TECHNICAL FIELD OF THE INVENTION

The present invention relates to vibration isolators used to reduce structural dynamic loads imposed on the payload (satellite/spacecraft, etc.) carried in the satellite launch vehicles.

THE STATE OF THE ART

Satellites are exposed to high level vibration loads coming from the launch vehicle in the course of flight. These structural vibrations are transmitted to the satellite by means of the adapter connected to the launch vehicle. There are known vibration isolation systems that reduce the vibration load transmitted from the launch vehicle. The vibration isolation system is comprised of a plurality of identical vibration isolators that are circularly placed on the adapter.

The patent document numbered US2014332632 discloses an apparatus that comprises a plurality of vibration isolation devices placed between and attached to each of the first adapter ring and the second adapter ring, wherein the vibration isolation device has a first adapter ring for interfacing with a launch vehicle payload interface ring, a second adapter ring for interfacing with a payload launch vehicle interface ring, wherein the first adapter ring has a first standard interface with the launch vehicle payload interface ring and the second adapter ring has a second standard interface with the payload launch vehicle interface ring. Accordingly, a plurality of vibration isolators is placed between the first adapter ring and the second adapter ring. Combined isolators reduce the transmission of dynamic loads from the launch vehicle to the spacecraft in the course of launching at low frequency and amplitude.

The patent document numbered US6199801 introduces a design, which uses a dual-beam dampener having a constrained layer integrated thereon. It is disclosed that the length, thickness, and width of the dual-beam flexible structure may be altered for correctly adjusting the axial isolation frequency of the whole-spacecraft. Preferably, titanium is selected as a beam material regarding its strength and weight ratio. Accordingly, flexible materials should have high strength, because they carry large dynamic and static loads. It is disclosed that for cases when the weight is not an issue, stainless steel may be preferred considering its low cost. It is further disclosed that the constrained layer dampers comprise viscoelastic material placed on beams and desired damping properties are added to these components. BRIEF DESCRIPTION OF INVENTION

The object of the present invention is to reduce significantly the random vibration input transmitted from the launch vehicle to the payload in a broad frequency band in axial and lateral directions.

The present invention, so as to achieve the aforementioned objects, comprises an upper connector that is adjusted to be connected to a payload placed on an adapter provided on a launch vehicle, and a lower connector that is adjusted to be connected to the adapter, and a vibration isolator that is arranged in an identical and adjacent manner in multiple numbers on an adapter. A vibration isolator comprises respectively, a carrier arm and a support arm having a mounting part provided on one of the proximal ends of which upper connector and the lower connector have them opposingly, and it further comprises an elevator element having an elevator arm extending between each of their distal ends so as to fix the carrier arm and the support arm at a certain distance from each other. The elevator arm connects the support arm and the carrier arm from one of the distal ends thereof, thereby moving them away in a manner that provides distance, and it provides reduced delivery of the carrier arm to the upper connector by providing the isolation of the vibrations coming from the adapter of the launch vehicle to the support arm with the form connected with the elevator arm. The vibration isolator formed by providing the arm structures, which surprisingly have simple geometry, and the beams, shows equivalent vibration isolation performance with similar complex systems.

In a preferred embodiment of the invention, the carrier arm and support arm are aligned parallel to each other, and the elevator arm extends along between them vertically. It is observed that this structure -although its vibration isolation performance is specific to the system in which it is used -, reduces the total vibration input by 3 to 5 times.

In a preferred embodiment of the invention, the upper connector, the lower connector, and the elevator element provided therebetween comprise metal alloy. Since the body of vibration isolators is required to carry a high level of loads and to show linear behavior, it is manufactured from a metallic material. The strength required for carrying a static load and low stiffness required for vibration isolation is provided by the metallic body. As material properties of metallic materials show less variability according to the temperature and frequency properties compared to rubber materials, the inventive vibration isolator acts linearly and therefore it provides facility for modeling and analysis. In a preferred embodiment of the invention, the metal alloy is selected from a group consisted of titanium, aluminum, or stainless steel. The strength value required for carrying a static load and the low stiffness values required for vibration isolation is provided by metallic bodies of the selected alloy.

