CA1107769A - Composite fibrous tube energy absorber - Google Patents
Composite fibrous tube energy absorberInfo
- Publication number
- CA1107769A CA1107769A CA326,678A CA326678A CA1107769A CA 1107769 A CA1107769 A CA 1107769A CA 326678 A CA326678 A CA 326678A CA 1107769 A CA1107769 A CA 1107769A
- Authority
- CA
- Canada
- Prior art keywords
- anvil
- force
- energy absorbing
- resin
- energy
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64C—AEROPLANES; HELICOPTERS
- B64C25/00—Alighting gear
- B64C25/32—Alighting gear characterised by elements which contact the ground or similar surface
- B64C25/58—Arrangements or adaptations of shock-absorbers or springs
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64C—AEROPLANES; HELICOPTERS
- B64C25/00—Alighting gear
- B64C25/32—Alighting gear characterised by elements which contact the ground or similar surface
- B64C25/58—Arrangements or adaptations of shock-absorbers or springs
- B64C25/60—Oleo legs
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64D—EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENTS OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT
- B64D25/00—Emergency apparatus or devices, not otherwise provided for
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F7/00—Vibration-dampers; Shock-absorbers
- F16F7/12—Vibration-dampers; Shock-absorbers using plastic deformation of members
Abstract
COMPOSITE FIBROUS TUBE ENERGY ABSORBER
Abstract of the Disclosure High velocity impact landing forces are attenuated in apparatus utilizing an energy absorbing tube of composite, fibrous material, that is, a fiber reinforced plastic.
The energy absorbing tube is disposed in force transmit-ting relation between an anvil disposed at one end and structure for applying a force to the opposite end of the tube to provide force attenuating apparatus. The tube is progressively crushed onto the anvil by the force apply-ing structure to dissipate energy. The force attenuating apparatus is used in an energy absorbing seat to provide occupant protection against high impact forces. Other uses of the force attenuating apparatus are landing gear mechanisms and vehicle bumper systems.
Abstract of the Disclosure High velocity impact landing forces are attenuated in apparatus utilizing an energy absorbing tube of composite, fibrous material, that is, a fiber reinforced plastic.
The energy absorbing tube is disposed in force transmit-ting relation between an anvil disposed at one end and structure for applying a force to the opposite end of the tube to provide force attenuating apparatus. The tube is progressively crushed onto the anvil by the force apply-ing structure to dissipate energy. The force attenuating apparatus is used in an energy absorbing seat to provide occupant protection against high impact forces. Other uses of the force attenuating apparatus are landing gear mechanisms and vehicle bumper systems.
Description
1~P77~9 The present invention relates to apparatus for at-tenuating forces by absorbing energy. More particularly, the invention relates to apparatus for attenuating forces generated upon high velocity impact, such as in crash situations.
In order to minimize crash damage to a vehicle and avoid injury to personnel in the vehicle, various force attenuation devices have been incorporated into the vehicle design. For example, seats in aircraft have incorporated energy absorbing mechanisms to cushion occupants of the aircraft from landing forces. Also, landing gear assemblies are provided with energy ab-sorbing systems and structures.
11~77~9 Prior art force attenuation apparatus for aircraft seats have generally included a compressible corrugated aluminum cylinder in the seat height adJustment mechanism to serve as an energy absorber. Accordingly, under high impact landing conditions, energy is dissipated ~hrough the permanent deforma-tion~ or crushing, of the energy absorber.
Representative of prior art force attenuating apparatus for a landing gear assembly is the two-stage system of energy absorbers disclosed in U. S. Patent No. 3,716,208 In that apparatus, the first stage of energyY-absorption involves driving a piston in an oil ~illed cylinder to move oil through control orifices and thereby reduee the forces applied to the airframe through the landing gear. The second stage of energy a~sorption involves actual deformation of the struts which connect ~he landing gear to the airframe.
Other meanc for attenuating forces generated upon landing of an aircraft with high vertical velocity is the crash attenuation landing gear disclosed in U. S. Patent No.
3,997,133. In that patent, there is disclosed, in combination with a cushioned strut, an energy dissipation structure in the form of a relatively thin walled aluminum cylinder. The a~paratus further includes a ring having a plurality of radial, upwardly facing c~tter blades ~or engaging the inner wall of the cylinder to do mechanical worlc upon movement of the cvlinder relative to the ring. More speci~ically, the mechanical work done by the ring is that of slicing the cylinder into longitudinal strips as relative movement ta1.~es nlace.
~77~9 A modification of the cylinder-cutter structure is disclosed in the patent and involves the utilization of a flaring structure in place of the cutter ring. In the modified apparatus, as the cylinder is forced downward over the working surface of the flaring structure, the edges of the cylinder are flared and the cylinder is torn.
The flaring operation absorbs energy, and thus attenuates forces.
Examples of energy absorbing systems as a vehicle bumper are those presently installed on passenger vehicles.
Basically, such systems are hydraulic filled energy absorb-ing cylinders.
The application of reinforced plastics to automotive structures, where such structures provide crashworthiness, is the subject matter of a study sponsored by the U.S.
Department of Transportation as reported in Report No.
DOT HS-801 771, entitled "Feasibility Study of Plastic Automotive Structures". This report presents an in depth study of the use of plastic automotive structures to pro-tect the passenger compartment during a frontal impact.
An object of the invention is to provide force at-tenuation apparatus that may be readily adapted for use in various portions of an aircraft or other vehicle to attenuate forces developed during high velocity impact landing or stopping, by absorbing energy.
Accordin~ to the invention there is provided force attenuation apparatus, comprising: an elongate member of ~ co~posite ~aterial comprising load-bearing fibers bonded by a resin, an anvil aYially aligned with said member and disposed adjacent one end thereof, and means for applying force to the end of said elongate member oppos3te said ~77{~9 anvil to progressively disintegrate said member at the face of said anvil.
The force attenuation apparatus of the present invention dissipates energy as the means for applying force to the elongate member progressively crushes the member onto the anvil.
In accordance with the present invention, at least in preferred forms, the elongate composite member is a closed or open section column whose wall comprises a fiber rein-1~ forced plastic whose fibers are at various angles withrespect to a plane extending transverse to an axis of the elon~ate member. The anvil onto which the elongate member is crushed may have a flat surface or may be a conic with positive or negative coning angle.
Suitable composite material for the elongate member of the force atten~ation apparatus has been ound to include graphite, fiber~lass, boron and aramid type fibers in a plastic resin.
The present invention is envisoned as being utilized in various applications involving the attenuation of forces and dissipation of energy. Among such applications are energy absorbing landing gear assemblies ~or aircraft, energy absorbing seats for aircraft and other vehicles, energy absorbing vehicle bumpers and various other like applications.
In order that the invention may be understood in detail, a detailed description of the invention is pro-vided herein with re~erence to the ~eneral concepts and an illustrative embodiment thereof which are illustrated in the appended drawings, wherein:
FIGURES la, lb and lc illustra~e the basic component ~ 77~9 parts of force attenuating apparatus in accordance with the present invention, and the operation thereof;
FIGURES 2a and 2b illustrate a modification of the apparatus shown in FIGURE l;
- 4a -~377~9 FIGURES 3a and 3b illustrate an anvil having a positive cone angle and a negative cone angle, respectively;
FIGURES 4a, 4b, 4c and 4d are graphs of the load-deflection curves for some fibrous materials used for the elongate composite member for apparatus of the present invention;
FIGURE 5 is a side view of an energy a~sorbing seat incorporating the force attenuating apparatus of the present invention;
FIGURE 6 is a rear view of the energy a~sorbing seat of FIGURE 5; ~
FI~URE 7 is a detailed view of the energy absorbing apparatus of the seat shown in FIGUP~ 5;
FIGURE 8 is a cross-sectional view of one suitable force attenuating apparatus for use in the energy absorbing seat shown in FI~URES 5 and 6;
FIGURE 9 is a perspective view of a landing gear support for a helico~ter incorporating the energy attenuating apparatu.s of the present invention;
FIGUP~ 10 is a cross-sectional view, partially cut away, of the energy absorbing apparatus of the landing gear support of FIGU~E g; and ~ IGURE 11 is a perspective view of a vehic~e bumPer system incorporating a rectangularly shaped energy absorbing member as a part of energy absorbing apparatus of th.e ~resent invention~
In accordance with the general principles of physics relating to work and energy dissipation, apparatus ~or attenuating forces during high velocity impact ha~e invo~ved the absor~ing or energy by having the force of impact to do mechan~cal work.
