embodiment of the crack growth suppression method, FIG. 1(a) is a schematic diagram showing the state before construction, and FIG. 1(b) is a schematic diagram showing the state after construction. is. FIG. 2 shows an insertion member used in the crack growth suppression method, FIG. -A direction arrow directional view. FIG. 3 shows the procedure for implementing the crack growth suppression method of this embodiment. FIG. FIG. 3(c) is an enlarged schematic perspective view showing a state in which a stop hole and a mounting groove are provided at the tip of the mounting groove, and an insertion member is mounted in the mounting groove to form a crack growth suppression structure. be.

As shown in FIG. 1(a), the method for suppressing crack propagation according to the present embodiment is intended to be applied to a crack 2 generated in a metal object, for example, a plate material 1 constituting a steel structure. be.

Here, first, the structure of the insertion member 3 used in this embodiment shown in FIGS. 2(a) and 2(b) will be described.

The insertion member 3 is plate-shaped as shown in FIGS. 2(a) and 2(b). One direction of the insertion member 3 indicated by an arrow in FIG. 3(b) is set as an insertion direction x into mounting grooves 4a and 4b, which will be described later.

Further, the insertion member 3 has a cross-sectional shape perpendicular to the insertion direction x, as shown in FIG. It is considered to be a shape. The center portion 6 and the end portions 5a and 5b of the insertion member 3 are located inside the stop hole 8 formed in the plate member 1 and the mounting grooves 4a and 4b, respectively, as indicated by the two-dot chain lines in FIG. 2(a). is the part that is placed in the

Portions 5a and 5b near both ends of the insertion member 3 are curved surfaces in which the outer surfaces 7a and 7b are continuous. The outwardly convex curved surfaces of the outer surfaces 7a and 7b preferably have a constant curvature. This is because the surfaces of the mounting grooves 4a and 4b on the end side away from the stop hole 8 are curved for the purpose of suppressing stress concentration. This is because the outer shapes of the portions 5a and 5b near the both ends of the member 3 are matched. The end portions of the mounting grooves 4a and 4b remote from the stop hole 8 are hereinafter referred to as deep sides of the mounting grooves 4a and 4b.

In addition, the insertion member 3 is configured so that the outer surfaces 9a and 9b on both sides of the center portion 6 narrowed between the portions 5a and 5b near both ends are continuous curved surfaces. This is to keep the change in the width dimension of the central portion 6 of the insertion member 3 continuous, so that the outer surfaces 9a and 9b are not formed with curved portions that tend to cause stress concentration.

As shown in FIG. 2(b), the insertion member 3 used in this embodiment has both end surfaces in the insertion direction x that are planes perpendicular to the insertion direction x. Also, the dimension L in the insertion direction x of the insertion member 3 is equal to or greater than the thickness t (see FIG. 3(a)) of the plate 1 in which the crack 2 is generated. is preferably set to This is to allow the insertion member 3 to be inserted into the mounting grooves 4a and 4b of the plate member 1 to be arranged over the entire plate thickness t of the plate member 1. As shown in FIG.

Machining of the outer shape of the insertion member 3 is preferably performed, for example, by electric discharge machining. It goes without saying that the machining of the outer shape of the insertion member 3 may employ a machining method other than electric discharge machining.

Also, the insertion member 3 may be made of high-strength steel (high-tensile steel) having a higher strength than the plate material 1, for example. This configuration is effective in preventing damage due to fatigue of the insertion member 3 itself when the insertion member 3 is attached to the attachment grooves 4a and 4b, as will be described later.

In the crack growth suppression method of this embodiment, as shown by the two-dot chain line in FIG. and a pair of mounting grooves 4a and 4b extending outside the stop hole 8 with set dimensions from an opening 10 opening in the peripheral wall of the stop hole 8. It is provided so as to penetrate in the plate thickness direction. A pair of mounting grooves 4 a and 4 b are provided in the stop hole 8 along the direction of the diameter of the stop hole 8 intersecting the direction in which the crack 2 extends.

