Functional Material Arresting System

Abstract

The present invention relates to a vehicle arresting system comprising an arrester bed of compressible foam material having bulk compressive strength and a central longitudinal axis extending from a front end to an opposite rear end, the arrester bed comprising an assembly of prefabricated blocks arranged in an even number of linear lanes of the prefabricated blocks, half of the sets being positioned to the left of the central longitudinal axis of the arrester bed and half of the sets being positioned to the right, each linear lane of the prefabricated blocks being inclined at an angle α toward the central longitudinal axis of the arrester bed, where 0°<α≦30°.

Description

[Technical field]

[0001] The present invention relates to an engineered material arresting system (EMAS) bed for slowing and steering vehicles / aircraft that cannot stop under their own power. More precisely, the invention relates to an EMAS bed that has a guidance effect on the vehicle that enters the bed. [Background technology]

[0002] A runway overrun is a landing accident with potentially fatal consequences caused by an aircraft failing to stop before reaching the end of the runway. Typical causes of runway overruns are pilot error, bad weather, and / or technical failure of the aircraft.

[0003] An Advanced Material Arresting System (EMAS) is a system installed at the end of a runway to help stop aircraft that are unable to stop before reaching the end of the runway. EMAS design typically involves optimizing the geometry of the bed to provide the best overall fleet performance. Fleet optimization requires compromises, resulting in suboptimal performance for some of the aircraft. Shallow beds and softer materials improve stopping performance for smaller aircraft, but larger aircraft require the opposite characteristics. As a result, there is a great incentive to develop EMAS concepts that can improve the performance of a mixed fleet of large and small aircraft. Since most airports service a wide range of aircraft, EMAS should advantageously be designed to stop aircraft of very different sizes, ranging from as little as 12 metric tons to as much as 450 metric tons. Aircraft may have very different tire sizes, ranging from less than 50 cm in diameter to more than 145 cm in diameter. EMAS are designed specifically for the typical fleet of aircraft served by a particular airport and are tailored to the space available beyond the end of the runway.

[0004] Prior Art EMAS typically consist of a large, shallow bed of absorbent material that engages the aircraft's tires and absorbs the aircraft's kinetic energy to bring the aircraft to a controlled stopping position. Commercially available EMAS use different types of construction, but the primary absorbent material is typically cementitious foam blocks or glass foam aggregate.

[0005] No. 3,967,704 describes a safety device for rapidly arresting the movement of vehicles such as airplanes and automobiles by forming a deceleration bed of crushable material adjacent to the vehicle's track. A foam is formed from an aminoplastic resin composition and placed in the bed adjacent to the vehicle's track where it is cured in situ to provide a compressive strength of 15 to 50 psi (0.10 to 0.34 MPa) and a compressive strength of 0.25 to 10 pounds per cubic foot (4 to 160 kg / m 3 This document describes an exemplary embodiment of a bed having a uniform thickness at a central location and sloping sides to provide a centering effect for the aircraft using it.

[0006] US 5,885,025 describes a vehicle arresting bed assembled from multiple blocks of porous concrete having a predetermined compressive gradient strength such that the landing gear of the aircraft experiences drag effective to slow various types of aircraft while providing deceleration within safe values. The arresting bed typically includes an entrance region of increasing depth from 9 to 24 inches (23 to 61 cm) formed of blocks having a first compressive gradient strength. A second region, tapering toward the first region and increasing in depth to 30 inches (76 cm), is formed from blocks having a greater compressive gradient strength. Thus, aircraft experience an increase in drag while passing through the bed, providing a stopping capability suitable for a variety of aircraft. A protective hard coat layer of porous concrete, of greater strength than the blocks, overlies the blocks, allowing service personnel to walk on the bed without being damaged. The arresting bed system may be provided in alternative configurations, such as a bed formed from aggregate including pieces of porous concrete with or without interspersed pieces of other compressible material and covered by a hard coat layer. This document further discloses an exemplary embodiment in which the block cell cement of the first row has a lower compressive gradient strength than the blocks of the subsequent rows in order to increase the longitudinal retardation effect of the aircraft.

