CRASH IMPACT ATTENUATOR SYSTEMS AND METHODS

Abstract

A crash attenuator system for deployment in front of a fixed structure includes a rail extending along a length of the crash attenuator system and a plurality of diaphragms initially disposed in spaced relation along the length of the rail. Each of the plurality of diaphragms moves along the rail, so that when a front end of the crash attenuator system receives an impact force from a vehicle, a first one of the diaphragms moves rearwardly along the rail and impacts a second one of the diaphragms so that both the first and second diaphragms move further rearwardly along the rail, this process continuing with additional ones of the diaphragms until the impact forces have been fully attenuated. A tearing member on the crash attenuator system engages material forming a tearable member of the crash attenuator system, the tearing member tearing material forming the tearable member to increase attenuation of the impact force.

Description

BACKGROUND OF THE INVENTION

The present invention relates generally to crash impact attenuators, and more particularly to motor vehicle and highway barrier crash impact attenuators comprising fixed systems protecting leading edges of abutments and other fixed roadside hazards.

Vehicular accidents on the highway are a major worldwide problem and are undoubtedly one of the largest causes of economic and human loss and suffering inflicted on the developed world today. In an effort to alleviate, in particular, the human toll of these tragic accidents, guardrails, crash cushions, truck-mounted crash attenuators, crash barrels, and the like have been developed to attenuate the impact of the vehicle with a rigid immovable obstacle, such as a bridge abutment.

A crash attenuator of the type described must absorb the vehicle impact energy without exceeding limits on the vehicle deceleration. In addition, it must accommodate both heavy and light weight vehicles. The lightest vehicle will set the limit on the maximum force produced by the attenuator and the heavy vehicle—which will experience a lower deceleration, and thus will determine the total impact deformation required. The force cannot exceed the light vehicle limit and therefore the initial force and deceleration is low, limiting the energy absorption. Increasing crash resistance as the vehicle “rides down” from its impact speed to zero is a vitally important feature of a crash attenuator system which meets rigid governmental safety standards. The present invention accomplishes this objective in an innovative, inexpensive, and very simple, but effective, manner.

The invention, together with additional features and advantages thereof, may best be understood by reference to the following description taken in conjunction with the accompanying illustrative drawing.

SUMMARY OF THE INVENTION

The present invention comprises, in one exemplary aspect, a crash attenuator system for deployment in front of a fixed structure, such as a bridge abutment. The system comprises a rail extending along a length of the crash attenuator system, a plurality of diaphragms initially disposed in spaced relation along the length of the rail, each of the plurality of diaphragms having a base end adapted to be movably engaged with the rail, so that when a front end of the crash attenuator system receives an impact force from an errant vehicle, a first one of the plurality of diaphragms moves rearwardly along the rail and impacts a second one of the plurality of diaphragms so that both the first and second ones of the plurality of diaphragms move further rearwardly along the rail, this process continuing with additional ones of the plurality of diaphragms until the impact forces have been fully attenuated. The system further comprises a tearing member on the crash attenuator system which is adapted to engage material forming a tearable member of the crash attenuator system, the tearing member and the tearable member being relatively movable when an impact force strikes the crash attenuator system so that the tearing member tears the tearable member, thereby increasing attenuation of the impact force.

In exemplary embodiments, the tearing member comprises a bolt, and may be disposed on one of the plurality of diaphragms, such as on a base end of the first one of the plurality of diaphragms. The tearing member may comprise a plurality of tearing members.

The tearable member extends along at least a portion of the length of the crash attenuator and includes a plurality of holes disposed therein, the plurality of holes extending along a length of the tearable member and spaced lengthwise from one another. The tearing member is engaged with one of the plurality of holes so that when an impact force is applied to the crash attenuator, relative motion occurs between the tearable member and the tearing member so that the relative motion causes the tearing member to tear the material between adjacent ones of the plurality of holes, thereby creating a continuous slot, the tearing of the material functioning to attenuate the impact force.

