WO1993023626A1

WO1993023626A1 - Impact-absorbing crash barrier

Info

Publication number: WO1993023626A1
Application number: PCT/FR1993/000446
Authority: WO
Inventors: Annie José POMERO
Original assignee: Pomero Annie Jose
Priority date: 1992-05-12
Filing date: 1993-05-10
Publication date: 1993-11-25
Also published as: FR2691124A1; FR2691124B1

Abstract

Device for reducing impact through intertial absorption consisting of an assembly of identical modules (1) having a generally cylindrical or similar shape. The modules are open at least at one of their bases and include at the periphery of their open base, evenly distributed notches (2) at right angles to the base along a length greater than the half-height of the modules. Consequently, the modules which are placed side by side can be made integral to one another by the insertion, into the notches (2), of identical modules (1) placed top to bottom until the latter touch the ground. A homogenous assembly is thereby formed that is capable of deformation under shock. Each module is made of a metallic or other material having low bend strength and minimal recurrent elasticity, or of a brittle material with low breaking strength. The invention can be used on roads as an impact-absorbing crash barrier placed in front of stationary structures.

Description

SHOCK ATTENUATOR OF A VEHICLE AGAINST A FIXED OBSTACLE. The present invention relates to a device intended to absorb the kinetic energy of a solid body in motion, and in particular of a motor vehicle, which comes to collide with said device, in order to attenuate the impact of said vehicle against an obstacle. fixed, such as a parapet, a bridge pillar, a pylon or a tree, in front of which the device is placed.

Certain devices pursuing the same goal have been implemented. They are generally containers containing a liquid which, at the time of impact, spurts through calibrated upper orifices, under the effect of the deformation of said container. Several such receptacles are juxtaposed forming groups separated from each other by movable transverse vertical partitions, the assembly of several groups thus formed being circumscribed by independent vertical plates which overlap in the manner of scales, and acquiring a certain lateral rigidity. thanks to cables stretched longitudinally.

Such a device has several drawbacks.

Firstly at the level of the high cost price by the nature of the watertight containers required and the presence of calibrated nozzles which require machining, and by the need for transverse partitions as well as by the need for special elements intended to receive the cables. tension which must transform all the containers into a block offering a certain lateral rigidity, without hampering the mobility of the containers inside this assembly, under the effect of a frontal impact.

Then at the level of implementation. Indeed the assembly of the various containers which have no link between them, their inclusion between the vertical movable partitions, the installation, the stowage and the tension of the cables, finally the covering of the whole by the lateral scales are all operations that require qualified personnel, and that cause a heavy investment.

There are also various devices operating by plastic deformation of certain parts, such as metal barrels for example which are placed side by side in greater or lesser number; here again, the complexity of the method of connecting the barrels and their anchoring to the ground, as well as to the obstacle, as well as the elements added to improve the resistance to lateral impact lead to a very high cost and to a difficulty of assembly. who oppose their wide dissemination.

According to other devices, it is dry sand which, under shock, must spring from the containers which contain it and which, for this, are largely

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open at the top. In this case, despite a tarpaulin covering all of the containers, the ambient humidity, when these are not completely untimely infiltration of rainwater, causes the compaction of the sand, thereby eliminating any damping effect. research. In addition, these devices are ineffective in the event of a side impact.

The present invention therefore aims to avoid these drawbacks. For this shock absorption is obtained by the deformation of hollow volumes placed on the ground and assembled, made either of a material capable of undergoing under the effect of shock a plastic deformation having a recurrent elasticity as weak as possible, or d 'a material fπ ^' abie capable of breaking into small pieces harmless to the passengers of a vehicle striking them, each of these volumes, which constitutes a module of the device, being automatically made integral with the modules juxtaposed by the simple embedding of identical modules placed head to tail, operation requiring no tools, no learning, or even no accessory element such as intermediate partitions, or finally no support or cable guide attached to the module itself.

FIG. 1 is a perspective view of a module shown by way of example of a hollow cylindrical shape forming the single element of the device, shown in two head-to-tail positions comprising the notches allowing their reciprocal embedding. The module which presents the notches in its lower part will be called male (m) and the one which presents them in its upper part, female (f).

Figure 2 is a top view of an assembly mode of such hollow modules of circular cylindrical shape, generally open on both sides, showing the side modules as well as different features allowing to increase the rigidity of the together with the crush, to increase its coefficient of friction on the ground and to increase its resistance to lateral impacts. Figure 3 is a partial top view of another method of assembling modules identical to the previous ones.

FIG. 4 is a perspective view of some modules assembled in accordance with FIG. 2.

Figure 5 is a partial top view of an assembly of cylindrical modules of elliptical shape, open on both sides.

