The present invention relates to a collision energy absorption column and a railroad vehicle provided with the collision energy absorption column which is provided in a leading-end vehicle of railroad vehicles.
Conventionally, as for railroad vehicles, in order to protect crews and passengers from a collision with an automobile, another railroad vehicle or the like, various structures for absorbing energy due to the collision has been proposed. For example, in Patent Document 1, a rail vehicle provided with a reinforcement member extending vertically in a vehicle end, and a bone member extending in a vehicle longitudinal direction is proposed. According to this structure, it absorbs energy by positively deforming when certain or greater load acts to the structure, the structure does not deform when less load acts to the structure.
Since each member of the conventional collision energy absorbing structure is made of metal, the structure is significantly heavy. Thus, this is one of the reasons of difficulties in reducing the entire weight of the railroad vehicle. Meanwhile, in order to protect the crews and passengers and to prevent each member from dropping out of its fitting part of the vehicle body, it is necessary to fully absorb the collision energy within a predetermined deflection amount. However, Patent Document 1 does not propose a railroad vehicle provided with a collision energy absorbing structure which satisfies the above-described two requirements. The purpose of the present invention is to provide a collision energy absorption column which can achieve both a weight reduction and sufficient collision energy absorption within the predetermined deflection amount.
A collision energy absorption column according to the present invention to be provided in an end part of a railroad vehicle and extend from an end beam toward a roof structure, comprising an outer member made of metal, the outer member having a channel shape or a hollow shape in a transverse cross section thereof, and an inner member made of reinforced plastic, the inner member being provided along an inner circumference of the outer member and extending in parallel with the outer member.
According to this configuration, since the inner member made of reinforced plastic does not directly contact a colliding object, the stress concentration immediately after the collision is small. That is, a crack generation after the collision can be delayed and larger collision energy can be accumulated. Then, when the collision energy is accumulated to a limit, the inner member will be eventually fractured, but at this point, the metal outer member still continues absorbing the collision energy, without being fractured. Thus, regardless of the column being partially made of resin, the large collision energy can be absorbed. In addition, the entire weight of the column can be reduced comparing with a case where the collision energy absorption column is entirely made of metal.
Further, by forming the transverse cross section of at least the outer member into a channel shape or a hollow shape, its section modulus becomes larger, compared with a case where the outer member is plate shape. Thus, since bending stress permitted becomes larger, the collision energy absorption column can receive a larger collision load, and can absorb larger collision energy.
Further, the outer member may be coupled to the end beam and the roof structure by a fastener, and the inner member may extend between an upper part of the end beam and a lower part of the roof structure, excluding the fastening part.
According to this configuration, since the collision energy absorption column is fastened with the end beam and the roof structure via the outer member made of metal, it does not need to fasten the inner member made of plastic with the end beam and the roof structure. Thus, since the inner member becomes easier to be deformed, with less restraints, larger collision energy can be absorbed until it is fractured. In addition, since it becomes unnecessary to extend the inner member up to the part which is fastened by the fastener, the cost can be reduced.
Further, the outer member may formed by joining two column halves extending along a column axis after the two column halves are arranged in a direction perpendicular to the column axis of the outer member, and a joined part of the column halves may extend along the column axis.
According to this configuration, the joined part of the column halves extends along the column axis. Thus, when the collision load is received from the direction perpendicular to the column axis, the joined part becomes difficult to be a starting point of a crack, compared with a case where the joined part is formed along the direction perpendicular to the column axis.
Further, each of the column halves may include a first plate part extending along the column axis, and second mutually parallel plate parts extending from both sides of the first plate part, perpendicular to the first plate part. Both the column halves may be arranged opposed to each other in a load direction of a collision load, and may be joined to each other at tip ends of the second plate parts. A plate face of the first plate part may face in a receiving direction of the collision load.
According to this configuration, since the two column halves are joined at the tip ends of the second plate parts, the position of the joint of both the column halves is located in the second plate part. The collision load is applied to the first plate part without the joined part. Thus, since the collision load is not directly applied to the joined part which tends to be a starting point of a fracture of the collision energy absorption column, easy fracturing can be prevented. Therefore, a collision energy absorption effect can be improved.
The reinforced plastic may be a plastic containing textiles and a volume content of the textiles may be 60% or more.
According to this configuration, since the textile content in the reinforced plastic is more than a predetermined amount, the intensity of the reinforced-plastic member against the collision load can be increased, and the resin column can be more difficult to be fractured.
In the collision energy absorption column according to the present invention, both the weight reduction and the sufficient collision energy absorption within the predetermined deflection amount can be achieved.
