WO1996038639A1 - A damped element - Google Patents

A damped element Download PDF

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Publication number
WO1996038639A1
WO1996038639A1 PCT/NZ1996/000055 NZ9600055W WO9638639A1 WO 1996038639 A1 WO1996038639 A1 WO 1996038639A1 NZ 9600055 W NZ9600055 W NZ 9600055W WO 9638639 A1 WO9638639 A1 WO 9638639A1
Authority
WO
WIPO (PCT)
Prior art keywords
plastically deformable
energy absorbing
element according
absorbing material
layer
Prior art date
Application number
PCT/NZ1996/000055
Other languages
French (fr)
Inventor
William Henry Robinson
Michael Denis Monti
Original Assignee
Industrial Research Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Industrial Research Limited filed Critical Industrial Research Limited
Priority to AU58480/96A priority Critical patent/AU5848096A/en
Publication of WO1996038639A1 publication Critical patent/WO1996038639A1/en

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Classifications

    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04H—BUILDINGS OR LIKE STRUCTURES FOR PARTICULAR PURPOSES; SWIMMING OR SPLASH BATHS OR POOLS; MASTS; FENCING; TENTS OR CANOPIES, IN GENERAL
    • E04H9/00—Buildings, groups of buildings or shelters adapted to withstand or provide protection against abnormal external influences, e.g. war-like action, earthquake or extreme climate
    • E04H9/02—Buildings, groups of buildings or shelters adapted to withstand or provide protection against abnormal external influences, e.g. war-like action, earthquake or extreme climate withstanding earthquake or sinking of ground
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64C—AEROPLANES; HELICOPTERS
    • B64C1/00—Fuselages; Constructional features common to fuselages, wings, stabilising surfaces or the like
    • B64C1/06—Frames; Stringers; Longerons ; Fuselage sections
    • B64C1/061—Frames
    • B64C1/062—Frames specially adapted to absorb crash loads
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D31/00—Protective arrangements for foundations or foundation structures; Ground foundation measures for protecting the soil or the subsoil water, e.g. preventing or counteracting oil pollution
    • E02D31/08—Protective arrangements for foundations or foundation structures; Ground foundation measures for protecting the soil or the subsoil water, e.g. preventing or counteracting oil pollution against transmission of vibrations or movements in the foundation soil
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
    • E04B1/00—Constructions in general; Structures which are not restricted either to walls, e.g. partitions, or floors or ceilings or roofs
    • E04B1/62—Insulation or other protection; Elements or use of specified material therefor
    • E04B1/92—Protection against other undesired influences or dangers
    • E04B1/98—Protection against other undesired influences or dangers against vibrations or shocks; against mechanical destruction, e.g. by air-raids
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
    • E04C3/00—Structural elongated elements designed for load-supporting
    • E04C3/02—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces
    • E04C3/29—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces built-up from parts of different material, i.e. composite structures
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
    • E04C3/00—Structural elongated elements designed for load-supporting
    • E04C3/30—Columns; Pillars; Struts
    • E04C3/36—Columns; Pillars; Struts of materials not covered by groups E04C3/32 or E04C3/34; of a combination of two or more materials
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04H—BUILDINGS OR LIKE STRUCTURES FOR PARTICULAR PURPOSES; SWIMMING OR SPLASH BATHS OR POOLS; MASTS; FENCING; TENTS OR CANOPIES, IN GENERAL
    • E04H12/00—Towers; Masts or poles; Chimney stacks; Water-towers; Methods of erecting such structures
    • E04H12/02—Structures made of specified materials
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D5/00—Blades; Blade-carrying members; Heating, heat-insulating, cooling or antivibration means on the blades or the members
    • F01D5/12—Blades
    • F01D5/14—Form or construction
    • F01D5/16—Form or construction for counteracting blade vibration
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03D—WIND MOTORS
    • F03D1/00—Wind motors with rotation axis substantially parallel to the air flow entering the rotor 
    • F03D1/06—Rotors
    • F03D1/065—Rotors characterised by their construction elements
    • F03D1/0675—Rotors characterised by their construction elements of the blades
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
    • F16F15/00—Suppression of vibrations in systems; Means or arrangements for avoiding or reducing out-of-balance forces, e.g. due to motion
    • F16F15/02—Suppression of vibrations of non-rotating, e.g. reciprocating systems; Suppression of vibrations of rotating systems by use of members not moving with the rotating systems
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
    • F16F7/00—Vibration-dampers; Shock-absorbers
    • F16F7/10—Vibration-dampers; Shock-absorbers using inertia effect
    • F16F7/104—Vibration-dampers; Shock-absorbers using inertia effect the inertia member being resiliently mounted
    • F16F7/108—Vibration-dampers; Shock-absorbers using inertia effect the inertia member being resiliently mounted on plastics springs
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64C—AEROPLANES; HELICOPTERS
    • B64C1/00—Fuselages; Constructional features common to fuselages, wings, stabilising surfaces or the like
    • B64C2001/0054—Fuselage structures substantially made from particular materials
    • B64C2001/0081—Fuselage structures substantially made from particular materials from metallic materials
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
    • F05B2240/00—Components
    • F05B2240/20—Rotors
    • F05B2240/30—Characteristics of rotor blades, i.e. of any element transforming dynamic fluid energy to or from rotational energy and being attached to a rotor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
    • F05D2240/00—Components
    • F05D2240/20—Rotors
    • F05D2240/30—Characteristics of rotor blades, i.e. of any element transforming dynamic fluid energy to or from rotational energy and being attached to a rotor
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B10/00—Integration of renewable energy sources in buildings
    • Y02B10/30—Wind power
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/70—Wind energy
    • Y02E10/72—Wind turbines with rotation axis in wind direction