FIG. 6 is a top view of an assembly of modules of polyhedral shape (octagonal in this case), showing the lateral modules as well as various features making it possible to increase the rigidity of the assembly during crushing, increase its coefficient of friction to the self and to increase its resistance to side impact.

_FE υιttE

Figure 7 is a perspective view of an edge module showing the passage of a continuous metal plinth running through the base of the device.

According to Figure 1 the basic module is a hollow module 1 which may have a shape from a closed geometric figure developed in a direction orthogonal to its plane with a diameter smaller than its height, which includes the vertical notches 2 regularly distributed around its periphery with a width sufficient to allow embedding which will be described and extending along the generator over a length substantially greater than the half height of the module. Here the module has been shown, by way of example, in a circular cylindrical form.

It is understood that such a module can be recessed in a secant manner at the notches 2 with any identical module placed head to tail which makes it possible to form an assembly of several modules according to different entanglement modes, the male modules and the modules females placed head to tail intersecting secantly at their notches, until the upper modules reach the ground.

Such an assembly of several identical modules is given by way of example in FIG. 4. As can be seen in FIG. 2, it makes it possible to form without any tool or any difficulty a homogeneous assembly capable of deforming as a whole. under the effect of a shock oriented in the longitudinal direction.

When it is expected that the kinetic energy is absorbed by the plastic deformation of the assembly, its absorption will obviously depend on the plasticity of each module which must in this case have as low a recurring elasticity as possible. Said assembly can therefore be produced with steel, soft iron, aluminum, or synthetic resin modules, or any other metal or any other material having similar characteristics of resistance to bending.

When it is expected that the kinetic energy is absorbed by the rupture of all or part of the assembly, its absorption will depend on the resistance to rupture of each module which must in this case have a brittleness such that its rupture produces that of small pieces, said material being in this case suitably proportioned concrete, cellular concrete or heterogeneous concrete loaded with nodules of expanded material such as expanded clay or expanded polystyrene or polyurethane, or any other material having similar characteristics.

We also note that the energy absorbed during a shock against such a set of entangled modules depends not only on the nature of the material, but also on the shape of the module and its method of assembly,

REPLACEMENT SHEET the absorbed energy can be determined by calculating the composition of the forces involved according to the direction of the shock, or experimentally.

Each module may indeed have a shape identical to itself circular cylindrical, for example, (FIG. 1 to 4), or elliptical cylindrical (FIG. 5),

It can also have the most diverse forms. Each module can indeed have a similar cross section for the male elements and the female elements or different. Similar forms require a certain number of qualities in the fields of symmetry, well described in the works dealing with these problems of assembling geometric figures or crystallography; one can say for example that the symmetrical figures such as the square, the rectangle, the rhombus, the hexagon, the octagon, etc. can perfectly give similar male and female modules of polyhedral prismatic type; some forms, having fewer elements of symmetry, cannot, but another male form can perfectly assemble these female forms. Similarly, certain symmetrical shapes mentioned above can be assembled by male modules of another shape, for example sections in hexagon (or octagon) can be connected by circular or square male sections etc.

The variety of possible assemblies is therefore considerable: it is considerations of ease of manufacture, assembly of cost and aesthetics which will guide the choice; the most interesting assemblies from this quadruple point of view will be: circular, elliptical, hexagonal and octagonal sections when the male modules and the female modules are identical; sections of hexagonal female shape with a circular male module, of octagonal shape for a square or circular male module, of diamond shape with circular male modules. Another consideration can be a different inertia in the section according to the plane of symmetry chosen: indeed, an attenuator can be more rigid in a direction of shock than in a perpendicular direction, if one chooses sections in ellipse (fig 5) rather than a regular octagon, etc. or a triangular assembly (fig 3).

This difference in rigidity is beneficial in lateral impacts on the attenuator: if the long axis of the ellipses, for example, is oriented towards the lateral zone of the attenuator, the latter will resist better a sinking and will make it possible to straighten the vehicle with less difficulties if the modules are ci cular, all other things being equal. Figure 5 illustrates this example.

REPLACEMENT SHEET Likewise, the entanglement of modules can be carried out according to different modes. According to FIG. 2, for example, it is carried out in such a way that the female cylindrical modules (f) tangent in groups of four, the two lines of the centers forming a cross, before a male module (m) locks them. between them being placed head to tail so that its center corresponds to the point of intersection of the center lines of the female modules, the notches of the male modules (m) penetrating into the notches of the female modules (f). In this case, the notches of each module are regularly distributed 90 'apart.

According to Figure 3, the entanglement is carried out in such a way that the cylindrical female modules (f) are tangent in groups of three, before a male module (m) comes to lock them between them being placed head to tail such so that its center corresponds to the geometric center of the three tangent points of the female modules. In this case the notches of each module are distributed on their periphery successively at 0 ^* , 60 ", 180" and 240 ".