`~
~77~9 B-7596 A number of the techniques in the prior art for utilizing the concepts of work and energy dissi~ation have been noted. It is recognized in the prior art techniques that ener~y can he dissipated through the permanent deformation of a mass of material, typically an aluminum alloy extrusion.
Referring now to FI~URE 1, there is diagrammatically illustrated an energy absorption force attenuation a~paratus 10 in accordance with the present invention which comprises an elongate member 12 made of a composite, fibrous material, such as, a fiber reinforced plastic, An anvil 14 is axially aligned with member 12 and disposed adiacent one end of member 12 The force to be attenuated through the absorption of energy by fibrous member 12 is applied to the o~posite end of me~ber 12 by suitable means, such as insert 16 to progressively crush mem~er 12 onto anvil 14 as sho~m in the series of illustrations of FIGU~ES la, lb and lc, thereby dissipa~ing energy.
Referring to FIGURE 2a, in accordance with the present invention the energy absorbing member 12 is preferabl~ a composite material consisting of a mixture of fibers and resins. The fibers give the material the necessary strength to ~unction as an energy absorber and the resin or "matri~" holds the fibers together and distributes applied loads to the fi~ers~ Fxa~ples of fibers for use in the energy absorbing member 12 include a material from the group comprising graphite, Kev1ar, fiber~lass and boron.
~ither thermoset or thermoplastic resins are mixed r.~ith the fibers during the contruction of the ener~y absor~ing member.
Fxamples of thermoset resins include polyesters, epoxies and 1~6317769 ;
;:
.
phenolics, with the epoxies havin~ excellent mechanical pro?erties ',~6,~,opLP~T~c~
~and dimensional stability. ~hc~r~p~atics incLude polystyrene, polycarbonate and polypropylene, along with others.
, Depending on the fiber and the selected resin, different ~ ~
construction techniques are em~loyed in the manufacture of , ` -the energy absorbing member 12. Typical of such construction techniques are filament or roving windings, tape or broad ~oods, ~, ~ laminate layup, pultrusion, chopped fiber molding, and pre and post forming. Each of these construction techniques has been ~' '- extensively used in the production of manufactured goods con-sisting of a mixture of a fiber and a resin.
Another variable in the manufacture of the energy absorbing member 12 is the fiber orientation which affects the energy absorbing characteristics o~ the member. Ftlber orient,~a-tions include various combinations of unidirectional fibersoriented at angles of zero degrees to ninety degrees wtlth respect to the column axis of the energy absorber or with respect to a transverse plane 15 as shown in FIGU~E 2~., To f~-rther control the energy absorbing characteristics of the mem~er 12, the location of each fiber layer or lamina within the laminate is selected to achieve the desired laminate pro~erties. If a spray-up or chopped fiber molding construction ~echni~ue is employed, the fibers may be randomly oriented, As illustrated in F~ E 2a, the energy absorbing member 12 has an open ended tubular configuration. ~ther open section con~igurations for the ener,~y absorbing mem~,er 12 include ,,-~ngle mem~,ers, I'-sh,aped memb~ers, channel members, ,and _7_ 77~9 ~-7596 "J", "I", or "~"-shaped members. In addition to open sections, the energy absorbing member 12 is also constructed from closed sections and typical of such shapes are circular, elliptical, square or rectangular.
Samples of the energy absorbing member 12 were constructed for testing of the invention; these tes~ members were open section cylinders as illustrated in FIGUR~ 2a. Three different materials, graphite, Kevlar and fiberglass with an '' epoxy resin were used in constructing these samples. The test members were "filament wound" using a roving or bundle of fibers impregnated with a resin with the roving or bundle of fibers progressively ~7rapped at the desired orientation angle until a predetermined wall thickness was achieved. Properties of tubular members made from the three above types of composite material are presented in Table 1.
BASIC PROPERTIES OF CO~OSITE FIBROUS ?~T~RIAL
Thickness Wei~,ht Elastic ~laterial (Inches) (Lb.)/Jnch Modulus Graphite/epoxy .033 .01638 2.48 x 1~6 Kevlar'/epoxy .077 .03212 1.09 x 106 FiberglassJepoxy.03~ .0}890 2.23 x 106 -'(Kevlar-4g is a Dupont trademar~) Based on tests run to date the hig~est s~ecific energy 25 ~absorption (foot ~oundslpounds ~r~ weight~ was o~tained from the graphiteJepoxy mixture. From these tests it ap~ears t~at the specific energy absorption of a narticular energ~ absorption ~1~77~9 !
member 12 is a function of how fine the material can be broken UD durin~ crushin~. The gra~hite/epoxy tube, for example, T~as "powdered" whereas the Kevlar tube remained somewhat intact after crushing.
Although the end of anvil 14 adjacent member 12 is shown in FIGU~E 1 to ~e flat with a squared peripheral edge, a similar diagrammatic illustration in FIGURE 2a of an energy absorption force attenuation apparatus in accordance with the ; present invention shows the edge of the anvil sha~ed in a configuration other than a flat plane,~-More particularly, the edge of the anvil 14 is beveled to form a truncated cone, The configuration of the anvil is more clearly shown in FIGU~E 2b.
The angle of bevel 14a, represented by a in FIGURE 2b is 45, Shaping the anvil onto which the energy absorbing member 12 is crushed into the cone configuration changes the crushing load for a particular size of member 12, Increasing the cone angle a from 0 to 45 causes the failure of the energy absorbing member 12 to crush at a lower load. Tests to substantiate this finding were conduct~d on energy absorbing members constructed with fibers oriented f45 with res~ect to the transverse plane 15. In a~dition, the mode of failure became a progressive delamination rather than a Drogressive com~ressi~e crushing failure, ~.owever, this will depend on the fi~er orlentat}on with regard to the trans~erse plane 15. For example~ fibers oriented parallel to the ~lane 15, that is, at an angle of 90 with respect to the member axls, will be broken rather than delaminated.
_g_ I
.- ~ r ~ 9 B-7596 Referring to FIGURES 3a and 3b, there is illustrated C DrJ 6 both a positive cone angle for the anvil 14 and a negative ~e~
angle, respectively. With the negative cone angle of FIGURE 3b ~ crushing loads have been calculated to increase if the anvil is coned inward and thus increase the energy absorbing eiciency (energy absorbed per pound of weight) of the member 12.
An important indicia of the effectiveness of force attenuation apparatus is its specific energy absor~tion efficiency factor. The specific energy absorption efficiency factor is an indication of the force attenuation capability of a system in relation to its weight. The dimensions of the factor are ~oo~ ~u~S
~o_t,'po~nds per pound o weight It has been found that the specific energy absorption efficiency of a system in accordance with the present invention is dependen~ upon not only the material used, but the angle a, which describes the bevel of the edge of the truncated cone formed on the end of an~il 14 as sho~7n in FIGURES 2a and 3.
Typical static load deflection curves for tubes made of each type of composite material listed in Table 1 used with various degrees of anvil edge beveling are sho~m in FI~URES 4a, 4b and 4c. The graphs in FIGURES 4a, 4b an~ 4c are plots of load in pounds versus deflection in inches, i.e., the stro~e or travel of force transmitting means 16. As will be noted, each of the curves for each material exhi~its an initial peak and valley representing the initial peak failure load. From the graphs for each material, it l~ill be apparent that the initially high pea~ ~ailure load can be reduced by edge beveling o~ the --~0- `
77~9 end of th~e tube. As depicted in the representative graph of FIGURE ~, following the initial peak and valley, the load deflection curves exhibit a portion I reflecting travel of force transmitting means 16 relative to anvil 14, during which there is a buildup of the load force. A transition portion II of each load deflection curve turns into a linear ~ortion III
representative of the constant load maintained b7 the tubular member as the force transmitting means travels downwardly to progressively crush the tubular member onto anvil 14. For an energy absorbing member 12 having a beveled end, portion II
of the curve is minimizçd leaving only portion III, as best ~1 illustrated in FIGURE ~ for a graphitelresin tubular member.
The linear portion of the load deflection cur~es indlcates that over essentially the entire len~th of the stro~e ~5 of the force transmitting meansj which stroke is equivalent to the length of the tubular member, the load is constant, thus absorbing energy efficiently.
From the static test data, the specific energy absorption efficiency for each system configuration can be calculated. The specific energy absorption e~ficiencies are presented in Table 2 for laminates of ~ 45 fiber orientation, and for comparison the specific energy absorption efficiency of a metal tube made o~ 3003-~14 aluminum alloy is also presented.
