Abstract:
A device used for providing dynamic isolation and damping of dynamic vibrations, in a passive way, originated in the launch vehicle of a space shuttle and reaching the payload or satellite. The device comprises a plurality of identical elementary unit elements, such that the device is designed in a modular way, allowing the individual modularity of each of the elementary unit elements. Each of the elementary unit elements is tailored and designed individually, and the complete device can be designed for each particular application and payload needed as a function of each of the elementary unit elements allowing an easy design and lower costs, for a wide range of payload applications. Each elementary unit element comprises a spring component and a damping component, such that the functionalities provided for each component are separated and can be individually tailored, thus providing a device having a wider range of adaptation capabilities.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application claims the benefit of the European patent application No. 12382057.3 filed on Feb. 20, 2012, the entire disclosures of which are incorporated herein by way of reference. 
     FIELD OF THE INVENTION 
     The present invention relates to a device used for providing dynamic isolation and damping of dynamic vibrations originated in the launch vehicle of a space shuttle and reaching the satellite. 
     BACKGROUND OF THE INVENTION 
     A space shuttle is designed for carrying payloads or satellites into different space orbits. Each space shuttle is a launch system comprising an external tank supplying the liquid oxygen and hydrogen fuel to the main engines, two solid rocket boosters providing the thrust needed for the lift-off of the whole space shuttle, and a satellite, orbiter or payload which has to be placed in a required orbit in the outer space. The space shuttle is designed as a function of the payload that is needed to be put into orbit in space. 
     During lift-off and ascent, the external tank in the space shuttle supplies the fuel and oxidizer under pressure to the main engines in the space shuttle. In the known prior art, these external tanks comprise two separate tanks, one comprising the liquid oxygen fuel and the other one comprising the liquid hydrogen fuel, such that each of these tanks is joined to the structure of the external tank by means of a metallic structure isolating and damping the vibrations and loads transmitted to the two tanks comprising the liquid fuel. Further developments have been made and the external tanks no longer comprise the mentioned configuration, but the whole external tank is rather divided internally into two chambers, one chamber comprising liquid hydrogen fluid and another one comprising liquid oxygen fuel, both chambers being separated by means of a membrane. This configuration results in the payload in the space shuttle receiving very high loads and vibrations which have been transmitted by the external structure. It is therefore needed to develop a device that is able to properly dampen and isolate the payload from these loads and vibrations. The device that has to be developed must be a device having, at the same time, enough stiffness, flexibility and dampening properties, and this would ideally need to be valid for every space shuttle and for every payload in it. 
     It is known from the state of the art, as per document U.S. Pat. No. 7,249,756 B1, a mounting system passively damped and isolated from vibrations, comprising a plurality of elements, each element having a very low profile, such that the system that is able to be used in a space shuttle for an application as the one just mentioned. However, the mounting system in U.S. Pat. No. 7,249,756 B1 presents several problems and disadvantages: as the damping and isolation functionalities in each of the elements forming the system are functionally and structurally joined, the design and characterization of these elements has to be made for each single application where the system is going to be used, therefore not allowing an easy and unique design. Besides, the same element configuration cannot be used for different space shuttles and different payloads, but rather need to be redesigned for each particular case. Furthermore, this design would not allow a growth potential and flexibility of redesign as, if for example higher stiffness is required, the element needs to be made wider and the number of elements would prevent this redesign from being placed within the space shuttle structure. Even one more disadvantage of the system in U.S. Pat. No. 7,249,756 B1 would be that it could not be properly used in composite material structures, which are the structures mostly used at present for space applications. 
     The present invention is intended to solve said disadvantages and limitations in the prior art. 
     SUMMARY OF THE INVENTION 
     In a first aspect, the present invention discloses a device used for providing dynamic isolation and damping of dynamic vibrations, in a passive way, originated in the launch vehicle of a space shuttle and reaching the payload or satellite. The device of the invention comprises a plurality of identical elementary unit elements, such that the device is designed in a modular way, allowing the individual modularity of each one of the elementary unit elements: therefore, each of the elementary unit elements is tailored and designed individually, such that the complete device can be designed for each particular application and payload needed as a function of each of the elementary unit elements, thus allowing an easy design and lower costs, for a wide range of payload applications. 
     Each of the elementary unit elements comprises a spring component and a damping component, such that the functionalities provided for each component are separated and can be individually tailored, thus providing a device having a wider range of adaptation capabilities. 