Any other assembly method can be carried out, this depending only on the shape of the module and the number and distribution of the notches 2 organized at its periphery.

One can even envisage tangles produced using modules of forms other than circular, such as those presented in FIG. 5 (elliptical) or FIG. 6 (octagonal).

For example one could indeed realize, according to FIG. 6, an assembly formed of octagonal female modules placed side by side, without entanglement between them, but linked in groups of four by the only means of identical male modules comprising notches 2 regularly distributed at 90 ^* .

In addition to the nature of the material which can vary, there is no limit in principle either in the form or in the method of assembly, each having mechanical characteristics which may correspond to stresses determined as a function of these two parameters.

It is thus understood that it will be easy to create kinetic energy absorbing assemblies by the use of different materials, by different shapes given to the basic module and by the realization of different modes of assembly of said modules.

In the same assembly, it is also possible to use modules which are homogeneous in their shape but different in their thickness, or made of materials different in their nature so that their coefficient of flexural strength varies from the impact front to at the end of

REPLACEMENT SHEET the assembly, in the vicinity of the fixed structure to be protected, so as to create in a single assembly a progressive increase in deceleration, followed by a constant deceleration which can be managed by the body until the vehicle reaches zero speed accidented before it reached the protected fixed structure. In order to counter lateral impacts, modules 3 are provided which are truncated vertically by the plane 4 which develops along a cord forming with the diameter parallel to the longitudinal axis of the entire device an acute angle open towards the outside from the notch 2 located in the lateral plane of the device up to beyond said module to partially cover, in the manner of a flake 5, the same plane 4 of the adjacent module in the direction of movement of vehicles capable of tangentially approaching the device .

In order to stiffen the assembly to further resist lateral impact, the cables 6 and 7 can easily be stretched from the fixed structure to be protected until it is anchored in the roadway located at the upstream end of the assembly, said cable cable passing freely in the aligned notches 2 of the female modules located on the sides of the device, and before the latter are capped by the male modules, which avoids any increase in the cost of the work due to the installation of special guide means and retaining said cables on the modules. Such an assembly of the cables is shown in FIGS. 2 and 6.

In order to eliminate the cost of constructing the head anchor blocks 8 and 9, the single cable 10, anchored at its two ends on the obstacle to be protected 11 surrounds all of the entangled modules, according to FIG. 2, in also passing through the notches 2 of the female modules, FIG. 4 shows the cable 7 placed at the bottom of the notches 2 of the female modules before the male modules come to imprison it between two notch bottoms.

In order to further increase the resistance to lateral impacts, to allow the vehicle in distress to resume its place on the road, a plate 12 vertical or inclined towards the interior of the device is welded to the base of the female modules according to at least one cord of these parallel to the longitudinal axis of the device, so as to form at least one kind of ploughshare in contact with the ground into which it penetrates under the effect of the vertical component of the shock, which has the advantage of competing to oppose the lateral displacement of the assembly already contained by cables 6 and 7, or the single cable 10.

For the same purpose, the metal plinth 17 can be slid, according to FIGS. 2, 5 and 7, at the base of the edge modules at the rear of the plane-shears 4-5 inside the notches 2 which they comprise. .

REM L CEMENT pEUSUJ ED ^~ C In cases where it would be necessary to increase the rigidity of the assembly, the male modules may include a cover 13 made of the same material as the module and may include the central opening 14. This cover 13 may also be made by a corrugated sheet, whose wave generators are oriented perpendicularly to the longitudinal direction of the assembly, in order to facilitate its folding on itself during a longitudinal impact.

The device thus being constituted according to one of the modes described above, it is understood that there is an inexpensive energy absorbing assembly by the simplicity of the basic module, by the ease of implementation without any tools and without requiring specialized personnel, said energy absorber being able to exhibit mechanical resistance characteristics that are best suited to the requirements of the place where it is located, its mechanical resistance being determined by the nature of the material used, by its thickness, by its geometric shape and its height, as well as by the method of assembly which is practiced, and which ensures a greater or lesser density of modules per m ₂ , by the organization finally, in the longitudinal direction of the same set of modules with a gradually different flexural strength depending on the desired result. It is also advantageous to note that the replacement in such a set of damaged modules is greatly facilitated.

Finally, the device eliminates any maintenance cost in the absence of shock. The advantage, which is the consequence, is the permanence over time of the mechanical characteristics of such a structure. The power of absorption of kinetic energy by such an assembly can be increased by the insertion of besides 16 of sand or liquid of adequate shape i ntroduced into the empty spaces located between the points of tangency of the female modules or male modules (fig 2) or in the spaces left empty between the octagonal modules (fi g 6), these locations coinciding with the openings 14 of the covers 13 with which the male modules can be fitted. These closed wineskins have light walls capable of bursting when the modules are crushed.

