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Low-profile, multi-axis, highly passively damped, vibration isolation mountRelated Patent Categories: Spring Devices, Resilient Shock Or Vibration AbsorberLow-profile, multi-axis, highly passively damped, vibration isolation mount description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070176337, Low-profile, multi-axis, highly passively damped, vibration isolation mount. Brief Patent Description - Full Patent Description - Patent Application Claims
BACKGROUND OF THE INVENTION [0001] The present invention relates to passively damped, vibration and shock load isolation apparatus suitable for use in protecting hardware and payloads from damaging vibration and shock loads, particularly those extreme loads seen in spacecraft launch systems. This application incorporates by reference all that disclosed within U.S. Pat. No. 6,202,961. [0002] The ability to isolate payloads from the vibration and shock loading of a supporting structure or vehicle, or conversely to isolate a structure or vehicle from the vibrations of an engine, motor, or other vibration inducing payload is of great value to the aerospace, automobile and vehicle industries world wide. The particular ability to provide substantial passive damping and vibration isolation in a compact and lightweight form, together with a completely linear elastic, high-strength load path has been the strength of the device disclosed in U.S. Pat. No. 6,202,961. [0003] A further characteristic of performance that is desired within vibration isolation devices is the ability to provide an independent and widely controllable compliance in all directions of vibration loading without sacrifice to strength and linearity of behavior, and without sacrifice to compactness or weight. [0004] High strength and linear load-deflection performance in all directions is highly desirable to mandatory in most vibration isolation applications. For spacecraft--launch vehicle applications, large magnitude vehicle accelerations having both longitudinal and lateral directional components require that high strength be maintained in all directions. Further, the overall system dynamics of the spacecraft and launch vehicle system must be predictable and carefully controlled, thereby the demand to avoid non-linear elastomers within the load path is without compromise. Additionally, extreme loads environments drive up the size and strength requirements of the payload and payload-to-launch vehicle interface hardware, such that the mass and space requirements of the apparatus must be continuously and aggressively minimized, thereby minimizing the cascading design impact to supporting hardware. [0005] A three-axis vibration isolation device patented earlier in part by this pair of inventors, disclosed in U.S. Pat. No. 6,290,183, provided the independently controllable, high strength, linearly elastic, multiple-axis compliance that is desired but with some sacrifice to longitudinal compactness. Damping within that device was also limited to the constrained-layer-on-beam-bending damping approach of the time, and effective primarily for longitudinal motions. Damping in the lateral directions of that device was light and thereby required any significant lateral motion damping to be added through means separate from the device. [0006] The device of U.S. Pat. No. 6,199,801, disclosed by the present two inventors and upon which the device of U.S. Pat. No. 6,290,183 was an extension, was the first its kind to provide for a passively damped vibration isolation device with high strength and linear-elastic performance. Other earlier approaches for vibration isolation and damping implementation wherein elastomers are used in the primary load path, remain inferior to those which maintain use of high-strength, linearly elastic materials throughout the primary load path. The device of U.S. Pat. No. 6,199,801 remained relatively stiff against lateral loading as compared to its longitudinal loading and thereby did not afford the desired levels of laterally directed vibration isolation. Hence the device of U.S. Pat. No. 6,290,183 answered the need for improved lateral vibration compliance but had its own limitations in terms of higher profile and light damping. [0007] The present invention addresses the need for a passive, highly damped vibration isolation device which provides independent and widely controllable compliance in all directions of vibration loading without sacrifice to strength and linearity of behavior, and without sacrifice to compactness or weight. BRIEF SUMMARY OF THE INVENTION [0008] The invention described within is a low profile, passively and highly damped, vibration isolation mount which in multiplicity provides a complete vibration load isolation mounting system. It provides an independently determinable compliance in all directions of vibration loading without sacrifice to strength and linearity of behavior, and without significant sacrifice to compactness of the payload-vehicle interface or to weight. It provides substantial damping and resulting reduction in vibration load transmission from support base to payload by utilizing the shear wall type constrained layer damping introduced in the predecessor device of U.S. Pat. No. 6,202,961. [0009] Comprised within the assembled mount is a flexure element that is optionally of one-piece construction but may also be of assembled form. In common relationship to the disclosed vibration isolation mount, a payload attaches to an upper flexure section and a launch vehicle or support base attaches to a lower flexure section of the mount's flexure element. The position and general directional relationship of the payload relative to the launch vehicle defines the commonly understood longitudinal direction of the combined vehicle, and similarly the upper flexure section and lower flexure sections are considered generally aligned to this longitudinal direction or axis, and herein are so described. The longitudinal axis of the combined vehicle may however be defined in any direction for which loading occurs and for which vibration isolation may be desired for implementation. Thereby the description of the disclosed invention as being generally aligned to a common longitudinal axis is not to be construed as being a constraint to any space