BOGIE FRAME FOR A RAILWAY VEHICLE

Abstract

A bogie frame for a railway vehicle, the bogie frame including structural members defining the frame, and one or more reinforcing components joining the structural members, the or each reinforcing component including: a first fibre-reinforced plastic layer having spaced first and second end portions, the first end portion attaching to a first structural member of the bogie frame, and the second end portion attaching to a second structural member of the bogie frame, wherein the first and second structural members are also joined together by one or more fastening bolts; and a second fibre-reinforced plastic layer disposed on a mid part of the first fibre-reinforced plastic layer between its first and second end portions such that the first and second end portions are left uncovered by the second fibre-reinforced plastic layer, wherein a central portion of the reinforcing component that is stronger than the first and second end portions.

Claims

1. A bogie frame (6) for a railway vehicle (1), the bogie frame (6) comprising structural members (14, 16) defining the frame (6), and one or more reinforcing components (60, 60a, 60b, 60c, 160, 260) joining the structural members (14, 16), the or each reinforcing component (60, 60a, 60b, 60c, 160, 260) comprising: a first fibre-reinforced plastic layer (70, 170, 270) having spaced first and second end portions (72, 74, 172, 174, 272, 274), the first end portion (72, 172, 272) attaching to a first structural member (14) of the bogie frame (6), and the second end portion (74, 174, 274) attaching to a second structural member (16) of the bogie frame (6), wherein the first and second structural members (14, 16) are also joined together by one or more fastening bolts (62); and a second fibre-reinforced plastic layer (76, 176, 276) disposed on a mid part of the first fibre-reinforced plastic layer (70, 170, 270) between its first and second end portions (72, 74, 172, 174, 272, 274) such that the first and second end portions (72, 74, 172, 174, 272, 274) are left uncovered by the second fibre-reinforced plastic layer (76, 176, 276), wherein the second fibre-reinforced plastic layer (76, 176, 276) forms with the mid part of the first fibre-reinforced plastic layer (70, 170, 270) a central portion (78, 178, 278) of the reinforcing component (60, 60a, 60b, 60c, 160, 260) that is stronger than the first and second end portions (72, 74, 172, 174, 272, 274), and wherein at least the first and second end portions (72, 74, 172, 174, 272, 274) of the first fibre-reinforced plastic layer (70, 170, 270) are transparent or translucent.

2. The bogie frame (6) according to claim 1, wherein the first fibre-reinforced plastic layer (70, 170, 270) is made of a glass-fibre-reinforced plastic, for example a glass-fibre-reinforced epoxy resin.

3. The bogie frame (6) according to claim 1, wherein the second fibre-reinforced plastic layer (76, 176, 276) is made of a carbon-fibre-reinforced plastic, for example a carbon-fibre-reinforced epoxy resin.

4. The bogie frame (6) according to claim 1, wherein the first end portion (172) is smaller than the second end portion (174).

5. The bogie frame (6) according to claim 1, wherein the first and/or the second end portion (272, 274) is divided into a plurality of fingers (296, 298) which attach to the respective structural member (14, 16).

6. The bogie frame (6) according to claim 1, wherein the or each reinforcing component (260) further comprises one or more sensors (394) configured to monitor strain in the first and/or second end portions (272).

7. The bogie frame (6) according to claim 1, wherein the or each reinforcing component (60) further comprises a removable cover (480) configured to protect an exposed surface of one of the first and second end portions (72, 74).

8. A bogie frame (6) according to claim 1, wherein the first and second end portions (72, 74, 172, 174, 272, 274) are adhesively bonded to respectively the first and second structural members (14, 16).

9. The bogie frame (6) according to claim 1, wherein the reinforcing component (60, 60a, 60b, 60c, 160, 260) extends between the first and second end portions (72, 74, 172, 174, 272, 274) in a direction which is parallel to that of the one or more fastening bolts (62) which join the first and second structural members (14, 16).

10. The bogie frame (6) according to claim 1, wherein the first structural member (14) is one of a pair of side members, which when mounted on the railway vehicle (1), extend in a longitudinal direction (L) of the railway vehicle (1) and the second structural member (16) is a centre member which, when mounted on the railway vehicle (1), extends in a transverse direction (T) of the railway vehicle (1) between the side members.

11. The bogie frame (6) according to claim 1, wherein the first structural member (14) and/or the second structural member (16) is formed of aluminium alloy.