~p~7t7~9 B-7596 SP~CIFIC EMERGY ABSORPTIO~ ~FT.-LB./LB.) Anvil End Configuration (~) ~Iaterial Flat l~ 30 4~
Graphite/epoxy 15200 9200 4l00 2300 Kevlar/eyoxy 5900 59~0 3500 l9~0 Fiberglass/epoxy 260~ 500~ 2600 2600 3003-Hl4 Al 7800 -- -- --The accuracy of the static load deflection curves of ~,~ FIGURES ~a~ e and ~ as an indication of the effectiveness of t'ne present invention for a dynamic-load application was checl~ed by conducting drop tests utilizing a graphite/epoxy tubular member having its filaments wound at approximately 45 to a plane transverse to the line o action of the a~lied force.
~he tubular member was impacted with a 122 pound mass dropped from two feet. Including the tube de1ection, the full drop height was 25.7 inches. The impact velocity of the mass was a~out twelve feet per second. The apparatus successfully attenuated the full 242 foot-pounds of energy without any rebound.
Using the energy ~rom the area under the static load-~ e~
deflection cur~e o~ FI~,URE 3~ and an anvil bevel o.f 0 a 1,63 inch stro~e was predicted. The dynamic drop measured a l.7~
inch stro'~e, indicating that the static load deflection ;nforma-tion would be representative for dynamic loadin~.
In order to show a re~resentative ap~lication of thepresent invention and illustrate its utility, an energy absorbing seat 20 is sho~m in FI~RES 5-8. The energy absorbing seat SlQ77~9 B-7596 .:
includes a seat support frame generally designated as 22 having , , j! feet 24 for placement on a surface. A contoured seat portion 26 ;
is also included and carried on seat support frame 22 in a manner to be described.
Referring next to FIGURES 5 and 6, seat s`up~ort frame ; 22 is sho~n in greater detail as having extension suPport arms I ;~
28 and 30 extending from feet Z4a and 24b, respectively.
Attached to the extension ar~s 28 and 30 is the seat portion 26 .~ ~
, by means of straps 32. An upper support channel 34 interconnects;
the two e~tension arms 28 and 30 and an attenuation brace 36 is bolted bet~Jeen the feet 24a and 24b. Force attenuation apparatus 38 is pro~ided and bolted between the attenuation brace 36 and the back surface of the seat portion 26. Basically, the attenuat~on apparatus comprises an elongate member of a composite material such as previously desaribed. It is connected in a force transmitting relation between the seat portion 26 and t'ne attenua~ion brace 36.
Referring to FIGURES 7 and 8, there is sho~m 1n detail the force attenuation apparatus 38 attached to ~he attenuation , 20 brace 36. At the lower end of the attenuation a~paratus 33 there is provided a cup-shaped end support 40 having mounted therein a static cylinder 42 that is concentric with an ~nner cylinder 44. ~he inner cylinder 44 te~minates in a closed end ,~ 4~ that functions as a force transmitting e~ement from the seat portion 26 to an energy a~sorbing mem~er 48 mounted within the cylinder 42. The energy a~sor~ing member 48 is of the type illustrated and described in FIGURES 1 and 2~ The structure of ~77~9 B-7596 the cylinders 42 and 44 and the energy absorbing member 48 are assembled into a working relationship by means of a fastener 50.
In the embodiment of the force attenuation a~paratus shown in FIGURES 7 and 8, the inner cylinder 44 is equipped with a spring 52 as part of a shock absorber between the inner : cylinder 44 and a tube 54 terminating in a bracket 55 directly bolted to the back o the seat 26. ,, O~erationally, during a high velocity impact landing ' situation, in which high im~act forces are developed that would otherwise be transmitted to personnel in seat portion 26, seat portion 26 would cause the inner cylinder 44 to ~rogressively crush the energy absorbing member 48, thereby dissipating energy and attenuating the impact force.
Upon extreme deceleration of an aircraft having energy lS absorbing seat 20 mounted therein, deceleration forces will be developed and applied through seat portion 25 to force trans-mitting means 3~. More specifically, and with regard to the illustrated force transmitting means in FlGU~ES 6, 7 and 8, the force will urge seat portion 26 downwardly relati~e to the attenuation brace 36, causing the inner cylinder 44 to move downwardly therewith relative to the cylinder 42, ~Iovement of the inner cylinder 44 downwardly will result. in the crushing of the energy absor~ing member 4~ against the end support 40, which end acts as an anvil. Accordingly, energy absorbing member 48 dissipates energy and attenuates the deceleration forces applied to seat 26 and consequently to the passenger seated therein, ~7~9 Referring once again to FIGURE 5, in the embodimentshown, energy absorbing seat 20 may be further provided with a conventional seat adjustment mechanism 58 whereby the height of seat portion 26 relative to the supporting surface may be adjusted.
Although the composite material energy absorbers utilized in energy absorbing seat 20 is shown incorporated in a separate mechanism, it is to be appreciated that the force attenuation apparatus of the present invention may be incorporated in other ways.
The present invention in its utilization of composite material in energy dissipating force attenuation apparatus provides several advantages over the aluminum alloy energy absorbers heretofore used.
As indicated in the tabular data of Table 2, the specific energy absorption efficiency of a composite material, especially graphite, is superior to that achieved with metal.
That is, composite fibrous materials provide more force attenua-tion for a given amount of weight. Especially in the aircraft
In order to minimize crash damage to a vehicle and avoid injury to personnel in the vehicle, various force attenuation devices have been incorporated into the vehicle design. For example, seats in aircraft have incorporated energy absorbing mechanisms to cushion occupants of the aircraft from landing forces. Also, landing gear assemblies are provided with energy ab-sorbing systems and structures.
11~77~9 Prior art force attenuation apparatus for aircraft seats have generally included a compressible corrugated aluminum cylinder in the seat height adJustment mechanism to serve as an energy absorber. Accordingly, under high impact landing conditions, energy is dissipated ~hrough the permanent deforma-tion~ or crushing, of the energy absorber.
Representative of prior art force attenuating apparatus for a landing gear assembly is the two-stage system of energy absorbers disclosed in U. S. Patent No. 3,716,208 In that apparatus, the first stage of energyY-absorption involves driving a piston in an oil ~illed cylinder to move oil through control orifices and thereby reduee the forces applied to the airframe through the landing gear. The second stage of energy a~sorption involves actual deformation of the struts which connect ~he landing gear to the airframe.
Other meanc for attenuating forces generated upon landing of an aircraft with high vertical velocity is the crash attenuation landing gear disclosed in U. S. Patent No.
3,997,133. In that patent, there is disclosed, in combination with a cushioned strut, an energy dissipation structure in the form of a relatively thin walled aluminum cylinder. The a~paratus further includes a ring having a plurality of radial, upwardly facing c~tter blades ~or engaging the inner wall of the cylinder to do mechanical worlc upon movement of the cvlinder relative to the ring. More speci~ically, the mechanical work done by the ring is that of slicing the cylinder into longitudinal strips as relative movement ta1.~es nlace.
~77~9 A modification of the cylinder-cutter structure is disclosed in the patent and involves the utilization of a flaring structure in place of the cutter ring. In the modified apparatus, as the cylinder is forced downward over the working surface of the flaring structure, the edges of the cylinder are flared and the cylinder is torn.
The flaring operation absorbs energy, and thus attenuates forces.
Examples of energy absorbing systems as a vehicle bumper are those presently installed on passenger vehicles.
Basically, such systems are hydraulic filled energy absorb-ing cylinders.
The application of reinforced plastics to automotive structures, where such structures provide crashworthiness, is the subject matter of a study sponsored by the U.S.
Department of Transportation as reported in Report No.
DOT HS-801 771, entitled "Feasibility Study of Plastic Automotive Structures". This report presents an in depth study of the use of plastic automotive structures to pro-tect the passenger compartment during a frontal impact.
An object of the invention is to provide force at-tenuation apparatus that may be readily adapted for use in various portions of an aircraft or other vehicle to attenuate forces developed during high velocity impact landing or stopping, by absorbing energy.
Accordin~ to the invention there is provided force attenuation apparatus, comprising: an elongate member of ~ co~posite ~aterial comprising load-bearing fibers bonded by a resin, an anvil aYially aligned with said member and disposed adjacent one end thereof, and means for applying force to the end of said elongate member oppos3te said ~77{~9 anvil to progressively disintegrate said member at the face of said anvil.
The force attenuation apparatus of the present invention dissipates energy as the means for applying force to the elongate member progressively crushes the member onto the anvil.
In accordance with the present invention, at least in preferred forms, the elongate composite member is a closed or open section column whose wall comprises a fiber rein-1~ forced plastic whose fibers are at various angles withrespect to a plane extending transverse to an axis of the elon~ate member. The anvil onto which the elongate member is crushed may have a flat surface or may be a conic with positive or negative coning angle.