fixed axis. [0010] The invention is further comprised of a viscoelastic material (VEM) layer which is attached to both the upper and lower flexure sections of the flexure element. Additionally, to the opposite face of the VEM layer, a relatively stiff constraining layer is attached that spans between the upper and lower flexure sections of the flexure element. [0011] Particular attributes of the flexure element and damping application combine to affect a vibration isolation mount of novel design. An aspect of the present invention retained from the referenced invention of U.S. Pat. No. 6,202,961 is the orientation of the constrained VEM layer relative to the flexure element. The VEM and constraining layers, rather than laying on the top of a flexure beam and being forced only to comply with the bent shape of that individual beam, are as described above, affixed to and across the sides of a flexure element in the manner of a shear wall. The constrained VEM thereby opposes the relative translational motion between the upper and lower flexure sections of the flexure element. The relative translational movement of the upper flexure section relative to the lower flexure section, even though minor, induces significant shear into the constrained VEM layer. With constrained VEM applied to the outer surface of the flexure element, critical damping percentages significantly greater than those of the prior art are achieved. A substantial additional increase in damping can be obtained by simply applying a constrained VEM layer to multiple locations between the upper and lower flexure sections of the flexure element. [0012] In the invention of the referenced U.S. Pat. No. 6,202,961, the short profile of the assembled isolation mount provided substantially greater lateral stiffness, which provided advantage relative to other systems of the prior art where relatively long struts and/or viscous dampers were necessary. However, a vibration isolation device providing a lateral compliance commensurate with the longitudinal compliance was desired. [0013] In the present invention, a well-controlled and determined lateral compliance commensurate with the longitudinal compliance is afforded. The introduction of a flexure loop section within the flexure element between the upper and lower flexure sections provides for introduction of such lateral compliance. The upper and lower flexure sections of the flexure element each provide an attachment means and an attachment proximate portion. The attachment proximate portion of the upper flexure section and the attachment proximate portion of the lower flexure section, to which the payload and vehicle respectively attach, are spaced apart longitudinally by a minimum controlled distance which is determined by the payload mass, static loads, and magnitude of vibration loads for which isolation is required. The flexure loop section connects the attachment proximate portion of the upper flexure section to that of the lower flexure section, and importantly is of such size, shape and cross section that is desired to affect the required longitudinal and lateral compliances, and is without dependence upon the minimal controlled distance between the attachment proximate portions or upon the cross section of those attachment proximate portions. [0014] The advantage achieved by the present invention relative to the prior art is the introduction of a vibration isolation device affording particularly prescribed longitudinal and lateral compliances with significantly high passive damping, and having commensurate advantage of a very modest increase of longitudinal profile of the overall payload and vehicle. Further, through the shaping of the flexure element plan view contours, the increase in the payload's effective plan profile can be kept quite modest and allow spacecraft-to-fairing clearances to not be appreciably increased, if at all. [0015] As with the referenced invention of U.S. Pat. No. 6,202,961, the present invention's maintenance of a completely high-strength material load path (such as that obtained with aluminum, titanium or steel) through the flexure element provides a more durable and reliable means for connecting a payload and vehicle than that available in systems of the prior art having a lower-strength elastomer or other easily yieldable material within the load path. Additionally, linear load-versus-deflection behavior characteristics are achieved, thus providing for more straightforward and predictable dynamic characteristics than available with those systems of the prior art utilizing elastomers in the load path. [0016] The present invention in a preferred embodiment can be utilized in multiplicity to affect a complete payload-to-vehicle vibration isolation system. To affect this system, a device is inserted into any or all mounting locations between a payload and vehicle or support structure. The attachment proximate portions of the upper and lower flexure sections lay within the fastener footprint of the payload to the support structure and the flexure loop sections lay aside of the fastener footprint. BRIEF DESCRIPTION OF THE DRAWINGS [0017] FIG. 1 is an isometric view of a low profile, multi-axis, highly passively damped, vibration isolation mount in accordance with an embodiment of the invention. [0018] FIG. 2 is an exploded view of the vibration isolation mount of FIG. 1. [0019] FIG. 3 is an isometric view of the flexure element comprised within the vibration isolation mount of FIG. 1. [0020] FIG. 4 is an isometric view of a vibration isolation system in accordance with an embodiment of the invention wherein multiple vibration isolation mounts of FIG. 1 are utilized to support and vibration isolate a payload from its support structure. [0021] FIG. 5 is an isometric view of a cylindrical form of a vibration isolation system in accordance with an embodiment of the invention. Continue reading about Low-profile, multi-axis, highly passively damped, vibration isolation mount... Full patent description for Low-profile, multi-axis, highly passively damped, vibration isolation mount Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Low-profile, multi-axis, highly passively damped, vibration isolation mount patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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