12. A method of monitoring the health of the bogie frame (6) according to claim 1, the method including: inspecting either or both of the transparent or translucent end portions (72, 74, 172, 174, 272, 274) of the reinforcing component (60, 60a, 60b, 60c, 160, 260) for damage (80) to the first fibre-reinforced plastic layer (70, 170, 270) in the end portions (72, 74, 172, 174, 272, 274); and determining that the joint between the first and second structural members (14, 16) is deteriorating when damage (80) to the first fibre-reinforced plastic layer (70, 170, 270) in the end portions (72, 74, 172, 174, 272, 274) is detected.

Description

SUMMARY OF THE FIGURES

[0042] Embodiments and experiments illustrating the principles of the invention will now be discussed with reference to the accompanying figures in which:

[0043] FIG. 1 shows a schematic side-view of a railway vehicle including a bogie;

[0044] FIG. 2A shows a schematic of an example bogie frame in a perspective view;

[0045] FIG. 2B shows an enlarged section of the bogie frame depicted in FIG. 2A, illustrating an example of a bolt connection between a side member and centre member;

[0046] FIG. 2C shows the bogie frame of FIG. 2A in a front and a section view, respectively;

[0047] FIG. 3A shows the bogie frame of FIG. 2A including additional elements;

[0048] FIG. 3B shows the bogie frame of FIG. 3B in an exploded view;

[0049] FIG. 4 shows the bogie frame of FIG. 3A in a side view;

[0050] FIG. 5 shows an enlarged section of the bogie frame depicted in FIG. 3A illustrating examples of integrated fastening elements;

[0051] FIGS. 6A-6C show examples of a first strengthener attachable to the bogie frame of FIG. 3A;

[0052] FIGS. 7-8 show examples of a second strengthener attachable to the bogie frame of FIG. 3A;

[0053] FIG. 9 shows a schematic drawing of a bogie frame which is a development of the bogie frame of FIG. 3A, including a plurality of reinforcing components;

[0054] FIG. 10 is a cross-sectional view of part of the bogie frame of FIG. 9, showing a fastening bolt and a reinforcing component;

[0055] FIG. 11 shows a schematic drawing of a simpler version of the reinforcing component;

[0056] FIG. 12 shows a schematic drawing of a damaged reinforcing component;

[0057] FIG. 13 shows a schematic drawing of part of the bogie frame of FIG. 9 having a plurality of reinforcing components;

[0058] FIG. 14 shows a schematic drawing of a variant reinforcing component;

[0059] FIG. 15 shows a schematic drawing of a reinforcing component according to a further variant;

[0060] FIG. 16 shows a schematic drawing of part of the bogie frame of FIG. 9 having the reinforcing component according to FIG. 15; and

[0061] FIG. 17 shows a schematic drawing of the reinforcing component of FIG. 11 fitted with removable covers.

DETAILED DESCRIPTION OF THE INVENTION

[0062] Further background to the present invention, and aspects and embodiments of the present invention will now be discussed with reference to the accompanying figures. Further aspects and embodiments will be apparent to those skilled in the art. All documents mentioned in this text are incorporated herein by reference.

[0063] FIG. 1 shows a schematic side-view of a railway vehicle 1 including a bogie 2. The bogie 2 is positioned underneath the railway vehicle 1 over the track 4. The bogie 2 comprises a bogie frame 6, 6 for supporting the railway vehicle 1. The bogie frame 6, 6 is coupled to a set of wheels 8 via respective axles (not shown).

[0064] Usually, two bogies (not shown) are fitted to each car body 10 of the railway vehicle 1, one near each end of the car body 10. However, the bogie 2 may be disposed between adjacent car bodies 10. The bogie 2 is important for providing stability to the railway vehicle 1 by absorbing strong vibrations and high centrifugal forces, particularly on curved sections of the track 4.

[0065] FIG. 2A shows an example of a bogie frame 6 in a perspective view. The depicted bogie frame 6 comprises two side members 14 and a centre member 16. The depicted straight side members 14 include extruded profiles 14a made of an aluminium alloy. Preferably, the aluminium alloy may be an aluminium alloy of the 6xxx series. The extrusion direction of the extruded profiles 14a is arranged in a longitudinal direction L of the railway vehicle 1 when the bogie frame 6 is mounted thereto.