[0007] US10,458,073B2 discloses a system and method for stopping an aircraft. In certain embodiments, the system and method may be useful for stopping light aircraft, since light aircraft do not have the weight to penetrate the typically available EMAS systems. The system is generally provided as a structure having a suspension layer of energy absorbing material. The lower part of the system may have a lower strength that is used as a way to suspend the stronger / more energy absorbing upper part of the system.

[0008] The concept of using prefabricated blocks of foam glass material has been explored by the U.S. Transportation Research Council and documented in ACRP Report 29 [1]. Glass foam block material was determined to have many desirable EMAS properties, including a nearly ideal compressive stress-strain curve, chemical inertness, low strain rate dependence, environmental durability, and flammability. The report describes design concepts that include glass foam arranged in prefabricated blocks or assembled on-site at the runway. The block concept includes joints and seams between the blocks, but can be constructed in a constructed approach to provide a continuous surface. Because glass foam is typically manufactured in relatively small block or board shapes, the report envisioned smaller boards being glued together to create larger blocks or constructed in layers to create a monolithic bed.

[0009] ACRP Report 29 also describes a prefabricated block of varying depths where multiple layers of compressible foam material with different compressive strengths are glued together with the softer layers located near the surface of the bed and the harder layers located near the bottom. This concept was intended to help improve the performance of arrestor-beds when there is a mixed fleet of aircraft. Lighter aircraft primarily engage with the softer layers of compressible foam near the surface, while heavier aircraft penetrate deeper and engage with the harder layers of foam near the bottom. The report describes modeling and simulation results that showed improved mixed fleet performance compared to an EMAS with a single material strength throughout the thickness.

[0010] The variable depth concept was first proposed in ACRP Report 29 as consisting of multiple layers or tiers of compressible foam bonded together to complete the thickness of the EMAS bed. The bottom layer of the block has the highest density and crush strength, while the top layer has the lowest density and crush strength. The variable depth nature of the bed provides improved mixed fleet stopping performance by allowing lighter aircraft to engage the softer upper layers, while heavier aircraft penetrate deeper and engage the harder underlayer of material.

[0011] From US2012 / 5247298 macro-patterned materials and their use in connection with vehicle arresting systems are known. Particular embodiments provide 3D folded materials, honeycombs, lattice structures, and other periodic cellular material structures that can be used to stop vehicles. The materials can be designed to have properties that allow them to reliably fracture in a predictable manner under pressure from the vehicle. The materials can be formed into various shapes and combined in various ways to provide the desired properties.

[0012] An aircraft overrun is an emergency situation in which one or more things go wrong. When an overrun occurs, the aircraft often does not exit along the runway centerline, but instead may be offset to the left or right. The aircraft may also not travel in a direction parallel to the runway, but instead may turn along the diagonal of the movement. Additionally, typical designs of runways include shallow side slopes to facilitate drainage, which may increase turning behavior in some situations. When an aircraft turns diagonally, it may end up taking a shorter path through the EMAS arrester bed. This results in an early exit along the side edge of the bed, thereby shortening the length of travel through the bed and reducing the protection that the EMAS is designed to provide. EMAS does not currently have design features to control the path of aircraft movement, and innovations that can provide a centering effect are desirable.

[0013] Object of the invention The primary objective of the present invention is to provide an Advanced Material Arresting System (EMAS) bed for slowing and steering vehicles / aircraft that cannot stop under their own power. Summary of the Invention

[0014] An arrester bed is a bed of compressible foam material placed on a spread of ground or forced into the ground, for example, like a basin filled with compressible foam material. Arrester beds are placed at the ends of runways in some embodiments, but may be placed / applied anywhere where it may be expected that a vehicle / aircraft will (unintentionally) require external assistance to make a controlled stop.

[0015] Arrester beds are typically made from an aggregate of granular compressible material that fills a basin placed on or in the soil / subsurface, or from prefabricated blocks of compressible material that are assembled on-site to form a bed on top of the soil / subsurface. The present invention relates to the latter arrester beds made by assembling and gluing prefabricated blocks. The adhesion of the prefabricated blocks to each other can be obtained, for example, by gluing, caulking, adhesive tape, etc.