In some embodiments of the invention, the holes are not evenly spaced along the length of the tearable member having the plurality of holes disposed therein. For example, adjacent ones of the plurality of holes nearer to one of the front and back ends of the crash attenuator may be more closely spaced than adjacent ones of the plurality of holes closer to the other of the front and back ends of the crash attenuator. In some circumstances, the plurality of holes are not uniform in size, respective to one another. For example, in the illustrated embodiment, the frontmost ones of the plurality of holes may be larger and more elongated than those of the plurality of holes which are located closer to the back end of the crash attenuator, though the directional orientation may be reversed depending upon application and desired attenuation characteristics.

In still other variants, the material forming the tearable member may be thinner toward one of the front and back ends of the crash attenuator, and thicker toward the other of the front and back ends of the crash attenuator. In any or all of the embodiments and variants discussed above, which may be utilized singly or in various combinations, the tearable member may comprise a plurality of stages as it extends from one of the front and back ends of the crash attenuator toward the other end of the front and back ends of the crash attenuator, wherein a first stage toward one of the front and back ends of the crash attenuator is softer than a second stage toward the other of the front and back ends of the crash attenuator.

In illustrated embodiments, the one of the front and back ends of the crash attenuator is the front end of the crash attenuator and the other of the first and second ends of the crash attenuator is the back end of the crash attenuator.

The first stage may be softer because the material forming the first stage is thinner than the material forming the second stage. The first stage may also be softer because the holes of the plurality of holes which are disposed in the first stage are closer together than the holes of the plurality of holes which are disposed in the second stage. The first stage may be softer, as well, because the holes of the plurality of holes which are disposed in the first stage are larger in size than the holes of the plurality of holes which are disposed in the second stage.

In particular embodiments of the present invention, the rail comprises first and second outer rails spaced apart in a widthwise direction, and the tearable member comprises a center rail. A plurality of fender panels are disposed along each side of the crash attenuator along its length, wherein frontmost ones of the plurality of fender panels are adapted to slide alongside of rearmost ones of the plurality of fender panels when the crash attenuator is impacted by a vehicle. A nose box is disposed at the frontmost end of the crash attenuator. The tearable member is stationary and the tearing member moves responsive to the impact force, in particular embodiments, though this may also vary, depending upon design goals.

In still another aspect of the invention, there is provided a crash attenuator system for deployment in front of a fixed structure, the system comprising a base portion having a first outer rail extending along a length of the base portion, a second outer rail spaced from the first outer rail and also extending along a length of the base portion, and a plurality of spaced cross-members extending across a width of the base portion and joining the first outer rail to the second outer rail. An upper attenuator portion comprises a plurality of diaphragms initially disposed in spaced relation along the length of the base portion. Each of the plurality of diaphragms has a base end adapted to be movably engaged with each of the first outer rail and the second outer rail, so that when a front end of the upper attenuator portion receives an impact force from an errant vehicle, a first one of the plurality of diaphragms moves rearwardly along the first and second outer rails and impacts a second one of the plurality of diaphragms, so that both the first and second ones of the plurality of diaphragms move further rearwardly along the first and second outer rails, this process continuing with additional ones of the plurality of diaphragms until the impact forces have been fully attenuated. A tearing member is disposed on the upper attenuator portion, which is adapted to engage material forming a tearable member of the upper attenuator portion, the tearing member and the tearable member being relatively movable when an impact force strikes the crash attenuator system so that the tearing member tears the tearable member, thereby increasing attenuation of the impact force.

In yet another aspect of the invention, there is disclosed a method of attenuating a crash impact force imposed by an errant vehicle which would otherwise strike an immovable object. The method comprises steps of receiving an impact force at a front end of a crash impact attenuator having a base portion and an upper attenuator portion and causing one or more members of the upper attenuator portion to move rearwardly along the base portion responsive to the impact force. A further step is one of causing a tearing member disposed on the crash impact attenuator to tear tearable material disposed on the crash impact attenuator as the one or more members of the upper attenuator portion move rearwardly, wherein tearing of the material acts to attenuate the impact force.