[0066] The depicted centre member 16 comprises a cast element 18 being a cast multi-chamber element 18 which may be made from metal casting. In the depicted examples of the centre member 16 shown in FIGS. 2A to 8, the entire centre member 16 is a cast element 18 being a multi-chamber element 18.

[0067] However, it may also be possible that only a part of the centre member 16 consists of a cast multi-chamber element 18 and further parts thereof may have other designs.

[0068] For example, the cast material of the multi-chamber element 18 may be iron-based or aluminium alloy. Preferably, the cast material may be an aluminium alloy. The depicted centre member 16 has an opening 18c in a top view, which is arranged symmetrically to a longitudinal axis of the centre member 16. By arranging the opening 18c as shown in FIG. 2A, the centre member 16 comprises two facing cross beams which are connected to each other at the sides of the centre member 16 adjacent to the extruded profiles 14a. This may allow for a uniform distribution of the lateral loads to be absorbed by the bogie frame 6.

[0069] In the upper surface 18a of the cast multi-chamber element 18 there are provided two recesses 18d for receiving first strengtheners 20, the bottom 18da of which lies in a plane parallel to the upper surface 18a. The insertion of the first strengtheners 20 into the recesses 18d will be described later in connection with FIGS. 6A and 6B.

[0070] FIG. 2B shows an enlarged section of the bogie frame 6 depicted in FIG. 2B illustrating an example of a bolt connection 22 between the side members 14 and the centre member 16. In particular, FIG. 2B depicts two contact surfaces 24 at which the side member 14 is jointed to the centre member 16. The depicted side member 14 is connected to the centre member 16 at the contact surfaces 24 by means of the bolt connection 22.

[0071] FIG. 2C shows the centre member 16 of the bogie frame 6 of FIG. 2C in a front view and the extruded profiles 14a of the side members 14 in a section view along the line A-A depicted in FIG. 2C. In this view, the plurality of chambers included in the multi-chamber element 18 is clearly visible. It can be seen that the chambers are formed, e.g., by ribs 18cb, 18cc disposed perpendicularly and parallel to the upper and lower surfaces 18a, 18b of the multi-chamber element 18. In addition, two inclined ribs 18ca are visible, which form a transition to the short side arms 18e of the multi-chamber element 18 being U-shaped in longitudinal section. The two inclined ribs 18ca may be arranged at a predetermined angle to the lower surface 18b of the multi-chamber element 18. Moreover, contact surfaces 24a are provided on each of the outward-facing sides of the side arms 18e.

[0072] Another contact surface 24a is provided adjacent to the upper surface 18a of the multi-chamber element 18 on both sides thereof facing a contact surface 24b of the extruded profile 14a. Further, one can recognize a fastening element 26 at a front side of the centre member 16, which is integrated in the cast structure of the multi-chamber element 18. This fastening element 26, may be an element for connecting the bogie frame 6 to a centre pin (not depicted) mounted on the car body 10.

[0073] Furthermore, it can be derived from FIG. 2C that the extruded profile 14a of the side member 14 comprises a plurality of hollow profiles 14b which may be obtained from a single extrusion process. In the depicted case, each extruded profile 14a includes five hollow profiles 14b. The extruded profiles 14a may be arranged at the railway vehicle 1 such that its extrusion direction is along the longitudinal direction L of the railway vehicle 1. This allows for providing side members 2 having a lightweight structure with high bending stiffness.

[0074] An advantage of the bogie frame 6 shown in the FIGS. 2A to 2C is that its arrangement corresponds to the multidirectional loads it must withstand. Since the side members 14 must withstand the bending load applied by the weight of the car body 10, the extruded profile 14a shown in FIG. 2C is suitable for achieving the lightweight structure with high bending stiffness. On the other hand, the centre member 16 must withstand not only the bending load but also lateral and torsion loads. Therefore, a more complex shape such as the U-shaped longitudinal section with multiple chambers shown in FIG. 2C is desirable, which can be provided by a casting process. In addition to saving weight, the depicted bogie frame 6 reduces the number of the single parts by incorporating fastening elements 26 into the cast structure.

[0075] FIG. 3A shows the bogie frame 6 including side members 14 with cast curved elements 28. FIG. 3B shows the bogie frame 6 of FIG. 3A in an exploded view.