The stop hole 8 is drilled as a circular hole including the tip of the crack 2 generated in the plate material 1 at the site where the steel structure is provided. Therefore, the diameter of the stop hole 8 is set to 2 mm or more in view of the tools to be used and the processing accuracy.

Each of the mounting grooves 4a and 4b has a shape capable of accommodating both end portions 5a and 5b of the insertion member 3, respectively.

It is preferable that the direction of the diameter of the stop hole 8 in which the mounting grooves 4a and 4b are provided is a direction that intersects the direction in which the crack 2 extends at an angle as close to a right angle as possible. This is because the load acting in the direction of opening the crack 2 is applied to both ends of the insertion member 3 in a state in which the portions 5a and 5b near both ends are inserted into the mounting grooves 4a and 4b. This is because the stress is transmitted as a tensile stress directed toward .

Each of the mounting grooves 4 a and 4 b has an opening 10 opening in the peripheral wall of the stop hole 8 with a groove width w 1 smaller than the diameter of the stop hole 8 . Each of the mounting grooves 4a and 4b has a widened portion 11 outside the peripheral wall of the stop hole 8 and having a groove width w2 larger than the groove width w1.

Each of the mounting grooves 4a and 4b is formed such that the shape of the inner surface including the inner surface of the widened portion 11 from the opening 10 and the portion on the inner side of the widened portion 11 is formed as a continuous curved surface. Part of 4a and 4b is designed not to cause stress concentration. Further, it is preferable that the curved surfaces of the mounting grooves 4a and 4b, which are outwardly convex on the far side, have a constant curvature. This is to more reliably avoid stress concentration in the mounting grooves 4a and 4b.

A portion where the groove width from the widened portion 11 to the opening portion 10 in each of the mounting grooves 4a and 4b monotonically decreases is a locking portion 12 arranged symmetrically with the stop hole 8 interposed therebetween.

As a result, in a state in which the end portions 5a and 5b of the insertion member 3 are inserted into the mounting grooves 4a and 4b, the end portions 5a and 5b of the insertion member 3 are engaged with the engaging portions 12 of the mounting grooves 4a and 4b. is locked, the load acting on the plate member 1 in the direction of opening the crack 2 can be transmitted from the plate member 1 to the insertion member 3 . Therefore, the deformation of the plate member 1 in the direction in which the crack 2 opens can be restrained by the insert member 3 attached to each of the attachment grooves 4a and 4b.

The shape of each of the mounting grooves 4a and 4b is similar to the shape of the portions 5a and 5b near both ends of the insertion member 3 so that the inner surfaces of the mounting grooves 4a and 4b and the portions near both ends of the insertion member 3 are similar to each other. It is preferable to make the gap between the outer surfaces of 5a and 5b as small as possible. Considering that the strength of the adhesive 13, which will be described later, is lower than the strength of the plate member 1 constituting the steel structure, this This is because the thickness of the layer of the adhesive 13 interposed between the facing surfaces of the mounting grooves 4a, 4b and the insertion member 3 can be improved by minimizing the thickness of the layer of the adhesive 13 as much as possible. . In FIGS. 2(a) and 3(c), the space between the mounting grooves 4a and 4b and the insertion member 3 is enlarged for convenience of illustration.

Next, a method for suppressing crack propagation according to the present embodiment using the insertion member 3 will be described.

In the crack growth suppression method of the present embodiment, first, as shown in FIG. A circular stop hole 8 is provided at a position corresponding to the tip of the crack 2 so as to eliminate the tip of the crack 2 so as to penetrate in the plate thickness direction. In the plate material 1, outside the stop hole 8 and at two places in the direction of the diameter of the stop hole 8 that intersects the extending direction of the crack 2 at an angle as close to a right angle as possible, are provided on the peripheral wall of the stop hole 8. A pair of mounting grooves 4a and 4b extending outward from the opening 10 (see FIG. 2(a)) are provided so as to penetrate in the plate thickness direction.