In certain variants of the method, the tearing member is a projection disposed on one of the one or more members of the upper attenuator portion, which is initially engaged with a hole formed in the tearable material. There are a plurality of holes in the tearable material, arranged longitudinally in spaced relation, and the tearing step comprises tearing the tearable material between the initially engaged hole and an adjacent one of the plurality of holes, to form a slot. The one or more members of the upper attenuator portion comprise one or more diaphragms, and the tearable material comprises a rail forming a part of the base portion.

The invention, together with additional features and advantages thereof, may best be understood by reference to the following description taken in conjunction with the accompanying illustrative drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of an exemplary embodiment of a crash attenuator constructed in accordance with the principles of the present invention, disposed in a deployed orientation;

FIG. 2 is an isometric view similar to FIG. 1, wherein the crash attenuator is in a partially compressed orientation, illustrating the crash attenuator with an inventive tearing member removed so tearing does not occur and the holes or apertures in the center rail are visible;

FIG. 2a is an isometric view similar to FIG. 2 wherein the inventive tearing member is present and tearing of the forward apertures 38 has occurred to attenuate the impact forces;

FIG. 3 is an isometric view similar to FIGS. 1 and 2, wherein the crash attenuator is in a fully compressed orientation, but the inventive tearing member has been removed so that tearing does not occur and the holes or apertures in the center rail are visible;

FIG. 3a is an isometric view similar to FIG. 3 wherein the inventive tearing member is present and tearing of the forward apertures 38 has occurred to attenuate the impact forces; and

FIG. 4 is a rearward looking view from the front end of the crash attenuator.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now more particularly to the drawings, FIGS. 1-4 illustrate an exemplary embodiment of a fixed crash impact attenuator system 10 of the type discussed above, wherein the design is sacrificial, in that it is intended for a single impact only, after which it is replaced. Thus, it is designed to be relatively inexpensive and simple in design and construction, yet highly effective in protecting the occupants of vehicles striking the attenuator.

Design considerations for the system 10 are that it meets U.S. federal TL (Test Level)-3 crash attenuation specifications, that it is narrow in profile, bi-directional capable, MASH (Manual for Assessing Safety Hardware) compliant, inexpensive, and free-standing (does not need to butt to rigid object, although it can, of course). The system is of a simple design and easy to manufacture (materials are standard sizes and shapes and fender panels are standard Thrie Beam-based), easy to assemble, and ships as a complete assembly. The base is the drill template, and anchor holes can be drilled with the unit 10 assembled. The length of the unit is designed, in an exemplary embodiment, is approximately 20-24 feet. Its width is 32 inches or less, which permits the units 10 to be shipped three-wide on a truck. The height is 32 to 36 inches. The unit 10 may be anchored to concrete, asphalt, or a hybrid of both, and it is anchored using standard anchors and adhesives. It is suitable for use in temperatures ranging from −40 degrees to 150+ degrees F.

In the illustrated exemplary embodiment, the system 10 comprises a base portion 12 having a ladder frame design, comprising a plurality of cross members 14 supporting first and second outer rails 16 and 18, respectively, as well as a center rail 20. The cross members 14 include anchor holes 22 for anchoring the base to the ground using bolt anchors or other suitable mechanical fasteners. In some instances, adhesive may be used instead or as well. The anchor holes 22, in the illustrated embodiment, are spaced along a length of each cross member 14, both outside of and within the first and second outer rails 16, 18.

The system 10 further includes an upper attenuator portion 24, which comprises a nose box 26, a plurality of diaphragms 28, and a plurality of fender panels 30. The nose box 26 may comprise a notice sign 32, and may include a crushable element in the front, behind the sign 32. The nose box 26 supports loads related to frontal, side, and angled nose impacts, and is supported on rollers 34, which allow the nose panel to move rearwardly along the outer rails 16, 18. The rollers 34 are designed to prevent binding/locking in an angled nose impact. As the nose box 26 moves rearwardly after a vehicular impact, attenuation may be activated.

The diaphragms 28 are disposed in spaced relation behind the nose box 26. They are made from standard shapes and sizes and have cross braces sized for loads. Each cross brace is positioned for ease of assembly of the fender panels 30. Each diaphragm 28 is slidably mounted at their base ends 36 on each side to the outer rails 16, 18, as illustrated.