Hereinafter, a collision energy absorption column according to one embodiment of the present invention is described with reference to the drawings. Note that, below, the same referential numerals or symbols are assigned to the same or corresponding elements throughout the drawings and, thus, redundant description of the elements is omitted. The concept of directions in this embodiment is in agreement with the concept of directions when a traveling direction of a railroad vehicle is forward and one faces the front. That is, a vehicle longitudinal direction corresponds to a front-to-rear direction or a rear-to-front direction, and a vehicle width direction corresponds to a left-to-right direction or a right-to-left direction.
[Configuration of Railroad Vehicle Provided with Collision Energy Absorption Column]
[Configuration of Collision Energy Absorption Column]
The inner member 4 is formed shorter in the vertical direction than the outer member 3. A first fastening area 30 and a second fastening area 31 where the inner member 4 does not exist are formed in an upper end part and a lower end part of the outer member 3, respectively. Within the first fastening area 30, a plurality of first through-holes 32 are formed in the outer member 3. Fasteners such as rivets or bolts are inserted into the first through-holes 32 to couple the arch rail 21 with the upper end of the collision energy absorption column 1. Further, a plurality of second through-holes 33 are formed in the outer member 3 within the second fastening area 31. Inside the second fastening area 31, a hollow reinforcing member 34 made of metal or reinforced plastic is provided. A plurality of through-holes 35 are formed in the circumference of the reinforcing member 34 so that the through-holes 35 are located in agreement with the second through-holes 33, respectively. Fasteners such as rivets or bolts are inserted into the second through-holes 33 and the through-holes 35 to couple the end beam 72 with the lower end part of the collision energy absorption column 1. The reason why the lower end part of the collision energy absorption column 1 is reinforced by the reinforcing member 34 is to prevent, when a collision load is applied centering on a lower part of the collision energy absorption column 1, the collision energy absorption column 1 from shearing or completely separating from the underframe.
As illustrated in
In addition, the welding line 62 extends in the vertical direction. Thus, the welding line 62 is more difficult to become a starting point of the crack when the collision load is received from a direction perpendicular to the vertical direction, compared with a case where the welding line 62 is formed along the direction perpendicular to the vertical direction. Here, in order to reduce the entire weight of the railroad vehicle, the collision energy absorption column may be made of resin. However, such a resin material has small ductility. Therefore, the resin collision energy absorption column may have difficulties to absorb the energy by deforming plastically. That is, since the resin collision energy absorption column is fractured without greatly deforming plastically, the energy cannot fully be absorbed.
Alternatively, the collision energy absorption column may be made of resin and only necessary parts may be reinforced by metal to achieve the weight reduction. In this case, welding is typically used for joining the metal reinforcements. However, according to this collision energy absorption column, when the collision energy is applied, the collision energy absorption column becomes easy to fracture unstably from the welding joined part. Therefore, there may be a possibility that the collision energy cannot fully be absorbed as the collision energy absorption column. In addition, at the time of the collision, if the collision load is applied to a part where the reinforcements are not applied, there may also be a possibility that expected performances cannot be demonstrated. In the collision energy absorption column 1 of the embodiment, since it adopts a dual structure of the outer member 3 and the inner member 4 having the higher tensile strength in the column longitudinal direction, the lighter weight, and the smaller ductility than the outer member 3, both the weight reduction and the sufficient collision energy absorption can be achieved.
[Energy Absorption Effects]
Next, in order to examine the energy absorption effect of the collision energy absorption column 1 of the embodiment, comparison results of a collision energy absorption column made only of reinforced plastic (hereinafter, simply referred to as “the reinforced-plastic collision energy absorption column”), a collision energy absorption column made only of metal (hereinafter, simply referred to as “the metal collision energy absorption column”), and the collision energy absorption column of this embodiment are described. Specifically, as illustrated in
The reinforced-plastic collision energy absorption column is comparatively lightweight even if it uses a thick plate, and as shown by the line (1), it can support a predetermined collision load with a short stroke. However, since the load Ps is reached while the stroke is short, the reinforced-plastic collision energy absorption column falls out of the vehicle structure before absorbing the predetermined collision energy. In addition, since the reinforced-plastic collision energy absorption column will not be deformed plastically, the effect to absorb the collision load is weak also in this regard. On the other hand, as shown by the line (2), the metal collision energy absorption column having the same mass as the reinforced-plastic collision energy absorption column of the line (1) plastically deforms by a comparatively small load. However, a load increase, i.e., an increasing rate of the energy to be absorbed is small as compared with a change in the stroke. Therefore, in order to absorb the predetermined collision energy Es with the stroke δs, it is necessary to construct the collision energy absorption column with a considerably thick plate which is difficult to be deformed plastically. However, the weight of the collision energy absorption column increases significantly.
