JPS6349097B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a device for attenuating forces by absorbing energy. In particular, the invention relates to a device for attenuating the forces generated in the event of a high-speed impact, such as in the case of a forced landing. Vehicle structures are provided with various force damping devices to minimize crash landing damage to the vehicle and to prevent injury to occupants within the vehicle. For example, aircraft seats are equipped with energy absorbing mechanisms to cushion the occupants of the aircraft from landing forces. The landing gear is also equipped with energy absorbing devices and structures. Conventional force damping devices for aircraft seats generally include a compressible corrugated aluminum cylinder within a seat height adjustment mechanism to act as an energy absorbing device. Landing conditions with high impacts therefore dissipate energy through permanent deformation or crushing of the energy absorbing device. Examples of conventional force damping devices for landing gear include:
A two-stage energy absorption device is described in US Pat. No. 3,716,208. In this device, the first
The stage's energy absorption drives a piston in an oil-filled cylinder that passes oil through a control orifice, reducing the forces exerted on the aircraft through the landing gear. The second stage of energy absorption actually deforms the struts that connect the landing gear to the fuselage. Other devices for damping the forces created when an aircraft lands at high directional speeds include U.S. Pat.
This is a forced landing attenuation landing system described in the specification of No. 3997133. This patent describes an energy dissipating structure in the form of a relatively thin-walled aluminum cylinder with a shock strut. The device further includes an annular body having a plurality of radially upwardly directed cutting blades associated with the inner wall of the cylinder for performing mechanical work upon movement of the cylinder relative to the annular body. In particular, the mechanical work performed by this annular body is to cut the cylinder into longitudinal strips when a relative movement occurs. A variation of the cylindrical cutter construction is described in the above-mentioned patent and utilizes a flared structure in place of the cutting ring. In this variant of the device, pressing the cylinder downward onto the working surface of the flared structure causes the edges of the cylinder to flare and tear the cylinder. This spreading action absorbs energy and attenuates force. Examples of energy absorbing devices as vehicle shock absorbers include devices currently installed in passenger cars. Such an installation is essentially a fluid-filled energy-absorbing cylinder. The application of reinforced plastic materials to automobile structures is
The ability of such structures to withstand impact is the subject of research sponsored by the US Department of Transportation, as reported in Report No. DOT HS-801771: Feasibility Study of Plastic Automotive Structures. This report describes a strength study of the use of plastic automobile structures to protect the passenger compartment during frontal impacts. Problems to be Solved by the Invention The aluminum alloy force damping device described in the above-mentioned US Pat. No. 3,997,133 is somewhat unsatisfactory in its force damping effect relative to the weight of the aluminum alloy energy absorbing member. In addition, members that apply force to aluminum alloy energy absorbing members, such as those that apply a sudden deceleration to only a portion of the travel distance of an aircraft passenger's seat, may apply a stronger and more dangerous force to the passenger; It had drawbacks such as being often affected by annular conditions such as corrosion. The aim of the invention is to eliminate this drawback. Means for Solving the Problems The present invention provides a tubular elongate member 12, 48, 7
8, 94, and an anvil 1 axially aligned with this elongated member.
4, 40, 82, 92, and an insert member 16, 44-54, which applies a force to the end of said elongated member located opposite the anvil.
84, 96, wherein the elongate member is constructed of a composite material of resin-bonded load-bearing fibers, and the force applied by the insert member causes the elongate member to the load-bearing fibers are selected at an angle of about 0° to 75° with respect to a plane extending transversely to the axis of the elongated member so as to cause the load-bearing fibers to progressively disintegrate in the plane of the anvil; A force damping device comprising a plurality of fibers oriented at an angle. According to the invention, the energy absorbing member, which is an elongated member made of a composite material consisting of load-bearing fibers, such as graphite fibers, bonded with a resin, such as an epoxy resin, is made into a tubular shape (i.e., has a closed cross-sectional shape). and by orienting said fibers at an angle in the range of about 0° to 75° with respect to a plane 15 extending transversely to the axis of the elongated member, when a force is applied to the insert member, the elongated member An axial force is applied to cause the elongated member to progressively break apart in the plane of the anvil in axial alignment therewith, as shown in FIGS. 1a-1c. EFFECTS OF THE INVENTION According to the present invention, a composite material consisting of load-bearing fibers bonded with a resin has a force damping effect stronger than that of an aluminum alloy for a given amount of weight. It is lighter in weight than aluminum alloys, and the dissipation of energy is carried out by the gradual disintegration of the energy-absorbing member throughout 100% of the travel of the insert, allowing automatic adjustment of the force damping action. Compared to energy absorbing members made of aluminum alloy, which dissipate energy during a short travel stroke, the damping effect is more gradual, and the impact force experienced by, for example, an aircraft passenger can be reduced. Furthermore, the composite material is less susceptible to annular conditions such as corrosion than aluminum alloys. Embodiments of the force damping device according to the invention will now be described in detail with reference to the accompanying drawings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG.