The fender panels 30 are standard in construction, being a standard Thrie beam panel, preferably fabricated of 10 or 12-gauge steel. When a vehicular impact occurs, and the attenuator is compacted, as shown successively in FIGS. 2, 2a and 3, 3a, the fender panels 30 are preferably designed to nest or double over one another in a sliding pattern, as illustrated in the drawings. The length of the fender panels 30 is determined by loads in side impacts, and panels are preferably designed to be common and interchangeable where possible. Bolts secure the foremost fender panel 30 to the nose box 26, and also secure the fender panels to the diaphragms 28. The rear of the panels 30 are secured by clips, rather than slots, in illustrated embodiments, though other attachment methods may be used. The system 10 is designed for standard Thrie beam transition pieces.

The steel forming the fender panels may be galvanized, and may be A36, A513, or A517, for example.

Various approaches for attenuating the crash/impact forces are within the scope of the invention. For example, ripper plates may be used, with varied and staged thicknesses and shapes to stage attenuation, laser/plasma cut patterns to stage attenuation, or a cutter located on the nose box 26, for example. Shearing bolts may be used, comprising double shear approaches or a cutter on the nose box 26, for example. Failing wire rope sections, comprising wire rope loops being pulled to failure, kinking of tube arches, cartridges with honeycomb (aluminum, steel, or plastic), crushable foam-filled cartridges, sand-filled cartridges, pea gravel filled cartridges, water-filled cartridges, cartridges filled with glass beads in oil, drawing a metal strip through offset rollers, a friction brake on a wire rope, a friction brake on bar stock, or velocity magnetics (magnetic attenuation) are all potential possibilities.

An attenuation approach which is illustrated in FIGS. 1-4 involves the center rail 20. As illustrated, the rail 20 is fixedly mounted to the cross members 14 of the base portion 12, in an upright orientation. As shown in FIGS. 2a and 3a, a plurality of holes or apertures 38 are disposed in spaced relation along a length of the rail 20.

Attenuation occurs as the upper attenuator portion 24 moves rearwardly upon impact by a vehicle, thus absorbing impact energy from the crash, and this attenuation capability is greatly enhanced by the employment of one or more inventive shear bolt or tearing member 40 (FIGS. 2b, 3b, and 4), which extends from the attenuator portion 24, and engages the holes 38. It should be noted, at this point, that FIGS. 2a, 3a are illustrated with the tearing member 40 removed, so that the holes 38 are shown, whereas FIGS. 2b, 3b show the crash attenuator with the tearing member 40 in place, as would be the case in an actual installation. It should also be noted that the terms “tear”, “rip”, “shear”, “slice”, “cut”, and the like are used interchangeably throughout this application to identify any process by which a slit is created in material to dissipate and attenuate impact energy. The terms “tear”, “tearing”, “tearable” and the like are used herein and in the appended claims as stand-ins for any of the above mentioned terms for creating a lengthwise slit in a crash attenuator component to attenuate impact energy, and are intended to be broad enough in scope to include any of these terms.

In the illustrated embodiment, the tearing member 40 is disposed on the frontmost diaphragm 28, as shown, but it is within the scope of the invention to employ a plurality of tearing members 40, spaced widthwise on one diaphragm 28 to tear corresponding structural members like rail 20, or opposing sides of the rail 20, or, alternatively, to employ one or more tearing members 40 on more than one of the plurality of diaphragms 28. As shown in FIGS. 2b, 3b, as the attenuator portion 24 moves rearwardly, the holes 38 are ripped by the tearing member 40, thus absorbing much of the crash impact forces by ripping the material forming the rail 20, between the holes 38, creating a slot 42 in the rail 20. The holes 38 may be tuned to optimize the tearing, and thus attenuation effect, by changing their spacing in different sections of the rail 20, and/or by changing the size of the holes. For example, the holes 38 may be more closely spaced in front portions of the rail 20, and may also be more elongated, to make the rail “softer” when crushed, whereas the holes 38 in more rearward portions of the rail 20 may be smaller and less elongated, and farther spaced apart, in order to make these portions of the attenuator “harder” when crushed, to attenuate higher forces. Additionally, if desired, the rail 20 may be made of thinner material (gauge) in the forward sections, and thicker material (gauge) in the rearward sections, for similar reasons. This adds to the “tuning” of the rail 20. Also, if desired, the material of the rail itself might be changed as the attenuator travels along the rail from front to rear, from one stage to the next. Of course, though in the illustrated embodiment it is desired that the softer portions be forward and the harder portions be rearward, differing design considerations may dictate a different orientation, such as softer portions being rearward and harder portions being forward.

