US3635182A - Damping arrangements - Google Patents

Damping arrangements Download PDF

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Publication number
US3635182A
US3635182A US883390A US3635182DA US3635182A US 3635182 A US3635182 A US 3635182A US 883390 A US883390 A US 883390A US 3635182D A US3635182D A US 3635182DA US 3635182 A US3635182 A US 3635182A
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Prior art keywords
tank
assembly
liquid
hull
receptacle
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US883390A
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English (en)
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James Arthur Haines Paffett
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National Research Development Corp UK
National Research Development Corp of India
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National Research Development Corp UK
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
    • B63B39/00—Equipment to decrease pitch, roll, or like unwanted vessel movements; Apparatus for indicating vessel attitude
    • B63B39/005—Equipment to decrease ship's vibrations produced externally to the ship, e.g. wave-induced vibrations
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63H—MARINE PROPULSION OR STEERING
    • B63H21/00—Use of propulsion power plant or units on vessels
    • B63H21/30—Mounting of propulsion plant or unit, e.g. for anti-vibration purposes
    • B63H21/302—Mounting of propulsion plant or unit, e.g. for anti-vibration purposes with active vibration damping

Definitions

  • SHEET 4 [1F 5 GAS RESERVOIR PATENTEU JAN] 81972
  • SHEET 5 [1F 5 DAMPING ARRANGEMENTS
  • the present invention relates to the damping of vibrations and in particular to the damping of vibrations in the hull of a ship or other floating vessel, e.g., an off-shore oil drilling rig.
  • vibrations may be induced in the hull of the vessel by the wave motion of the sea or by operation of the ships propellers.
  • wave motion of the sea or by operation of the ships propellers.
  • the wave-induced vibrations are compatible in frequency to those of the seas wave motion and resonance occurs. The inherent damping in such ships is low.
  • a method of damping vibrations in the hull of a floating vessel by transferring vibrational energy from the hull to a liquid-gas system within the hull.
  • the vibrational energy is absorbed within the system by compression and expansion of the gas by the liquid and finally dissipated by friction in the liquid-gas system.
  • the method may also include the step of changing the gas pressure within the liquid-gas system to tune said system to match the natural frequency of the hull.
  • an assembly for damping vibrations in the hull of a floating vessel comprising a container for a liquid-gas system wherein a pocket of gas is trapped by a free surface of the liquid so that vibration of the hull results in motion of the liquid within the container to expand and compress the gas and dissipate the vibrational energy in the liquid-gas system.
  • the container comprises a tank, a receptacle having at least a lower portion extending into the tank, a closed upper end to the receptacle, and port means permanently connecting the interior of said lower portion with the interior of the tank.
  • Connection means may be provided for connecting the upper portions of the receptacle and the tank with exterior sources of positive, negative, or atmospheric pressure as the case may be.
  • the receptacle may be provided by a cylindrical structure extending between the top deck and the base of the hull, the closed upper end of the receptacle being provided by a plate rigidly secured across the structure.
  • the receptacle may be bounded by vertical plates extending between opposite sides of the tank and the closed upper end of the receptacle is provided by a horizontal plate secured between said vertical plates.
  • the receptacle is preferably provided with imperforate vertical baffles for controlling liquid flow within the receptacle.
  • the tank for the damping system is provided by a ballast tank or fresh water tank in the hull.
  • the assembly in an alternative embodiment of the invention (for damping transverse vibrations in the hull), includes a U- tube structure, an upright limb of the U-tube structure providing the container above referred to, and the base limb of the U-tube structure extending substantially from side to side of the hull.
  • the container comprises two similar liquid-containing arms each presenting a free liquid surface trapping a pocket of similar gas, the arms and a tank portion of the container joining said anns being arranged in annular fashion in the hull whereby the assembly is responsive to torsional vibrations in the hull.
  • the invention also includes a hull or vessel using one or more of the various damping assemblies above referred to.
  • the principal vibrations in the hull may be considered as bending vibrations which may be in the vertical or horizontal planes.
  • FIG. 1A is a plan view of part of a ships hull illustrating a damping assembly in accordance with a first embodiment of the present invention located amidships of the hull;
  • FIG. 1B is a plan view of part of a ships hull illustrating a damping assembly in accordance with a second embodiment of the present invention located amidships of the hull;
  • FIG. 2A is a vertical section of the first embodiment looking forward and taken along the line Il-II of FIG. 1A;
  • FIG. 2B is a vertical section of the second embodiment looking aft and taken along the line lI-ll of FIG. 18;