The process of providing the plate member 1 with the stop hole 8 and the mounting grooves 4a and 4b is, for example, by drilling a circular hole through the plate member 1 in the plate thickness direction, centering on the tip of the visually identified crack 2. to form a stop hole 8. Next, in the plate material 1, cuts extending in the outer peripheral direction from the peripheral wall of the stop hole 8 are provided with a cutter at locations where the mounting grooves 4a and 4b are to be formed on the peripheral edge of the stop hole 8. After that, each mounting groove is cut by electrical discharge machining. 4a and 4b may be finished into a shape as indicated by the two-dot chain line in FIG. 2(a).

If the stop hole 8 and the mounting grooves 4a and 4b having the predetermined shapes described above can be formed, the processing for forming the stop hole 8 and the mounting grooves 4a and 4b in the plate material 1 can be performed by a processing method other than electric discharge machining. Needless to say, it may be adopted. The processing of providing the stop hole 8 in the plate member 1 and the processing of providing the mounting grooves 4a and 4b may be performed in any order, or may be performed in parallel. .

After forming the stop hole 8 and the mounting grooves 4a and 4b in the plate member 1, as shown in FIG. An adhesive (structural adhesive) 13 is applied to the outer surfaces of the side portions 5a and 5b and then inserted. The adhesive 13 may be applied to the inner surfaces of the mounting grooves 4a and 4b, or may be applied to both the outer surfaces of the portions 5a and 5b near the ends of the insertion member 3 and the inner surfaces of the mounting grooves 4a and 4b. may

After that, the adhesive 13 is cured, and the portions 5a and 5b of the insertion member 3 near both ends are attached to the inner sides of the attachment grooves 4a and 4b in a state of being fixed by adhesion.

As a result, as shown in FIG. are connected to each other through the insertion member 3 . Therefore, the plate member 1 is formed with the crack growth suppression structure of the present embodiment.

In the crack growth suppression structure formed by the crack growth suppression method of the present embodiment, the crack 2 is sharpened due to the provision of the stop hole 8 at the position corresponding to the tip of the crack 2 in the plate material 1. tip is missing. Therefore, the plate material 1 to which the crack growth suppression structure of the present embodiment is applied prevents the crack 2 from propagating past the stop hole 8 even if a load acting in the direction of opening the crack 2 is applied. can be suppressed.

It should be noted that, for example, when a crack 2 that changes intricately in the plate thickness direction occurs in the plate material 1, even if the stop hole 8 is provided at a location corresponding to the tip of the visually confirmed crack 2, the stop hole 8 may not be used. A tip of the crack 2 may remain at the periphery of the hole 8 .

However, when a load acting in the direction of opening the crack 2 acts on the plate material 1 to which the crack growth suppression structure of the present embodiment is applied, the load acts on the mounting grooves 4a and 4b provided in addition to the stop hole 8. From the inner surface, the stress in the tensile direction is transmitted to the insert member 3 through the layer of the solidified adhesive 13 and received by the insert member 3 . Furthermore, since the insertion member 3 has portions 5a and 5b closer to both ends, which are thicker than the central portion 6, are locked to the respective locking portions 12 of the mounting grooves 4a and 4b. The load in the direction of opening the crack 2 can be received by the insertion member 3 more reliably.

As a result, even if the tip of the crack 2 remains at the periphery of the stop hole 8 in the plate material 1, the crack growth suppression structure of the present embodiment prevents the crack 2 from reaching the tip of the crack 2. The crack 2 can be prevented from growing by reducing the stress acting in the opening direction.

Furthermore, since the insertion member 3 has a shape that does not have a bent portion that causes stress concentration, damage due to fatigue of the insertion member 3 itself can be suppressed.

Moreover, since the mounting grooves 4a and 4b provided in the plate member 1 do not have bent portions that cause stress concentration on the inner surface thereof, new cracks originating from the points of stress concentration in the mounting grooves 4a and 4b do not occur in the plate member 1. can be suppressed.

Since the insertion member 3 is attached to the attachment grooves 4a and 4b by adhesion via the adhesive 13, the plate member 1 is not heated, so that the plate member 1 is not heated. No stress occurs.