[0016] The present invention is based on the recognition that the observed weakness of the joints between the prefabricated blocks, which typically have a lower shear strength than the continuous regions of the prefabricated blocks, can be exploited to impart a directional load to the arrester bed that helps to center the path of travel of the vehicle passing through the arrester bed. That is, instead of arranging the prefabricated blocks in the typical rectangular grid of the prior art, by angling the orientation of the prefabricated blocks, the retarding forces exerted on the vehicle wheels have a lateral component that provides an effect of assisting the vehicle to move along the longitudinal central axis of the arrester bed.

[0017] Accordingly, in a first aspect, the present invention relates to a vehicle arresting system comprising an arrester bed placed on a base / ground and having a longitudinal central axis extending from a front end to a rear end opposite the front end, the arrester bed comprising a plurality of prefabricated blocks of compressible foam material assembled and adhered side by side, the assembly of the prefabricated blocks comprising a set of an even number of straight lanes 11 of prefabricated blocks 10, half of the set being positioned on the left side of the longitudinal central axis of the arrester bed and half of the set being positioned on the right side, Each straight lane 11 of the prefabricated blocks 10 is inclined at an angle a towards the longitudinal central axis of the arrester bed 1, where 0° < a ≤ 30°, and when viewed from above, the set of straight lanes 11 forms a series of continuous inverted V patterns along the longitudinal central axis of the arrester bed, and the prefabricated blocks 10 are shaped and dimensioned such that they completely cover / fit exactly the surface area of the base / ground on which the arrester bed is placed.

[0018] As used herein, the term "longitudinal" refers to the direction in which a vehicle / aircraft entering the arrester bed is expected to move across the arrester bed. As used herein, the term "front end" is the side on which a vehicle / aircraft is expected to enter the arrester bed / EMAS, and the "rear side" is the side opposite the front end. The arrester bed may, in some embodiments, be shaped as a longitudinally rectangular bed (when viewed from above), i.e., having a relatively short width compared to its diagonal length.

[0019] The term "arrestor bed" as used herein refers to a bed of compressible foam material placed on a spread of ground or forced into the ground, for example like a basin filled with compressible foam material. The arrestor bed is placed in some embodiments at the end of a runway, but may be placed / applied anywhere where it may be expected that a vehicle / aircraft will become in need of (unwittingly) external assistance to make a controlled stop. However, in the following, the arrestor bed is described in relation to the need to avoid airfields and aircraft overrun accidents, but the arrestor bed according to the invention is not limited to aviation / airfields and may be applied to absorb kinetic energy and to stop any wheeled vehicle that crosses the arrestor bed at any position, whenever such functionality is desired. Arrestor beds are also referred to in the literature as "functional material arresting systems (EMAS)". These terms are used interchangeably herein.

[0020] The present invention according to the first aspect is not bound to any particular design, size or location, but encompasses any size and design of arrester bed known or conceivable to a person skilled in the art. Moreover, the present invention is not dependent on how the arrester bed is made and assembled. Any known conceivable method of forming a bed of prefabricated blocks of compressible foam material at the location where the arrester bed is to be placed is included in the present invention, so long as the arrester bed has an inclined straight line of prefabricated blocks that form a continuous series of inverted V-shaped patterns along the longitudinal center axis with respect to the direction from the front end to the rear end of the arrester bed.

[0021] The term "compressible foam material" as used herein encompasses any material known to one skilled in the art to be suitable as a deformable / foldable material that engages the oncoming wheels of a vehicle / aircraft and absorbs kinetic energy from the vehicle / aircraft to bring the vehicle / aircraft to a controlled stop. Examples of suitable materials include, but are not limited to, cellular cement, cellular cement-based materials, foamed cement, polymer foam, honeycomb, metal honeycomb, vermiculite, perlite, ceramic foam, foam glass, and other isotropic or anisotropic compressible / deformable materials, or combinations thereof.