  • FIG. 3 is a diagrammatic illustration of a control system for use with the embodiments of the other figures;
  • FIG. 4 is a diagrammatic side view of an alternative embodiment of the invention to that shown in FIGS. 1A to 23;
  • FIG. 5 is a diagrammatic view of a further embodiment of the invention, also suitable for damping transverse vibrations in the hull;
  • FIG. 6 is a diagrammatic view of another embodiment of the invention for damping torsional vibrations in the hull.
  • FIG. 7 illustrates a simplified mathematic model of the hull and its damping system.
  • the principal modes of vibration of the hull are the twonode vertical and the twonode horizontal modes in which the vessel bends about two nodal regions spaced apart along the hull.
  • the vessel presents a respective stiffness K and the vibrational motion of the ship is associated with a respective damping factor C
  • the damping assembly has corresponding properties, the stiffness (K being dependent on the trapped pocket(s) of gas in the liquid-gas system and the damping factor (C being introduced principally by the viscous forces involved as the liquid in the assembly moves over the containing surfaces of the assembly.
  • the effective mass M of the damping assembly is associated with that of the liquid contained (when the assembly liquid is at rest) between the two levels associated with the free surface of the liquid trapping the (or a) pocket of gas and the other liquid surface(s) present in the assembly. This compares with a corresponding mass M for the vessel.
  • the quantities M,, M etc. will depend on the size and shape of the damping assembly, tank and the gas spaces and the fluids in them. Numerical values may be estimated from experiments, or, in some simple configurations, by calculation. As above indicated the vessel and its damping assembly may be replaced by the mathematical model of FIG. 7 for the purposes of calculating the behavior of the vessel and the assembly. This provides a starting point for designing the damping assembly or a first model of the assembly from which the final version can be arrived at after the necessary trials and experiments have been carried out on the model. Further details may be had from a paper entitled Machinery Induced Vibra' tions and the references given in this paper.
  • Frequency is increased by reducing the volume of a gas space, as for example, by lowering its roof;
  • the frequency may be raised by a uniform increase of pressure throughout the tank
  • the equivalent suspended mass M may be made large by having tall unbalanced water columns
  • the damping assembly may be tuned by altering either the total amount of water in the tank, or by altering the differential liquid levels.
  • the hull or partitions must not be overstressed by raising or reducing pressures
  • FIGS. 1A and 2A two such assemblies for damping vibrations in the hull 12 of a floating vessel, are located one on each side of the vessel centerline 14 to provide a symmetrical arrangement.
  • the exact positioning of the assemblies along the length of the hull is a matter of choice and will be decided taking into account all the various factors involved in the building and running of the vessel which in this case is a medium size oil tanker having a number of storage/ballast tanks 16.
  • the damping assemblies have been positioned amidships of the vessel and this has the advantage that the tanks for the damping liquid may be large so that a relatively large amount of liquid may be used in the damping system to improve its effectiveness.
  • the damping system or systems are located near one end of the vessel (preferably the stern), then the effect of the smaller tanks is at least partially compensated for by the greater displacement of the hull there (and hence of the damping liquid) as the hull bends about its node positions in response to the exciting force.
  • FIG. 2A shows a vertical section of such a ballast tank modified in accordance with the present invention to provide a liquid-gas damping system for the hull.
  • an identical system is located in the corresponding ballast tank on the other side of centerline l4.
  • the wing tank 16 shown in FIG. 2A provides the tank of the liquid-gas damping assembly 10 shown in FIG. 2A.
  • the receptacle 20 of this system is bounded at each end by a pair of transverse bulkheads 22 and on each side by a pair of spaced plates 24 extending downwardly from the top deck 26 of the hull and extending from end to end of the tank 16.
  • the plates 24 terminate short of the hull bottom to define a slot 30 permanently connecting the interior of the lower portion of the receptacle 20 with the interior of the tank 16.
  • the closed top of receptacle 20 is provided by a plate 32 incorporatingan inspection hatch to allow inspection of the receptacle as and when necessary.
  • Three pipes 34 extending upwardly from plate 32 to above top deck 26 provide connection means whereby the upper portion of receptacle 20 may be connected with an exterior source of positive, negative, or atmospheric pressure as the case may be.
  • Similar (but shorter) pipes 36 are provided for the tank 16.
  • Valves 38, 40 are provided in these pipes so that the receptacle or tank may be sealed 011' or connected up as desired.
  • the assembly structure is completed by two imperforate transverse partition plates 42 located between top plate 32 and the lower edges 28 of side plates 24 and dividing he upper portion of the receptacle into three regions each associated with a respective one of the pipes 34.
