Abstract: The invention is an improved apparatus for damping a wide range of oscillatory or wave motions in a plate, beam, shell or skin. The apparatus includes linearly-extending triangular hinged flexures in the form of spaced apart V-shaped spacer elements with the V substantially normal to the surface of the damped member, each flexure having two substantially rigid legs and a hinge flexure and a body portion adjacent the vertex of the V. An elongated substantially extensionally stiff constraining member is positioned in an offset, substantially parallel relationship to the surface of the damped member. A damping layer of a energy-dissipating viscoelastic material (VEM) connects the body portions of the hinged flexures to the constraining member. One or more of the spacer elements may have a lever attached to its body portion, the lever amplifying motion induced in its flexure toward the distal end of the lever.

Abstract: A motor mount is described for preventing the transmission of noisy vibration of the motor on vehicle body parts on which the motor is mounted by its motor housing. The motor housing is held by a carrier part that surrounds it. The carrier part is surrounded at a radial distance by a mounting part at least in some areas. The mounting part is connected to the carrier part by an elastic sound-absorbing intermediate layer that is subjected substantially to tensile stresses.

Abstract: The present invention relates to a vibration damped laminate articles having improved force (torque and/or pressure and/or stress) retention, a method of making one article type and novel tools used to make the one article type. The first laminate comprises at least one layer of damping material between at least two substrate layers. At least one deformation area is present in the laminate wherein the substrate(s) are plastically deformed such that they are closer than non-deformed areas of the substrate and wherein the damping material has less mass than in a non-deformed area of the article; the deformation areas providing the areas of good force retention, for an attachment device attached thereto. The second laminate, which is not deformed, contains an additive of sufficient modulus, diameter and loading, in a vibration damping layer to provide improved force retention.

Abstract: A vibration absorbing device for a speaker enclosure is tuned upon installation to the speaker enclosure to achieve maximum attenuation of vibrations in a selected frequency range. The vibration absorber, which includes a series of vibration damping plates separated by spacers, is positioned at varying degrees of overhang on a mounting plate on a panel of the enclosure until attenuation of the desired frequency band is maximized. Then the absorber is secured to the speaker enclosure with an appropriately sized permanent mounting plate.

Abstract: A retaining plate is disposed along and spaced apart by a predetermined distance from the surface of a noise source in an automotive vehicle component so as not to be displaced away from the surface of the noise source. A sheet-like elastic member is compressedly interposed between the noise source and the retaining plate. As a result, the effect of reducing the noise due to vibration is attained without substantially increasing the weight of the automotive vehicle components and without adversely affecting the sealability and other performances required to the components.

Abstract: A vibration attenuating device for loudspeaker enclosures and other mechanical vibrating bodies includes one or more damping plates of viscoelastic material positioned to receive vibration energy transferred from the vibrating body. The vibration energy is transferred away from the speaker enclosure or other body and is dissipated as heat due to the internal molecular structure of the viscoelastic material, suppressing noise normally produced by the vibrating body. In various different embodiments, the vibration damping device includes damping plates shaped or mounted in such a way as to provide for attenuation of a wide band of frequencies of vibration. The damping plates themselves may each have a configuration providing for continuously varying frequency response along the length or circumference of the plate, and there may be included a plurality of different-sized plates, each responding essentially to a different frequency band.

Abstract: A vibration attenuating device for loudspeaker enclosures and other mechanical vibrating bodies includes one or more damping plates of viscoelastic material positioned to receive vibration energy transferred from the vibrating body. The vibration energy is transferred away from the speaker enclosure or other body and is dissipated as heat due to the internal molecular structure of the viscoelastic material, suppressing noise normally produced by the vibrating body. In various different embodiments, the vibration damping device includes damping plates shaped or mounted in such a way as to provide for attenuation of a wide band of frequencies of vibration. The damping plates themselves may each have a configuration providing for continuously varying frequency response along the length or circumference of the plate, and there may be included a plurality of different-sized plates, each responding essentially to a different frequency band.

Abstract: An acoustical barrier having a central aperture that is defined by a flexible seal. The acoustical barrier has an inwardly directed flange circumscribing of the central aperture and spacing the mass layer from a wall a predetermined distance. The wall has an aperture in which is disposed a moisture seal through which a pass-through component extending from one side of the wall to another side of the wall is positioned. The pass-through component is mounted to an article that is disposed within the central aperture of the acoustical barrier. The flexible seal is positioned away from the moisture seal and blocks the transfer of acoustical noise from one side of the wall to the other.