Suitable composite material for the elongate member of the force atten~ation apparatus has been ound to include graphite, fiber~lass, boron and aramid type fibers in a plastic resin.
The present invention is envisoned as being utilized in various applications involving the attenuation of forces and dissipation of energy. Among such applications are energy absorbing landing gear assemblies ~or aircraft, energy absorbing seats for aircraft and other vehicles, energy absorbing vehicle bumpers and various other like applications.
In order that the invention may be understood in detail, a detailed description of the invention is pro-vided herein with re~erence to the ~eneral concepts and an illustrative embodiment thereof which are illustrated in the appended drawings, wherein:
FIGURES la, lb and lc illustra~e the basic component ~ 77~9 parts of force attenuating apparatus in accordance with the present invention, and the operation thereof;
FIGURES 2a and 2b illustrate a modification of the apparatus shown in FIGURE l;
- 4a -~377~9 FIGURES 3a and 3b illustrate an anvil having a positive cone angle and a negative cone angle, respectively;
FIGURES 4a, 4b, 4c and 4d are graphs of the load-deflection curves for some fibrous materials used for the elongate composite member for apparatus of the present invention;
FIGURE 5 is a side view of an energy a~sorbing seat incorporating the force attenuating apparatus of the present invention;
FIGURE 6 is a rear view of the energy a~sorbing seat of FIGURE 5; ~
FI~URE 7 is a detailed view of the energy absorbing apparatus of the seat shown in FIGUP~ 5;
FIGURE 8 is a cross-sectional view of one suitable force attenuating apparatus for use in the energy absorbing seat shown in FI~URES 5 and 6;
FIGURE 9 is a perspective view of a landing gear support for a helico~ter incorporating the energy attenuating apparatu.s of the present invention;
FIGUP~ 10 is a cross-sectional view, partially cut away, of the energy absorbing apparatus of the landing gear support of FIGU~E g; and ~ IGURE 11 is a perspective view of a vehic~e bumPer system incorporating a rectangularly shaped energy absorbing member as a part of energy absorbing apparatus of th.e ~resent invention~
In accordance with the general principles of physics relating to work and energy dissipation, apparatus ~or attenuating forces during high velocity impact ha~e invo~ved the absor~ing or energy by having the force of impact to do mechan~cal work.
`~
~77~9 B-7596 A number of the techniques in the prior art for utilizing the concepts of work and energy dissi~ation have been noted. It is recognized in the prior art techniques that ener~y can he dissipated through the permanent deformation of a mass of material, typically an aluminum alloy extrusion.
Referring now to FI~URE 1, there is diagrammatically illustrated an energy absorption force attenuation a~paratus 10 in accordance with the present invention which comprises an elongate member 12 made of a composite, fibrous material, such as, a fiber reinforced plastic, An anvil 14 is axially aligned with member 12 and disposed adiacent one end of member 12 The force to be attenuated through the absorption of energy by fibrous member 12 is applied to the o~posite end of me~ber 12 by suitable means, such as insert 16 to progressively crush mem~er 12 onto anvil 14 as sho~m in the series of illustrations of FIGU~ES la, lb and lc, thereby dissipa~ing energy.
Referring to FIGURE 2a, in accordance with the present invention the energy absorbing member 12 is preferabl~ a composite material consisting of a mixture of fibers and resins. The fibers give the material the necessary strength to ~unction as an energy absorber and the resin or "matri~" holds the fibers together and distributes applied loads to the fi~ers~ Fxa~ples of fibers for use in the energy absorbing member 12 include a material from the group comprising graphite, Kev1ar, fiber~lass and boron.
~ither thermoset or thermoplastic resins are mixed r.~ith the fibers during the contruction of the ener~y absor~ing member.
Fxamples of thermoset resins include polyesters, epoxies and 1~6317769 ;
;:
.
phenolics, with the epoxies havin~ excellent mechanical pro?erties ',~6,~,opLP~T~c~
~and dimensional stability. ~hc~r~p~atics incLude polystyrene, polycarbonate and polypropylene, along with others.
, Depending on the fiber and the selected resin, different ~ ~
construction techniques are em~loyed in the manufacture of , ` -the energy absorbing member 12. Typical of such construction techniques are filament or roving windings, tape or broad ~oods, ~, ~ laminate layup, pultrusion, chopped fiber molding, and pre and post forming. Each of these construction techniques has been ~' '- extensively used in the production of manufactured goods con-sisting of a mixture of a fiber and a resin.
Another variable in the manufacture of the energy absorbing member 12 is the fiber orientation which affects the energy absorbing characteristics o~ the member. Ftlber orient,~a-tions include various combinations of unidirectional fibersoriented at angles of zero degrees to ninety degrees wtlth respect to the column axis of the energy absorber or with respect to a transverse plane 15 as shown in FIGU~E 2~., To f~-rther control the energy absorbing characteristics of the mem~er 12, the location of each fiber layer or lamina within the laminate is selected to achieve the desired laminate pro~erties. If a spray-up or chopped fiber molding construction ~echni~ue is employed, the fibers may be randomly oriented, As illustrated in F~ E 2a, the energy absorbing member 12 has an open ended tubular configuration. ~ther open section con~igurations for the ener,~y absorbing mem~,er 12 include ,,-~ngle mem~,ers, I'-sh,aped memb~ers, channel members, ,and _7_ 77~9 ~-7596 "J", "I", or "~"-shaped members. In addition to open sections, the energy absorbing member 12 is also constructed from closed sections and typical of such shapes are circular, elliptical, square or rectangular.
Samples of the energy absorbing member 12 were constructed for testing of the invention; these tes~ members were open section cylinders as illustrated in FIGUR~ 2a. Three different materials, graphite, Kevlar and fiberglass with an '' epoxy resin were used in constructing these samples. The test members were "filament wound" using a roving or bundle of fibers impregnated with a resin with the roving or bundle of fibers progressively ~7rapped at the desired orientation angle until a predetermined wall thickness was achieved. Properties of tubular members made from the three above types of composite material are presented in Table 1.
BASIC PROPERTIES OF CO~OSITE FIBROUS ?~T~RIAL
Thickness Wei~,ht Elastic ~laterial (Inches) (Lb.)/Jnch Modulus Graphite/epoxy .033 .01638 2.48 x 1~6 Kevlar'/epoxy .077 .03212 1.09 x 106 FiberglassJepoxy.03~ .0}890 2.23 x 106 -'(Kevlar-4g is a Dupont trademar~) Based on tests run to date the hig~est s~ecific energy 25 ~absorption (foot ~oundslpounds ~r~ weight~ was o~tained from the graphiteJepoxy mixture. From these tests it ap~ears t~at the specific energy absorption of a narticular energ~ absorption ~1~77~9 !
member 12 is a function of how fine the material can be broken UD durin~ crushin~. The gra~hite/epoxy tube, for example, T~as "powdered" whereas the Kevlar tube remained somewhat intact after crushing.
Although the end of anvil 14 adjacent member 12 is shown in FIGU~E 1 to ~e flat with a squared peripheral edge, a similar diagrammatic illustration in FIGURE 2a of an energy absorption force attenuation apparatus in accordance with the ; present invention shows the edge of the anvil sha~ed in a configuration other than a flat plane,~-More particularly, the edge of the anvil 14 is beveled to form a truncated cone, The configuration of the anvil is more clearly shown in FIGU~E 2b.
The angle of bevel 14a, represented by a in FIGURE 2b is 45, Shaping the anvil onto which the energy absorbing member 12 is crushed into the cone configuration changes the crushing load for a particular size of member 12, Increasing the cone angle a from 0 to 45 causes the failure of the energy absorbing member 12 to crush at a lower load. Tests to substantiate this finding were conduct~d on energy absorbing members constructed with fibers oriented f45 with res~ect to the transverse plane 15. In a~dition, the mode of failure became a progressive delamination rather than a Drogressive com~ressi~e crushing failure, ~.owever, this will depend on the fi~er orlentat}on with regard to the trans~erse plane 15. For example~ fibers oriented parallel to the ~lane 15, that is, at an angle of 90 with respect to the member axls, will be broken rather than delaminated.
_g_ I
.- ~ r ~ 9 B-7596 Referring to FIGURES 3a and 3b, there is illustrated C DrJ 6 both a positive cone angle for the anvil 14 and a negative ~e~
angle, respectively. With the negative cone angle of FIGURE 3b ~ crushing loads have been calculated to increase if the anvil is coned inward and thus increase the energy absorbing eiciency (energy absorbed per pound of weight) of the member 12.