[0076] In this example, each side member 14 comprises a straight extruded profile 14a and two cast curved elements 28 made from metal casting. The depicted straight extruded profiles 14a include a plurality of holes 64 for connecting them with the centre member 16 by bolt connections (fastening bolts) 62 (cf. FIG. 2B). The depicted cast curved elements 28 can be jointed to the straight extruded profiles 14a by a bolt connection 42 or the adhesive bond at joining points 34, which will be further described in connection with FIGS. 4 and 5.

[0077] For example, the cast curved elements 28 may be made of iron or aluminium alloy. Preferably, the cast curved elements 28 may be made of an aluminium alloy. Most preferably, the aluminium alloy may be a cast alloy of the 7x xx.x series.

[0078] The cast curved elements 28 shown in FIGS. 3A and 3B include a first section 28a, formed as an open hollow profile 28aa with lateral openings 28ab on both sides, the first section 28a having an arcuate shape in longitudinal section (cf. also FIG. 4). Furthermore, the cast curved elements 28 comprise a second section 28b adjacent to the first section 28a, which is formed as a closed hollow profile 28bb having a rectangular longitudinal section. The second section 28b includes an integrated receptacle 28ba for receiving at least one wheel 8 of the railway vehicle 1.

[0079] In other words, the curved element 28 comprises an integrated connecting part 28ba that allows the curved element 28 to be coupled to at least one wheel 8 of the railway vehicle 1. This means that cast curved elements 28 allow the bogie frame 6 to be connected to the set of wheels 8 via the integrated connecting parts 28ba.

[0080] As visible in FIG. 3B, the cast curved element 28 is connected to the extruded profile 14a of the side member 14 by joining an outer end of the first section 28a, disposed opposite to an end adjacent to the second section 28b, to an outer end of the extruded profile 14a. Since the cast curved elements 28 are jointed to the extruded profile 14a by a bolt connection 22 and/or an adhesive bond, stresses due to welded joints can be avoided, allowing an improvement in the mechanical strength and stiffness of the bogie frame 6.

[0081] FIG. 4 shows the bogie frame 6 of FIG. 3A in a side view. In this view it becomes apparent that the depicted side member 14, which comprises a straight extruded profile 14a and two cast curved elements 28, allocates a space 36 between the bogie 2 and the car body 10 in which electric sensors and structural components of the railway vehicle 1 may be arranged. Additionally, the shape of the cast curved elements 28 including a first section 28a and a second section 28b, as described in connection with FIGS. 3A and 3B, is clearly visible in the side view of FIG. 4. Inside the open profile 28aa of the first section 28a, joining points 38a are disposed for attaching strengtheners 38 to the curved element 28.

[0082] Furthermore, the position of the joining points 38a, at which the cast curved element 28 is connected to the extruded profile 14a, is depicted in FIG. 4. It can be seen, that in case of bolt connections 42 at these joining points 38a, the position has to be adjusted to avoid interference with the holes 64 for bolt connection between the side members 14 and the centre member 16.

[0083] FIG. 5 shows an enlarged section of the bogie frame 6 depicted in FIG. 3B illustrating examples of integrated fastening elements 26, 40. Beside the integrated fastening element 26, which may be used for connecting the bogie frame 6 to the centre pin (not depicted), a further bracket 40 is shown in FIG. 5, which may be used for attaching the motors (not shown) or the brakes (not shown) of the railway vehicle 1 to the bogie frame 6. The depicted bogie frame 6 enables an improvement in mechanical strength and stiffness at the interface of the bracket 40 and the fastening element 26 to the centre member 16, as these elements 26, 40 can already be formed during casting, so that no subsequent welding is necessary.

[0084] Furthermore, the enlarged section of the bogie frame 6 shown in FIG. 5 illustrates the joining points with the respective bolt connections 42 for coupling the curved element 28 to the extruded profile 14a. Furthermore, joining points for attaching strengtheners 38 to the curved element 28 can be seen, which are described in more detail in the following FIGS. 6A-6C.

[0085] FIG. 6A-6C show examples of a first strengthener 20, 44 attachable to the bogie frame 6. In particular, FIG. 6A shows an exploded view of exemplary strengtheners 44 and exemplary first strengtheners 20 which can be attached to the cast curved element 28 and the cast multi-chamber element 18, respectively. FIG. 6B shows an example of a first strengthener 20 embedded in the upper surface 18a of the multi-chamber element 18 of the centre member 16, and FIG. 6C shows an example of a strengthener 44 attached to the cast curved element 28 of the side member 14.