The diaphragms 28 serve to transfer the load of a side impact from the diaphragm to the pavement, through the cross members 14 and anchors 22. This anchoring to the pavement makes the pavement itself a structural member for the attenuator system 10.

Thus, important features of the present invention include, for example:

1) low cost;2) free standing (not an end treatment—not relying on the structure being shielded for structural support);3) easy assembly—a 20 ft. assembly may be trucked to the site and easily bolted to the ground—standard material lengths make for easier shipping;4) tunability may be altered to adapt to different crash standards and applications.

Accordingly, although an exemplary embodiment of the invention has been shown and described, it is to be understood that all the terms used herein are descriptive rather than limiting, and that many changes, modifications, and substitutions may be made by one having ordinary skill in the art without departing from the spirit and scope of the invention.

Claims

1. A crash attenuator system for deployment in front of a fixed structure, the system comprising: a rail extending along a length of the crash attenuator system;a plurality of diaphragms initially disposed in spaced relation along the length of the rail, each of the plurality of diaphragms having a base end adapted to be movably engaged with the rail, so that when a front end of the crash attenuator system receives an impact force from an errant vehicle, a first one of the plurality of diaphragms moves rearwardly along the rail and impacts a second one of the plurality of diaphragms so that both the first and second ones of the plurality of diaphragms move further rearwardly along the rail, this process continuing with additional ones of the plurality of diaphragms until the impact forces have been fully attenuated; anda tearing member on the crash attenuator system which is adapted to engage material forming a tearable member of the crash attenuator system, the tearing member and the tearable member being relatively movable when an impact force strikes the crash attenuator system so that the tearing member tears the tearable member, thereby increasing attenuation of the impact force.

2. The crash attenuator system as recited in claim 1, wherein the tearing member comprises a bolt.

3. The crash attenuator system as recited in claim 1, wherein the tearing member is disposed on one of the plurality of diaphragms.

4. The crash attenuator system as recited in claim 3, wherein the tearing member is disposed on a base end of the first one of the plurality of diaphragms.

5. The crash attenuator as recited in claim 1, wherein the tearing member comprises a plurality of tearing members.

6. The crash attenuator as recited in claim 1, wherein the tearable member extends along at least a portion of the length of the crash attenuator and includes a plurality of holes disposed therein, the plurality of holes extending along a length of the tearable member and spaced lengthwise from one another, the tearing member being engaged with one of the plurality of holes so that when an impact force is applied to the crash attenuator, relative motion occurs between the tearable member and the tearing member so that the relative motion causes the tearing member to tear the material between adjacent ones of the plurality of holes, thereby creating a continuous slot, the tearing of the material functioning to attenuate the impact force.

7. The crash attenuator as recited in claim 6, wherein the holes are not evenly spaced along the length of the tearable member having the plurality of holes disposed therein.

8. The crash attenuator as recited in claim 7, wherein adjacent ones of the plurality of holes nearer to one of the front and back ends of the crash attenuator are more closely spaced than adjacent ones of the plurality of holes closer to the other of the front and back ends of the crash attenuator.

9. The crash attenuator as recited in claim 6, wherein the plurality of holes are not uniform in size, respective to one another.

10. The crash attenuator as recited in claim 8, wherein ones of the plurality of holes nearer to the one of the front and back ends of the crash attenuator are larger and more elongated than those of the plurality of holes which are located closer to the other of the front and back ends of the crash attenuator.

11. The crash attenuator as recited in claim 6, wherein the material forming the tearable member is thinner toward one of the front and back ends of the crash attenuator, and thicker toward the other of the front and back ends of the crash attenuator.