An important indicia of the effectiveness of force attenuation apparatus is its specific energy absor~tion efficiency factor. The specific energy absorption efficiency factor is an indication of the force attenuation capability of a system in relation to its weight. The dimensions of the factor are ~oo~ ~u~S
~o_t,'po~nds per pound o weight It has been found that the specific energy absorption efficiency of a system in accordance with the present invention is dependen~ upon not only the material used, but the angle a, which describes the bevel of the edge of the truncated cone formed on the end of an~il 14 as sho~7n in FIGURES 2a and 3.
Typical static load deflection curves for tubes made of each type of composite material listed in Table 1 used with various degrees of anvil edge beveling are sho~m in FI~URES 4a, 4b and 4c. The graphs in FIGURES 4a, 4b an~ 4c are plots of load in pounds versus deflection in inches, i.e., the stro~e or travel of force transmitting means 16. As will be noted, each of the curves for each material exhi~its an initial peak and valley representing the initial peak failure load. From the graphs for each material, it l~ill be apparent that the initially high pea~ ~ailure load can be reduced by edge beveling o~ the --~0- `
77~9 end of th~e tube. As depicted in the representative graph of FIGURE ~, following the initial peak and valley, the load deflection curves exhibit a portion I reflecting travel of force transmitting means 16 relative to anvil 14, during which there is a buildup of the load force. A transition portion II of each load deflection curve turns into a linear ~ortion III
representative of the constant load maintained b7 the tubular member as the force transmitting means travels downwardly to progressively crush the tubular member onto anvil 14. For an energy absorbing member 12 having a beveled end, portion II
of the curve is minimizçd leaving only portion III, as best ~1 illustrated in FIGURE ~ for a graphitelresin tubular member.
The linear portion of the load deflection cur~es indlcates that over essentially the entire len~th of the stro~e ~5 of the force transmitting meansj which stroke is equivalent to the length of the tubular member, the load is constant, thus absorbing energy efficiently.
From the static test data, the specific energy absorption efficiency for each system configuration can be calculated. The specific energy absorption e~ficiencies are presented in Table 2 for laminates of ~ 45 fiber orientation, and for comparison the specific energy absorption efficiency of a metal tube made o~ 3003-~14 aluminum alloy is also presented.
~p~7t7~9 B-7596 SP~CIFIC EMERGY ABSORPTIO~ ~FT.-LB./LB.) Anvil End Configuration (~) ~Iaterial Flat l~ 30 4~
Graphite/epoxy 15200 9200 4l00 2300 Kevlar/eyoxy 5900 59~0 3500 l9~0 Fiberglass/epoxy 260~ 500~ 2600 2600 3003-Hl4 Al 7800 -- -- --The accuracy of the static load deflection curves of ~,~ FIGURES ~a~ e and ~ as an indication of the effectiveness of t'ne present invention for a dynamic-load application was checl~ed by conducting drop tests utilizing a graphite/epoxy tubular member having its filaments wound at approximately 45 to a plane transverse to the line o action of the a~lied force.
~he tubular member was impacted with a 122 pound mass dropped from two feet. Including the tube de1ection, the full drop height was 25.7 inches. The impact velocity of the mass was a~out twelve feet per second. The apparatus successfully attenuated the full 242 foot-pounds of energy without any rebound.
Using the energy ~rom the area under the static load-~ e~
deflection cur~e o~ FI~,URE 3~ and an anvil bevel o.f 0 a 1,63 inch stro~e was predicted. The dynamic drop measured a l.7~
inch stro'~e, indicating that the static load deflection ;nforma-tion would be representative for dynamic loadin~.
In order to show a re~resentative ap~lication of thepresent invention and illustrate its utility, an energy absorbing seat 20 is sho~m in FI~RES 5-8. The energy absorbing seat SlQ77~9 B-7596 .:
includes a seat support frame generally designated as 22 having , , j! feet 24 for placement on a surface. A contoured seat portion 26 ;
is also included and carried on seat support frame 22 in a manner to be described.
Referring next to FIGURES 5 and 6, seat s`up~ort frame ; 22 is sho~n in greater detail as having extension suPport arms I ;~
28 and 30 extending from feet Z4a and 24b, respectively.
Attached to the extension ar~s 28 and 30 is the seat portion 26 .~ ~
, by means of straps 32. An upper support channel 34 interconnects;
the two e~tension arms 28 and 30 and an attenuation brace 36 is bolted bet~Jeen the feet 24a and 24b. Force attenuation apparatus 38 is pro~ided and bolted between the attenuation brace 36 and the back surface of the seat portion 26. Basically, the attenuat~on apparatus comprises an elongate member of a composite material such as previously desaribed. It is connected in a force transmitting relation between the seat portion 26 and t'ne attenua~ion brace 36.
Referring to FIGURES 7 and 8, there is sho~m 1n detail the force attenuation apparatus 38 attached to ~he attenuation , 20 brace 36. At the lower end of the attenuation a~paratus 33 there is provided a cup-shaped end support 40 having mounted therein a static cylinder 42 that is concentric with an ~nner cylinder 44. ~he inner cylinder 44 te~minates in a closed end ,~ 4~ that functions as a force transmitting e~ement from the seat portion 26 to an energy a~sorbing mem~er 48 mounted within the cylinder 42. The energy a~sor~ing member 48 is of the type illustrated and described in FIGURES 1 and 2~ The structure of ~77~9 B-7596 the cylinders 42 and 44 and the energy absorbing member 48 are assembled into a working relationship by means of a fastener 50.
In the embodiment of the force attenuation a~paratus shown in FIGURES 7 and 8, the inner cylinder 44 is equipped with a spring 52 as part of a shock absorber between the inner : cylinder 44 and a tube 54 terminating in a bracket 55 directly bolted to the back o the seat 26. ,, O~erationally, during a high velocity impact landing ' situation, in which high im~act forces are developed that would otherwise be transmitted to personnel in seat portion 26, seat portion 26 would cause the inner cylinder 44 to ~rogressively crush the energy absorbing member 48, thereby dissipating energy and attenuating the impact force.
Upon extreme deceleration of an aircraft having energy lS absorbing seat 20 mounted therein, deceleration forces will be developed and applied through seat portion 25 to force trans-mitting means 3~. More specifically, and with regard to the illustrated force transmitting means in FlGU~ES 6, 7 and 8, the force will urge seat portion 26 downwardly relati~e to the attenuation brace 36, causing the inner cylinder 44 to move downwardly therewith relative to the cylinder 42, ~Iovement of the inner cylinder 44 downwardly will result. in the crushing of the energy absor~ing member 4~ against the end support 40, which end acts as an anvil. Accordingly, energy absorbing member 48 dissipates energy and attenuates the deceleration forces applied to seat 26 and consequently to the passenger seated therein, ~7~9 Referring once again to FIGURE 5, in the embodimentshown, energy absorbing seat 20 may be further provided with a conventional seat adjustment mechanism 58 whereby the height of seat portion 26 relative to the supporting surface may be adjusted.
Although the composite material energy absorbers utilized in energy absorbing seat 20 is shown incorporated in a separate mechanism, it is to be appreciated that the force attenuation apparatus of the present invention may be incorporated in other ways.
The present invention in its utilization of composite material in energy dissipating force attenuation apparatus provides several advantages over the aluminum alloy energy absorbers heretofore used.
As indicated in the tabular data of Table 2, the specific energy absorption efficiency of a composite material, especially graphite, is superior to that achieved with metal.
That is, composite fibrous materials provide more force attenua-tion for a given amount of weight. Especially in the aircraft
2~ industry, such achievement represents a significant contribution to the art.
~ t is also an advantaqe of this invention that the dissipation of energy is greatly enhanced by the ability to completely destroy the material throughout 10~ of the stro~e.
It is, of course, the case that corrugated aluminum and other metals do not exhibit complete destructiGn or 100~ deflection.
~p~
Accordingly, from the basic principles of physics, the full extent of available work and energy dissipation available over the stroke distance cannot be fully achieved with metal as it can be with composite material. This is significant in that occupants of an aircraft will be decelerated over only a portion of the stroke distance, and they will undergo higher and more dangerous forces.
A further advantage of the present invention is that the force attenuation apparatus will be unaffected by environmental condidtions, such as corrosion and the like.
The foregoing description of an illustrative èmbodiment of the present invention has been directed to but one application of the present invention; however, the present invention may be utilized in various other applications involving the need and desire for the attenuation of forces and dissipation of energy.
Among such other applications are energy absorbing landing gear for aircraft and engine and transmission supports in aircraft, as well as vehicle bumper systems.
