HK1154370B - Method for reinforcing structure for railway rolling stock and structure for railway rolling stock - Google Patents

Description

Method for reinforcing railway vehicle structure and railway vehicle structure

Technical Field

The present invention relates to a method of reinforcing a railway vehicle structure including corrugated plates and a frame body, and a railway vehicle structure.

Background

It has been conventionally known to use stainless steel, aluminum, or other materials as a railway vehicle structure. In a roof panel of a roof structure and a floor panel of a underframe of a railway vehicle, corrugated plates (hereinafter referred to as "thin corrugated plates") having a small thickness and a corrugated cross section are used in order to reduce the weight while maintaining the strength. Conventionally, reinforcing measures have been taken to enhance the rigidity of a roof structure and a fragile portion of a underframe of a railway vehicle by welding a reinforcing plate or the like. However, in the case where the weak portion to be reinforced is a part of the thin corrugated plate, it is difficult to join the reinforcing material by a welding method or by a bolt. For example, when the welding method is used, the manufacturing accuracy is lowered due to thermal strain, and when bolts are used, there is a problem that the bolt holes are broken, and the sealing performance for preventing water inflow (hereinafter referred to as water tightness) is lowered. And there is a problem in that the weight of the roof panel and the floor panel is increased by the reinforcing method.

Patent documents 1 to 4 propose techniques of using a carbon fiber reinforced resin for an outer panel and a frame member of a railway vehicle. By using these techniques, the vehicle structure can be greatly reduced in weight.

Patent document 1: japanese patent laid-open publication No. 5-213189;

patent document 2: japanese patent laid-open publication No. 6-263029;

patent document 3: japanese patent laid-open publication No. 7-81556;

patent document 4: japanese patent No. 3219278.

Disclosure of Invention

However, according to these techniques, since the main part of the railway vehicle structure is made of the carbon fiber reinforced resin, the ratio of the carbon fiber reinforced resin used in the structure is high. Since carbon fiber-reinforced resins are expensive and difficult to recycle as compared with metals, vehicle structures mainly composed of carbon fiber-reinforced resins have problems in that the cost is significantly increased and the recyclability is deteriorated. Therefore, in view of cost and recycling property, a thin corrugated plate made of metal such as stainless steel is used as a structural member, but it is currently the case that the weak portion of such a thin corrugated plate cannot be reinforced appropriately. Further, when the structural element formed of the carbon fiber reinforced resin is formed into a three-dimensional shape, a step of forming the carbon fiber reinforced resin into a predetermined shape is required, and the manufacturing efficiency is poor.

Accordingly, an object of the present invention is to improve the manufacturing accuracy and water-tightness of a railway vehicle structure, and to reduce the weight of a vehicle body, and to achieve a desired cost, recycling property, and manufacturing efficiency.

The method for reinforcing a railway vehicle structure according to the present invention includes a step of arranging a fiber sheet on at least a part of a metal frame and a step of bonding the fiber sheet to a part of the metal frame with an impregnating adhesive resin to form a fiber-reinforced resin member, in a structure including the metal frame and the metal frame connected to the metal frame and having a corrugated cross section perpendicular to a vehicle longitudinal direction. The term "fiber sheet" refers to a sheet in which fibers such as carbon fibers used for a fiber-reinforced resin are formed in a cloth shape and are not impregnated with a resin.

In the above method, a fiber-reinforced resin member bonded to a flexible fiber sheet is easily formed by impregnating and bonding the sheet to a portion of a metal sheet having a corrugated cross section in accordance with the shape of the sheet with an impregnating and bonding resin, and the structural body can be reinforced by a simple work while reducing the weight of the vehicle body. Further, since the fiber sheet is disposed on a part of the plate and impregnated and bonded to the plate, it is possible to avoid a reduction in manufacturing accuracy due to thermal strain and a reduction in water tightness due to a defect of the bolt hole. Further, since the fiber sheet is disposed in a part of the plate and the frame and the plate, which are main parts, are made of metal, appropriate cost and recycling property can be maintained. As described above, in the railway vehicle structure, it is possible to improve the manufacturing accuracy and the water-tightness, to reduce the weight of the vehicle body, and to maintain the appropriate cost, the recycling property, the manufacturing efficiency, and the like.