  • a valve 43 (which can be operated from deck 26) allows communication between the tank 16 and the space (44) above the top plate 32.
  • a valve 45 allows space 44 to be opened to the atmosphere if desired.
  • the receptacle 20 is partially filled with water 46 to trap a volume of pressurized air 48 between free water surface 50 and the receptacle top 32.
  • Valve 38 is closed to maintain the pressure of air 48 whilst valves 40 are open to atmosphere so that the water surface 52 in tank 16 is free to assume levels higher than the level of water in the receptacle.
  • Valve 43 is maintained closed.
  • the trapped air is at a pressure in the region of two atmospheres absolute when the assembly is at rest but since the period of any particular mode will depend on the amount of cargo being carried by the vessel at the time, fresh tuning may be advisable if and when this loading is changed.
  • this space may be sealed off (by closing the appropriate valve) so that its pressure will increase and decrease with vibrations of the liquid 46 in the same way as does the pressure in the trapped pocket earlier referred to.
  • This latter arrangement is capable of giving relatively high operational frequencies in the damping assembly.
  • valve 43 may be maintained open to allow the free passage of liquid between the tank 16 and the space 44. This may have the advantage of increasing the mass of damping fluid in the assembly 10 and of utilizing the otherwise wasted space 44 during operation of the assembly.
  • valve 45 will be operated and connected up in the same way as valves 40 so that the liquid 46 behaves more or less as a single surface extending across the whole area of the tank 16.
  • FIGS. 18 and 2B show a second embodiment in which the receptacle 20 is now provided by a cylindrical or tubular structure 60 rather than by the plates and bulkheads used in the first embodiment.
  • Corresponding members or parts of members in the two embodiments have been identified in the second embodiment by the same reference numerals as used in the description of the first embodiment wherever possible and details of the purpose, construction, or function of these members may be had if necessary by reference to that earlier description.
  • FIGS. 1B and 2B lends itself more favorably to the case in which the tanker is to be initially constructed with a view to providing a damping assembly in accordance with the invention rather than that in which an existing tanker is to be modified in accordance with the invention.
  • the structure 60 comprises a cylindrical steel plate assembly extending from the top deck 26 of the hull to the ships bottom 62.
  • the closed top 32 for the receptacle is now provided by a circular plate also incorporating an inspection hatch as in the first embodiment.
  • the connection means mas between the lower portion of the receptacle and the tank in is this time provided by rectangular ports 64 spaced about the periphery of the receptacle in its lower portion. it will be noted that the partitions 42. of the first embodiment have no counterpart in the second embodiment.
  • the dimensions of the assembly will depend on the size of hull in which it is employed but typically the tank illustrated would have a height of about 70 feet, a length (axially of the ship) of about 80 feet and a width (transversely of the ship) of about 120 feet. In such a case the diameter of the cylindrical structure 6110 would probably be about 20 feet.
  • valves 3ft, 4'! are operated to connect the spaces about the liquid surfaces 50, 52 to atmosphere or with appropriate pressure sources (negative or positive as the case may be) in order to provide the required difference in liquid levels between the surfaces 50, 52.
  • the tuning arrangement of FIG. 3 may be used for this purpose but with the plurality of pipes 34 replaced by a pair of such pipes, one for each structure 60.
  • the valves are then closed (unless the space concerned is at atmospheric pressure in which case the valve concerned may be left open if desired) and the system is ready for operation.
  • the quantity of liquid water lb
  • the pressures and liquid levels tune the as sembly to suit the expected vibrations to be damped.
  • the principle of operation of the assembly is as above described with respect to the first embodiment and it will not be further described at this point.
  • water for ballast may be introduced into the tank 16 by an appropriate pump, eg, using ducting MN).
  • the valves 38, ilt) are left open during the introduction of water into the tank to allow the escape of any fumes which may be present as a result of the previous cargo.
  • the mass of liquid introduced will be critical insofar as this mass will play a part in determining the operational characteristics of the damping system.
  • the pipes 3 1, 36 are then connected up with the appropriate pressure source or vacuum source (or to at mosphere) to provide a trapped pocket of gas in the system and establish a rating for the system which enables it to be tuned to match the natural frequency of the hull.
  • a pneumatic tuning arrangement for the assembly of FIGS. 1A and 2A is shoum in FIG. 3 and comprises a compressed gas or air reservoir 70 connected with six pipes 34 (of which only three are shown) for pressurizing the two damping assemblies 10.
  • Pipes 3d are fed in parallel from a common feed branch 72 and each has an associated isolating valve 74! and excess pressure safety valve 76.
  • Pressure in the branch pipe 72 is indicated by a pressure gauge 78.