The shock attenuating device thus being constituted, according to the different modes described above, it is understood that a vehicle striking it lengthwise along the arrow A parallel to the side (fig 2 and 6) will slide along the scales 5 without entering the mass of the device made rigid by cables 6 and 7 and possibly the plates 12 and the plinth 17, and will be brought back to the roadway without great damage and without having struck the protected fixed obstacle. In the event of a frontal collision, according to arrow B (fig 2 and 6) the vehicle will penetrate into the mass of the device, its kinetic energy being

SUBSTITUTE SHEET absorbed by the deformation of the modules, the deceleration thus obtained depending on the shape of the modules, their mode of entanglement (fig 2, 3, 5 or 6) and possibly the presence of inert masses 16, the rigidity of the assembly being provided by cables 6 and 7, as well as plates 12 and plinth 17.

So that depending on the value of the kinetic energy of the vehicle which thus strikes the device, it will penetrate more or less deeply into the assembly, but will rarely reach the protected fixed obstacle; or, in any case, if it reaches it, it will be at a speed sufficiently reduced so that it does not cause passengers much physical damage, and the protected work will be only slightly damaged.

REPLACEMENT SHEET

Claims

CLAIMS 1 ") Shock attenuator of a vehicle against a fixed obstacle comprising, placed side by side on the ground, a set of modules capable of undergoing r under the effect of a shock a deformation which can go as far as their rupture , characterized in that the modules (1) constituting it are hollow volumes generated by the envelope of a closed geometric figure forming the cross section of said volumes open at at least one of their bases and having at the periphery from this base, uniformly distributed over each of said modules, notches (2) developing in a direction orthogonal to said base over a length substantially greater than the half-height of the module, said modules being made integral with one another by the only embedding in a secant manner from similar modules placed head to tail on several modules tangent to each other, the notches (2) of the latter penetrating into the notches (2) of the mo dules placed on the ground until said similar modules reach the ground themselves, said notches (2) being of sufficient width to allow said embedding.

2 ") shock attenuator according to claim 1 characterized in that the modules are of cylindrical, ci rculai or elliptical shape. 3") shock attenuator according to claim 1 characterized in that the modules are of the polyhedral straight prismatic type.

4 ") shock attenuator according to any one of claims 2 to 3, characterized in that it comprises half-modules (3) truncated vertically by the plane (4) which develops along a cord forming with the parallel diameter to the longitudinal axis of the entire device an acute angle open towards the outside from the notch (2) located in the lateral plane of the device, up beyond the module concerned to partially cover, in the manner of the 'flaking (5), the same plane (4) of the adjacent module in the direction of movement of vehicles capable of tangentially approaching the device.

5 ") shock attenuator according to any one of claims 1 to 4 characterized in that each module is made, in suitable thickness, of a material capable of plastic deformation having a recurrent elasticity as low as possible, such as iron, aluminum, synthetic resins.

6 ") shock attenuator according to any one of claims 1 to 4 characterized in that each module is made, in suitable thickness, of a brittle material capable in case of rupture to divide into small pieces such as concrete suitably dosed, ie cellular concrete, heterogeneous concrete charged with nodules of expanded materials.

REMΛACEMEN SHEET - 7 ") shock attenuator according to any one of claims 5 or 6, characterized in that the cables (6) and (7) are stretched lengthwise on either side of the axis of the attenuator, close to each of its sides, from the fixed structure (11) to be protected to the anchors (8) and (9) located at the front of said attenuator, and passing freely through the notches (2) of the modules installed.

8 ^* ) shock attenuator according to any one of claims 5 or 6, characterized in that a single cable (10) anchored at each of its ends in the work (11) to be protected, and passing freely through the notches (2) modules installed, encloses all of said attenuator that it travels close to its sides.

9 ") shock attenuator according to any one of the preceding claims, characterized in that the so-called female modules (f) carry welded to their base along at least one cord of said module a metal plate (12) vertical or inclined towards the inside the device, parallel to the longitudinal axis of the assembly, flush with the ground by its lower edge and capable of nesting in the ground under the effect of the vertical component of a lateral impact.

10 ") shock attenuator according to any one of the preceding claims, characterized in that a metal plinth (17) is installed on each side of the device behind the planes-scales (4- 5), at the inside the notches (2) of all the edge modules.

11 ") shock attenuator according to any one of the preceding claims, characterized in that the base of the modules opposite their notches (2) is closed by a cover (13) of corrugated sheet integral with said modules and carrying in its center l opening (14).

12 ") shock attenuator according to any one of the preceding claims, characterized in that an inert mass such as a shell (16) of sand or water, closed and having light walls capable of bursting during the crushing of the modules is introduced into the free spaces existing between the adjoining modules.

REPLACEMENT LIGHT