[0022] When a compressible foam material is subjected to a stress load, the foam material reaches a certain plateau value, σ, at which the foam material begins to fracture / compress. u , the stress load is maintained until the foam material is gradually compressed during the plateau stress until all or nearly all of the voids in the foam microstructure collapse. At this point, the material has significantly stiffened and further compression requires dramatically higher stress / compression forces. A typical compressive stress-strain curve for a compressible foam material is shown in Figure 2. The degree of compression at the end of the plateau is determined by the maximum compressive strain of the material, ε max , and is important in determining the overall energy absorption potential of a compressible foam material since energy absorption is related to the area under the stress-strain curve. Larger maximum compressive strain values ​​correspond to a longer plateau region in the load curve and higher energy absorption. As used herein, the term "compressive strength" refers to the plateau value, σ, as determined by ASTM CI165-07(2017), unless otherwise specified. u , refers to.

[0023] The compressible foam material of the arrester bed has a mechanical strength adjusted so that the arrester bed cannot carry the wheels of the vehicle / aircraft entering the arrester bed, but sinks a distance within the compressible foam material so that the compressible foam material absorbs kinetic energy from the vehicle / aircraft and forces the vehicle / aircraft to a stop, as shown in the photograph of Figure 1. The compressive strength of the compressible foam material that provides an effective but controlled stopping action against the vehicle / aircraft depends greatly on the expected tire pressure that will be pressed against the surface of the arrester bed by the wheels of the vehicle / aircraft entering the arrester bed. Since the mass of the vehicle / aircraft can vary widely, the range of compressive strengths that provide an effective stopping action also varies widely. It is therefore necessary to adapt the compressive strength of the compressible foam material of the arrester bed depending on the vehicle / aircraft that is intended to be stopped by it. However, the determination of the required compressive strength is within the ordinary skill of the person skilled in the art and may be performed by experimental material testing and / or numerical modeling, as described in ACRP Report 29 [1] (see, for example, Chapters 8 and 9). In practice, for vehicle arresting system applications at passenger airfields, the compressible foam material may advantageously have a compressive strength in the range of 6.9 to 689.8 kPa (1 to 100 psi), preferably 68.9 to 620.5 kPa (10 to 90 psi), more preferably 137.9 to 551.8 kPa (20 to 80 psi), more preferably 206.8 to 482.6 kPa (30 to 70 psi), and most preferably 275.8 to 413.7 kPa (40 to 60 psi).

[0024] In some embodiments, each prefabricated block may be made of several smaller blocks 7 glued together in a vertical stack, for example by gluing. This gives the prefabricated block a layered, layered structure. This method of assembling the prefabricated blocks into an arrester bed is sometimes called the block method. An example of such an assembly for making an EMAS is shown diagrammatically in FIG. 4a). The figure shows a schematic illustration of an arrester bed 1 consisting of several rows 2, each row consisting of several prefabricated blocks 10 of compressible energy absorbing material arranged side by side. As can be seen from the detailed enlargement, each prefabricated block 10 of the bulk part of the arrester bed is composed of several, here four, layers 9 of smaller blocks 7 stacked and glued on top of each other. In this embodiment, the tapering at the front end and / or sides of the arrester bed may be obtained simply by applying a smaller number of smaller blocks in the stack for the first row of the arrester bed and / or at the end of each row.

[0025] In some embodiments, the block may have a layered, layered structure, where each layer is made of smaller blocks 8, and where each layer is offset with respect to the layer below it, such that the smaller blocks 8 form a brick pattern as shown in FIG. 4b). That is, the prefabricated block comprises a vertical stack of multiple layered layers 9 glued together, where each layered layer 9 is made of a second multiple smaller blocks 8 arranged in a single horizontal plane, and the smaller blocks 8 of the layered layer 9 are offset from the lower layer to the upper layer with respect to the multiple smaller blocks 8 of the layered layer 9 below and / or above it, such that the smaller blocks 8 of the prefabricated block form a brick pattern. Such a structure results in an arrester bed with more monolithic mechanical properties.

[0026] In some embodiments, the arrester bed can be provided with a cover layer on top of the compactible energy absorbing material to protect it from the environment, jet blast, etc. The present invention can apply any known conceivable cover layer known to those skilled in the art as suitable for an arrester bed made of foamed / compressible energy absorbing material. Examples of suitable cover layers include a thin plastic top, a cement board top, a polymer coating or sealant, a paint, or a combination thereof. The exemplary embodiment shown in Figure 4a) and Figure 4b) comprises a cover layer 5.