Referring to FIGURES 9 and 10, there is shown force attenuation apparatus of the present invention as part of a landing gear assembly. The landing gear assembly 64 is shown attached to the fuselage 66 of a helicopter by means of a pivot arm 68 and a support bracket 7~. At the outboard end of the pivot arm 68 there is pivotally attached an axle assembly 72 supporting a wheel 74. Coupled between the axle assembly 72 and the support bracket 7~ is a force attenuating apparatus 76 77~9 that includes an energy absorbing member 78 and an oleo-pneumatic shock strut 80. The shock strut 80 is conventional hardware with a retention cup 82 formed as an integral ~art of the strut housing. ~ounted within the cup 82 is the energy absorbing member 78 that is fitted at its u~per end into a r~tention cup 84 that is ~ivotally mounted to the sup~ort ~racket 70.
Referring specifically to FIGURE 1~, the energy absorbing member 78 has an inward taper throughout its leng,th from the end fitted into the retention CUD 84 to the lower end at the retention cu~ 82. To secure the upper end of the energy absorbing member 78 into the retention cup 84 a retaining ring 86 is assembled between the member and the inner diameter of the retention cup. Similarly, a retaining ring 88 is asse~bled between the energy absorbing member 78 and the inner wall of the retention cup 82.
Operationally, the retention cu~ 84 functions as the force transmitting element and the retention cu~ 82 functions as an anvil. During a high impact landing or a crash situation for a vehicle having the landing gear assembly of FIG~RE 9 mounted thereto, the deceleration forces will be developed an~ a~plied through the retention cu 84 to the ener~y absorbing member 78. This force will urge the ene~gv absorbing ~ember 73 downwardly relative to the retention cup 82. Movement of the retention cup 84 relati~e to the retention cup 82 ~
2~ result in the crushing of the energy absorbing mem~er 78 against the cup 82 functioning as an anvil. Accordingly, the energy absorbing me~ber 73 dissipates energy and attenua.es the deceleratlon forces applied to the fuselage 6~.
77~3 The present in~ention, though particularlY suited for aircraft applications due to the great force at~enuation capability and rel tively light weight ~rovided, is nonetheless also readily apDlicable to ground transDortation vehicles as well. Referring to FIGU~E 11, there is schematically illustrated a vehicle bumper assem~ly incorporating the force attenuating ap~aratus of the ~resent invention. An existing frame member 90 extends from the con~entional vehicle frame as ~art of the humper assembly. Welded or otherwise secured within the frame ` member 90 is an anvil 92 as ~art of the force attenua~ing ap~aratus. ~n the illustrated application of the ~orce attenuating apparatus an ener&y absorhing me~her 94 is configured to be mounted within the ~ra~e member 90 having an inner end in contact with the anvil 92. As shown, the member 94 is rectangular in shape with rounded corners. Typically, the energY absorbing member 94 is made of a graphite/epox~ composition by a ~ultrusion manufacturing technique.
Attached to the outer end o~ the energy absorbing member 94 is a vehicle bumper 96 that is carried by the member in a normal bumper relationship with the vehicle. The energy absorbing member 94 carries normal axial and bending loads without stroking or crushing against the anvil 92. Only during high energy impact conditions when the ~orce ap~lied through the btlmper 96 to the energv absorbing member 94 exceeds the threshold of the graphite/epoxy material will the member 4 begin to crush against the anvil a2. B~ring this hi~h energy impact or crash condition the energy absor~ing member 94 progressively crushes against the an~ 2 thereby absorbing the high impact energy.
These and other applications of the invention, as well as modifications to the illustrative embodiment described herein, will be apparent to those skilled in this art. It is the Applicants' intention in the following claims to coyer the present invention in all such uses, and with all modifications, as fall within the scope of the invention.
~ t is also an advantaqe of this invention that the dissipation of energy is greatly enhanced by the ability to completely destroy the material throughout 10~ of the stro~e.
It is, of course, the case that corrugated aluminum and other metals do not exhibit complete destructiGn or 100~ deflection.
~p~
Accordingly, from the basic principles of physics, the full extent of available work and energy dissipation available over the stroke distance cannot be fully achieved with metal as it can be with composite material. This is significant in that occupants of an aircraft will be decelerated over only a portion of the stroke distance, and they will undergo higher and more dangerous forces.
A further advantage of the present invention is that the force attenuation apparatus will be unaffected by environmental condidtions, such as corrosion and the like.
The foregoing description of an illustrative èmbodiment of the present invention has been directed to but one application of the present invention; however, the present invention may be utilized in various other applications involving the need and desire for the attenuation of forces and dissipation of energy.
Among such other applications are energy absorbing landing gear for aircraft and engine and transmission supports in aircraft, as well as vehicle bumper systems.
Referring to FIGURES 9 and 10, there is shown force attenuation apparatus of the present invention as part of a landing gear assembly. The landing gear assembly 64 is shown attached to the fuselage 66 of a helicopter by means of a pivot arm 68 and a support bracket 7~. At the outboard end of the pivot arm 68 there is pivotally attached an axle assembly 72 supporting a wheel 74. Coupled between the axle assembly 72 and the support bracket 7~ is a force attenuating apparatus 76 77~9 that includes an energy absorbing member 78 and an oleo-pneumatic shock strut 80. The shock strut 80 is conventional hardware with a retention cup 82 formed as an integral ~art of the strut housing. ~ounted within the cup 82 is the energy absorbing member 78 that is fitted at its u~per end into a r~tention cup 84 that is ~ivotally mounted to the sup~ort ~racket 70.
Referring specifically to FIGURE 1~, the energy absorbing member 78 has an inward taper throughout its leng,th from the end fitted into the retention CUD 84 to the lower end at the retention cu~ 82. To secure the upper end of the energy absorbing member 78 into the retention cup 84 a retaining ring 86 is assembled between the member and the inner diameter of the retention cup. Similarly, a retaining ring 88 is asse~bled between the energy absorbing member 78 and the inner wall of the retention cup 82.
Operationally, the retention cu~ 84 functions as the force transmitting element and the retention cu~ 82 functions as an anvil. During a high impact landing or a crash situation for a vehicle having the landing gear assembly of FIG~RE 9 mounted thereto, the deceleration forces will be developed an~ a~plied through the retention cu 84 to the ener~y absorbing member 78. This force will urge the ene~gv absorbing ~ember 73 downwardly relative to the retention cup 82. Movement of the retention cup 84 relati~e to the retention cup 82 ~
2~ result in the crushing of the energy absorbing mem~er 78 against the cup 82 functioning as an anvil. Accordingly, the energy absorbing me~ber 73 dissipates energy and attenua.es the deceleratlon forces applied to the fuselage 6~.
77~3 The present in~ention, though particularlY suited for aircraft applications due to the great force at~enuation capability and rel tively light weight ~rovided, is nonetheless also readily apDlicable to ground transDortation vehicles as well. Referring to FIGU~E 11, there is schematically illustrated a vehicle bumper assem~ly incorporating the force attenuating ap~aratus of the ~resent invention. An existing frame member 90 extends from the con~entional vehicle frame as ~art of the humper assembly. Welded or otherwise secured within the frame ` member 90 is an anvil 92 as ~art of the force attenua~ing ap~aratus. ~n the illustrated application of the ~orce attenuating apparatus an ener&y absorhing me~her 94 is configured to be mounted within the ~ra~e member 90 having an inner end in contact with the anvil 92. As shown, the member 94 is rectangular in shape with rounded corners. Typically, the energY absorbing member 94 is made of a graphite/epox~ composition by a ~ultrusion manufacturing technique.
Attached to the outer end o~ the energy absorbing member 94 is a vehicle bumper 96 that is carried by the member in a normal bumper relationship with the vehicle. The energy absorbing member 94 carries normal axial and bending loads without stroking or crushing against the anvil 92. Only during high energy impact conditions when the ~orce ap~lied through the btlmper 96 to the energv absorbing member 94 exceeds the threshold of the graphite/epoxy material will the member 4 begin to crush against the anvil a2. B~ring this hi~h energy impact or crash condition the energy absor~ing member 94 progressively crushes against the an~ 2 thereby absorbing the high impact energy.
These and other applications of the invention, as well as modifications to the illustrative embodiment described herein, will be apparent to those skilled in this art. It is the Applicants' intention in the following claims to coyer the present invention in all such uses, and with all modifications, as fall within the scope of the invention.
Claims (38)
1. Force attenuation apparatus, comprising:
an elongate member of a composite material comprising load-bearing fibers bonded by a resin;
an anvil axially aligned with said member and disposed adjacent one end thereof;
and means for applying force to the end of said elongate member opposite said anvil to progressively disintegrate said member at the face of said anvil.
an elongate member of a composite material comprising load-bearing fibers bonded by a resin;
an anvil axially aligned with said member and disposed adjacent one end thereof;
and means for applying force to the end of said elongate member opposite said anvil to progressively disintegrate said member at the face of said anvil.