Abstract: A resonance absorber for the damping of structure-borne vibrations has a number of freely swinging slats with different resonance frequencies. The slats are arranged on a common base which can be connected with a body to be damped, and are constructed as double slats comprising a damping coating which is in each case squeezed between the two slats elements.

Abstract: A vehicle oil pan assembly which is acoustically insulated for noise reduction includes an oil pan having a normal configuration with a base and enclosing sidewalls and further including a peripheral flange which is disposed adjacent an upper edge of the sidewall and which is used to attach the oil pan to the vehicle engine. In order to insulate the oil pan so as to reduce any noise which may otherwise be transmitted by the oil pan, a noise reducing/sound deadening enclosure is attached to the oil pan. In order to facilitate the attachment of the enclosure to the oil pan, a plurality of support brackets are welded to the oil pan and each bracket includes a plurality of support tabs. The noise-reducing enclosure is arranged with an outer skin and a foam isolation layer and the outer skin is molded so as to include a plurality of latching portions. The final component in the attachment system is a plurality of spring clips. There is one tab for each latching portion and one clip for each tab.

Abstract: The vibration absorber for the absorption of structure-borne sound has a wave conducting element made of mass-spring elements layered on top of each other and extending in the wave propagation direction. The mass-spring elements are configured as bending beams or plates, with a resilience which decreases in the wave propagation direction. The mass-spring elements are connected with each other by spacers which are arranged offset in respect to each other, in such a way that when they are affected by pressure or pulling at least one mass-spring element is bent.

Abstract: An acoustic isolator is incorporated between a noise generating device and a support structure, such as between a transmission housing and an airframe. The isolator has a first fitting which attaches to the noise generating device, and a second fitting which attaches to the support structure, with an acoustic attenuation member disposed therebetween. Preferably, a first elastomer member is disposed between a pair of vertical walls of the first and second fittings. Optionally, a second elastomer member is disposed between an upper surface of the supporting structure and a lower surface of the second fitting such that horizontal loads are reacted therethrough. Alternatively the first and second elastomers comprise a spherical elastomer member and a cylindrical elastomer member in the form of a spherical bearing.

Abstract: The invention proposes an apparatus for damping or absorbing vibrations in an exhaust system of a vehicle, having two connection ends, at least one bellows and absorbing cushions, in which bellows are arranged on either side of said cushions. This leads to a better standardization, adaptability and design of such an apparatus and in particular in the case of the same angular movement the two bellows are less stressed or greater angular movements are possible.

Abstract: A new method and device for actively-controlled constrained layer (ACLD) treatment which can be used as an effective means for damping out vibrations and sounds from flexible structures are described. The ACLD treatment consists of a visco-elastic damping layer which is sandwiched between two piezo-electric layers. The three-layer composite ACLD, when bonded to a surface which is subject to vibrational and/or sound disturbances, acts as a smart constraining layer damping treatment with built-in sensing and actuation capabilities. The sensing capability is provided by the piezo-electric layer bonded to the surface of the flexible structure, whereas the actuation or control capability is generated by the other piezo-electric layer which acts as an active constraining layer.

Abstract: The invention relates to an acoustic insulation screen. The screen comprises a cushion (5) consisting of a flexible bag (4) inflated with a gas under pressure and allowing the gas to flow freely inside the bag, said bag being selected so as not to transmit vibration energy from one point of the bag to another, and the gas being selected from gases in which the speed of sound is greater than the speed of sound in the air. The invention applies particularly to the protection of the payload compartment in a launcher.

Abstract: A vehicle oil pan assembly which is acoustically insulated for noise reduction includes an oil pan having a normal configuration with a base and enclosing sidewalls and further including a peripheral flange which is disposed adjacent an upper edge of the sidewall and which is used to attach the oil pan to the vehicle engine. In order to insulate the oil pan so as to reduce any noise which may otherwise be transmitted by the oil pan, a noise reducing/sound deadening enclosure is attached to the oil pan. In order to facilitate the attachment of the enclosure to the oil pan, a plurality of support brackets are welded to the oil pan and each bracket includes a plurality of support tabs. The noise-reducing enclosure is arranged with an outer skin and a foam isolation layer and the outer skin is molded so as to include a plurality of latching portions. The final component in the attachment system is a plurality of spring clips. There is one tab for each latching portion and one clip for each tab.