In a preferred embodiment of the invention, it comprises a vibration damping element adapted to be placed on the area between the carrier arm, the elevator arm, and the support arm. In a preferred embodiment of the invention, the vibration damping element is provided by means of a viscoelastic layer and a restrictor plate placed on a side wall so as to restrict axial movement. The damping required for reducing the vibration levels in the resonance portions is provided by viscoelastic material having a high damping ratio, and a restrictor layer having a high stiffness value. The restrictor plate forces viscoelastic material to become deformed in shear mode by restricting the viscoelastic material's movement under the vibration load. Since the strain energy of viscoelastic materials in shear mode is higher, the achieved damping ratio increases. The desired damping ratio may be achieved by altering the material thickness of the viscoelastic material and thickness of the restrictor plate. Also, different damping ratios may be provided by choosing a different type of viscoelastic material and altering the surface area on which damping is applied.

A preferred embodiment of the invention is in the form of a hole coaxial with each other within the mounting parts of the upper connector and the lower connector. Thus, the vibration isolator may be directly attached to the payload and adapter. Owing to the high damping ratios of the inventive vibration isolation system, its displacement under the harmonic vibration load in relatively low frequencies is low. Due to the low displacement of the satellite, space needs to be created in order to prevent the satellite from hitting the payload fairing is reduced and therefore, the dynamic envelope separated for the satellite within the payload fairing extends. Furthermore, since it ensures the mechanical connection between the satellite and the launch vehicle, it has the capacity to carry the mass of the satellite and the inertial loads resulting from the quasi-static acceleration of the launch vehicle.

In a preferred embodiment of the invention, the carrier arm, the support arm and the elevator arm extending along therebetween are in the form of a combined integrated C-profile. Thus, thanks to its double bend structure, a vibration isolator, which may achieve the desired isolation property and may be produced easily, has been obtained. The C-profile form offers a flexible usage area according to its load amount and adapter geometry. One or more C-profiles may be extended in different axes by combining them with axial symmetry or by combining them vertically to each other. In a preferred embodiment of the invention, the carrier arm, the support arm and the elevator arm extending along therebetween has a rectangular-like cross-sectional shape. This situation facilitates manufacturing.

In order to achieve said object, the present invention comprises a launch vehicle having a vibration isolator as described above and in which each vibration isolator is fixed upwardly to the adapter from its lower connector at a distance from each other along a circular line. In the launch vehicle having this vibration isolation system, random vibration input on the broad frequency band in axial and lateral directions on the payload is reduced significantly.

BRIEF DESCRIPTION OF DRAWINGS

FIGURE 1 illustrates the schematic view of the vibration isolation system's position on the adapter in a launch vehicle that carries the payload.

FIGURE 2 illustrates a representative schematic view of the vibration isolation system comprised of vibration isolators placed circularly.

FIGURE 3a illustrates the perspective view of the metallic body of the vibration isolator in an elevated representational embodiment thereof that extends on two axes.

FIGURE 3b illustrates the perspective view of the vibration isolator shown in Figure 3a when the damping application is implemented on its metallic body.

FIGURE 4a illustrates the perspective view of the metallic body of a representative embodiment of the vibration isolator in the C-profile structure.

FIGURE 4b illustrates the perspective view of the vibration isolator shown in Figure 4a when the damping application is implemented on its metallic body.

FIGURE 5a illustrates the perspective view of the metallic body of a representative embodiment of the vibration isolator that is elevated from the lower part.

FIGURE 5b illustrates the perspective view of the vibration isolator shown in Figure 5a when the damping application is implemented on its metallic body. DETAILED DESCRIPTION OF INVENTION

In this detailed description, the present invention is described without any limitations, and by making references to the examples to ensure that the present invention is understood fully.

In Figure 1 , a launch vehicle (1) on which the inventive vibration isolation system (10) is shown schematically. Launch vehicle (1) carries a payload (2), for example, a communication satellite, located on an adapter (3) provided in the launch vehicle, on the vibration isolators (10) provided therebetween. The adapter (3) provides payload (2) to be connected to the upper stage (4) of the launch vehicle.

In Figure 2, an exemplary placement of the vibration isolators (10) is shown schematically. An elevator element (30) in the lateral parts of the vibration isolators (10), which are formed as a plus sign, are placed side by side and facing each other at a certain distance. An upper connector (20) faces upwards towards the payload (2).