The railway vehicle structure of the present invention includes a metallic frame, a metallic plate joined to the frame and having a corrugated cross section perpendicular to the longitudinal direction of the vehicle, and a fiber-reinforced resin member joined to a part of the plate to reinforce the plate.

With the above configuration, as described above, it is possible to improve the manufacturing accuracy and the water-tightness, to reduce the weight of the vehicle body, and to maintain the cost, the recycling property, the manufacturing efficiency, and the like appropriately.

According to the present invention, in the railway vehicle structure, it is possible to improve the manufacturing accuracy and the water-tightness, to reduce the weight of the vehicle body, and to maintain the appropriate cost, the recycling property, the manufacturing efficiency, and the like.

Drawings

Fig. 1 is a perspective view of a part of a railway vehicle structure according to embodiment 1 of the present invention;

fig. 2 is a perspective view of a main portion of the roof structure shown in fig. 1;

FIG. 3 is an enlarged view showing a part of a section taken along line III-III of FIG. 2;

FIG. 4 (a) is a perspective view showing a defoaming roller for a plane, and (b) is a perspective view showing a defoaming roller for a corner;

FIGS. 5 (a) to (d) are explanatory views of a step of reinforcing the roof panel shown in FIG. 1 when a crack occurs;

FIG. 6 (a) is a plan view of a main portion of a connecting portion between the roof panel and the end structure shown in FIG. 1, (b) is a sectional view of the main portion thereof, and (c) is a schematic view corresponding to FIG. 6 (b) of a conventional example;

FIG. 7 is a main perspective view showing a connecting portion of the under frame and the floor shown in FIG. 1;

fig. 8 is a main part perspective view of the roof structure according to embodiment 2 of the present invention;

FIG. 9 is an enlarged view of a portion of the section along line IX-IX of FIG. 8;

FIG. 10 is an enlarged view of a portion of the X-X line section of FIG. 8;

fig. 11 is a schematic view corresponding to fig. 9 of the roof structure according to embodiment 3 of the present invention;

fig. 12 is a schematic view of the roof structure shown in fig. 11 corresponding to fig. 10;

description of the symbols

1 a railway vehicle structure;

2 a roof structure;

a 3-side structure;

4, a bottom frame;

5, a frame body;

6, a vehicle roof plate;

9, a floor board;

11 primer;

12 a carbon fiber-reinforced resin member;

13. 113A-H, 213A-C, 313A-C carbon fiber sheets;

14 is impregnated with a bonding resin.

Detailed Description

Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1

Fig. 1 is a perspective view showing a part of a railway vehicle structure 1 according to embodiment 1 of the present invention. As shown in fig. 1, the railway vehicle structure 1 includes a roof structure 2, side structures 3, end structures (not shown), and a underframe 4. The roof structure 2 includes a metal frame 5 including a side member and a rafter, and a metal roof panel 6 connected to an upper surface of the frame 5. The side structure 3 includes a metallic side outer plate 7 constituting a side wall and a plurality of metallic frame members joined to an inner surface of the side outer plate 7. A metal floor 9 is connected to the upper surface of the metal underframe 4. The metal used for these members may be stainless steel, aluminum, or other metal.

Fig. 2 is a main part perspective view of the roof structure 2. Fig. 3 is an enlarged view of a portion of the III-III line section of fig. 2. As shown in fig. 2 and 3, the roof panel 6 is a thin corrugated plate in which crests 6a and troughs 6b extending in the vehicle longitudinal direction X are alternately arranged in the vehicle width direction, and is corrugated in a cross section perpendicular to the vehicle longitudinal direction X. The roof panel 6 is thinner than the side outer panel 7 of the side structure 3, and has a thickness of 0.5 to 1.0mm (e.g., 0.6 mm). The roof panel 6 of the present embodiment is provided with a carbon fiber reinforced resin member 12 that can reinforce a partial region (for example, a central portion in the vehicle longitudinal direction X). The carbon fiber reinforced resin member 12 has a larger wall thickness than the roof panel 6.