12. The crash attenuator as recited in claim 6, wherein the tearable member comprises a plurality of stages as it extends from one of the front and back ends of the crash attenuator toward the other of the first and second ends of the crash attenuator, wherein a first stage toward the one of the front and back ends of the crash attenuator is softer than a second stage toward the other of the first and second ends of the crash attenuator.

13. The crash attenuator as recited in claim 12, wherein the one of the front and back ends of the crash attenuator is the front end of the crash attenuator and the other of the first and second ends of the crash attenuator is the back end of the crash attenuator.

14. The crash attenuator as recited in claim 12, wherein the first stage is softer because the material forming the first stage is thinner than the material forming the second stage.

15. The crash attenuator as recited in claim 12, wherein the first stage is softer because the holes of the plurality of holes which are disposed in the first stage are closer together than the holes of the plurality of holes which are disposed in the second stage.

16. The crash attenuator as recited in claim 12, wherein the first stage is softer because the holes of the plurality of holes which are disposed in the first stage are larger in size than the holes of the plurality of holes which are disposed in the second stage.

17. The crash attenuator as recited in claim 1, wherein the rail comprises first and second outer rails spaced apart in a widthwise direction, and the tearable member comprises a center rail.

18. The crash attenuator as recited in claim 1, and further comprising a plurality of fender panels disposed along each side of the crash attenuator along its length, wherein frontmost ones of the plurality of fender panels are adapted to slide alongside of rearmost ones of the plurality of fender panels when the crash attenuator is impacted by a vehicle.

19. The crash attenuator as recited in claim 1, and further comprising a nose box disposed at the frontmost end of the crash attenuator.

20. The crash attenuator as recited in claim 1, wherein the tearable member is stationary and the tearing member moves responsive to the impact force.

21. A crash attenuator system for deployment in front of a fixed structure, the system comprising: a base portion comprising a first outer rail extending along a length of the base portion, a second outer rail spaced from the first outer rail and also extending along a length of the base portion, and a plurality of spaced cross-members extending across a width of the base portion and joining the first outer rail to the second outer rail;an upper attenuator portion comprising a plurality of diaphragms initially disposed in spaced relation along the length of the base portion, each of the plurality of diaphragms having a base end adapted to be movably engaged with each of the first outer rail and the second outer rail, so that when a front end of the upper attenuator portion receives an impact force from an errant vehicle, a first one of the plurality of diaphragms moves rearwardly along the first and second outer rails and impacts a second one of the plurality of diaphragms so that both the first and second ones of the plurality of diaphragms move further rearwardly along the first and second outer rails, this process continuing with additional ones of the plurality of diaphragms until the impact forces have been fully attenuated; anda tearing member disposed on the upper attenuator portion which is adapted to engage material forming a tearable member of the upper attenuator portion, the tearing member and the tearable member being relatively movable when an impact force strikes the crash attenuator system so that the tearing member tears the tearable member, thereby increasing attenuation of the impact force.

22. A method of attenuating a crash impact force imposed by an errant vehicle which would otherwise strike an immovable object, the method comprising: receiving an impact force at a front end of a crash impact attenuator having a base portion and an upper attenuator portion;causing one or more members of the upper attenuator portion to move rearwardly along the base portion responsive to the impact force; andcausing a tearing member disposed on the crash impact attenuator to tear tearable material disposed on the crash impact attenuator as the one or more members of the upper attenuator portion move rearwardly, wherein tearing of the material acts to attenuate the impact force.

23. The method as recited in claim 22, wherein the tearing member is a projection disposed on one of the one or more members of the upper attenuator portion which is initially engaged with a hole formed in the tearable material.

24. The method as recited in claim 23, wherein there are a plurality of holes in the tearable material, arranged longitudinally in spaced relation, and the tearing step comprises tearing the tearable material between the initially engaged hole and an adjacent one of the plurality of holes, to form a slot.

25. The method as recited in claim 24, wherein the one or more members of the upper attenuator portion comprise one or more diaphragms, and the tearable material comprises a rail forming a part of the base portion.