  • the arrangement is completed by an inlet valve 80 for isolating the reservoir '70 if desired and an outlet valve 32 for exhausting pipes 34 to atmosphere.
  • the valve 43 is provided in accordance with a preferred feature of the invention to allow passage of cargo oil from the tank into the volume d4 above the receptacle 260. During operation of the tank as part of damping assembly, this volume is of course drained of oil and the valve 43 may be maintained closed, if desired, to prevent the ingress of ballast (damping) liquid into the volume 44.
  • the cargo oil in the case of a tanker
  • nitrogen or some other inert gas must be chosen for the pocket of gas trapped in the receptacle instead of air.
  • the cylindrical receptacle structure of FIGS. 18 and 2B could be replaced by a rectangular boxlike structure.
  • a more striking variation is shown in lFlG. t which illustrates an embodiment especially suited for use in adapting an existing bull in accordance with the present invention.
  • the receptacle takes the form of an inflatable bag 99 of plastics material such as polythene or a rubberized plastics material such as PVC- proofed terylene or rubber reinforced nylon secured within a rectangular tank llo (by tie-cords 92) below the surface 52 of the liquid 46.
  • the bag is substantially circular when viewed in plan.
  • the damping assembly may be located at any convenient position within the hull, e.g., in a central tank of the hull if such tank exists.
  • the assembly may be located in a side tank of the hull and if necessary to preserve symmetry, two such assemblies are located on opposite sides of the ships centerline as already described with reference to the earlier embodiments.
  • the assemblies are located amidships of the vessel with the inflatable bags 90 replacing the tubular structures at of FIGS. M3 and 2Botherwise the damping assembly may be substantially identical to that of the earlier embodiments except that the pipes 34! are now replaced by an appropriate tube 93.
  • This tube may be associated with the tuning arrangement of HG. 3 modified by the replacement of the six pipes 34 (in the FIG. llA-ZA embodiment) by a pair of tubes 93, one for each of the flexible bags 90.
  • Operation of the flexible bag embodiment is substantially identical to that already described with respect to the earlier embodiments except that the lower end of the bag 90 now carries a mesh 96 for controlling liquid flow into and out of the receptacle.
  • a similar mesh, or a grid, may be provided if desired in the earlier embodiments, e.g., across slot 30 in the first embodiment and somewhere between the rectangular ports 64 and the liquid surface 50 in the second embodiment.
  • FIG. 5 illustrates diagrammatically a damping assembly which damps transverse horizontal vibrations in the ship, e.g., as introduced into the hull by the ship's engines or the seas wave motion.
  • This assembly varies from the embodiments above described in that the receptacle and tank of these earlier structures are in effect joined together to provide a simple U-shape configuration.
  • the upright receptacle" limb (H20) of the U-tube (W0) as before comprises a closed end (1412) in which a pocket of gas (1148) is trapped by a free liquid surface At its lower end the limb communicates directly with the tank portion of the lU-tube construction provided by the horizontal limb 1116 and second upright limb 21s.
  • the trapped gas 1 above the free liquid surface 150 is pressurized and tuned using the FIG. 3 arrangement suitably modified.
  • the other limb 2H6 of the U-tube construction is left open to at mosphere. With such an arrangement the liquid columns in the two limbs 12011, 211% of the tube construction will be of different heights and the assembly will therefore also be capable of damping vertical vibrations of particular frequencies in the hull 12.
  • both limbs may be sea ed from the atmosphere if desired and the spaces above the liquid surfaces in the limbs partially evacuated or connected up with appropriate sources of pressurized gas. If it is only desired to damp transverse vibrations in the hull with this assembly, it is not necessary that the two liquid columns should be of different heights (when the assembly is in its rest position). It is, however, necessary that a volume of gas be trapped by a free surface of the liquid so that expansion and compression of the gas can take place and it follows that at least one limb of the U-tube structure must be sealed at its end to contain the pocket of gas.
  • two such stabilizing assemblies can be provided arranged, e.g., in contrary fashion, about the centerline 14 of the hull.
  • FIG. 6 shows a damping assembly for damping torsional vibrations in the hull 12.
  • the assembly comprises two receptacles 320 in which gas 348 is trapped by the free liquid surfaces 350.
  • the lower portions of the receptacles are connected (through valves 330) with the tank portion 316 of the assembly and as will be clear from the discussion of the earlier embodiments, torsional movement of the hull will cause displacement of the two surfaces 350 to expand and compress the trapped pockets of gas 348 to dissipate the torsional vibrational energy of the hull.
  • the present invention also extends to a hull and a vessel using one or more of the various damping assemblies above described.
  • the FIG. arrangement might be used in conjunction with the FIG. 1A, 2A and/or the FIG. 1B, 2B assemblies.