The carbon fiber reinforced resin member 12 is specifically bonded by degreasing a portion to be reinforced on the upper surface of the roof panel 6, applying a primer 11 (for example, an epoxy resin) impregnated with an adhesive resin to the portion, and leaving the portion. Next, the primer 11 that cures with time is coated with an adhesive resin 14 (e.g., an epoxy resin) as a lower base, and a carbon fiber sheet 13 that is not impregnated with resin is laminated thereon before the lower base is cured. In this case, the carbon fiber sheet 13 is arranged in a corrugated shape along the roof panel 6 with its fiber direction substantially parallel to the vehicle longitudinal direction X. Next, the carbon fiber sheet 13 is coated with the impregnated adhesive resin 14, and the carbon fiber sheet 13 is left to stand while its surface is flattened by impregnating the impregnated adhesive resin 14 with the carbon fiber sheet 13 by deaeration rollers 20 and 30 (see fig. 4). Then, as time passes, the impregnated bonding resin 14 is cured, and the carbon fiber reinforced resin member 12 bonded to the roof panel 6 is formed. With this, the carbon fiber reinforced resin member 12 exerts an effect of reinforcing a predetermined portion of the thin roof panel 6. In the case where the recessed portion 6c is locally present in the portion of the roof panel 6 to be reinforced, the recessed portion 6c may be filled with the putty 15 so that the surface of the putty 15 and the surface of the portion adjacent thereto are formed into one surface, and then the primer 11 may be applied. However, if the curvature of the concave portion 6c is small, the primer 11 may be applied without filling the putty 15. One or more carbon fiber sheets 13 may be used.

Fig. 4 (a) is a perspective view showing the defoaming roller 20 for a plane, and fig. 4 (b) is a perspective view showing the defoaming roller 30 for a corner. As shown in fig. 4 (a) and (b), the defoaming rollers 20 and 30 include rod-shaped support portions 20a and 30a, roller portions 20b and 30b provided at one ends of the support portions 20a and 30a and having a plurality of grooves formed in the circumferential direction, and grip portions 20c and 30c provided at the other ends of the support portions 20a and 30 a. The roller portion 30b of the corner defoaming roller 30 is narrower than the roller portion 20b of the planar defoaming roller 20, and the surface is generally convex when viewed in a direction perpendicular to the rotation axis of the roller portion 30 b. These defoaming rollers 20 and 30 are used separately in different places, and the carbon fiber sheet 13 is impregnated with the impregnating adhesive resin 14 by rolling the roller portions 20b and 30b on the surface of the carbon fiber sheet 13 to form a corrugated shape that can match the roof panel 6 while expelling air between the roof panel 6 and the carbon fiber sheet 13.

Fig. 5 (a) to (d) are explanatory views for explaining a step of reinforcing the crack C of the roof panel 6. As shown in fig. 5 (a) and (b), reinforcement in the case where a crack C occurs in a part of the roof panel 6 will be described. In this case, as shown in fig. 5 (C), a portion including the crack C in the roof panel 6 is removed to form a circular hole-shaped opening S. Subsequently, as shown in fig. 5 (d), the opening S is closed by a cover plate 40. In this case, the cover plate 40 is temporarily fixed at two peripheral portions to the opening edge of the roof panel 6 by welding or the like. Thereafter, the carbon fiber sheet is bonded to the upper surface of the cover plate 40 and its periphery with an impregnating adhesive resin through a primer to form a carbon fiber reinforced resin member. Depending on the state of the crack C, the carbon fiber sheet may be directly bonded to the crack C and its periphery with an impregnating adhesive resin without providing the opening S. For example, when the crack does not progress further after the crack has occurred, the crack is linear, and water leakage is small, the crack does not need to be removed. On the other hand, when cracks continue to develop and are visible to the eyes and water leaks are relatively large, it is preferable to provide a cover plate after removing the cracks.