[0027] The arrester bed may, in some embodiments, have a depth variation in compressive strength, where the compressive strength increases as the depth of the bed increases. This provides the arrester bed with improved performance in the case of a mix of vehicles / aircraft, as the wheels of lighter vehicles only engage the softer upper layers, while the wheels of heavier vehicles / aircraft engage deeper into the arrester bed, as illustrated diagrammatically in Fig. 3a) and Fig. 3b). In an embodiment in which the prefabricated block 10 has a layered structure, the depth variation in compressive strength can be obtained by simply gluing together smaller blocks 7, 8 having progressively stronger compressive strengths at lower depths, such that the bottom layer has the highest compressive strength, the top layer has the weakest strength, and each successive layer has a weaker compressive strength than the smaller block below it. An example of such an embodiment is shown in Fig. 3a) and Fig. 3b).

[0028] In an exemplary embodiment having a layered structure with depth variation in compressive strength, the upper layers produce a softer material response under vehicle / aircraft tire loads than the solid compressible energy absorbing material, thereby acting similarly to a lower density compressible energy absorbing material with lower compressive strength. The lower layers produce a stiffer material response under aircraft tire loads, and in the limit, the strength approaches that of the solid compressible energy absorbing material. The bottom layer may be a continuous compressible energy absorbing material with no voids. In an exemplary embodiment, the one or second plurality of smaller blocks 7, 8 in the top layer 9 of the layered prefabricated block 10 has a first compressive strength, the one or second plurality of smaller blocks 7, 8 in the first layered layer 9 below the top layer has a second compressive strength, the one or second plurality of smaller blocks 7, 8 in the second layered layer 9 below the top layer has a third compressive strength, and so on down to the bottom layer 9, where the first compressive strength<second compressive strength<third compressive strength, and so on down to the bottom layer 9.

[0029] It is clear from the context that the angle α relative to the longitudinal central axis of the arrester bed is an angle formed in the horizontal plane such that the inclination of the straight lanes creates a lateral force on the vertically oriented wheels moving longitudinally through the arrester bed. Thus, as used herein, the term "angle α" relates to the angle at which the straight lanes of the prefabricated blocks incline in the horizontal plane towards the longitudinal central axis of the arrester bed in the direction of movement, as illustrated diagrammatically in FIG. 5. The figure shows an exemplary embodiment of an arrester bed 1 assembled by prefabricated blocks 10 arranged in a set of linear lanes or rows, indicated in the figure by their longitudinal sides 21. The figure also shows one straight line 11 of the prefabricated blocks 10 with a rectangular staple marked with reference number 11 and the direction of one row 2 with a rectangular staple marked with reference number 2. The arrester bed has a front end where the vehicle / aircraft to be stopped arrives and enters the arrester bed in the direction of travel indicated by the two staple arrows. As can be seen in the figure, the inclination of the straight lanes is such that they slope from either side of the axis toward the central longitudinal axis indicated by the staple line marked A-A'.

[0030] In some embodiments, the set of straight lines of the prefabricated block may be inclined at an angle α, where 0°<α≦28°, preferably 1°≦α≦25°, more preferably 2°≦α≦23°, more preferably 3°≦α≦20°, more preferably 4°≦α≦15°, more preferably 5°≦α≦15°, and most preferably 5°≦α≦10°, toward the central longitudinal axis of the bed that forms an inverted V-pattern with respect to the direction from the front end to the rear end of the arrester bed.

[0031] In some embodiments, the prefabricated blocks may be shaped to interlock with each other when assembled to facilitate assembly at the runway construction site. The prefabricated blocks may feature interlocking geometric features at their edges. The connection features may be designed to interlock in height, for example by a tongue-and-groove interlocking mechanism as illustrated in FIG. 6a, or in planar direction, for example by complementary male and female jigsaw puzzles resembling the geometric structures as illustrated in FIG. 6b. FIG. 6a) illustrates diagrammatically a single prefabricated block and an assembly of three blocks. The blocks have, in side view, a groove-type geometric structure 21 and, on the other side, a tongue-type geometric structure 22, such that when they are assembled in a line, the groove of the block interlocks with the tongue of the next block in the lane. Similarly, as can be seen in FIG. 6b), FIG. 6b) illustrates a single prefabricated block 10 and an assembly of four blocks when viewed from above, where the prefabricated block 10 has two male geometric structures 23 and two female geometric structures 24 that interlock with each other when assembled. Links may be designed with link tolerances ranging from one millimeter to several centimeters to accommodate thermal expansion of a large bed of many linked blocks. Linkages can also provide a smoother stopping force for the aircraft by eliminating gaps between the blocks, because such gaps can create a vibrating speed bump effect on the aircraft tires during arrestment.

