USA As Represented by Secretary of the Navy

Roger M Crane

Eugene C Fischer

Paul A Coffin

Donald James Dorr

Kathleen A Corona-Bittick

Aleksander B Macander

Paul Coffin

D Michael Bergen

Kerry T Slattery

Daniel D Coppens

John W Gillespie, Jr

George C Tunis

Usman A Sorathia

Wayne C Jones

Robert DeNale

Timothy L Dapp

Colin P Ratcliffe

Armando L Santiago

Douglas C Loup

Harry E Prince

Stephen M Andersen

The present invention's composite-to-metal attachment methodology&#x2014;bolt-free and adhesive-free&#x2014;features the implementation of an intermediary structure containing metallic fibrous material. The intermediary structure couples a first adherend (which contains nonmetallic fibrous material) with a second adherend (which contains metallic nonfibrous material). The intermediary structure's fibrous attribute is availed of for effecting its co-cure attachment to the first adherend. The intermediary structure's metallic attribute is availed of for effecting its weld attachment to the second adherend. According to typical inventive practice, respective panels of the first adherend and the intermediary structure are arranged and connected so as to describe a stepped configuration at the interface between the first adherend and the intermediary structure. The first adherend and a first portion of the intermediary structure are co-impregnated with a uniform resinous system and are co-cured. A second portion of the intermediary structure is welded with respect to the second adherend.

Hybrid composite welded joint

A nondestructive inspection method for composite structures, including thick core structures, is disclosed that imparts a vibration force into the structure and analyzes the response over a range of frequencies to find possible damaged areas. The composite structure is struck to induce vibration at a series of test points and the response of the composite structure as a function of acceleration at each test point is measured. The structural anomalies in the composite structure occur at structural stiffness irregularities near anomalies and are detected with a Gapped Smoothing Method operating on the data and plotting a structural irregularity index as a function of frequency and position.

Nondestructive method for detecting structural anomalies in composites

An energy-absorbing &ldquo;smart&rdquo; bumper system features a variably controllable valve which is responsive to impact conditions. The initially closed valve opens upon maximization of the pressure reading upon the bumper, and maintains the same open setting (in other words, the same valve area) during such period of pressure maximization. During the succeeding period of pressure declination from maximum, the valve undergoes ongoing adjustment of its open setting (in other words, ongoing adjustment of its valve area) so that the reaction force of the bumper remains constant. The valve closes (in other words, the valve area becomes zero) when the pressure falls abruptly toward zero (an occurrence which correlates with a similar plummet in reaction force, as well as with near or approximate motionlessness of the impacting body), thereby avoiding or curtailing an unwanted rebound effect.

High energy impact absorption fender system using valvular control logic

An energy-absorbing bumper system features a variably controllable valve which is responsive to impact conditions. The initially closed valve opens upon maximization of the pressure reading upon the bumper, and maintains the same open setting (in other words, the same valve area) during such period of pressure maximization. During the succeeding period of pressure declination from maximum, the valve undergoes ongoing adjustment of its open setting (in other words, ongoing adjustment of its valve area) so that the reaction force of the bumper remains constant. The valve closes (in other words, the valve area becomes zero) when the pressure falls abruptly toward zero (an occurrence which correlates with a similar plummet in reaction force, as well as with near or approximate motionlessness of the impacting body), thereby avoiding or curtailing an unwanted rebound effect. Conventional bumper systems are dependent upon adaptation of size and/or number of fenders in order to suit different marine vessels in terms of energy absorption; by comparison, the inventively &ldquo;smart&rdquo; bumper system is readily adaptable to diverse marine vessels.

Tailorable elastomeric composite pneumatic fender system for absorbing high energy impact

The impact absorption system uniquely features arrangement of composite structures which include fiber-reinforced high strain-to-failure viscoelastic matrix material. According to many embodiments, a gravitationally or buoyantly suspended hollow fiber-reinforced urethane reaction bumper is closely and anteriorly situated with respect to fiber-reinforced urethane tension tubes which are secured at the ends and disposed in an approximately vertical plane. In operation, an incoming marine vessel impacts the bumper which in turn impacts the tubes. The invention takes advantage of the great deformability, high energy absorbency and other beneficial properties of fiber-reinforced high strain-to-failure viscoelastic matrix material. Moreover, applicability/adaptability of individual bumper systems to varieties of marine vessels is made possible through analysis and arrangement/rearrangement/exchange/interchange of structural components. The bumper and the tension tubes can be designed and selected on individual and collective bases.

Elastomeric composite bumper system and method for absorbing high energy

A structural enclosure, box-like for many embodiments, which effectively tains an explosion, thereupon remaining virtually intact and minimizing fragmentation. The structural wall has a sandwich-like arrangement of two fiber-reinforced matrix material skins and a foam core situated between the two skins, at least one skin having fiber-reinforced high strain-to-failure viscoelastic matrix material. The core foam material selectively varies in density so as to provide appropriate rigidity or flexibility at different locations of the structural enclosure. The fiber-reinforced high strain-to-failure viscoelastic matrix material can be deformed elastically to large strains, has demonstrably high energy-absorbing characteristics, and is relatively lightweight. Upon explosive impact, the inner skin largely deforms so as to be energy-absorbent of the pressure wave caused by the explosive charge, the foam core crushes so as to also be energy-absorbent, the outer skin largely deforms, and both skins contain debris.