Abstract: A method of forming a damping plate from a fiberglass reinforced plastic base plate and a layer of cushioning material by utilizing a restrainer plate on the other side of the layer of cushioning material from the base plate and which is thinner than the base plate and no thicker than the layer of cushioning material. The cushioning material is formed with a plurality of openings so as to afford flow of liquid adhesive into the openings to assure uniform distribution and good bonding during assembly. The plate may be employed as a portion of a hull of a watercraft for sound deadening.

Abstract: A sound insulating device having a shock absorbing mechanism put between an upper material and a lower material, for absorbing vibrational impact sounds wherein the shock absorbing mechanism comprises a spring mechanism that elastically deforms under the effect of an impact load thereby absorbing vibrational impact sounds, and a shock absorber disposed between the spring mechanism and the upper material or the lower material, the shock absorber having a weakened portion that deforms elastically prior to the elastic deformation of the spring mechanism. Vibrational light weight impact sounds as well as vibrational heavy weight impact sounds can be absorbed by absorbing the vibrational light weight impact sounds by the elastic deformation of the weakened portion, without deteriorating the habitability.

Abstract: An appliance muffler for absorbing sound wave vibrations and impact from foreign objects employed to muffle noise transmissions produced by the appliance and to protect the outer surface of the appliance, wherein the appliance muffler comprises a flexible appliance jacket mounted over the appliance base and a flexible and stretchable appliance container sleeve mounted over the container.

Abstract: There is presented an underwater vehicle tailcone assembly including a ford flange, a first tubular sheath extending rearwardly from the forward flange, and elastomer material bonded to inner and outer surfaces of the first sheath to form a forward chamber wall. The assembly further includes an aft flange, a second tubular sheath extending forwardly from the aft flange, and elastomer material bonded to inner and outer surfaces of the second sheath to form an aft chamber wall. The assembly still further includes a rigid housing wall disposed between a rearward end of the forward chamber wall and a forward end of the aft chamber wall. The forward chamber wall, the housing wall, and the aft chamber wall form a continuous tailcone wall from a forward edge of the forward flange to a rearward edge of the aft flange.

Abstract: A method and article for damping acoustic energy caused vibrations comprises forming a damping surface comprising an alloy containing from about 13.5 to about 24.5 atom percent tin with the balance being essentially titanium or a titanium-chromium alloy containing from about 52 to about 56 atom percent chromium, about 8 to about 12 atom percent aluminum, and the balance essentially titanium.

Abstract: A load bearing structural support for machinery which provides a mechanism or dissipating both mechanical and vibrational energy comprises a high damping flexible reinforcement of fiber preform infiltrated with a viscoelastic material which has a high elongation to failure property and provides a significant damping ability. In one embodiment, an I-Beam is formed by a pair of L-shapes and a T-shape. The two L-shapes are placed back to back, with the T-shape placed therebetween forming an I-beam. At least one flexible reinforcement is then positioned between the vertical segments of the T-shape and the two L-shapes to isolate the T-shape. The T-shape is actually "floating" between the L-shapes. In another embodiment, the flexible reinforcement is suspended between at least a pair of spaced anchors with a vertical support of the same flexible reinforcement attached to or integral with the suspended flexible reinforcement portion and its free end anchored to a stable base.

Abstract: A vibration reduction assembly for isolating the top cover from the machine, for use in combination with a dynamoelectric machine having a cover for guiding air into and out of the machine while protecting the machine from airborne water and dirt. The vibration reduction assembly comprises a plurality of spaced neoprene pads provided between the cover and the machine, the pads of a density and size selected to obtain low transmissibility and amplification of vibration caused by the machine thereby reducing vibration of the machine; a plurality of closed cell foam rubber strips positioned between adjacent ones of the plurality of neoprene pads, the strips for filling space between the cover and for protecting the machine from incident atmospheric precipitation and dust. The cover is affixed to the machine with a plurality of bolts, each bolt engaging a neoprene washer and a neoprene sleeve to eliminate metal to metal contact.