[0032] In some embodiments, the block with depth variation may have inclined layered layers oriented toward the centerline of the arrester bed. That is, by having the layered layers 9 of the prefabricated block 10 inclined so that the layered layers 9 are substantially parallel (i.e. horizontal) to the longitudinal central axis of the arrester bed and inclined so that they slope downward laterally toward the longitudinal central axis of the arrester bed, the layered layers are inclined so that they slope downward toward the centerline. Figure 7a) is a perspective view from the side and top of a single block 10 having six layers 9 of compressible energy absorbing material with gradually weaker compressive strength toward the top. As can be seen in the figure, each layered layer is somewhat inclined toward the centerline, shown as staple lines marked A and A'. Figure 7b) illustrates the same block as Figure 7a), but now viewed from the front surface side. A wheel 12 entering the block 10 and travelling longitudinally comes into contact with a relatively large amount of weakly compressible energy absorbing material on its right side (relative to the direction of travel) and is therefore subjected to a lateral force towards the centreline, as shown by the black arrow in the figure.

[0033] An exemplary embodiment of an arrester bed assembled by blocks with layered layers of varying depth and inclination is shown in FIG. 8. In this exemplary embodiment, the arrester bed 1 comprises eight blocks with layered layers of varying depth and inclination in each row (lateral direction), namely four blocks 10 on the left side of the centerline A-A' and four blocks 13 on the right side. The layer inclination of the blocks 10 on the left side of the centerline causes the layered layers to be inclined downwards towards its right side, and the layer inclination of the blocks 13 on the right side of the centerline causes the layered layers to be inclined downwards towards its left side. As shown in this example, an aircraft approaching the arrester bed off-line, for example to the left side of the arrester bed, experiences a lateral force that tries to guide the aircraft to be aligned on the centerline. This effect is in addition to the orientation effect of the set of linear stripes / zones with a compressive strength lower than the bulk compressive strength according to the present invention.

[0034] In some embodiments, the prefabricated block may comprise one or more linear through voids, channels or holes aligned vertically on the lateral sides of the block such that the through voids, channels or holes of successive blocks in each linear lane align and form a through void, channel or hole extending through the entire linear lane of the block. These through voids, channels or holes in the linear lane form linear zones in the arrester bed that have a compressive strength lower than the bulk compressive strength of the arrester bed and are oriented toward the central axis at the same angle as the inclination angle of the linear lane of the block, thus enhancing a centering effect that helps the vehicle / aircraft pass through the arrester bed in parallel and along the longitudinal central axis of the arrester bed formed by the relatively weak joints along the side walls of the prefabricated block. [Brief description of the drawings]