[0086] The depicted strengthener 44 is a flat element which can be inserted into the cast structure of the curved element 28 of the side member 14 (cf. FIG. 6C). Since the depicted cast curved element 28 is designed as an open profile, the stiffness of the curved element 28 can be increased by inserting the flat reinforcing element 44 thereto.

[0087] Each strengthener 44 may be fixed to the respective cast curved element 28 by a bolt connection via the joining points 44a. It may be also possible to fix the strengtheners 44 to the cast curved elements 28 by means of adhesive bonds. The strengthener 44 may be made of steel and/or carbon fibre-reinforced plastic (CFRP). The strengtheners 44 may be produced using a casting process or any other suitable production process.

[0088] The depicted first strengtheners 20 are also flat elements having approximately the form of a bird. They are inserted into a recess 18d provided in the upper surface 18a of the multi-chamber element 18 such that it forms a flat surface with the latter (cf. FIG. 6B). To achieve this flat surface, a shape of the recess 18d in a plane parallel to the upper or lower surface 18a, 18b may correspond to a shape of the first strengthener 20 in longitudinal and transverse directions thereof, and a depth of the recess 18d may correspond to a thickness of the first strengthener 20.

[0089] Having a bird shape means for the first strengthener 20 to extend longitudinally and transversely of the railway vehicle 1 when inserted into the recess 18d in the upper surface 18a of the multi-chamber element 18a. In this case, an extension in the longitudinal direction L of the railway vehicle 1 is larger than an extension in the transverse direction thereof. Furthermore, the bird shape of the first strengthener 20 results in a symmetrical shape of the extension in the longitudinal direction L of the railway vehicle 1, wherein a width of the extension in this longitudinal direction L increases with increasing distance from a transverse axis of the first strengthener 20.

[0090] The bird shape may, for example, be achieved by forming an outer contour of the first strengthener 20 in a top view such that an outer contour of a side thereof facing an outside of the centre member 16 in the longitudinal direction L of the railway vehicle 1 has a W-shape and an outer contour of an opposite side has a T-shape, wherein the bottom of the W and the top of the T are facing each other (cf. also FIG. 2B). Opposite ends of the T-shaped and W-shaped outer contour may be connected to each other by a straight line, to complete the entire outer contour of the first strengthener 20 (and the corresponding recess 18d).

[0091] Inserting the first strengthener 20, having approximately the form of a bird in a top view, in a recess 18d in the upper surface 18a of the multi-chamber element 18 further increases the stiffness thereof without limiting the space required for mounting the components of the railway vehicle 1.

[0092] The first strengtheners 20 may also be made of steel and/or CFRP. They may be fixed to the centre member 16 by bold connections and or adhesive bonds. The first strengtheners 20 may be produced using a casting process or any other process appropriate to create the specific shape of the first strengthener 20.

[0093] FIGS. 7 and 8 show examples of a second strengthener 48 attachable to the bogie frame 6.

[0094] In particular, FIG. 7 shows an enlarged section of the centre member 16 to which second strengtheners 48 are attached. The second strengtheners 48 include struts 48a, having a cylindrical cross section, which are mounted with mounting brackets 50 on the upper surface 18a of the multi-chamber element 18.

[0095] The struts 48a extend in longitudinal direction of the centre element 16, which means they can increase the stiffness in lateral direction of the bogie frame 6. In the presented case, each second strengthener 48 uses three mounting brackets 50 to keep the struts 48a in the desired position. The second strengtheners 48 may be connected via the mounting brackets to the upper or lower surface 18a, 18b of the cast multi-chamber element 18 by a bolt connection and/or an adhesive bond.

[0096] Preferably, the second strengtheners 48 may be made of CFRP. This allows for increasing the stiffness of the centre member 16 without increasing its weight significantly.

[0097] FIG. 8 depicts a further example of the second strengthener 48 which uses elastic adhesive bonds 52 having high damping properties to mount the second strengthener 48 on the upper surface 18a of the multi-chamber element 18. Especially, the struts 48a of the second strengthener 48, having a rectangular cross section, are equipped with the elastic adhesive bonds 52 via which the struts 48a are fixed to the mounting brackets 50.

[0098] Furthermore, the brackets 50 may also be fixed to the upper surface 18a of the multi-chamber element 18 via elastic adhesive bonds (not shown). The damping effect of the elastic adhesive material can contribute to absorption of the vibration and noise when transmitting through the bogie frame 6. In addition, the bonding with the elastic adhesive can contribute to reduction of the thermal stress induced by the mismatch of the thermal properties between the CFRP and the cast material of the multi-chamber element 18. This results in improved mechanical strength and stiffness at the adhesive bond area on the upper surface 18a of the multi-chamber element 18.