2. An anvil mount 14 is disposed adjacent one end of the member 12 in axial alignment with the member 12. The force that is to be attenuated by the absorption of energy by the fibrous member 12 is
By applying a suitable force applying member such as 6 to the opposite end of the member 12 and progressively crushing the member 12 against the anvil 14 as shown in FIGS. 1a, 1b and 1c, In other words, anvil stand 1
Energy is dissipated by progressively collapsing the 4 planes. According to the invention, as shown in FIG. 2a, the energy absorbing elongated member (hereinafter referred to as energy absorbing member) 12 may be a composite material consisting of a mixture of fibers and resin. The fibers provide the material with the necessary strength to act as an energy absorber, and the resin or matrix holds the fibers and distributes the loads on them. Energy absorbing member 1
Examples of fibers used in 2 include materials from the group consisting of graphite, Kevlar glass fibers and boron. A thermosetting or thermoplastic resin is mixed with the fibers during construction of the energy absorbing member. Examples of thermoset resins include polyester resins, epoxy resins, and phenolic resins, with epoxy resins having superior mechanical properties and dimensional stability. Thermoplastic resins include polystyrene, polycarbonate, and polypropylene, as well as others. Depending on the fiber and resin selected, different construction methods are used in the manufacture of the energy absorbing member 12. Examples of such construction methods include wrapping of filaments or rovings, tapes or strips, combinations of laminates,
Pultrusion, incorporation of cut fibers, and pre- and post-forming. Each of these construction methods is expensive to use in producing products comprised of fiber and resin mixtures. Other manufacturing methods for the energy absorbing member 12 include:
There are fiber orientation methods that affect the energy absorption properties of this component. The fiber orientation method involves the use of a variety of unidirectional fibers oriented at angles between 0° and 90° with respect to the column axis of the energy absorber or with respect to the transverse plane 15, as shown in FIG. 2a. Make combinations. To further control the energy absorption properties of member 12, the positioning of each fiber layer or each laminate within the laminate is selected to provide the desired laminate properties. When using spray or cut fiber molding methods, the fibers are randomly oriented. The energy absorbing member 12, which is an elongated member, is
It can have a circular, oval, square or rectangular cross-sectional shape. In FIG. 2a, only the energy absorbing member 12 of circular cross section is shown. All of the energy absorbing members 12 have a tubular structure with a closed cross-sectional shape, and some of the energy absorbing members 12 may be constructed with groove-shaped members such as a J-shape. Like other energy absorbing members, this groove-shaped member also has a continuous, ie closed, cross-sectional shape. All energy absorbing members 12 are open at both ends. Energy absorbing member 12 for testing the present invention
A sample was prepared. Three different materials were used to make these samples: graphite, Kevlar, and fiberglass along with epoxy resin. These test members were filament wound using rovings or bundles of resin-impregnated fibers that were progressively wound at the desired orientation angle to a predetermined wall thickness. Table 1 shows the properties of each tubular member made from the three types of composite materials described above.

【table】

[Table] Highest specific energy absorption (ft lb/ft lb/ft) from graphite-epoxy resin mixtures based on previously conducted tests.
Weight lb) was obtained. It is clear from these tests that the specific energy absorption of a particular energy absorbing member is a function of the fineness with which the material can be fractured during crushing. After crushing, for example, the graphite-epoxy resin tubing was crushed while the Kevlar tubing remained somewhat intact. Although the end of the anvil 14 adjacent the member 12 is shown in FIG. 1 as being flat with a square periphery, the energy absorbing force damping device according to the invention shown in FIG. The part has a shape other than a flat surface. In particular, the peripheral edge of the anvil base 14 is cut diagonally to form a conical base. Anvil stand 1
The shape of 4 is evident in Figure 2b. Slope 14a
The angle α in FIG. 2b is 45°. When the energy absorbing member 12 is pressed against the anvil stand 14 and disintegrated into pieces, if the anvil stand 14 is formed in a conical shape, the conical angle α is
As the angle increases from 0° to 45°, the energy absorbing member can be broken apart with lower loads. To demonstrate this finding, tests were conducted on energy absorbing members constructed with fibers oriented ±45° relative to the lateral plane 15.