     Furthermore, the elementary unit elements are preferably manufactured of a composite material, so that the device of the invention can be used in composite structures within a space shuttle. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing objects and many of the attendant advantages of this invention will become more readily appreciated as the same becomes better understood by reference to the following detailed description when taken in conjunction with the accompanying drawings, wherein. 
         FIGS. 1   a ,  1   b  and  1   c  show a schematic general view of the configuration of a space shuttle damping and isolating device according to the present invention, showing the plurality of elementary unit elements for different payload configurations. 
         FIG. 2  shows a schematic view of the elementary unit element configuring the space shuttle damping and isolating device according to the present invention. 
         FIGS. 3   a  and  3   b  show detailed views of the elementary units forming the spring component in the elementary unit element configuring the space shuttle damping and isolating device according to the present invention. 
         FIGS. 4   a ,  4   b  and  4   c  show detailed views of the plurality of elementary units forming the spring component in the elementary unit element configuring the space shuttle damping and isolating device according to the present invention. 
         FIG. 5  shows a detailed view of the damping component in the elementary unit element configuring the space shuttle damping and isolating device according to the present invention. 
         FIG. 6  shows a detailed view of the damping component and of the spring component being joined in order to constitute the elementary unit element configuring the space shuttle damping and isolating device according to the present invention. 
         FIGS. 7   a ,  7   b ,  7   c  and  7   d  show schematically different views of the quasi-parallel working mode of the space shuttle damping and isolating device according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The invention discloses a device  10  used for providing dynamic isolation and damping of dynamic vibrations, in a passive way, originated in the launch vehicle of a space shuttle and reaching the payload or satellite. The device  10  of the invention comprises a plurality of identical elementary unit elements  20 , such that the device  10  is designed in a modular way, allowing the individual modularity of each one of the elementary unit elements  20 .  FIGS. 1   a ,  1   b  and  c  show schematic views of the device  10  according to the present invention, comprising a plurality of elementary unit elements  20 , this device  10  being located at any position in the upper stage structures of the launch vehicle, in such a way that this device  10  interferes in the load path from the launch vehicle to the space shuttle. 
     As shown in  FIGS. 1   a ,  1   b  and  1   c , the proposed baseline where the device  10  of the invention is set has a diameter of 1780 mm, which represents a standard diameter measurement for space shuttles and satellites. It is also a standard for space shuttles and satellites to have a maximum of 144 equidistance positions within the diameter of 1780 mm, such that the fixing of the device  10  is made by a fixing element in each one of these 144 positions. In the embodiment shown in  FIG. 1   a , the device  10  comprises 144 identical elementary unit elements  20 . Because the same device  10  will be used for a wide range of space shuttles and payloads, typically in the range of 1 ton to 6 tons, the modular configuration of the device  10  will differ depending on the payload to support; for example, payloads comprised between 4.5 and 6 tons will use a device  10  comprising 144 identical elementary unit elements  20 , payloads comprised between 3.5 and 4.5 tons will use a device  10  comprising 72 identical elementary unit elements  20 , and payloads below 3.5 tons will use a device  10  comprising 36 identical elementary unit elements  20 , for example. Other different configurations of the device  10  will also be possible, and these mentioned only represent typical embodiments. 
       FIG. 2  shows a general view of each of the elementary unit elements  20  in the device  10 , providing dynamic isolation and damping functions by means of a combination of a spring component  11  and a damping component  12 . The spring component  11  is formed by two symmetric stacks  111  and  112 , each stack  111  or  112  comprising a plurality of leaf springs  113 . The damping component  12  is formed by at least one stack  125  comprising a plurality of damping leafs  120 . The stacks  111  and  112  in the spring component  11  and the at least one stack  125  forming the damping component  12  (the embodiment shown in the attached Figures shows a damping component  12  comprising three stacks  125 ) are joined together at their ends by joining elements  30 , preferably by mechanically preloaded bolt elements, as shown in  FIG. 2 . Besides, inserts  400 , typically screwed, are assembled at the top and bottom parts of the two symmetric stacks  111  and  112 , in order to provide mechanical interfaces with the adjacent structures to which the device  10  is joined. 