Abstract: An elongate chain member having first and second ends is arranged for biased securement relative to the first and second ends for mounting peripherally about a brake rotor during a training procedure to dampen vibrations and audible noise. The invention is arranged to further include vibration dampener blocks within individual links of the chain member.

Abstract: A double-wall hollow body comprises an inner hollow body and a cooperating outer hollow body. The outer hollow body is frictionally attached to the inner hollow body, and is radially spaced from the inner body so that an annular space is formed between the two bodies. Acoustic-damping insulating material is contained within the annular space, and forms an interlayer between the inner and outer bodies. An end of the double-wall hollow body is formed by respective ends of the inner and outer hollow bodies that rest directly against each other without insulating material. The inner hollow body is separated over an entire circumference from the outer hollow body by the insulating interlayer. Various methods of manufacturing the foregoing double-wall hollow body are also described. For instance, to apply the insulating material to the inner hollow body, such body may be heated and then rolled into the insulating material.

Abstract: A Viscoelastic medium with fibers dispersed throughout eliminates the need for a constraining layer, thus reducing the size and weight of a damping treatment.

Abstract: An acoustical barrier, an aperture and a pipe or cable passing therethrough wherein the aperture has a number of radially extending slits which define a plurality of radial sectors which also extend from the aperture. One or more grooves are arranged in the sectors concentrically about the aperture to increase the radial flexibility of the sectors so that the sectors more closely conform with the shape of the pipe or cable passing through the aperture and thereby reduce the spacing between the slits and reduce the noise passing through the seal.

Abstract: A two-layer, vibration-absorbing and anti-corrosive, abrasion-resistant coating for rigid substrates, in particular for sheet metals in the underbody region of motor vehicles, for reducing the noise caused by impacting particles, comprises an inner layer, facing the substrate, of a polymer A and a plasticizer P.sub.1, and a covering layer of a polymer B and a plasticizer P.sub.2, such that either the polymers A and B have a different chemical composition and the polymer A is essentially incompatible with the plasticizer P.sub.2 and the polymer B is essentially incompatible with the plasticizer P.sub.1, or both layers contain essentially the same concentration of one plasticizer (P.sub.1 =P.sub.2), so that there is no risk of one layer being impaired by the plasticizer from the other layer.

Abstract: A vibration damper includes a suspended mass connected to a pipeline or similar structural member by a support ring and an assembly of interconnected, generally cylindrical damper members formed of an elastomer material suitable to be stressed in shear. The damper assembly is of modular construction so that the damper can be easily tuned to particular frequency and amplitude conditions of different pipes and spans, respectively.

Abstract: A noise-absorbing medium is provided as an insert within the inner volume of the outlet chamber of a displacement-type pump. In an axial-flow displacement pump, this is the chamber into which pumped hydraulic fluid is discharged, for side-ported delivery to piping which serves the end-use actuator or other use component of the involved hydraulic system. The noise-absorbing medium is a preformed body (or bodies) of foamed elastomeric material having a sealed external skin and containing tiny closed cells of entrapped gas at low pressure; the encapsulated gas within the body bears a predetermined fractional volumetric proportion to the overall volume of the body, and the overall volume of the body also bears a predetermined relation to the overall volume of the outlet chamber.

Abstract: In order to obtain a particularly soft spring characteristic the rubber spring element consisting of relatively hard material having good mechanical strength is traversed by cavities and hollow channels, which intersect said cavities, in such a manner that the area of the inside cross-section of the hollow channels amounts to at least 25% of the area of the largest inside cross-section of the nearest cavity traversed by this hollow channel, while the hollow channels may directly intersect in the rubber matrix.

Abstract: A sound- and/or vibration-damping coating, which comprises a layer of a relatively hard substance (2) having pores, interstices, cavities (3) and/or hollows (12) containing a material (4) which has a higher plasticity or elasticity than said substance (2), and an element provided with said coating. This coating may be applied on said element by applying to the surface of the latter a surface treatment ensuring the adhesion of the layer of relatively hard substance (2), by applying this layer to the so treated surface by projection of said substance in the at least molten state and as droplets, by using known per se techniques, and by entering said material (4) into cavities (3) formed between coagulated droplets of said substance (2).