2. The force attenuation apparatus of Claim 1 wherein said elongate composite member is a tube.
3. The force attenuation apparatus of Claim 1 wherein said fibers comprise a plurality of filaments oriented at a selected angle with respect to a plane extending trans-verse to an axis of said member.
4. The force attenuation apparatus of Claim 1 wherein the face of said anvil is flat.
5. The force attenuation apparatus of Claim 1 wherein said anvil has a truncated cone around the periphery of the end adjacent said elongate member.
6. The force attenuation apparatus of Claim 1 wherein said anvil has an inverted cone at the end adjacent said elongate member.
7. The force attenuation apparatus of Claim 1 wherein said elongate member has a bevel formed on the end thereof facing said anvil.
8. The force attenuation apparatus of Claim 1 wherein the face of said anvil has an annular taper at an angle that is greater than 0° and less than 90° relative to a plane transverse to the axis of said anvil.
9. The force attenuation apparatus of Claim 1 wherein the composite material comprises graphite and a resin.
10. The force attenuation apparatus of Claim 1 wherein the composite material comprises fiberglass and a resin.
11. The force attenuation apparatus of Claim 1 wherein the composite material comprises an aramid type fiber and a resin.
12. The force attenuation apparatus of Claim 1 wherein the composite material comprises boron and a resin.
13. Force attenuation apparatus, comprising in combination:
a tubular member comprising a filament wound about the axis of said member at a selected angle with respect to a plane extending transverse to the axis of said member, said filament bonded together by a resin;
an anvil axially aligned with said member and disposed adjacent one end thereof; and means for applying a compressive force to said member to progressively disintegrate said member at the face of said anvil.
a tubular member comprising a filament wound about the axis of said member at a selected angle with respect to a plane extending transverse to the axis of said member, said filament bonded together by a resin;
an anvil axially aligned with said member and disposed adjacent one end thereof; and means for applying a compressive force to said member to progressively disintegrate said member at the face of said anvil.
14. Force attenuation apparatus of Claim 13 including a second filament wound about the axis of said member at a second selected angle with respect to said plane.
15. Force attenuation apparatus of Claim 13 wherein the end of said member facing said anvil is beveled to reduce the initial shock transmitted through said member when said member is driven against said anvil.
16. An energy absorbing seat, comprising:
a seat support frame having feet for placement on a surface;
a seat portion mounted on said support frame for relative downward movement;
an energy absorber disposed in a force transmitting relation between said frame and said seat portion;
said energy absorber comprising an elongate member of a composite material comprising load bearing fibers bonded by a resin;
an anvil supported from said frame and axially aligned with said member; and means joined to said seat portion for applying force to the end of said member opposite said anvil to pro-gressively disintegrate said member at the face of said anvil when said seat portion moves downward relative to said frame.
a seat support frame having feet for placement on a surface;
a seat portion mounted on said support frame for relative downward movement;
an energy absorber disposed in a force transmitting relation between said frame and said seat portion;
said energy absorber comprising an elongate member of a composite material comprising load bearing fibers bonded by a resin;
an anvil supported from said frame and axially aligned with said member; and means joined to said seat portion for applying force to the end of said member opposite said anvil to pro-gressively disintegrate said member at the face of said anvil when said seat portion moves downward relative to said frame.
17. The energy absorbing seat of Claim 16 wherein said elongate member is a tube.
18. The energy absorbing seat of Claim 16 wherein said elongate member has a bevel formed on the end thereof facing said anvil.
19. An energy absorbing seat, comprising:
a seat support frame having first and second substan-tially parallel extensions, each extension having a foot on the lower end for placement on a surface;
first and second tubular members coaxially mounted to move one within the other, one of said members attached to the foot of each extension;
an energy absorber of composite material comprising load-bearing fibers bonded by a resin, said absorber configured as an elongate member and disposed in a force transmitting relation between an anvil in one of the tubular members and the upper end surface in the second of said tubular members;
a seat portion mounted to said second tubular member;
and said energy absorber driven against said anvil when said seat portion is forced downward relative to said surface to progressively disintegrate said energy absorber at the face of said anvil.
a seat support frame having first and second substan-tially parallel extensions, each extension having a foot on the lower end for placement on a surface;
first and second tubular members coaxially mounted to move one within the other, one of said members attached to the foot of each extension;
an energy absorber of composite material comprising load-bearing fibers bonded by a resin, said absorber configured as an elongate member and disposed in a force transmitting relation between an anvil in one of the tubular members and the upper end surface in the second of said tubular members;
a seat portion mounted to said second tubular member;
and said energy absorber driven against said anvil when said seat portion is forced downward relative to said surface to progressively disintegrate said energy absorber at the face of said anvil.
20. The energy absorbing seat of Claim 19 wherein said elongate member has a bevel formed on the end thereof facing said anvil.
21. Force attenuating apparatus having an energy absorbing member, means for transmitting force to one end of said member, and an anvil on the opposite side of said energy absorbing member from said force transmitting means, char-acterized in that said energy absorbing member is made of a composite material comprising load-bearing fibers bonded by a resin, said energy absorber driven against said anvil by said means for transmitting force to progressively dis-integrate said energy absorber at the face of said anvil.
22. The force attenuating apparatus of Claim 21 wherein the energy absorbing member is a tube.
23. The force attenuating apparatus of Claim 22 wherein said fibers comprise filaments wound at a selected angle with repsect to a plane transverse to the longitudinal axis of the elongate member.
24. The force attenuating apparatus of Claim 21 wherein the composite material comprises graphite and a resin.
25. The force transmitting apparatus of Claim 21 wherein the composite material comprises fiberglass and a resin.
26. The force transmitting apparatus of Claim 21 wherein the composite material comprises an aramid type fiber and a resin.
27. The force transmitting apparatus of Claim 21 wherein the composite material comprises boron and a resin.
28. The force attenuating apparatus of Claim 21 wherein said energy absorbing member has a bevel formed on the end thereof facing said anvil.
29. A landing gear for an aircraft, comprising:
means for providing a primary support to the aircraft when in contact with a landing surface;
first coupling means for providing an attachment of said means for supporting to the fuselage of the aircraft;
second coupling means including force attenuation apparatus for providing a second attachment of said means for supporting the fuselage to the aircraft; and the force attenuation apparatus including an elongate member of composite material comprising load-bearing fibers bonded by a resin, an anvil axially aligned with said member and disposed adjacent one end thereof, and means for applying force to the end of said elongate member opposite said anvil to progressively disintegrate said member at the face of said anvil.
means for providing a primary support to the aircraft when in contact with a landing surface;
first coupling means for providing an attachment of said means for supporting to the fuselage of the aircraft;
second coupling means including force attenuation apparatus for providing a second attachment of said means for supporting the fuselage to the aircraft; and the force attenuation apparatus including an elongate member of composite material comprising load-bearing fibers bonded by a resin, an anvil axially aligned with said member and disposed adjacent one end thereof, and means for applying force to the end of said elongate member opposite said anvil to progressively disintegrate said member at the face of said anvil.
30. The landing gear of Claim 29 wherein said elongate member has a bevel formed on the end thereof facing said anvil.
31. The landing gear of Claim 29 wherein said second coupling means includes a shock strut disposed between said means for supporting and the force attenuation apparatus.
32. The landing gear of Claim 31 wherein said elongate member has an inward taper from the end at said means for applying force to the end at said anvil.
33. The landing gear of Claim 29 wherein said fibers comprise a plurality of filaments oriented on a selected angle with respect to a plane extending transverse to the axis of said elongate member.
34. A vehicle bumper system, comprising:
a frame extension forming an integral part of the main frame of the vehicle;
force attenuation apparatus coupled to said frame extension, said force attenuation apparatus including an energy absorbing member comprising load-bearing fibers bonded by a resin, an anvil in engagement with one end of said member, and means for applying a force to the end of said elongate member opposite said anvil to progressively disintegrate said member at the face of said anvil; and a bumper fastened to said force attenuation apparatus.
a frame extension forming an integral part of the main frame of the vehicle;
force attenuation apparatus coupled to said frame extension, said force attenuation apparatus including an energy absorbing member comprising load-bearing fibers bonded by a resin, an anvil in engagement with one end of said member, and means for applying a force to the end of said elongate member opposite said anvil to progressively disintegrate said member at the face of said anvil; and a bumper fastened to said force attenuation apparatus.