     One of the main advantages of the device  10  of the invention comes from the configuration of each elementary unit element  20  comprising a spring component  11  and a damping component  12  working in a quasi-parallel mode as follows: the working way of the elementary unit element  20  is based in the combination of the axial-vertical  200  relative displacement (up-down) of the two symmetric stacks  111  and  112 , providing the main stiffness properties for each elementary unit element  20 , together with the radial-horizontal  300  relative displacement (right-left) of the two symmetric stacks  111  and  112  joining the at least one stack  125  forming the damping component  12  at their ends, providing the main damping properties for each elementary unit element  20 . The geometry and configuration of the leaf spring  113  in the stacks  111  and  112  drives the ratio of both relative displacements, of the axial-vertical  200  relative displacement (up-down) and of the radial-horizontal  300  relative displacement (right-left), therefore providing a multiplication factor (&lt;1 or &gt;1) that can be defined according to design needs. The fact that this ratio of relative displacements can be different from 1, results in the working mode of each elementary unit element  20  being not completely parallel, but quasi-parallel. This has the advantage that the design of the damping properties and of the stiffness properties can be made individually and through the ratio just mentioned, in such a way that: when the ratio is below 1, the damping properties in the elementary unit element  20  are higher than the stiffness properties; however, when the ratio is above 1, the stiffness properties in the elementary unit element  20  are higher than the damping properties. 
       FIGS. 7   a - 7   d  show schematically the quasi-parallel working mode of the device  10 , as well as the angles and ratios. As such,  FIG. 7   a  shows the still mode configuration of the device  10 , such that the stack  111  forms an angle α with the damping component  12 . Symmetrically, the stack  112  forms also an angle α with the damping component  12 . In the still mode shown in  FIG. 7   a , the initial angle α is of 45°; the working mode of the device  10  was parallel, this angle α would be maintained throughout the movement of the stacks  111  and  112  with respect to the damping component  12 , so that the ratio of the axial-vertical  200  relative displacement (up-down) and of the radial-horizontal  300  relative displacement (right-left) would be equal to 1 (see different positions of the device  10  shown in  FIG. 7   c ). However, in the quasi-parallel mode of the invention, the ratio of the axial-vertical  200  relative displacement (up-down) and of the radial-horizontal  300  relative displacement (right-left) is different from 1, as the angle α is not 45°, which results in the working mode of each elementary unit element  20  being not completely parallel, but quasi-parallel. As it has been previously described, the design of the damping properties and of the stiffness properties can be made individually and through the ratio just mentioned, in such a way that: when the ratio is below 1, the radial-horizontal  300  relative displacement (right-left) is higher than the axial-vertical  200  relative displacement (up-down), the angle α is below 45° and the damping properties in the elementary unit element  20  are higher than the stiffness properties (see representations in  FIG. 7   b ); when the ratio is above 1, the axial-vertical  200  relative displacement (up-down) is higher than the radial-horizontal  300  relative displacement (right-left), the angle α is greater than 45° and the stiffness properties in the elementary unit element  20  are higher than the damping properties (see representations in  FIG. 7   d ). 
     The device  10  of the invention is sized as to its elementary unit elements  20  to support static and dynamic loads going through the structures of the space shuttle. To that, it is possible to match any stiffness/strength/damping requirement using the adequate configuration of the spring component  11  and of the damping component  12 : this means that the concept underlining the invention offers an additional modularity to the design, making it possible to match different isolation requirements (stiffness and damping) at the level of the elementary unit element  20  itself. 
     The selected materials used for the spring component  11  and for the damping component  12  can be further reviewed if needed, or even combined, accordingly the stiffness, the loads to be supported and the damping requirements and, hence, the design at the level of the elementary unit elements  20  is susceptible of potential optimizations and/or of updates to evolutions of requirements. One possible embodiment (as the one shown in  FIG. 2 ) comprises five leaf springs  113  on each stack  111  and  112 , Preferably, the same material forming these leaf springs  113  also configures some of the damping leafs  120  forming the damping component  12  in the embodiment shown in  FIG. 2 , this material preferably comprising carbon fiber reinforced polymer, CFRP (further explanation of the materials for the damping component  12  will follow). 
     Each symmetrical stack  111  and  112  configuring the spring component  11  of the elementary unit element  20  comprises a stack of a plurality of leaf springs  113  of certain dimensions: preferably, in the embodiment of  FIG. 2 , each stack  111  or  112  comprises five leaf springs  113  each, made of CFRP, with the following dimensions: 2 mm thickness, 30 mm width and 200 mm length. The package of the stacks  111  and  112  is guaranteed by means of the edge holes  41  and pads  40 , as shown in  FIGS. 3   a  and  3   b . Besides, each leaf spring  113  is also drilled at the center, providing an interface hole  42 . Thus, the edge holes  41  provide the assembly of the leaf springs  113  in each stack  111  and  112 , while the interface holes  42  serve as an interface with other elements. 