  • the embodiments above described are designed to damp vibrations only of a particular frequency or limited range of frequencies so that separate assemblies will normally be required for each mode of vibration required to be damped. In practice only the two node modes are usually dealt with. However, if for example vibration induced by the engine is especially troublesome, one damping assembly in accordance with the present invention might be positioned adjacent the engine (stem) end of the ship and another damping assembly for damping vibrations induced by the wave motion of the sea might be located amidships or at the bow or stem of the hull.
  • the damping assemblies of the present invention are equally useful in other types of large vessel. Where these vessels include suitable ballast or fresh water tanks, or even possibly fuel tanks, then the tank or tanks concerned can be utilized to provide the tank of the damping assembly if desired. Alternatively the assembly might be designed as a complete unit for insertion in an existing ship or it might be incorporated into the ship during construction of the ship.
  • An assembly for damping vibrations in the hull of a floating vessel comprising a container for a liquid-gas system wherein a pocket of gas is trapped by a free surface of the liquid so that vibration of the hull results in motion of the liquid within the container to expand and compress the gas and dissipate the vibrational energy in the liquid-gas system, said container comprising a tank, a receptacle having at least a lower portion extending into the tank, a closed upper end to the receptacle, and port means permanently connecting the interior of said lower portion with the interior of the tank, the receptacle being provided by a cylindrical structure, the closed upper end of the receptacle being provided by a plate rigidly secured across the structure.
  • An assembly for damping vibrations in the hull of a floating vessel comprising a container for a liquid-gas system wherein a pocket of gas is trapped by a free surface of the liquid so that vibration of the hull results in motion of the liquid within the container to expand and compress the gas and dissipate the vibrational energy in the liquid-gas system,
  • the container comprising a tank, a receptacle having at least a lower portion extending rnto the tank, a closed upper end to the receptacle, port means permanently connecting the interior of said lower portion with the interior of the tank, and connection means for connecting the upper portions of the receptacle and the tank with an exterior pressure source, the receptacle being bounded by vertical plates extending between opposite sides of the tank and the closed upper end of the receptacle being provided by a horizontal plate secured between said vertical plates.
  • An assembly for damping vibrations in a floating hull comprising a tank within the hull containing a constant mass of liquid, means dividing the free surface of the liquid in said tank into at least a first portion and a second portion, means providing an airtight receptacle above one of said free surface portions, and a pocket of gas trapped in said receptacle by said one portion of the free surface, whereby in operation movement of the liquid relative to the tank causes alternate expansion and compression of the trapped gas so that the vibrational energy associated with vibrational distortions of the hull is transferred to the liquid-gas system where it is dissipated principally by work done by the liquid in moving over surfaces provided by the assembly.
  • connection means for connecting the receptacle with exterior sources of positive, negative or atmospheric pressure.
  • An assembly as claimed in claim 3 adapted to damp principally vertical vibrations in the floating hull, the assembly including means for establishing the pressure of said trapped gas at a different value, when the liquid is at rest, from the pressure of the gas in contact with the other portions of the free surface, whereby in operation the vibrational energy transferred to the assembly comprises the energy associated with periodic bending of the hull in the vertical mode.
  • tubular structure includes port means permanently connecting the interior of its lower portion with the interior of the tank.
  • An assembly as claimed in claim 3 adapted to damp principally transverse vibrations, in which assembly the tank is substantially U-shaped in vertical cross secton so as itself to provide the means for dividing the free liquid surface into said first and second portions, and including means sealing one arm of the U-shaped tank above the free liquid surface portion in that arm to provide said receptacle, whereby in operation the vibrational energy transferred to the assembly comprises the energy associated with periodic bending of the hull in the transverse mode.
  • An assembly as claimed in claim 3 adapted to damp principally torsional vibrations wherein, at rest, the assembly is substantially symmetrical about a central vertical plane, and the tank is substantially annular with its annular axis contained in a vertical plane which is at right angles to said central plane, the substantially annular form of the tank being interrupted at its upper end by two upright terminal tank portions adjacent to and on either side of said central plane, the liquid presenting said free surface portions in said terminal upright portions of the tank.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • Ocean & Marine Engineering (AREA)
  • Vibration Prevention Devices (AREA)
US883390A 1968-12-10 1969-12-09 Damping arrangements Expired - Lifetime US3635182A (en)