Figure 3a illustrates the perspective view of the metallic body of one of the vibration isolators (10). Two vibration isolators (10) in C-form having a mirror symmetry to each other are connected in a center point as vertical couples. Thus, from the top view, a cage structure having a plus sign form has been obtained. The vibration isolator (10) comprises an upper connector (20) having a form of arms extending to four sides and a parallel and co-formed lower connector (30) and an elevator element (30) extending therebetween. Each upper connector (20) has a support arm (24) extending in the same direction in the opposite direction as connecting at one proximal end (26). The carrier arms (24) are connected at their proximal ends (26) in a mounting part (22) provided in the center point. The mounting part (22) comprises a connection hole vertically opened all along on a lamella. Carrier arms (24) carry the payload (2) that they are connected to from the mounting part (22) by means of a connector (60). Each carrier arm (24) is connected to the elevator arm (34) of the elevator element (30) from its upper part (32) by forming a bend from its distal end (28) opposite to its proximal ends (26). The elevator arm (34) connects to the distal end (48) of each support arm (44) of the lower connector (40) from its lower part (36) vertically extending downwards to the placement plane by forming a bend. One proximal end (46) of the lower connector (40) opposite to the distal end (48) is connected to a mounting part (42) from the center point. The mounting part (42) comprises a connection hole on a lamella just as mounting part (22) of the upper connector (20). The connection holes on the mounting parts (22, 42) of the upper and lower connectors (20, 40) extend on the coaxial axis parallel to the vertical axis of the elevator arm (34). The elevator element (30) has a side wall (37) of each elevator arm (34) and an inner wall (35) facing inside of the cage structure of the vibration isolator (10). In Figure 3b, a vibration damping element (50) comprising a viscoelastic layer (54) affixed vertically on to the side wall (37) and a restrictor plate (52) affixed on the viscoelastic layer (54) are shown. The vibration damping element (50) covers up the metallic body on the cage structure from every direction.

Figure 4a illustrates a perspective view of the metallic body of a vibration isolator (10). The vibration isolator (10) in C-form, which forms a unit module in its simplest form, has a carrier arm (24) having a flat form and a rectangular cross-section, an identically formed support arm (44), and an elevator arm (34) connected as a bending form by extending between their distal ends (28, 48). The elevator arm (34) is relatively thicker than the carrier arm (24) and the support arm (44) to which it is connected to the distal ends (28,48) from the opposing upper part (32) and the lower part (36). In distal ends (28,48), there are mounting parts (22,42), which have a lamella structure and a connection hole extending vertically and coaxially in the middle part thereof. Figure 4b illustrates the exploded view of the vibration isolator (10) in the C profile to cover the vibration damping element (50). The viscoelastic layer (54) having a lamellar thin structure is placed on a side wall (47) of the lower connector (40) as it is in the other walls, facing the upper wall (45) and the restrictor plate (52) is parallelly covered thereon.

Figure 5a illustrates the perspective view of the metallic body of the vibration isolator (10) obtained by combining two G profiles with mirror symmetry to each other in a different geometry. Different from the C-form, each G-formed support arm (44) is bent with the bend structure to form an intermediate elevator part (43) and the proximal end (46) of the support arm (44) is partially elevated. Thus, the lower connector (40) is approached to the mounting part (42) and the upper connector (20) is approached to the mounting part (32). Figure 5b illustrates the exploded view of the cage structure covered with the vibration damping element (50). Here, in the inner chamber where the cage structure is being limited, firstly, the viscoelastic layer (54) is mounted on the body of the vibration isolator (10) from both opposing sides, and the restrictor plate (52) is affixed thereon as facing to the side wall (47) among others. REFERENCE NUMERALS

1 Launch Vehicle 36 Lower Part

2 Payload 37 Side wall

3 Adapter 40 Lower connector

4 Upper stage 42 Mounting part

10 Vibration Isolator 43 Intermediate elevator part 20 Upper Connector 44 Support arm 22 Mounting part 45 Upper wall 24 Carrier Arm 46 Proximal end 26 Proximal End 47 Side wall 28 Distal End 48 Distal end 30 Elevator Element 50 Vibration damping element 32 Upper Part 52 Restrictor plate

34 Elevator Arm 54 Viscoelastic layer

35 Inner Wall 60 Connector