Abstract: A shape memory alloy used for both sensing and damping vibration of a structure. In one embodiment, a flat bar (12) is mounted from one end on its edge so that its other end vibrates from side-to-side at its natural resonant frequency. A vibration damping wire (30) extending longitudinally along one surface of the bar is mounted under tension between spaced apart standoffs (32); a sense wire (42) is similarly mounted along the opposite surface of the bar. The vibration damping wire and sense wire comprise a nickel-titanium (Nitinol) alloy, having a relatively high specific damping coefficient. Absorption of kinetic energy by the vibration damping wire when it is stretched by deflection of the bar greatly reduces the time required to passively damp vibration of the bar, compared to its undamped resonant time. the vibration damping wire is heated above a transition temperature by an electrical current pulse while relaxed to restore it to its unstretched length.

Abstract: The present noise reduction system provides a tool and a method to dampen the vibration of sheet material such as a panel, a metal sheet or a skin while performing a manufacturing operation on it, for instance riveting, drilling, etc. This noise reducing tool is held in place by vacuum and thus avoids the disadvantages associated with gluing and mechanical or magnetic fixing devices. This noise reducing tool includes a flexible pad made of a metal back sheet with a vibration damping sheet adhered to it and having an air seal surrounding the damping sheet such that the pad is held against the panel by action of a vacuum intermediate the damping sheet and the panel.

Abstract: A damping treatment for bodies where the temperature may rise above 150.degree. C. consists of a number of stand-off cantilever, sandwich type dampers (1), consisting of a layer of viso-elastic material (3) sandwich between two rigid metal plates (4, 5), which are attached to a support (2) that can be attached to the body (7). The support (2) is thermally isolated from the body (7) and is positioned at a position of high amplitude of a radiating frequency that is to be reduced.

Abstract: A seismic isolator for absorbing earthquake vibrations is provided which comprises a laminated member arranged to be interposed between a structure and a foundation, the laminated member comprising thin steel sheets having concavities and convexities extending in a single direction, flexible sheets stacked alternately with the steel sheets, and upper and lower end plates, all these sheets and plates being unitarily and fixedly bonded together. The upper and lower end plates are fixed to the structure and the foundation, respectively, in such a manner that the concavities and convexities extend in a direction in which earthquake vibrations are to be isolated from the structure. The seismic isolator of the present invention is particularly suitable for use with a bridge.

Abstract: A vibration-controlling member is made by containing a flake-shaped powdery substance having vibration controlling action in a retainer adhered to one surface of a surface sheet. Any external shock imparted to the member is subjected to the vibration controlling action due to a grain boundary friction of the powdery substance.

Abstract: A mount capable of being pressed into an installed position in a hole in a plate. The mount has inner and outer concentric annular elements connected together by an intermediate flexible thermoplastic elastomeric web. The outer annular element has a peripheral groove which receives the plate and a deflectable wall with a chamfered outer surface and a series of slots. The flexible web permits the inner element to vibrate with respect to the plate and thereby isolate an item from the plate.

Abstract: Acoustic damping is provided by a dimensionally-recoverable article, either in single layer or constrained-layer form. The single layer, or the damping layer of a constrained-layer article, comprises a mixture of a damping component (generally having a high tangent delta value) and a hold-out component (generally having a significant crystallinity).

Abstract: A method and apparatus for damping the vibration of a reinforced skin structure (e.g., the fuselage of an aircraft) over a wide frequency range (wideband) in order to reduce the vibration and transmitted noise, and improve the sonic fatigue life, of the structure is disclosed. Wide range damping is accomplished by viscoelastically attaching constraining elements, which can be continuous or segmented, to the skin and to the reinforcing members that support the skin. The viscoelastic attachment between the constraining elements and the reinforcing members directly damp the vibrations of the reinforcing members; and, the viscoelastic attachment between the constraining elements and the skin directly damp the vibrations of the skin.

Abstract: Acoustic noises are suppressed in a large format drafting plotter (10) utilizing a paper drive motor (22) mechanically coupled to a paper drive shaft (20) by a geared timing belt (26) from the motor to a pulley (24) on the drive shaft by suitably modifying the pulley. The pulley is modified by enlarging the drive shaft hole (38) in the center thereof so as to provide slip-mounting of the pulley on the drive shaft. A winged clamp (30) is provided, mounted on the pulley, and having a central portion (34) having an opening (36) therethrough for engaging a portion of the drive shaft and a tightening screw (40) for securing the winged clamp to the drive shaft. The winged clamp also has two opposed extensions (42), which are each maintained between a pair of bosses (44) on the outside surface (24a) of the pulley, and isolated therefrom by a pair of isolator pads (32) comprising a compliant material.