High-energy-absorbing enclosure for internal explosion containment

Composite structures which are cost-effectively fabricated using conventional resin transfer molding or filament winding technique, featuring utilization of fiber fabric material or individually stranded fiber tow material as the fiber reinforcement material for high strain-to-failure viscoelastic matrix material, and affording desired structural performance and superior performance in terms of flexibility, damping and damage-tolerance.

Flexible high-damping composite structures and fabrication thereof

A multiple-layered, translatedly rib-stiffened, composite hollow cylinder d method for fabrication thereof utilizing filament winding technique known in the art. Selective utilization of high strain-to-failure viscoelastic matrix material, without resort to secondary processing, results in improved damping characteristics in terms of dissipation of mechanical and acoustic energy as well as improved structural characterics in terms of damage tolerance.

Method for fabricating a high-damping rib-stiffened composite hollow

A structural enclosure, box-like for many embodiments, which effectively contains an explosion, thereupon remaining virtually intact and minimizing fragmentation. The structural wall has a sandwich-like arrangement of two fiber-reinforced matrix material skins and a foam core situated between the two skins, at least one skin having fiber-reinforced high strain-to-failure viscoelastic matrix material. The core foam material selectively varies in density so as to provide appropriate rigidity or flexibility at different locations of the structural enclosure. The fiber-reinforced high strain-to-failure viscoelastic matrix material can be deformed elastically to large strains, has demonstrably high energy-absorbing characteristics, and is relatively lightweight. Upon explosive impact, the inner skin largely deforms so as to be energy-absorbent of the pressure wave caused by the explosive charge, the foam core crushes so as to also be energy-absorbent, the outer skin largely deforms, and both skins contain debris.

A design for a high damping composite joint which dissipates vibrations through the use of air gaps and viscoelastic material minimizing the transfer of vibrations to the metallic coupling. Viscoelastic material is used with adhesive to provide for increased energy dissipation by the joint. As the load increases on the joint, the load transfers from adhesive to the viscoelastic. The viscoelastic begins to take the load of the joint at the point where the adhesive becomes plastic. Acoustic vibrations are then dissipated in the viscoelastic and are prevented from being transferred to the metallic coupling by air gaps provided in the joint. The amount of viscoelastic and adhesive used depends on the anticipated load. Finite element analysis is used to calculate optimal amounts of viscoelastic and adhesive.

High damping composite joint for mechanical vibration and acoustic

A multiple-layered, translatedly rib-stiffened, composite hollow cylinder d method for fabrication thereof utilizing filament winding technique known in the art. Selective utilization of high strain-to-failure viscoelastic matrix material, without resort to secondary processing, results in improved damping characteristics in terms of dissipation of mechanical and acoustic-energy as well as improved structural characterics in terms of damage tolerance.

High-damping rib-stiffened composite hollow cylinder core configuration

A double hull structure includes a controllably crushable stand-off struce for maintaining a separation between inner and outer hulls and may be retrofit onto existing hulls either in modular and/or break-away sections or as a complete 'shoe' enclosing the existing hull. This retrofittable hull is preferably of a non-metallic composite material which reduces or eliminates corrosion of the existing hull, extending the usable lifetime thereof. The controllably crushable stand-off structure is designed to provide sequential failure, preferably by sequential energy absorbing brittle fractures with little elastic deformation, to provide protection of the existing hull during collisions and/or groundings and thus enhance cargo containment. The brittle fracture is preferably provided by the use of non-metallic composite material in beams of the stand-off structure and/or the inclusion of syntactic foams.

Retrofittable monolithic box beam composite hull system

Cylinder-to-cylinder attachment method and construction featuring nonutiltion of mechanical fasteners or bonding, especially advantageous for attachment of cylinders which are composite or to be subjected to hydrostatic pressure. A fastening ring is interpositionally and rotatively engaged and aligned with a toothed axial end of each cylinder whereby the inwardly radial teeth for each cylinder appropriately mesh with the outer grooved circumferential surface of the fastening ring. The resultant joint is easily detachable and less susceptible than conventional joints to damage, breakage, degradation, stress concentrations and fluid infiltration.

Attachment methodology for composite cylinder assembly

A multiple-layered, translatedly rib-stiffened, composite hollow cylinder d method for fabrication thereof utilizing filament winding techniques known in the art. An inner skin is wound over a mandrel; then, circumferential ribs are wound over the inner skin, pin rings are placed at the axial ends of the mandrel, longitudinal stringers are engaged with the pin rings and wound over the circumferential ribs, circumferential bands are wound near the axial ends over the longitudinal stringers, and another skin is wound over the circumferential bands and longitudinal stringers; these steps, commencing with the winding of circumferential ribs and concluding with the winding of an additional skin, are repeated as many times as desired, each repetition forming an additional layer, with the circumferential ribs for each additional layer being longitudinally staggered in relation to the circumferential ribs for the previous layer. The cylinder in accordance with this invention is a superior enclosure in terms of mechanical vibrational energy dissipation, directionally controllable thermal energy transmission, and structural damage tolerance; moreover, it advantageously permits a continuous fabrication procedure.

Multi-layered translated rib-stiffened composite hollow cylinder assembly

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.

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Arnold, MD, United States of America

Roger M Crane