FIG. 6 (a) is a plan view of a main part showing a connecting part between the roof panel 6 and the end structure 50, and FIG. 6 (b)

Is a sectional view of a main part thereof, and FIG. 6 (c) is a schematic view corresponding to FIG. 6 (b) of the conventional example. As shown in fig. 6 (c), in the conventional example, when the front end portion of the roof panel 6 is joined to the upper end portion of the end structure 50, since the sealing property is required, the two are fixed to each other by spot welding W1, and fillet continuous welding W2 is further performed. Accordingly, the strain of the roof panel 6 due to the heat influence of the fillet continuous welding W2 is relatively large. Therefore, as shown in fig. 6 (a) and (b), the front end portion of the roof panel 6 is overlapped on a part of the upper end portion of the end structure 50, and the end portions are joined to each other by spot welding W1, the carbon fiber sheet is arranged so as to span over and cover the front end portion of the roof panel 6 and the upper end portion of the end structure 50, and the carbon fiber sheet is spanned over and bonded to the front end portion of the roof panel 6 and the upper end portion of the end structure 50 by impregnating adhesive resin, so that the carbon fiber reinforced resin member 51 is formed. With this, the strain of the roof panel 6 due to the thermal influence of the fillet continuous welding can be avoided, the sealing performance can be ensured, and the end portion of the roof panel 6 can be reinforced.

Fig. 7 is a perspective view of a main part showing a connecting portion of the underframe 4 and the floor 9. As shown in fig. 7, the floor panel 9 is a thin metal plate having a corrugated cross section perpendicular to the vehicle longitudinal direction X, and has a thickness of 0.6 to 1.2mm (e.g., 0.6 mm). A rear end member 60 having an inverted concave cross section and extending in the vehicle width direction is connected to the upper surface of the end beam 61 of the underframe 4. Before the end of the floor panel 9 is welded to the side surface of the rear end member 60 by fillet welding, a carbon fiber sheet is bonded to the end of the floor panel 9 with a primer therebetween in advance by an impregnated bonding resin to form a carbon fiber reinforced resin member 62. This can improve the rigidity of the floor panel 9 and stabilize the shape thereof. Thereafter, if the end portion of the floor panel 9 is connected to the side surface of the rear end member 60 by fillet welding, the floor panel 9 can be stabilized in shape by the carbon fiber reinforced resin member 62, and therefore, the occurrence of strain due to thermal influence can be suppressed. The carbon fiber reinforced resin member 62 may be provided in a position separated from the end of the floor panel 9 (fillet welded portion) by a distance L1 of 5 to 10mm and in a width range of a distance L2 of 50 to 100 mm.

As described above, the fiber-reinforced resin member 12 bonded to the roof panel 6 or the like can be easily formed by impregnating and bonding the flexible carbon fiber sheet 13 with the impregnating and bonding resin 14 along a partial region of the roof panel 6 or the floor panel 9 made of metal having a corrugated cross section, and the roof panel 6 or the like can be reinforced by simplified construction while achieving weight reduction of the vehicle body. Further, since the carbon fiber sheet 13 is disposed in a partial region of the roof panel 6 or the like and impregnated and bonded, the manufacturing accuracy is not lowered due to thermal strain, and the water tightness is not lowered due to bolt holes. The carbon fiber sheet 13 is disposed in a partial region of the roof panel 6 and the like, and the frame body 5, the roof panel 6 and the like, which are main parts, are made of metal, so that it is possible to maintain a desired cost and recycling property. As described above, the railcar structure 1 can improve the manufacturing accuracy and the water-tightness, reduce the weight of the vehicle body, and maintain the appropriate cost, the recycling property, the manufacturing efficiency, and the like.