[0099] FIG. 9 shows a schematic drawing of a second bogie frame 6 which is a development of the first bogie frame 6 described above. Features of the second bogie frame 6 corresponding to those of the first bogie frame 6 are referred to herein and in the accompanying Figures by the same reference characters. Compared to the first bogie frame 6, the second bogie frame 6 is shown in FIG. 9 with additional equipment mounted on the centre member 16. Significantly, the second bogie frame 6 also includes a plurality of reinforcing components 60. The reinforcing components 60 are different from the strengtheners 20, 44, 48 in that the reinforcing components 60 strengthen the joints between the side members 14 and the centre member 16, whereas the strengtheners 20, 44, 48 strengthen the respective side members 14 and centre member 16 individually. The centre member 16 is bolted to the pair of side members 14 via a plurality of fastening bolts 62. Each of the pair of side members 14 may be considered a first structural member 14 of the bogie frame 6, and the centre member 16 may be considered a second structural member 16 of the bogie frame 6.

[0100] Although the fastening bolts 62 are configured to receive most of the load between the side members 14 and the centre member 16, the side members 14 are also joined to the centre member 16 by the reinforcing components 60, which extend between the side members 14 and the centre member 16 in the transverse direction T of the railway vehicle 1, which is substantially parallel to the direction of the fastening bolts 62. Specifically, in FIG. 9 there are four reinforcing components 60, with one at each corner of the centre member 16, whereby each side member 14 is joined to the centre member 16 by a pair of the reinforcing components 60.

[0101] In normal operation, each fastening bolt 62 and each reinforcing component 60 forms a joint between the structural members 14, 16 and supports a respective load across the structural members 14, 16. If one of the fastening bolts 62 partially or completely fails, its load transfers to the remaining bolts 62 and to the reinforcing component(s) 60 across the same joint. This load transfer can increase the load across a particular reinforcing component 60 to such an extent that visible damage accumulates on that reinforcing component 60, as discussed in more detail below. In this way, the joints between the side members 14 and the centre member 16 can be monitored for failure of the fastening bolts 62, even when most of the fastening bolts 62 have not failed and the joint as a whole appears to be fully intact and capable of transmitting the necessary loads between the structural members 14, 16. Therefore, the visible damage gives an early indication that a fastening bolt 62 has failed, providing an opportunity to tighten, repair or replace the failed bolt 62 before subsequent failure of any of the remaining bolts 62 or rupture of either of the reinforcing components 60 occurs.

[0102] FIG. 10 is a cross-sectional view of part of the bogie frame 6. The cross-section lies in a plane normal to the longitudinal direction L and bisects one of the fastening bolts 62 and one of the reinforcing components 60. The reinforcing component 60 can be seen to be attached to an upper surface 18a of the bogie frame 6, where it is adjacent to and aligned with the fastening bolt 62 in order to minimise the separation between the reinforcing component 60 and the fastening bolt 62.

[0103] In this configuration, failure of the particular fastening bolt 62 can be identified with more certainty. In particular, if the reinforcing component 60a is visibly more damaged than the other reinforcing component 60 on the same side of the centre member 16, it is more likely that the damage was caused by failure of the particular fastening bolt 62 rather than other more distant fastening bolts.

[0104] Each reinforcing component 60 is formed as a strip and comprises a planar, first fibre-reinforced plastic layer 70 having a first end portion 72 and a second end portion 74, the first 72 and second 74 end portions being spaced in the direction T. The first end portion 72 is attached to a platform formed on an upper surface 15 of the side member 14 (first structural member 14). The second end portion 74 is attached to a platform formed on an upper surface 18a of the centre member 16 (second structural member 16).

[0105] The first end portion 72 and the second end portion 74 are adhesively bonded to their platforms on the side member 14 and the centre member 16, respectively. A structural adhesive such as epoxy, acrylic or urethane can be used to form the adhesive bond. The adhesive bond is generally lighter than an equivalent mechanical fixing and reduces stress concentrations in the reinforcing component 60 and the structural members 14, 16.