     Each leaf spring  113  also comprises preferably three flat pads  40 , preferably rectangular, located at the edges, where the edge holes  41  are, and also at the center, where the interface hole  42  is (see  FIGS. 3   a  and  3   b ). The flat pads  40  have the following purposes: 
     provide a flat contact surface; 
     separate the leaf springs  113 ; 
     provide strength compensation to the interface holes  42  and to the edge holes  41 ; 
     allow the assembly of the stacks  111  and  112  by further tightening by means of bolts at the edge holes  41 ; 
     allow interface inserts tightening by means of inserts at the interface holes  42 . 
       FIGS. 4   a ,  4   b  and  4   c  show the configuration of the stacks,  111  or  112 , by means of a plurality of leaf springs  113 , preferably five leaf springs  113 , that come together at the edges through the flat pads  40  at the edge holes  41 , such that the stack formed,  111  or  112 , is also properly joined at the interface holes  42  through flat pads  40 . 
     The damping component  12 , as shown in  FIG. 5 , comprises a plurality of stacks  125 , preferably three, as shown in the embodiment of the cited  FIG. 5 . The embodiment of  FIG. 5  shows a total of five damping leafs  120  for each of the three stacks  125 , making a total of five layers for each stack  125 , configured in the sandwich-type, in the following preferred way: 
     a primary CFRP layer  121 ; 
     a damping layer  122 , preferably made of silicone rubber; 
     a third CFRP layer, comprising two symmetric leafs  123  and  123 ′; 
     a fourth damping layer  124 , preferably made of silicone rubber; 
     a fifth layer of CFRP  125 . 
     The third layer or center layer is formed by two symmetric leaves  123  and  123 ′, allowing relative displacement and shear deformation of the leaves  123  and  123 ′, preferably made of silicone rubber, at each side, therefore providing a simple energy dissipation mechanism. Furthermore, assembly holes  130  at both ends are provided, together with assembly flat pads  140 , facilitating the integration with the spring component  11  of the elementary unit element  20 , at the edge holes  41 . 
     Final integration of the above-described parts forming each of the elementary unit elements  20  configuring the complete device  10  used for providing dynamic isolation and damping of dynamic vibrations of the invention is shown in  FIG. 6 , and will be explained as follows: 
     the plurality of symmetric leaf springs  113  come together at the edges, through the edge holes  41  and flat pads  40 , together with the interface holes  42  and flat pads  40 , thus being formed the two symmetric stacks  111  and  112 ; 
     the plurality of damping leafs  120  come together at the edges, through the assembly holes  130  and pads  140 , thus being formed each of the stacks  125  of the damping component  12 . 
     The assembly of the stacks  111  and  112  configuring the spring component  11 , together with the stacks  125  configuring the damping component  12 , is preferably made at edge holes  41  mating the holes  130  in the damping component  12 , by means of joining elements  30 , preferably numbering four, these joining elements preferably comprising stainless steel screwed bolts, which further preload the full packages of stacks of  111 ,  112  and  125  by tightening nuts on top, this tightening being properly done by means of the flat pads of stacks  111  and  112  at the edges  40 , mating the pads  140  at the edges of the stacks  125 . 
     The mechanical interface of the device  10  with the adjacent structures at the space shuttle is provided by means of inserts  400 , preferably two, and more preferably being these inserts  400  made of aluminum alloy, such that these inserts are located at the central interface holes  42  of each stack  111  and  112  configuring the spring component  11 , also with the help of the central flat pads  40 . These inserts  400  are self tightened one against the other up to preload the top and bottom flat surfaces of the stacks  111  and  112 . These inserts are preferably screwed in order to provide a quick and easy interface with the rest of the structures in the space shuttle.  FIG. 6  shows the way the total assembly of device  10  is formed. 
     Furthermore, the elementary unit elements  20  are preferably manufactured in composite material, so that the device  10  of the invention can be used in composite structures within a space shuttle. 
     Although the present invention has been fully described in connection with preferred embodiments, it is evident that modifications may be introduced within the scope thereof, not considering this as limited by these embodiments, but by the contents of the following claims. 
     As is apparent from the foregoing specification, the invention is susceptible of being embodied with various alterations and modifications which may differ particularly from those that have been described in the preceding specification and description. It should be understood that I wish to embody within the scope of the patent warranted hereon all such modifications as reasonably and properly come within the scope of my contribution to the art.