Embodiment 2

Fig. 8 is a main part perspective view of the roof structure 102 according to embodiment 2 of the present invention. Fig. 9 is an enlarged view of a portion of the section along line IX-IX of fig. 8. Fig. 10 is an enlarged view of a portion of the X-X line section of fig. 8. As shown in fig. 8, in the roof structure 102 of the present embodiment, a plurality of carbon fiber thin plates 113A to 113H, which are rectangular in plan view, are laid on the upper surface of a partial region of the roof panel 6 with the primer 11 (see fig. 9) interposed therebetween. The step of forming the carbon fiber reinforced resin member by bonding these carbon fiber sheets 113A to 113H to a partial region of the roof panel 6 with an impregnated bonding resin is the same as that of embodiment 1, and therefore, a detailed description thereof is omitted here.

As shown in fig. 9, the roof panel 6 is joined to the frame 5 by spot welding W2. The rear end portion 113Aa of the carbon fiber sheet 113A and the front end portion 113Ba of the carbon fiber sheet 113B adjacent to the rear thereof are positioned above the frame 5. These opposing end portions 113Aa and 113Ba are arranged directly above the spot weld W2 with a gap therebetween. As shown in fig. 10, the right end 113Ab of the carbon fiber sheet 113A and the left end 113Cb of the carbon fiber sheet 113C adjacent to the right thereof are positioned at the peak 6a of the roof panel 6. These opposing ends 113Ab and 113Cb are joined to each other in an overlapping manner.

As described above, the carbon fiber sheets 113A to 113H are laid and arranged in a plurality of rectangular shapes in plan view, and the carbon fiber sheets to be handled by the operator at one time are small in size and convenient to handle. The end portions 113Aa and 113Ba of the carbon fiber thin plates 113A and 113B facing each other in the vehicle longitudinal direction keep a gap from the spot welding point W2, and therefore the end portions 113Aa and 113Ba are stably bonded. Further, since the adjacent end portions 113Ab, 113Cb of the carbon fiber thin plates 113A, 113C in the vehicle width direction are positioned at the peak portion 6a of the roof panel 6, impregnation and bonding operations of these end portions 113Ab, 113Cb are facilitated, and the bonding of these end portions 113Ab, 113Cb is stabilized. Since the end portions 113Ab and 113Cb overlap each other, even if there is an error in the size of one of the carbon fiber sheet plates 113A to 113H, the plurality of laid carbon fiber sheet plates can be easily formed into a desired size as a whole by adjusting the overlapping amount. The other structures are the same as those of embodiment 1, and therefore, the description thereof is omitted.

Embodiment 3

Fig. 11 is a schematic view corresponding to fig. 9 of a roof structure 202 according to embodiment 3 of the present invention. Fig. 12 is a schematic view of the roof structure 202 shown in fig. 11 corresponding to fig. 10. As shown in fig. 11 and 12, in the roof structure 202 of the present embodiment, a plurality of carbon fiber thin plates 213A to 213C and 313A to 313C are arranged in a stacked (for example, 2-layer) manner. As shown in fig. 11, the vehicle longitudinal direction end portions 313Aa and 313Ba of the carbon fiber thin plates 313A and 313B of the 2 nd layer are arranged apart from the vehicle longitudinal direction end portions 213Aa and 213Ba of the carbon fiber thin plates 213A and 213B of the 1 st layer by about 5 to 10mm, and the opposite end portions 313Aa and 313Ba are spaced apart from each other. That is, the end portions of the laminated carbon fiber sheets are arranged in a stepped shape, whereby the concentration of stress can be reduced.

As shown in fig. 12, the vehicle transverse direction end portions 213Ab, 213Cb of the carbon fiber thin plates 213A, 213C of the 1 st layer and the vehicle transverse direction end portions 313Ab, 313Cb of the carbon fiber thin plates 313A, 313C of the 2 nd layer are arranged at substantially the same positions as viewed from above. The right end portions 213Ab, 313Ab of the carbon fiber thin plates 213A, 313A and the left end portions 213Cb, 313Cb of the carbon fiber thin plates 213C, 313C adjacent to the right thereof are positioned at the peak portion 6a of the roof panel 6. These opposing right end portions 213Ab and 313Ab and left end portions 213Cb and 313Cb are disposed to protrude toward each other without overlapping each other.