Abstract: A light viscoelastic damping structure has a plurality of damping strips widely separated on the surface of a lightweight panel. The strips may be arranged parallel or at right angles to each other. Each damping strip includes a viscoelastic damping layer, a first honeycomb structure having opposing face sheets and attached to one surface of the damping layer, and a second honeycomb structure having face sheets on opposing sides thereof attached to the damping layer and to the panel.

Abstract: Adjustable packing strips (3, 4) are held on the inside of a carrying sheet (6) covered with sound-absorbing material (5), and are slidable by adjustment elements (7, 9), which can be actuated and fastened from the outside, within an adjustment chamber isolated against the sounds of a sound-emitting body (2) to project the packing strips beyond the peripheral edge (6A) of the carrying sheet (6).

Abstract: In a body subject to a cyclic energy of such a nature as to cause the body to mechanically vibrate with a principal motion in a first direction, a dry friction damper has a first sliding element fixed to the body, the first sliding element having a first rigid dry sliding surface extending in a second direction having a component perpendicular to the first direction. A second stationary element has a second rigid dry sliding surface extending in the second direction. A normal force is applied between the first and second surfaces, resulting in damping of vibrations by dry friction damping.

Abstract: This invention is directed to a vibration damping soundproof sheet for use in vehicles, in which the surface of the soundproof layer is made flat irrespective of the or uneven configuration at the surface of a vehicle. The soundproof layer-forming material comprises a formed rubber blend in which a foaming agent and other rubber blending agents are blended with a rubber type polymer in which the soundproof layer-forming material contains from 15 to 85% by weight of 1,2-polybutadiene ingredient.

Abstract: A rubber vibration isolator is used as a muffler hanger or muffler mount between a car body and a muffler to hang the latter from the former. The isolator includes a body made of rubber-like elastic material whose damping factor is high, two holes, upper and lower, formed in the center of the body of rubber-like elastic material, and a weight provided between the two holes and supported at opposite sides thereof by rubber-like elastic members. The rubber vibration isolator is advantageous in that coefficients of transfer of vibrations of both high and low frequencies, respectively, are lowered.

Abstract: Apparatus for reducing mechanical vibrations in a first part of a structure, in which these vibrations occur through its connection to a part of the structure which is the source of the mechanical vibration. This apparatus comprises an electromagnet rigidly connected to the first part of the structure and a body of magnetizable material connected via a resilient element to the first part of the structure, while an air gap is provided between the electromagnet and the body. The electromagnet is energized by a variable current through at least one coil and it exerts an attractive force on said body which is oscillating due to the vibrations occurring in the first part of the structure. The restoring force exerted by the resilient element on the secondary body has the effect of lowering the resonant frequency of the second body on the resilient element as compared to the resonant frequency of the apparatus when no current passes through the coil.

Abstract: A disc brake (10) having friction pads (42) and (44) whose arcuate foot prints (80, 82, 84) on a rotor (12) is les than a nodal diameter of a frequency that would create an undesirable noise during a brake application.

Abstract: A composite board having an excellent vibration-suppressing sound-shielding performance can be obtained by joining a plurality of board materials with each other by the intermediary of a tacky adhesive. This tacky adhesive contains, as its principal components, one or more kinds of polymers selected from the group consisting of natural rubber, synthetic rubbers, various resins (acrylic resin, silicone resin, etc.). A sheet-like base material such as a paper sheet can be used in association with the tacky adhesive layer in the composite board, and such type of composite boards have an excellent vibration-suppressing sound-shielding performance as compared to the composite boards in which the tacky adhesive layer is not associated with a sheet-like material.

Abstract: For decoupling an exhaust system while suppressing or damping motion and cutting down noise as far as possible, a flexible joint or articulation for the exhaust system of a motor vehicle has a flexible duct part with support parts joined with its ends for outer damping members. The flexible duct part is so designed that the support parts are overlapped on the outer side of the duct part forming pockets acting as housings for compacts of compressed metal wire for damping motion of the support parts in relation to each other.