By applying an axial force to the energy absorbing member, when the fibers are oriented at an angle of about 0° to 75° with respect to the transverse plane 15, as shown in FIGS. 1a to 1c, It has been found that the energy absorbing member at the face of the anvil most effectively disintegrates into pieces in a gradual manner. Figures 3a and 3b each show an anvil stand 14.
This conical angle and the negative conical angle are shown for . For the negative cone angle shown in FIG.
It was calculated to increase the amount of energy absorbed per hit. An important indication of the effectiveness of a force damping device is its specific energy absorption efficiency coefficient. This specific energy absorption efficiency coefficient is an indication of the force damping capacity of the device in relation to its weight. The dimension of this coefficient is ftlb/weight lb. The specific energy absorption efficiency of the device of the present invention is determined not only by the materials used, but also by the angle that defines the slope of the peripheral edge of the conical pedestal formed at the end of the anvil pedestal 14, as shown in FIGS. 2a, 3a, and 3b. It turns out that this is due to α. Static loads applied to the energy absorbing member 12 made of the various composite materials shown in Table 1 when anvils with slope angles α of 0°, 15°, 30°, and 45° are used. The deflection curves are shown in Figures 4a and 4b.
and FIG. 4c. Figure 4a, 4th
The diagrams in FIGS. b and 4c are diagrams of the load lb versus the deflection in, ie the travel of the force transmitting insert 16. As shown, each curve for each material shows initial peaks and valleys representing initial peak failure loads.
As can be seen from the diagrams for each material, the initial high peak failure loads can be reduced by bevelling the edges of the ends of the tubular members. 4th a
Following the initial peaks and valleys as shown in the diagram, the load-deflection curve shows a portion that reflects the movement of the force transmitting insert 16 relative to the anvil 14. Load force is generated in this part. The transition portion of each load-deflection curve is a straight line portion representing a constant load sustained by the tubular member 12 as the force transmitting insert 16 moves downwardly and progressively crushes the tubular member 12 against the anvil 14. Move. For energy absorbing members 12 with beveled ends, the curved portions are lowest leaving only the portions as illustrated in Figure 4d for graphite-resin tubular members. The linear portion of the load-deflection curve indicates that the load is constant and therefore the energy absorption efficiency is constant over approximately the entire length of the force-transmitting insert travel, which corresponds to the length of the tubular member. The specific energy absorption efficiency for each device shape can be calculated from static test data. These specific energy absorption efficiencies are shown in Table 2 for laminates with fiber orientation of ±45°. Also shown for comparison is the specific energy absorption efficiency of a metal tubular member made of 3003-H14 aluminum alloy.

[Table] The accuracy of the static load deflection curves in Figures 4a, 4b, 4c, and 4d as an indication of the effectiveness of the present invention when a dynamic load is applied is based on the line of action of the applied force. This was investigated by conducting a drop test using a graphite-epoxy resin tubular member wrapped with filament at an angle of approximately 45° in the lateral plane. This tubular member falls from a height of 2ft.
The impact was made with a mass of 122lb. The total drop height, including the deflection of the tubular member, was 25.7 inches. This device effectively attenuated a total of 242 ft-lb of energy without momentum. Using the energy from the area under the static load deflection curve in Figure 4a and setting the diagonal cutting angle of the anvil to 0°, a travel of 1.63 inches was predicted. Also, in the dynamic fall, the travel was 1.75 inches. This shows that static load deflection information is representative of the case of dynamic load. The energy absorbing seat 20 is shown in FIGS.
It is shown in FIGS. 7 and 8. The energy absorbing seat 20 according to the invention includes a seat support 22 with legs 24 positioned on a surface. A contoured seat portion 26 is also provided and attached to the seat support 22 as described below. As seen in FIGS. 5 and 6, seat support 22 has extended support arms 28 and 30 extending from legs 24a and 24b, respectively. Each extension arm 2
The two extension arms 28, 30, to which the seat part 26 is attached by means of straps 32, are interconnected by means of an upper support channel profile 34. Further, a damping retainer 36 is bolted between the legs 24a and 24b. A force damping device 38 according to the invention is provided and bolted between the damping stay 36 and the back of the seat part 26. 7 and 8 show the force damping device 38 mounted on the damping stay 36 in detail. Attenuation device 3
The lower end of 8 is provided with an end support 40 which acts as a cup-shaped anvil in which is mounted a fixed cylinder 42 concentric with an internal cylinder 44. Internal cylinder 44 terminates in a closed end 46 which acts as a force-applying member to an energy absorbing elongate member 48 mounted within cylinder 42 from seat portion 26 . Energy absorbing member 48 is of the type illustrated in FIGS. 1 and 2. The structure consisting of each cylinder 42, 44 and energy absorbing member 48 is assembled in operative relationship by a clamping piece 50. In the embodiment of the force damping device shown in FIGS. 7 and 8, the upper end of tubular member 54 is connected to bracket 56.