[0035] [Figure 1] Figure 1 is reproduced from Wikipedia https: / / en.wikipedia.org / wiki / Engineered_materials_arrestor_system showing a photograph of an aircraft wheel entering the EMAS bed and being arrested. [Diagram 2] FIG. 2 shows a typical compressive stress-strain curve for a compressible foam material. [Figure 3a)] FIG. 3a) is a schematic diagram illustrating the penetration depth of a heavy wheel (FIG. 3a) penetrating an arrester bed having a layered structure of multiple layers of compressible foam material, with the upper layers having a lower compressive strength and the lower layers of compressible foam material having a higher compressive strength. [Figure 3b)] FIG. 3b) A schematic diagram illustrating the penetration depth of a light wheel (FIG. 3b)) entering an arrester bed having a layered structure of multiple layers of compressible foam material, where the upper layers have a lower compressive strength and the lower layers have a higher compressive strength of the compressible foam material. [Figure 4a)] FIG. 4a is a diagram illustrating a schematic diagram of an exemplary embodiment of a block type arrester bed. [Figure 4b] FIG. 4b is a diagram illustrating a schematic diagram of an exemplary embodiment of a monolith type arrester bed. [Diagram 5] FIG. 5 is a diagram illustrating a schematic top view of an exemplary embodiment of an arrester bed according to the present invention having angled lanes of prefabricated blocks. [Figure 6a)] FIG. 6a) is a diagram illustrating an exemplary embodiment of a building block having interlocking geometric shapes. [Figure 6b] FIG. 6b) is a diagram illustrating an exemplary embodiment of a building block having interlocking geometric shapes. [Figure 7a)] FIG. 7a) is a diagram illustrating an exemplary embodiment of a prefabricated block having a layered structure with depth variations and sloping layers. [Figure 7b] FIG. 7b) is a diagram illustrating an exemplary embodiment of a prefabricated block having a layered structure with depth variations and sloping layers. [Figure 8] FIG. 8 is a diagram illustrating an arrester bed assembled from the blocks shown in FIG. 7a) and FIG. 7b). [Figure 9] FIG. 9 shows the calculated lateral forces on a B737 main gear entering a tilted bed of foam glass at different tilt angles. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] The invention is explained in further detail by means of an exemplary embodiment of an arrester bed intended to stop an aircraft entering the bed.

[0037] The exemplary embodiment of the arrester bed is constructed of prefabricated blocks of foam glass having a compressive strength of 50 psi assembled to form linear lanes of prefabricated blocks angled at 15° toward the central longitudinal axis of the arrester bed. The linear lanes form a pattern similar to the exemplary embodiment illustrated in FIG.

[0038] The dimensions of the prefabricated blocks in the bulk section of the straight line were 2.13 m length and width, and 76 cm height. The prefabricated blocks located at the edge of the arrester bed, and adjacent on both the left and right sides relative to the central longitudinal axis, were shaped to create a continuous rectangular arrester bed with a width of 49 m and a length of 98 m. The arrester bed thus covers a surface area comparable to that of a small football field.

[0039] The longitudinal sides between adjacent straight lanes of the arrester bed blocks form a set of angled zones of relatively weak compressive strength compared to the compressive strength of the blocks. This creates a directional central force. In automobiles, this type of force is observed by the rutting of the road surface, which in that context is called tramway track.

[0040] The effective horizontal load of crushable foam on an aircraft tire depends on the inclination angle of the tire relative to the channel or lane of material. The resultant lateral and longitudinal forces (F x and F y ) can be calculated by integrating the component forces around the circumference of the tire in contact with the crushable foam. As the path of tire travel becomes more perpendicular to the foam layer interface, the average lateral force decreases toward zero. Similarly, once the tire is completely over the boundary of the crushable foam layer, the lateral forces are balanced and the net force decreases toward zero.

[0041] As an example, the lateral forces on the main gear tires of a B737 entering a straight lane of a block at different angles were calculated for several inclination angles of 15, 30, 45, 60, and 75 degrees and are shown in Figure 9. The main gear of a B737 with a rated load of 199 kN (44,700 lbf) has a radius of 113 cm (44.5 in) and a width of 42 cm (16.5 in). The condition scenario was simplified to include a single exposed surface of the crushable foam adjacent to the void. The directional load was calculated by integrating along the arc length of the tire in contact with the crushable foam. The calculations were performed at a series of positions as the tire gradually enters the crushable foam by moving in the direction of travel.

[0042] As can be seen from Figure 9, the lateral forces in this example reach their highest magnitude and are maintained over the longest travel length at the shallow 15 degree tilt angle. As the material becomes more perpendicular to the direction of travel at tilt angles greater than 45 degrees, the lateral load becomes weaker and shorter.

[0043] If the tire engages the foam material at a 15 degree tilt angle and the effective engagement depth is 2 / 3 of the turning radius, or 2 / 3 x 18.5 inches = 12.4 inches (31.5 cm). Referring to the 15 degree curve in FIG. 9, the peak lateral force is 0.42 kip per inch of material depth or 420 lbf (735 N / cm). The total lateral force is therefore Fx = 420 lbf / in x 12.4 in = 5,200 lbf (23.1 kN). Dividing this peak load by the tire rated normal load gives 5,200 lbf / 44,700 lbf = 11.6%. This level of load is significant and acts on all aircraft tires, resulting in an effective central force on the aircraft of approximately 11.6% of the aircraft weight. As shown by the plot, this load rises and falls over a long travel distance of approximately 60 inches (152 cm).