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JP (1) JPS491836B1 (zh)
DE (1) DE1961756C3 (zh)
ES (1) ES374398A1 (zh)
FR (1) FR2033204A1 (zh)
GB (1) GB1289307A (zh)
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Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4100873A (en) * 1975-11-14 1978-07-18 Netherlands Offshore Company (Nederlandse Maatschappij Voor Werken Buitengaats) B.V. Floating craft
US5853103A (en) * 1996-09-20 1998-12-29 Nissan Motor Co., Ltd. Fuel tank structure
US6298540B1 (en) * 2000-09-28 2001-10-09 Eaton Corporation Combined fuel pump, level sender and rollover venting valve for a fuel tank
US6761508B1 (en) 1999-04-21 2004-07-13 Ope, Inc. Satellite separator platform(SSP)
US20060060174A1 (en) * 2004-09-17 2006-03-23 Takashi Ashida Oil tank for engine-driven vehicle
US20090050743A1 (en) * 2006-12-13 2009-02-26 Embraer-Empresa Brasileira De Aeronautica S.A. Aircraft fuel tanks, systems and methods for increasing an aircraft's on-board fuel capacity
US8053034B1 (en) * 2008-02-19 2011-11-08 Colin Dickinson High performance tank systems
US20180127004A1 (en) * 2016-11-07 2018-05-10 Gunderson Llc Covered hopper car with stiffened bulkheads
EP3874161A4 (en) * 2018-11-02 2022-08-03 University of Maine System Board of Trustees TUNING MASS DAMPER FOR FLOATING STRUCTURES
EP4086159A3 (en) * 2021-05-07 2023-03-01 University of Maine System Board of Trustees Motion absorbing system and method for a structure
US11932360B2 (en) 2018-11-02 2024-03-19 University Of Maine System Board Of Trustees Tuned mass damper for floating structures