35. The vehicle bumper system of Claim 34 wherein said anvil is attached to said frame extension and said bumper is fastened to said means for applying force.
36. The vehicle bumper system of Claim 34 wherein said energy absorbing member has a generally rectangular configuration.
37. The vehicle bumper system of Claim 34 wherein said energy absorbing member is a graphite/epoxy resin composition.
38. The vehicle bumper system of Claim 34 wherein said energy absorbing member has a bevel formed on the end thereof facing said anvil.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US90438178A | 1978-05-10 | 1978-05-10 | |
| US904,381 | 1978-05-10 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1107769A true CA1107769A (en) | 1981-08-25 |
Family
ID=25419050
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA326,678A Expired CA1107769A (en) | 1978-05-10 | 1979-04-30 | Composite fibrous tube energy absorber |
Country Status (10)
| Country | Link |
|---|---|
| JP (1) | JPS556078A (en) |
| AR (1) | AR222485A1 (en) |
| AU (1) | AU529114B2 (en) |
| BR (1) | BR7902826A (en) |
| CA (1) | CA1107769A (en) |
| DE (1) | DE2918280A1 (en) |
| ES (1) | ES253799Y (en) |
| FR (1) | FR2425584A1 (en) |
| GB (1) | GB2020780B (en) |
| IL (1) | IL57223A0 (en) |
Families Citing this family (20)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3045141C2 (en) * | 1980-11-29 | 1987-07-09 | Messerschmitt-Bölkow-Blohm GmbH, 8000 München | Safety steering column for motor vehicles |
| DE3049425C2 (en) * | 1980-12-30 | 1991-09-05 | Messerschmitt-Bölkow-Blohm GmbH, 8000 München | Impact protection component |
| DE3213462A1 (en) * | 1982-04-10 | 1983-10-13 | Audi Nsu Auto Union Ag, 7107 Neckarsulm | SAFETY STEERING COLUMN FOR MOTOR VEHICLES |
| FR2537542B1 (en) * | 1982-12-08 | 1985-11-15 | Aerospatiale | SKID LANDING GEARS COMPRISING COMPONENTS PROVIDED WITH AN ENERGY ABSORPTION DEVICE BY PLASTIC DEFORMATION AND / OR EFFORT LIMITATION, AND COMPONENTS OF THIS TYPE |
| GB2141807A (en) * | 1983-06-18 | 1985-01-03 | Ford Motor Co | Energy absorption arrangement |
| GB8413692D0 (en) * | 1984-05-29 | 1984-07-04 | Btr Plc | Energy absorption |
| DE3833048C2 (en) * | 1988-09-29 | 1994-03-24 | Bayerische Motoren Werke Ag | Bumpers for motor vehicles, in particular passenger cars |
| DE3930137A1 (en) * | 1989-09-09 | 1991-03-21 | Bayer Ag | SHOCK ABSORBER IN THE FORM OF A SHOCK ABSORBER |
| JP2858181B2 (en) * | 1991-01-21 | 1999-02-17 | 横浜ゴム株式会社 | Energy absorbing structure |
| FR2681308B1 (en) * | 1991-09-17 | 1993-12-17 | Messier Bugatti | LIFTABLE ANTI-CRASH SHOCK ABSORBER. |
| DE4206789C1 (en) * | 1992-03-04 | 1993-02-11 | Mercedes-Benz Aktiengesellschaft, 7000 Stuttgart, De | Seat frame and cushion squab in bus - are adjustably joined to seat back, pivot round rear axis on seat subframe and include deformation element at front |
| US5248129A (en) * | 1992-08-12 | 1993-09-28 | Energy Absorption Systems, Inc. | Energy absorbing roadside crash barrier |
| DE4230670C2 (en) * | 1992-09-14 | 1996-05-30 | Daimler Benz Aerospace Airbus | Upholstery arrangement for a seat, in particular an aircraft seat |
| DE4332961A1 (en) * | 1993-09-28 | 1995-03-30 | Dethleffs Gmbh | Table base for caravans |
| DE4425829C1 (en) * | 1994-07-21 | 1995-10-12 | Daimler Benz Aerospace Ag | Helicopter structural element in sandwich form |
| EP0719635B1 (en) * | 1994-12-26 | 2003-01-22 | Honda Giken Kogyo Kabushiki Kaisha | Laminated structure of fiber reinforced plastics and shock-absorbing structure |
| DE19625715C1 (en) * | 1996-06-27 | 1997-10-09 | Krauss Maffei Ag | Vehicle seat with damper below |
| US6308809B1 (en) * | 1999-05-07 | 2001-10-30 | Safety By Design Company | Crash attenuation system |
| GB2373561A (en) * | 2001-03-20 | 2002-09-25 | Michael Tate | An energy dissipating road wheel tether |
| US20080283667A1 (en) * | 2006-12-08 | 2008-11-20 | The Boeing Company | Hybrid composite-metal aircraft landing gear and engine support beams |
Family Cites Families (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2971566A (en) * | 1958-01-27 | 1961-02-14 | Sud Aviation | Pilot seats for aircraft, more particularly for helicopter |
| DE1086131B (en) * | 1958-01-27 | 1960-07-28 | Sud Aviation | Adjustable pilot's seat, especially for helicopters |
| US3143321A (en) * | 1962-07-12 | 1964-08-04 | John R Mcgehee | Frangible tube energy dissipation |
| US3265163A (en) * | 1964-03-05 | 1966-08-09 | Bendix Corp | Shock absorber |
| GB1038358A (en) * | 1964-07-17 | 1966-08-10 | Gq Parachute Comp Ltd | Improvements in or relating to shock absorbing devices |
| US3339674A (en) * | 1965-03-12 | 1967-09-05 | Gen Motors Corp | Energy absorbing device |
| FR1440146A (en) * | 1965-04-16 | 1966-05-27 | Alsacienne Atom | Braking device for a moving mass |
| US3532379A (en) * | 1968-05-02 | 1970-10-06 | Boeing Co | Crashload attenuating aircraft crewseat |
| US3552525A (en) * | 1969-02-12 | 1971-01-05 | Hexcel Corp | Energy absorber |
| US3716208A (en) * | 1970-06-11 | 1973-02-13 | Textron Inc | Energy absorbing landing gear |
| US3847426A (en) * | 1971-09-17 | 1974-11-12 | F Mcgettigan | Frangible buffer apparatus for vehicles |
| GB1391780A (en) * | 1971-12-24 | 1975-04-23 | Gkn Sankey Ltd | Composite materil comprising a matrix having therein reinforcement elements |
| JPS4893045A (en) * | 1972-03-14 | 1973-12-01 | ||
| JPS49148385U (en) * | 1974-03-13 | 1974-12-21 | ||
| US3997133A (en) * | 1975-07-30 | 1976-12-14 | Textron, Inc. | Crash attenuation landing gear |
-
1979
- 1979-04-30 CA CA326,678A patent/CA1107769A/en not_active Expired
- 1979-05-03 AU AU46706/79A patent/AU529114B2/en not_active Ceased
- 1979-05-06 IL IL57223A patent/IL57223A0/en not_active IP Right Cessation
- 1979-05-07 DE DE19792918280 patent/DE2918280A1/en active Granted
- 1979-05-09 BR BR7902826A patent/BR7902826A/en unknown
- 1979-05-10 FR FR7911894A patent/FR2425584A1/en active Granted
- 1979-05-10 JP JP5638779A patent/JPS556078A/en active Granted
- 1979-05-10 GB GB7916243A patent/GB2020780B/en not_active Expired
- 1979-05-10 ES ES1979253799U patent/ES253799Y/en not_active Expired
- 1979-05-10 AR AR276476A patent/AR222485A1/en active
Also Published As
| Publication number | Publication date |
|---|---|
| GB2020780A (en) | 1979-11-21 |
| JPS6349097B2 (en) | 1988-10-03 |
| FR2425584A1 (en) | 1979-12-07 |
| GB2020780B (en) | 1983-02-02 |
| AU529114B2 (en) | 1983-05-26 |
| IL57223A0 (en) | 1979-09-30 |
| FR2425584B1 (en) | 1985-05-17 |
| DE2918280A1 (en) | 1979-11-22 |
| DE2918280C2 (en) | 1992-04-09 |
| AR222485A1 (en) | 1981-05-29 |
| ES253799U (en) | 1981-04-01 |
| BR7902826A (en) | 1979-11-27 |
| JPS556078A (en) | 1980-01-17 |
| ES253799Y (en) | 1981-10-16 |
| AU4670679A (en) | 1979-11-15 |
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Legal Events
| Date | Code | Title | Description |
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| MKEX | Expiry |