As described above, if a plurality of carbon fiber thin plates 213A to 213C and 313A to 313C are laminated, desired strength and rigidity can be easily provided to the roof panel 6 and the like. The other structures are the same as those of embodiment 1, and therefore, the description thereof is omitted.

Examples

Next, an example of a construction procedure for joining a carbon fiber reinforced resin member to a railway vehicle structure will be described. The construction is carried out at an ambient temperature of about 0 to 40 ℃. First, various materials such as a carbon fiber sheet, a primer, and an impregnated adhesive resin are prepared. The carbon fiber sheet used was a high-elastic type direction member (FTS-C8-30 manufactured by Nippon iron composites Co., Ltd. (Nippon iron コンポジット Co., Ltd.)). The carbon fiber contained in the carbon fiber sheet is characterized in that the tensile strength is 1900N/mm²A tensile modulus of elasticity of 6.4 × 10⁵N/mm². The primer was a 2-liquid mixed epoxy resin (FP-NSL manufactured by Nippon iron composites: viscosity: about 1000 mPas), and a 2-liquid mixed epoxy resin (FR-E3 PL manufactured by Nippon iron composites: viscosity: about 4400 mPas) was used as the impregnating adhesive resin. Then, the following steps (1) to (7) are sequentially performed.

(1) Substrate processing

A predetermined portion to be reinforced is ground by a grinder (for example, # 100), or is subjected to so-called BG #80 finishing (the finishing direction is the vehicle longitudinal direction). Then, the surface of the predetermined portion is sufficiently degreased with acetone to remove dirt.

(2) Cutting of carbon fiber sheets

The carbon fiber sheet is cut into a desired shape corresponding to the predetermined portion with a cutting tool such as a cutter blade or a straight blade.

(3) Application of a primer

Brushing the primer with a coating roller at, for example, 200g/m²The coating is applied at the ratio of (a) to (b), and then cured for 2 to 4 hours or more (preferably about one day). Here, the primer is applied to protect the surface immediately after the roof panel is polished, and also to prevent the carbon fiber from directly contacting the roof panel and corroding due to a potential difference between the carbon fiber and the roof panel. That is, the primer also functions as an insulating layer. The amount of the primer applied is controlled because it is difficult to control the thickness of the resin during the application. The reason why the viscosity of the primer is lower than that of the impregnated bonding resin is to make the primer have a better affinity with the surface of the roof panel.

(4) Impregnated adhesive resin primer

The impregnated adhesive resin was primed with brush bristles from a coating roll. For example, 500g/m for each layer impregnated with adhesive resin²And (6) coating the bottom. The impregnated adhesive resin was mixed and measured at a predetermined mixing ratio (base agent: curing agent: 2: 1), and then uniformly mixed with a doctor blade.

(5) Adhesion of carbon fiber sheet

Before the primer coating is cured, the carbon fiber sheet is pressed by hand by an operator to be adhered along the corrugations of the roof panel. In this case, the carbon fiber sheet is not displaced because the impregnating adhesive resin has a high viscosity. The carbon fiber sheet was stroked with a deaeration roll, and the fibers were impregnated with the impregnated adhesive resin, and then left to stand for about 30 minutes. During the standing, the fiber was further impregnated by capillary action (the impregnated resin floated from between the fibers).

(6) Coating with impregnating adhesive resin

The brush bristles are coated with an impregnating adhesive resin by a coating roll. For example, the impregnating adhesive resin is used in the form of each layer of 300g/m²Primer coatingThe coating is less. Here, the primer coating is applied in an amount of 500g/m per layer²And 300g/m is adopted for each additional coating layer²Primer coating is much used for the purpose of supporting the sheet in the impregnation operation, and also for the purpose of efficiently impregnating the sheet with the resin by utilizing capillarity, as compared with over coating.

(7) After layer 2

And (4) returning as required, and adhering the carbon fiber sheets of the 2 nd and later layers. The amount of resin used between the sheets is determined in consideration of workability and ease of impregnation, but may be changed in accordance with the amount of fibers per unit volume so that the ratio of fibers to resin is kept substantially the same.