[0044] References 1. Matt Barsotti et al. (2009), “ACRP Report 29: Developing Improved Civil Aircraft Arresting Systems” US Transportation Research Board, DOI:10.17226 / 14340

Claims

1. A vehicle arresting system comprising an arrester bed (1) resting on a base / ground and having a central longitudinal axis extending from a front end to a rear end opposite said front end, said arrester bed (1) comprising a plurality of prefabricated blocks (10) of compressible foam material assembled and bonded side by side, said assembly of prefabricated blocks comprising a set of an even number of linear lanes (11) of prefabricated blocks (10), half of said sets being positioned to the left of said central longitudinal axis of said arrester bed and half of said sets being positioned to the right; A vehicle arresting system, characterized in that each straight line (11) of the prefabricated block (10) is inclined at an angle α toward the longitudinal central axis of the arrester bed, where 0°<α≦30°, and when viewed from above, the set of straight lanes (11) form a series of continuous inverted V-patterns along the longitudinal central axis of the arrester bed, and the prefabricated blocks (10) are shaped and dimensioned such that they completely cover / fit the surface area of ​​the base / ground on which the arrester bed is placed.

2. 2. The vehicle arresting system of claim 1, wherein the set of relatively low compressive strength straight lines are inclined at an angle α, where 0°<α≦28°.

3. 3. The vehicle arresting system of claim 1 or 2, wherein the compressible foam material is a material selected from cellular cement, cellular cement material, foamed cement, polymer foam, honeycomb, metal honeycomb, vermiculite, perlite, ceramic, foam glass, and other isotropic or anisotropic compressible / deformable materials, or combinations thereof.

4. 3. The vehicle arresting system of claim 1 or 2, wherein the compressible foam material has a compressive strength in the range of 1 to 100 psi.

5. 3. The vehicle arresting system of claim 1, wherein the arrester bed has a depth variation in compressive strength that increases with increasing bed depth, obtained by providing the arrester bed with a layered structure of multiple layers of compressible foam material having a higher compressive strength for each successive layer of compressible foam material up to a bottom layer of the arrester bed.

6. 3. The vehicle arresting system of claim 1 or 2, wherein the prefabricated blocks are adhered together by gluing, caulking, or adhesive tape.

7. The assembly block (10) is a vertical stack of layered layers (9) bonded together, each layer (9) consisting of one smaller block (7); or 3. The vehicle arresting system of claim 1 or 2, comprising a vertical stack of a plurality of layered layers (9) bonded together, each layered layer (9) consisting of a second plurality of smaller blocks (8) arranged in a single horizontal plane, the smaller blocks (8) of a layered layer (9) being offset from lower to upper layer relative to the plurality of smaller blocks (8) of the layered layer (9) below and / or above it, such that the smaller blocks (8) of the prefabricated block (10) form a brick pattern.

8. 8. The vehicle arresting system of claim 7, wherein the one or the second plurality of smaller blocks (7, 8) of the upper layer (9) of the layered prefabricated block (10) has a first compressive strength, the one or the second plurality of smaller blocks (7, 8) of a first layered layer (9) below the upper layer has a second compressive strength, and the one or the second plurality of smaller blocks (7, 8) of a second layered layer (9) below the upper layer has a third compressive strength, and so on down to the lower layered layer (9), where the first compressive strength<the second compressive strength<the third compressive strength, and so on down to the lower layered layer (9).

9. 9. The vehicle arresting system of claim 8, wherein the layered layers (9) of the prefabricated block (10) are inclined such that the layered layers (9) are substantially parallel to a longitudinal central axis of the longitudinal direction and are inclined laterally downward toward the longitudinal central axis of the arrester bed.

10. 3. The vehicle arresting system of claim 1 or 2, wherein the prefabricated block (10) further comprises interconnecting geometric features at its edges.

11. 3. The vehicle arresting system of claim 1 or 2, wherein the prefabricated block (10) further comprises one or more linear through voids, channels, or holes oriented perpendicular to a side of the block.

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