It should be noted that the method for suppressing crack growth and the structure for suppressing crack growth according to the present embodiment have been described as being applied to the crack 2 generated in the plate material 1 that constitutes the steel structure. On the other hand, the crack growth suppression method and the crack growth suppression structure of the present disclosure can be used to prevent cracks from occurring in welds where plate materials arranged on the same plane in a steel structure are butt-welded, and cracks from these welds. Of course, it may be applied to cracks extending in one or both plates.

[Second embodiment]
FIG. 4 shows a second embodiment of the crack growth suppression method, FIG. 4(a) is a schematic diagram showing the state before construction, and FIG. 4(b) is a schematic diagram showing the state after construction. is. FIG. 5 shows the implementation procedure of the method for suppressing crack growth according to the present embodiment. FIG. The insertion member is attached to the attachment groove extending from the stop hole provided at the tip of the crack growth suppression structure. FIG. It is a BB direction arrow directional view.

In FIGS. 4(a), 4(b), 5(a), 5(b), and 5(c), the same reference numerals are given to the same parts as in the first embodiment, and the explanation thereof will be omitted.

As shown in FIG. 4( a ), the crack growth suppression method of the present embodiment is used as a bent portion (discontinuous portion) in a metal object, for example, a deck plate that becomes a corner portion of a bridge that is a steel structure. 14 and the upper edge of the U-rib 15 arranged therebelow.

One side wall (web) 15a of the deck plate 14 and the U-rib 15 is, for example, as shown in FIG. The upper edges of the inclined side walls 15a are butted and welded.

As shown in FIG. 5B, the insertion member 3 used in this embodiment has the same configuration as the insertion member 3 shown in FIGS. ing.

In the crack growth suppression method of the present embodiment, first, at a position corresponding to the tip of the crack 2a generated in the joint 16 as shown in FIGS. As shown in FIGS. 5(b) and 5(c), a stop hole 8 similar to that shown in FIGS. 2(a) and 3(b) is formed. A pair of mounting grooves 4a, 4b extending to the

Each of the mounting grooves 4a and 4b is arranged along the direction of the diameter of the stop hole 8 that intersects the direction in which the crack 2a extends. At this time, it is preferable that the direction of the diameter of the stop hole 8 in which the mounting grooves 4a and 4b are provided is a direction that intersects the direction in which the crack 2a extends at an angle as close to a right angle as possible. This is for the same reason as in the first embodiment.

The depth direction (depth direction) of the stop hole 8 and the pair of mounting grooves 4a and 4b is set in a direction that is not parallel to either the lower surface of the deck plate 14 or the side surface of the side wall 15a. This is so that the insertion member 3 can be inserted into the mounting grooves 4a and 4b from the space 17 between the deck plate 14 and the side wall 15a.

In this embodiment, as shown in FIG. 5(b), the depth direction of the stop hole 8 and the pair of mounting grooves 4a and 4b is set to be perpendicular to the side wall 15a. Further, the stop hole 8 and one mounting groove 4b are formed to penetrate the side wall 15a. According to this configuration, the insertion member 3 to be inserted into the mounting groove 4b can be arranged over the entire plate thickness of the side wall 15a. In addition, force can be transmitted between the side wall 15a and the insertion member 3 inserted into the mounting groove 4b while suppressing bias in the plate thickness direction of the side wall 15a.

On the other hand, the deck plate 14 is provided with the stop hole 8 and the other mounting groove 4a in a range up to a position corresponding to the position where the mounting groove 4b penetrates the side wall 15a. As a result, the deck plate 14 can be provided with the stop hole 8 and the mounting groove 4a in the area including the junction 16 with the side wall 15a where the crack 2a is generated.

The stop hole 8 and each mounting groove 4a, 4b can be provided at a position corresponding to the tip of the crack 2a, and the insertion member 3 can be inserted from the space 17 between the deck plate 14 and the side wall 15a. Of course, the depth direction may deviate from the direction perpendicular to the side wall 15a as long as it is possible to perform the operation of inserting it into each of the mounting grooves 4a and 4b.