Claims (6)

1. A method of reinforcing a fragile portion of a roof panel or a floor panel of a railway vehicle structure, comprising

A step of arranging a flexible fiber sheet in a fragile portion of a metal panel such that a fiber direction thereof is in a vehicle longitudinal direction, the structure including the metal panel including a metal frame and a roof panel or a floor panel connected to the frame and having a corrugated cross section perpendicular to the vehicle longitudinal direction; and

bonding the fiber sheet to the fragile portion of the metal plate with an impregnated bonding resin to form a fiber-reinforced resin member for reinforcing the metal plate;

the metal-made plate is formed to have a wall thickness thinner than that of the fiber-reinforced resin member,

the step of disposing a fiber sheet includes a step of disposing the fiber sheet in a corrugated shape along a sheet made of the metal;

the step of forming the fiber-reinforced resin member includes degreasing the fragile part of the metal plate, applying a primer, curing the primer, applying the impregnating adhesive resin to the fragile part, priming the fragile part, laminating the fiber sheet before curing the impregnating adhesive resin, applying the impregnating adhesive resin to the top of the laminated fiber sheet, and impregnating the impregnated adhesive resin into the fiber sheet.

2. The method of reinforcing a fragile portion of a roof panel or a floor panel of a railway vehicle structure according to claim 1, wherein a recessed portion formed in the fragile portion of the metal panel is formed to be flush with a surface of an adjacent portion by applying putty to the recessed portion before the step of arranging the fiber sheet.

3. A method of reinforcing a fragile portion of a roof panel or a floor panel of a railway vehicle structure according to claim 1,

removing a portion surrounding a crack formed on a fragile portion of the metal-made sheet to form an opening and blocking the opening with a cover sheet, prior to the step of arranging the fiber sheet,

the step of arranging the fiber sheet is to arrange the fiber sheet so that the fiber sheet covers the covering sheet and the periphery thereof.

4. A method of reinforcing a fragile portion of a roof panel or a floor panel of a railway vehicle structure according to claim 1,

the metal-made plate is a roof panel, the roof panel is spot-welded to the frame body,

the step of disposing the fiber sheets is to lay a plurality of the fiber sheets such that ends of the plurality of fiber sheets facing each other in the vehicle longitudinal direction are disposed directly above the spot-welded portions with a space therebetween.

5. A method of reinforcing a fragile portion of a roof panel or a floor panel of a railway vehicle structure according to claim 1,

the step of arranging the fiber sheets comprises laying a plurality of the fiber sheets,

the plurality of fiber sheets are respectively formed into a rectangular shape in a plan view,

the step of arranging the fiber sheets disposes facing ends of adjacent fiber sheets among the plurality of fiber sheets on corrugated peaks of the metal plate.

6. A railway vehicle structure in which a fragile portion of a roof panel or a floor panel is reinforced, comprising

A frame body made of metal,

A metal-made plate of a roof panel or a floor panel joined to the frame and having a cross section perpendicular to the longitudinal direction of the vehicle formed in a corrugated shape, and

a fiber-reinforced resin member in which a flexible fiber sheet is impregnated and bonded to a fragile portion of the metal plate with an impregnating and bonding resin, and the fiber-reinforced resin member is joined to the fragile portion of the metal plate such that the fiber direction of the fiber sheet is arranged in the vehicle longitudinal direction to reinforce the metal plate,

the fiber-reinforced resin member is formed by degreasing a brittle portion of the metal plate, applying a primer, curing the primer, applying the impregnating adhesive resin to the primer, laminating the fiber sheet before curing the impregnating adhesive resin, applying the impregnating adhesive resin to the fiber sheet, and impregnating the impregnated adhesive resin into the fiber sheet,

the metal-made plate is formed to have a wall thickness thinner than that of the fiber-reinforced resin member,

the fiber-reinforced resin member is arranged in a corrugated shape along the metal plate.