As compared with the lines (1) and (2), as shown by a line (3), when the collision energy absorption column 1 of this embodiment receives the collision load, the metal outer member 3 begins a local plastic deformation at a comparatively early stage, but the reinforced-plastic inner member 4 fractures before the outer member does (at a point B in
(Analysis Result #1)
In order to examine the above-described energy absorption effect, the applicant considered an analysis column 5 having a shape illustrated in
Upon the analysis, the analysis column 5 only having the 9-mm thickness first half 50 is called CASE1, the analysis column 5 only having the 11.7-mm thickness first half 50 is called CASE2, the analysis column 5 having the 9-mm thickness first half 50 and the 20-mm thickness second half 51 made of CFRP is called CASE3, and the analysis column 5 having the 9-mm thickness first half 50 and the 20-mm thickness second half 51 made of CFRP is called CASE3′. Note that the masses of the analysis columns 5 of CASE2, 3 and 3′ are identical. As for CASE3′ and CASE3, both ends of the second half 51 of the analysis column 5 are not restrained in CASE3′, while both ends of the analysis column 5 are restrained in CASE3. Note that in CASE1 and CASE2, both ends of the second half 51 of the analysis column 5 are restrained. Material characteristics of CFRP which forms the second half 51, specifically, values of Young's modulus or modulus of elasticity E1 and E2, Poisson's ratio ν, shear coefficient G12, tensile strength N1t and N2t, compressive strength N1C and N2C, and shear strength S12 are as illustrated in Table 1.
Here, as for subscripts 1 and 2 of the above symbols, the subscript 1 means that it is a value in the longitudinal direction of the analysis column 5, and the subscript 2 means that it is a value in a direction perpendicular to the longitudinal direction of the analysis column 5. In addition, CFRP which forms the second half 51 is an orthotropic material in consideration of breakage.
The analysis result of the relation between the reaction force and the displacement at the time of applying the collision load to the analysis column 5 is illustrated in the graph of
In
In addition, as illustrated in
(Analysis Result #2)
The applicant further considered an analysis column 100 illustrated in
The analysis results of relations between a reaction force and a displacement at the time of applying a collision load to the analysis columns 100 are illustrated in a graph of
Further, the analysis column 100 of CASE4 according to the line (1) as illustrated in
Further, since the analysis column 100 where the metal outer rectangular column 110 and the reinforced-plastic inner rectangular column 120 are combined demonstrates the same or better energy absorption characteristics as/than the analysis column 100 only using the metal outer rectangular column 110, it was found that, by forming the collision energy absorption column 1 into the dual structure of the metal outer member 3 and the reinforced-plastic inner member 4, the thickness of the outer member 3 can be made thinner while absorbing larger collision energy. As described above, since the outer member 3 is formed by welding the two column halves 6, the welding of the column halves 6 becomes easier by forming each column half 6 thinner and, thus, a heat distortion at the time of welding both the columns halves 6 can be smaller. In the collision energy absorption column 1 of the above embodiment, both the outer member 3 and the inner member 4 are hollow in cross section. However, alternatively, both the cross sections of the outer member 3 and the inner member 4 may have channel shapes. Further, the cross sections may be, not limited to the rectangular shapes, any other various shapes, such as circular shapes or ellipses.
In the collision energy absorption column 1 of the above embodiment, although the outer member 3 is formed in a half body, it is not limited to this. For example, a hollow member made of an aluminum extruded material may also be used. Although the collision energy absorption column 1 of the above embodiment is linear, it may also be a column shape having a curvature. In the collision energy absorption column 1 of the above embodiment, the roof structure and the underframe are coupled by the fasteners, but they may also be coupled by welding or other ways. The outer member 3 and the inner member 4 may have the same length. In the above embodiment, although two collision energy absorption columns 1 are provided at the end of the railroad vehicle structure 2, one or three or more collision energy absorption columns 1 may also be provided. Further, the corner post 80 illustrated in
The present invention is useful, when it is applied to a collision energy absorption column provided in a leading-end vehicle of railroad vehicles.
Number | Date | Country | Kind |
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2012-133890 | Jun 2012 | JP | national |
Filing Document | Filing Date | Country | Kind |
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PCT/JP2013/003681 | 6/12/2013 | WO | 00 |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO2013/187059 | 12/19/2013 | WO | A |
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