As a result, this bracket 56 is bolted directly to the back of the seat portion 26. A spring piece 52 is provided as part of the damper between the internal cylinder 44 of the force damping device 38 and the tube member 54 supporting the seat part 26. The seat portion 26 is a belt piece 32
Although attached to the extension arms 28, 30 of the seat support frame 22 by the seat support 22, it is clear that the seat portion 26, together with the strap 32, can be moved relative to the extension arms 28, 30. The forces applied to the seat part 26 are thus transmitted to the energy absorbing member 48 via the insert member consisting of the tube member 54, the spring piece 52, the inner cylinder 44 and the closed end 46. In operation, the internal cylinder 44 progressively crushes the energy absorbing member 48 by the seat section 26 to dissipate energy and absorb impact forces during landings with high velocity impacts that typically result in high impact forces being transmitted to the person in the seat section 26. Attenuate. During extreme deceleration of an aircraft equipped with energy absorbing seat 20, deceleration forces are generated and applied through seat portion 26 to force transmission damping device 38. Especially Figure 6,
With respect to the force damping device 38 shown in FIGS. 7 and 8, the force urges the seat portion 26 downwardly relative to the damping stay 36 and moves the internal cylinder 44 downwardly relative to the cylinder 42. internal cylinder 44
The downward movement of the energy absorbing member 48 forces it against the end support 40, which acts as an anvil. The energy absorbing member 48 thus dissipates energy and dampens the damping force exerted on the tower occupant following and seating the seat portion 26. In the embodiment shown in FIG. 5, the energy absorbing seat 20 is further provided with a conventional seat adjustment mechanism 58 for adjusting the height of the seat portion 26 relative to the support surface. Although the composite energy absorbing members utilized in the energy absorbing seat 20 are shown as cooperating with a separate mechanism, it will be appreciated that the force damping system of the present invention may be cooperating in other manners. The present invention has several advantages when utilized in energy dissipative force damping devices over previously used aluminum alloy energy absorbing members. As shown in Table 2, the specific energy absorption efficiency of composite materials, especially graphite, is superior to the efficiency obtained with metal materials. That is, the composite fibrous material provides a stronger force damping effect for a given amount of weight. Particularly in the aircraft industry, such structures are extremely useful. It is also an advantage of the present invention that energy dissipation is significantly increased by fully destroying the material through 100% of the stroke. Of course, corrugated aluminum and other metal materials do not undergo sufficient failure or 100% deflection. Therefore, basic principles of physics dictate that the dissipation of available work and energy over the travel distance is possible in composite materials but not in metallic materials. This means that the occupants of the aircraft are subject to stronger and more dangerous forces, with only a portion of the distance being decelerated. Another advantage of the present invention is that the force damping device is not affected by environmental conditions such as corrosion and the like. Although the foregoing description of an illustrative embodiment of the invention relates to only one application of the invention, the invention can be utilized in a variety of other applications, including the need for force attenuation and energy dissipation. . Among such other uses are energy absorbing landing gear for aircraft and aircraft engine and transmission supports as well as vehicle shock absorbers. 9 and 10, the force damping system of the present invention is shown as part of the landing gear. This landing gear 6
4 is attached to the helicopter fuselage 66 by a pivot arm 68 and a support bracket 70. Pivoting arm 6
An axle device 72 supporting wheels 74 is provided at the outer end of the wheel 8.