Families Citing this family (4)

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Publication number Priority date Publication date Assignee Title
JPS4881115A (zh) * 1972-01-31 1973-10-30
GB2261490B (en) * 1991-11-07 1995-08-02 Orian Technology Ltd Ship's hull vibration damper
CN106114804B (zh) * 2016-08-01 2018-02-13 上海海事大学 船舶主机气囊隔振器控制系统及控制方法
CN106218846B (zh) * 2016-08-02 2018-08-14 上海海事大学 一种船舶气囊隔振装置高度调节控制系统及其方法

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US968927A (en) * 1908-07-15 1910-08-30 Hermann Frahm Means for preventing the rolling of ships.
US2722194A (en) * 1954-02-16 1955-11-01 Hoffman Eugene Claude Attenuator to reduce ship's propeller vibrations
US2889795A (en) * 1956-07-09 1959-06-09 Jersey Prod Res Co Stabilization of a floating platform

Patent Citations (3)

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Publication number Priority date Publication date Assignee Title
US968927A (en) * 1908-07-15 1910-08-30 Hermann Frahm Means for preventing the rolling of ships.
US2722194A (en) * 1954-02-16 1955-11-01 Hoffman Eugene Claude Attenuator to reduce ship's propeller vibrations
US2889795A (en) * 1956-07-09 1959-06-09 Jersey Prod Res Co Stabilization of a floating platform

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4100873A (en) * 1975-11-14 1978-07-18 Netherlands Offshore Company (Nederlandse Maatschappij Voor Werken Buitengaats) B.V. Floating craft
US5853103A (en) * 1996-09-20 1998-12-29 Nissan Motor Co., Ltd. Fuel tank structure
US6761508B1 (en) 1999-04-21 2004-07-13 Ope, Inc. Satellite separator platform(SSP)
US6298540B1 (en) * 2000-09-28 2001-10-09 Eaton Corporation Combined fuel pump, level sender and rollover venting valve for a fuel tank
US20060060174A1 (en) * 2004-09-17 2006-03-23 Takashi Ashida Oil tank for engine-driven vehicle
US7717233B2 (en) * 2004-09-17 2010-05-18 Yamaha Hatsudoki Kabushiki Kaisha Oil tank for engine-driven vehicle
US7648103B2 (en) * 2006-12-13 2010-01-19 EMBRAER—Empresa Brasileira de Aeronautica S.A. Aircraft fuel tanks, systems and methods for increasing an aircraft's on-board fuel capacity
US20090050743A1 (en) * 2006-12-13 2009-02-26 Embraer-Empresa Brasileira De Aeronautica S.A. Aircraft fuel tanks, systems and methods for increasing an aircraft's on-board fuel capacity
US8053034B1 (en) * 2008-02-19 2011-11-08 Colin Dickinson High performance tank systems
US20180127004A1 (en) * 2016-11-07 2018-05-10 Gunderson Llc Covered hopper car with stiffened bulkheads
US10562545B2 (en) * 2016-11-07 2020-02-18 Gunderson Llc Covered hopper car with stiffened bulkheads
EP3874161A4 (en) * 2018-11-02 2022-08-03 University of Maine System Board of Trustees TUNING MASS DAMPER FOR FLOATING STRUCTURES
US11932360B2 (en) 2018-11-02 2024-03-19 University Of Maine System Board Of Trustees Tuned mass damper for floating structures
EP4086159A3 (en) * 2021-05-07 2023-03-01 University of Maine System Board of Trustees Motion absorbing system and method for a structure

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GB1289307A (zh) 1972-09-13
NL6918544A (zh) 1970-06-12
ES374398A1 (es) 1972-01-01
DE1961756C3 (de) 1980-02-14
DE1961756A1 (de) 1970-07-16
FR2033204A1 (zh) 1970-12-04
JPS491836B1 (zh) 1974-01-17
DE1961756B2 (de) 1979-06-13

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