The processing for providing the stop hole 8 and the mounting grooves 4a and 4b may be the same as in the first embodiment.

After forming the stop hole 8 and the mounting grooves 4a and 4b as described above, as shown in FIGS. As in the case of the form, it is inserted with the adhesive (structural adhesive) 13 applied. Any other application method may be adopted for the adhesive 13 as long as the insertion member 3 inserted into each of the mounting grooves 4a and 4b can be adhered and fixed to each of the mounting grooves 4a and 4b. This is the same as in the case of the first embodiment.

After that, the adhesive 13 is cured, and the insertion member 3 is attached to the inside of each of the attachment grooves 4a and 4b in a state of being fixed by adhesion.

As a result, as shown in FIGS. 4(b) and 5(c), the crack 2a generated in the joint 16 is formed with a stop hole 8 at a portion corresponding to the tip of the crack 2a, and a stop hole 8 is formed. 8 are connected to each other through the insertion member 3, which are positioned in the direction intersecting with the direction in which the crack 2a extends. Therefore, the joint portion 16 is formed with the crack growth suppression structure of the present embodiment.

The crack growth suppression structure formed by the crack growth suppression method of the present embodiment is provided with a stop hole 8 at a position corresponding to the tip of the crack 2a in the joint 16, so that the crack 2a becomes sharp. The tip is missing. Therefore, even if a load acting in the direction of opening the crack 2a acts on the deck plate 14 and the U-rib 15, the crack 2a is stopped. It is possible to suppress progress beyond the hole 8 .

Further, in the crack growth suppression structure of the present embodiment, even if the tip of the crack 2a remains at the periphery of the stop hole 8, the crack 2a is opened by the deck plate 14 and the U-rib 15. When a directional load is applied, the load is received by the insert member 3 attached to the attachment grooves 4a and 4b as in the first embodiment.

Therefore, the same effects as those of the first embodiment can be obtained by the crack growth suppression construction method and the crack growth suppression structure of the present embodiment.

In the crack propagation structure of the present embodiment, the protruding portions of the insert member 3 from the deck plate 14, the side wall 15a, and the joint portion 16 may be removed, or these portions may be removed in advance. It is of course possible to use an insert member 3 having a similar shape.

In addition, the crack growth suppression construction method and the crack growth suppression structure of the present disclosure are not limited only to the above embodiments.

The crack growth suppression method and crack growth suppression structure of the present disclosure can be applied to any metal object other than the plate material 1 and the joint 16 between the bridge deck plate 14 and the U-rib 15 in which a crack has occurred. Good, of course. Cracks generated in the metal object may be cracks other than cracks due to fatigue (fatigue cracks).

In addition, the direction, arrangement, and size of the stop hole 8 and the mounting grooves 4a and 4b may be appropriately changed according to the internal shape and external shape of the cracked metal object and the depth direction of the crack. is of course. Further, it goes without saying that the shape of the insertion member 3 in the insertion direction x may be appropriately changed according to the stop hole 8 and the mounting grooves 4a and 4b.

From the viewpoint of avoiding stress concentration as much as possible, it is preferable that the inner surfaces of the mounting grooves 4a and 4b on the far side are curved surfaces with a constant curvature. The curvature may change along the way.

The illustrated cross-sectional shape of the insertion member 3 is an example, and if the thickness of the portions 5a and 5b near both ends is made larger than the thickness of the central portion 6 therebetween, the plate of the portions 5a and 5b near both ends thickness, the thickness of the central portion 6, the ratio of both thicknesses, the dimensional ratio between the longitudinal direction and the direction perpendicular thereto in the cross-sectional shape, the position where the thickness of the portions 5a and 5b near both ends and the central portion 6 therebetween changes, and The plate thickness change rate and the like may be changed as appropriate.

Further, the insertion member 3 may partially have flat surfaces (flat surfaces) connected to the curved surfaces on the outer surfaces 7a and 7b of the end portions 5a and 5b and the outer surfaces 9a and 9b of the central portion 6. FIG. Similarly, the shape of each of the mounting grooves 4a and 4b may partially include a flat surface (flat surface) connected to the curved surface.