It is pivoted. Connected between the axle assembly 72 and the support bracket 70 is a force damping device 76 comprising an energy absorbing elongate member 78 and a hydropneumatic shock strut 80. Impact strut 80 is conventional with a retaining cup 82 formed as an integral part of the strut housing. Mounted within the cup 82 is an energy absorbing member 78 having an upper end fitted within a retaining cup 84 which is pivotally connected to the support bracket 70. 10, the energy absorbing member 78 tapers inwardly throughout its length from the end that fits into the retaining cup 84 to the lower end of the retaining cup 82. A retaining ring 86 is assembled between the absorbing member 78 and the inner diameter of the retaining cup 84 to secure the upper end of the energy absorbing member 78 within the retaining cup 84. Similarly, a retaining ring 88 is assembled between the energy absorbing member 78 and the inner wall of the retaining cup 82. In operation, the insert retaining cup 84 acts as a force-applying member and the retaining cup 82 acts as an anvil. During a high-impact or forced landing of a vehicle equipped with the landing gear of FIG. This force urges the energy absorbing member 78 downwardly relative to the retaining cup 82. Movement of retaining cup 84 relative to retaining cup 82 causes energy absorbing member 78
is pressed against the cup-shaped body 82 which acts as an anvil. Therefore, the energy absorbing member 78
dissipates energy and attenuates the deceleration force applied to the fuselage 66. Although the invention is particularly suited for aircraft applications due to its high force damping capacity and relatively low weight, it is also readily applicable to ground transportation vehicles. FIG. 11 shows an example of a vehicle shock absorber equipped with the force damping device of the present invention. An existing frame member 90 extends from a conventional vehicle frame as part of the present shock absorber. An anvil 92 is welded or otherwise secured within the frame member 90 as part of the main force damping device.
In the illustrated application of the present force damping device, an elongated energy absorbing member (hereinafter referred to as energy absorbing member) 94 is configured to be mounted within a frame member 90 whose inner end contacts an anvil base 92. . As shown, the absorbing member 94 has a rectangular shape with rounded corners. For example, the energy absorbing member 94 is made from a graphite-epoxy resin composition using the paltrusion process. Attached to the outer end of the energy absorbing member 94 is a vehicle shock absorber 96 which acts as a force applying member to the energy absorbing member supported by the absorbing member 94 in a normal shock absorber relationship with respect to the vehicle. It is only during high energy impact conditions where the force applied to the energy absorbing member 94 through the insert buffer 96 exceeds the limits of the graphite-epoxy resin material that the absorbing member 94 begins to collapse against the anvil 92.
During this high energy impact or impact condition, the energy absorbing member 94 progressively collapses against the anvil 92 to absorb the high impact energy. Although the present invention has been described above in detail with reference to its embodiments, it goes without saying that the present embodiments can be modified in various ways without departing from the spirit of the invention.

[Brief explanation of the drawing]

1a, 1b and 1c are longitudinal sectional views showing the successive operating states of the basic components of one embodiment of the force damping device of the present invention, and FIG. 2a is the force damping device shown in FIG. 1. FIG. 2b is an enlarged side view of the anvil of the damping device of FIG. 2a. 3rd a
Figures 3 and 3b are side views of the anvil base with positive and negative cone angles, respectively, of the force damping device of the present invention. Figures 4a, 4b, 4c and 4d are diagrams of load-deflection curves for several fibrous materials used in composite elongate members for force damping devices of the present invention. Figure 5 is a side view of the energy absorbing seat equipped with the force damping device of the present invention, Figure 6 is a rear view of the energy absorbing seat shown in Figure 5, and Figure 7 is the energy absorbing seat of the energy absorbing seat shown in Figure 5. FIG. 8 is an enlarged axial view of a suitable force damping device for use with the seat of FIG. 5; Fig. 9 is a perspective view of a supporting landing gear for a helicopter equipped with the force damping device of the present invention, Fig. 10 is an enlarged axial sectional view of the energy absorbing member of the landing gear of Fig. 9, and Fig. 11 is the force damping device of the present invention. 1 is a perspective view of a vehicle shock absorber incorporating an energy absorbing member with a rectangular cross section as part of the vehicle; FIG. 12, 48, 78, 94... Elongated member (energy absorbing member), 14, 40, 82, 92... Anvil stand, 16, 44-54, 84, 96... Insertion member.

Claims (1)

Claims: 1. A tubular elongate member; an anvil axially aligned with the elongate member; and an insert member for applying a force to an end of the elongate member opposite the anvil. a force damping device comprising: the elongate member being constructed of a composite material comprising resin-bonded load-bearing fibers; and the force applied by the insert member causes the elongate member to move toward the anvil base. The load-bearing fibers are oriented at a selected angle in the range of about 0° to 75° with respect to a plane extending transversely to the axis of the elongated member so as to progressively break apart in a plane. A force damping device comprising a plurality of predetermined fibers.