DE1941600C - Shock absorber with load transfer element and a honeycomb structure - Google Patents

Description

The invention relates to a shock absorber with a load introduction member and a honeycomb structure with a cell axis direction parallel to the direction of movement of the load input element.

The problem of shock absorption relates in particular to that which occurs relatively infrequently during operation Absorbing peak forces through honeycomb structures. Such structures experience during shock absorption permanent plastic deformation. They can therefore only be used once and must be exchanged for further use. Such problems with landing skids are known of helicopters (German Patent 915 533) and landing gear of spacecraft, e.g. B. at the Apollo lunar module (see publication from Hexcel Product Inc., Berkeley, California, “Honeycomb as an energy absorbing material «- honeycombs as an energy absorption material - byj.Brentjes, 8. Structures, Structural Dynamics and Material Conference, March 29 and 30, 1967). In both cases the normal landing impacts must be absorbed by elastic deformation of the landing struts, however, the excessive stress is caused by plastic deformation of interposed shock absorbers intercepted without breaking the components themselves.

The use of honeycomb structures for such purposes has the disadvantage that the force-displacement characteristic shows a steep rise at the beginning of the load, combined with a high load peak. As a result, this high peak load must be exceeded before the structure can take effect can be.

A well-known way of eliminating the initial peak load consists of pre-compressing the honeycomb structure before it is used, with the load peak has already been exceeded (e.g. US Pat. No. 3,130,819). The disadvantage here is that the final Energy absorption capacity is thereby reduced. Another well-known way to eliminate the initial peak load and at the same time a gentler one To achieve an increase in force consists in providing the honeycomb material with a profiled surface (e.g. U.S. Patent 2,973,172). The disadvantage here is that each honeycomb block is a special, complex one Requires machining by means of expensive tools.

The invention is based on the object of reducing the load peak and a gentler increase in force to achieve without the honeycomb structure prior to its use for shock absorption a pretreatment must be subjected.

According to the invention, this object is achieved in that the load introduction element or the opposite one Housing bottom on its side facing the flat contact surface of the honeycomb structure has such a profiling that progressively larger surfaces (e.g. cones, pyramids, Calottes) of the load application member come to rest on the honeycomb structure.

The advantage of profiling the Lasteinidtgi K: \ ies to achieve a desired force-V>: g-curve consists in its unique treatment; ·, mg compared to that of each individual at the sowing / arriving Honeycomb structure. In addition, depending on the application, the piling can be carried out in an exact form - Ih: - calculates and executes. Furthermore, the shaping or profiling does not require bc. ύ · - the honeycomb structure must be taken into account.

According to a further embodiment of the invention isi lie the shape of the load introduction member by step hair dryer ^; jy layering of flat plates approximated. This has the advantage that the load application is always perpendicular to the respective contact surface of the honeycomb structure. For example, in the case of a pointed, conical profile, the honeycomb structure would split and the function of the Siot absorber would be adversely affected. Such a malfunction is avoided, however, by the approximated step-shaped profiling of the load initiating member.

Such acting shock absorbers can due to the easy installation and removal possibility of the honeycomb structure in aircraft suspension struts, landing stilts, tow bars, buffer blocks, packaging more sensitive Devices as well as for the attenuation of Abflugplatlcn and other more can be used.

An exemplary embodiment is described below and explained on the basis of sketches.

F i g. 1 shows force-displacement characteristics with and without a load application element;

F i g. 2 shows a shock absorber with the arrangement of a stepped profile on the load introduction member;

Fig. 3 shows the shock absorber according to FIG. 2, however with the arrangement of a stepped profile on the housing base;

Fig. 4 shows an aircraft strut with built-in Shock absorber.

In Fig. 1, the natural characteristic curve 1 is a honeycomb structure the force-displacement curve 2 is compared. The peak load shown in characteristic curve 1 is based on the critical deformation or buckling load at the beginning of the plastic deformation of each other connected cell walls. After exceeding this critical deformation or buckling load, a continuous one Forming process initiated under a practically constant load, for example with aluminum and paper honeycombs for progressive folding, with cell walls made of glass fiber reinforced plastics to progressive breakage and pulverization Hpi-spI-

^: ? i ^nd _t - ³ , is ^{such an} 8 ^e r shock absorber 3 ™ · ³ ™ " ^load guide element 4 or 4 'with and without stepped profiling or 5' schematically

S? K? · Λ Γ ⁶ ?! " ^Execution " ^m TS the load introduction member 4 or 4 'in the direction of the

SS? "'τ ⁶ ' Ä. ^Richt " ^ arrow) a Jfabenstrut

area Γη J «, ³ « 'ΐ ^ T ** ^{1 associated contact areas} or 8. Load introduction member 4 or 4 'and Wa-

iSK ¹ ^ V ' ^{Are surrounded by the} ° * «« »^ 9-. While m F i g. 2 d = e stepped professional

JieniiigS directly arranged on the load application element4

yourself ¹ ? "ρ IF", ^which acts on the surface, is the: Profiling 5 'in FIG in two illustrations of Figures 2 and 3, the 'standing and acts upon surface 11 or U i _n contact' on the stepped layering or Profilierung5 and 5 'until reaching the constant force gradually increases with Wabenstruktur7 bzw.7. This a smoother rise in the force-displacement curve 2 (see Fig. I) is achieved without a load peak occurring

Finally, FIG. 4 shows a practical example of the use of a shock absorber with a honeycomb structure 12 and load introduction member 13 arranged therein in an aircraft spring strut 14. If the strut 14 or the normal shock-absorbing device 15 is de; If the aircraft is overstrained on the runway 16, the overworking that occurs is transferred to the built-in honeycomb structure 12. This honeycomb structure 12, deformed or unusable by Hirch, must then be replaced by a new one; which can be done through the easy back and forth expansion option ν η shock absorber.

1 sheet of drawings

Claims (2)

Patent claims: 1. Shock absorber, consisting of a housing with load introduction member and a honeycomb structure enclosed in the housing with flat surfaces and with Zeilachsrichtung parallel to the direction of movement of the load introduction member, characterized in that the load introduction member (4) or the opposite housing base (10 ') on its flat contact surface ( 8 or S ") of the honeycomb structure (7 or 7 ') facing side has such a profiling that, when loaded, progressively larger surfaces (z. B. cones, pyramids, domes) of the load introduction member (4 or 10') to the plant come to the honeycomb structure (7 or T) . 2. Shock absorber according to claim 1, characterized in that that the shape of the load introduction member (4 or 10 ') is more even through stepped layering Plates (5 or 5 ') is approximated.