From the viewpoint that the mounting grooves 4a and 4b provided together with the stop hole 8 at the cracked portion of the metal object make it easier for the insertion member 3 to receive the force acting in the direction of opening the crack, the crack is formed. It is preferable to arrange them along the direction of the diameter of the stop hole 8 that intersects the extending direction at right angles. However, each of the mounting grooves 4a and 4b may be arranged along the direction of the diameter of the stop hole 8 whose crossing angle with the crack is not perpendicular.

The stop holes 8 provided at the tips of both cracks 2, 2a, the mounting grooves 4a, 4b, and the insertion member 3 mounted in the mounting grooves 4a, 4b may not be uniform in size and shape.

The second embodiment may be applied to arbitrary angle bends in metallic objects. Furthermore, the second embodiment may be applied to cracks that occur in portions where the surface is convexly curved, or cracks that occur in portions where the surface is curved and becomes convex or concave.

It goes without saying that various modifications can be made without departing from the gist of the present invention.

1 plate material (metallic object), 2, 2a crack, 3 insertion member, 4a, 4b mounting groove, 5a, 5b portions near both ends, 6 central portion, 7a, 7b outer surface, 8 stop hole, 9a, 9b outer surface, 10 Opening 11 Widened portion 12 Locking portion w1 Groove width w2 Groove width x Insertion direction

Claims (5)

A process of providing a stop hole at a position corresponding to the tip of the crack at the location where the crack occurs in the metal object;
A process of providing a pair of mounting grooves extending outward from a position along the diameter of the stop hole that intersects the direction in which the crack extends in the peripheral wall of the stop hole at the location where the crack occurs in the metal object; , do
In each of the mounting grooves, the groove width of the opening opening to the peripheral wall of the stop hole is set to be smaller than the diameter of the stop hole, and each of the mounting grooves is outside the peripheral wall of the stop hole. formed as a shape having a widened portion having a groove width larger than the groove width of the opening at a position where
The end-side portions of the insertion member having a shape in which the plate thickness of the end-side portions to be attached to the respective mounting grooves is larger than the plate thickness of the central portion are adhered to the insides of the respective mounting grooves. to fix it,
each of the mounting grooves is formed as a locking portion whose groove width monotonically decreases from the widened portion toward the opening;
A method for suppressing crack growth in which the portions near both ends of the insertion member are locked in the locking portions of the mounting grooves while the portions near the ends of the insertion member are inserted into the mounting grooves. The method for suppressing crack growth according to claim 1, wherein the insertion member has curved outer surfaces on both sides of the central portion. 3. The method for suppressing crack growth according to claim 1, wherein each of the mounting grooves is provided along a diametrical direction that perpendicularly intersects the crack in the stop hole. The stop hole and each mounting groove are provided so as to penetrate the metal object,
The dimension of the insertion member in the direction of insertion into each of the mounting grooves is set to be equal to or greater than the thickness of the portion of the metal object where the stop hole and each of the mounting grooves are provided. 4. The method for suppressing crack growth according to any one of 3. a stop hole provided at a position corresponding to the tip of the crack at the location of the crack in the metal object;
a pair of mounting grooves extending outward from a position along the diametrical direction of the stop hole intersecting the extending direction of the crack in the peripheral wall of the stop hole;
an insertion member having a shape in which the plate thickness of portions near both ends attached to each of the mounting grooves is larger than the plate thickness of the central portion;
The end portions of the insertion member are adhered and fixed inside the respective mounting grooves,
each of the mounting grooves is formed as a locking portion in which the groove width monotonically decreases from the widened portion located outside the peripheral wall of the stop hole toward the opening opening in the peripheral wall of the stop hole ,
A crack characterized in that the portions near both ends of the insertion member are locked to the locking portions of the mounting grooves in a state in which the portions near the ends of the insertion member are inserted into the mounting grooves. Progress control structure.

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