[0106] The reinforcing component 60 further comprises a second fibre-reinforced plastic layer 76 disposed on a mid part of the first fibre-reinforced plastic layer 70 between its first end portion 72 and its second end portion 74 such that the first and second end portions 72, 74 are left uncovered by the second fibre-reinforced plastic layer 76. The second fibre-reinforced plastic layer 76 forms with the mid part of the first fibre-reinforced plastic layer 70 a central portion 78 of the reinforcing component 60 that is stronger than the first and second end portions 72, 74.

[0107] Additionally, the first 72 and second 74 end portions of the first fibre-reinforced plastic layer 70 are transparent or translucent. Preferably, the first fibre-reinforced plastic layer 70 is made of glass fibre-reinforced plastic (GFRP), e.g. a glass-fibre-reinforced epoxy resin, which is inherently translucent. Preferably, the second fibre-reinforced plastic layer 76 is made of a carbon-fibre-reinforced plastic (CFRP), e.g. a carbon-fibre-reinforced epoxy resin.

[0108] In FIG. 10, the mid part of the first fibre-reinforced plastic layer 70 and second fibre-reinforced plastic layer 76 narrow to a central waist. In addition, the first 72 and second 74 end portions are each divided into two fingers (although being bisected on the cross-sectional view of FIG. 10, only one finger of each end is actually shown in FIG. 10). Such features are discussed below in more detail in respect of FIG. 15. However, FIG. 11 shows a schematic drawing of a simpler version of the reinforcing component 60 in which the first fibre-reinforced plastic layer 70 is a simple rectangle, and the second fibre-reinforced plastic layer 76 is a further simple rectangle, centrally disposed on the mid part of the first fibre-reinforced plastic layer 70.

[0109] FIG. 12 shows a schematic drawing of the reinforcing component 60 of FIG. 11 after it has sustained damage. Visible damage accumulation in the form of cracks 80 due to load transfer into the component after failure of a fastening bolt 62 is focused in the transparent or translucent first 72 and second 74 end portions of the first fibre-reinforced plastic layer 70 rather than in the central portion 78 which is strengthened by the second fibre-reinforced plastic layer 76. In other words, the reinforcing component 60 is deliberately configured to have weaker regions at the first 72 and second 74 end portions, to direct damage to accumulate in regions where it can be made visible upon inspection.

[0110] FIG. 13 shows a schematic drawing of part of the bogie frame 6 in which a plurality of reinforcing components 60a, 60b, 60c of the simpler version are spaced at regular intervals in a row along a line of the joint between the structural members 14, 16. Each reinforcing component 60a, 60b, 60c extends parallel to and directly above a respective fastening bolt, the positions of which are indicated by their holes 64a, 64b, 64c.

[0111] In this configuration, the reinforcing components 60a, 60b, 60c can provide a visual indication of how the joint may be opening under bolt failure. For example, if the joint is opening more at the end of the row where reinforcing component 60a is located, then the expectation would be that the amount of visible damage accumulation would be greatest in the first and/or second end portions 72, 74 of reinforcing component 60a, and least in the first and/or second end portions 72, 74 of reinforcing component 60c. Conversely, if the joint is opening more at the other end of the row, then the expectation would be reversed, with greater amounts of visible damage accumulation in the first and/or second end portions 72, 74 of reinforcing component 60c. Related to this, the locations of the reinforcing components 60a, 60b, 60c may assist with identification of the fastening bolt which has failed. For example, if the fastening bolt at hole 64a fails, more of its load will tend to transfer to the closest reinforcing component 60a than to the other reinforcing components 60b, 60c. Consequently, the formation of cracks 80 in the first 72 and/or second 74 end portions of the closest reinforcing component 60a may be an indication that the fastening bolt in the first hole 64a has failed.

[0112] The reinforcing components 60 of the bogie frame 6 in FIG. 9 and the reinforcing components 60a, 60b, 60c of the bogie frame 6 in FIG. 13 are all shown being substantially identical to each other. However, a given bogie frame 6 may have reinforcing components 60 which exhibit different mechanical properties, e.g. different strengths. This can be useful to manage an uneven load distribution across the joint between the side member 14 and the centre member 16. For instance, if one fastening bolt 62 transmits a greater load than other fastening bolts, an adjacent reinforcing component may be correspondingly strengthened in order that it can accept a higher load transfer from that bolt in the event of bolt failure.

[0113] In FIGS. 9 to 13, the reinforcing components 60, 60a, 60b, 60c have equally sized first end portions 72 and second end portions 74. In contrast, FIG. 14 shows a variant, asymmetric reinforcing component 160 in which the first end portion 172 is smaller than the second end portion 174. The first fibre reinforcing plastic layer 170 has the same configuration as in FIG. 12, but in FIG. 14 the first end portion 172 extends from the central portion 178 over a shorter distance than the second end portion 174. In other words, the second fibre reinforcing plastic layer 176 is bonded to the first fibre reinforcing plastic layer 170 closer to the first end portion 172.

[0114] By such an adjustment, the load distribution in the reinforcing component 160 can be such that damage accumulation in the first end portion 172 is more concentrated and therefore easier to view than damage accumulation in the second end portion 174. Conveniently, the first end portion 172 can then be located at a more accessible location on the bogie frame 6, e.g. on an outer side of the bogie frame 6 attaching to the side member 14, rather than attaching to the less reachable centre member 16.

[0115] FIG. 15 shows a schematic drawing of a further variant reinforcing component 260 in which the first end portion 272 and the second end portion 274 spread out from a central waist and are each divided into a row of fingers 296, 298 for attaching to the respective structural member 14, 16. The fingers 296, 298 of each row can be spaced at regular intervals along the line of the joint between the first and second structural members 14, 16.

[0116] Like the row of reinforcing components 60a, 60b, 60c of FIG. 13 each row of fingers 296, 298 can then provide a visual indication of how the joint may be opening under bolt failure. For example, if the joint is opening more at one end of the row than the other, then there is an expectation that visible damage accumulation will be greater in the fingers closer to that end than in the other fingers. Similarly, if a given finger is closer to a fastening bolt 62 than the other fingers, then visible damage accumulation in that finger may be an indication of failure of that bolt.

[0117] Typically, the fingers 296, 298 of the first end portion 272 and the second end portion 274 are attached to the respective structural elements 14, 16 by distinct and separate adhesive bonds. Accordingly, interfacial failure of the adhesive bond of one of the fingers (e.g. a delamination crack) is then less likely to extend across to an adjacent finger.

[0118] FIG. 16 shows a schematic drawing of the bogie frame 6 including the reinforcing component 260 of FIG. 15. The fingers 296 of the first end portion 272 of the reinforcing component 260 are attached to the centre member 16 in a row along the line of the joint, and the fingers 268 of the second end portion 274 are attached to the side member 14 in a row along the line of the joint.

[0119] However, the fingers 296 of the first end portion 272, which are inward of the side member 14, also carry respective sensors 394, such as strain gauges, configured to monitor strain in the first end portion 272. In this way, the first end portion 272 can still be monitored despite being relatively inaccessible to visual inspection. The sensors 394 also enable the reinforcing component 260 to be monitored continuously, e.g. to obtain data of the load across the joint in real time. This can speed up diagnosis of fastening bolt failure.

[0120] FIG. 17 shows a schematic drawing of the reinforcing component 60 of FIG. 11 but fitted with removable covers 480 to protect both the first end portion 72 and the second end portion 74. The removable covers 480 are configured to cover the otherwise exposed surface of the first fibre-reinforced plastic layer 70. The covers 480 prevent surface damage to or dirt accumulation on the end portions 72, 74 which could otherwise reduce or obscure the visibility of cracks 80 in the first fibre reinforce plastic layer 70. The covers 480 are removed for the performance of maintenance inspection of the end portions 72, 74, and are then refitted or replaced.

[0121] The features disclosed in the foregoing description, or in the following claims, or in the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for obtaining the disclosed results, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

[0122] While the invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art when given this disclosure. Accordingly, the exemplary embodiments of the invention set forth above are considered to be illustrative and not limiting. Various changes to the described embodiments may be made without departing from the spirit and scope of the invention.

[0123] For the avoidance of any doubt, any theoretical explanations provided herein are provided for the purposes of improving the understanding of a reader. The inventors do not wish to be bound by any of these theoretical explanations.

[0124] Any section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described.

[0125] Throughout this specification, including the claims which follow, unless the context requires otherwise, the word comprise and include, and variations such as comprises, comprising, and including will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

[0126] It must be noted that, as used in the specification and the appended claims, the singular forms a, an, and the include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from about one particular value, and/or to about another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by the use of the antecedent about, it will be understood that the particular value forms another embodiment. The term about in relation to a numerical value is optional and means for example +/?10%.