Definitions

  • This invention relates to reducing the effects of induced motion or displacement in elements such as beams or columns of a structure, in aerials and masts, and in a variety of other applications.
  • Tuned mass dampers are used to damp vibration or motion in structures which may be exposed to wind, vibration from other sources, seismic motion or similar.
  • tuned mass dampers may be used in telecommunications masts or aerials on top of buildings.
  • Tuned mass dampers can be expensive to tune and are tuned to a particular frequency whereas the frequency of seismic motion is unpredictable.
  • the invention may be used in large structures such as buildings or bridges to reduce the effects of motion induced during earthquakes or from strong winds.
  • the invention may also be used to damp vibration from industrial machinery or engines or the like for example, or in other applications where it is desired to isolate from or damp any motion, vibrations or similar.
  • the present invention provides an improved or at least alternative damping system.
  • the invention comprises an element with a layer of a plastically deformable energy absorbing material over at least a part of an external and or internal surface of the element and bonded to or integral with the surface(s) of the element, which is effective to reduce or damp motion or vibration induced in the element.
  • the element may be a longitudinally extending element such as a cylindrical or non- cylindrical tube, a column, a beam of any configuration, a propeller or turbine blade, an aerial or mast, or similar.
  • the element may also be a planar element in which it is desired to reduce or damp motion or vibration such as part of a piece of equipment such as a printed circuit board or metal wall of a casing for example.
  • the planar element may be a complex planar element, such as the floor pan or other panel of a motor vehicle, a panel of an aeroplane fuselage or wing, part of a ship, or similar.
  • the plastically deformable energy absorbing material is preferably lead, but other plastically deformable energy absorbing materials which may be used include alloys of lead, aluminium at elevated temperature e.g. about 200°C, tin, zinc, brass, ion. super plastic alloys, or any other material having a low rate of work hardening.
  • Thin sheets of lead may be bonded to surfaces of the element, such as the internal and/or external surfaces of a cylindrical element, the sides and/or top and bottom surfaces of a beam, or similar.
  • the lead or other plastically deformable material may be applied by spraying, extrusion coating, electroplating, flux or electronic deposition, or other technique. Bonding of the lead to the surface(s) of the element may be by mechanical or chemical bonding.
  • the lead or other plastically deformable material may be applied to the surface of the element, such as the entire external and/or internal surfaces of a cylindrical or non-cylindrical tube or column, the external surfaces of a solid column or similar, or to only part of the surface by applying the lead or similar in zones or regions so positioned to effectively reduce or damp any motion or vibration induced in the element.
  • strips of lead or other plastically deformable material may be bonded to a planar surface or similar.
  • Lead may be applied by spraying or coating over selected regions.
  • the element will be formed of a material which is elastic relative to the plastic damping material which is applied to the element, and the element will typically be formed of steel or similar, or fibreglass or other synthetic material having properties of elasticity which it is desired to damp.
  • Elements of the invention may be used in the construction of larger structures such as aerials or masts or pylons to isolate them from vibration or motion due to winds. They may also be used in the construction of large structures such as buildings or bridges to damp seismic motion. They may be used in any other application were it is desired to isolate from or damp any motion, vibrations, or similar. Small or miniature size elements of the invention may be used in sensitive electronic equipment such as the mechanism of a video recorder etc or in other similar applications. Numerous applications of elements of the invention are envisaged where damping or reduction of vibration or motion is required.
  • the layer of lead or other plastically deformable material may optionally comprise a further layer over or surrounding it, such as a layer of steel or other material to enhance or vary the mechanical properties of the element, or a protective layer such as a plastic or synthetic layer or similar.
  • the invention also comprises a method of manufacturing an element or reducing or damping motion or vibration induced in an element, comprising providing a layer of a plastically deformable energy absorbing material over at least a part of an external and/or internal surface of the element bonded to or integral with the surface(s) of the element, which is effective to reduce motion or vibration induced in the element.
  • Figure 1 shows a section of a tubular element having a lead layer on its exterior
  • Figure 2 is a cross-sectional view of the tubular element of Figure 1 ,
  • Figure 3 shows a section of a tubular element having a lead layer on its interior
  • Figure 4 is a cross-sectional view of the tubular element of Figure 3
  • Figure 5 shows a section of a tubular element having lead layers on the exterior and interior of the element
  • Figure 6 is a cross-sectional view of the tubular element such of Figure 5
  • Figure 7 shows an I beam having lead layers applied to both sides of the vertical web of the I beam
  • Figure 8 shows an I beam having lead layers applied to the top and bottom horizontal surfaces of the I beam
  • Figure 9 shows an L beam or element having a lead layer applied to the vertical and horizontal surfaces on one side of the element
  • Figure 10 shows part of a hollow blade of a propeller or turbine having a lead coated layer applied to the interior
  • Figure 11 shows a planar element having lead applied to a part of one side of the planar element.
  • the tubular element 1 of Figure 1 has a thin layer of lead 2 applied to the exterior of the tubular element.
  • the tubular element 1 may be a telecommunications aerial on top of a building for example, which may be subjected to buffeting from high winds, which it is desired to damp against motion or vibration.
  • the aerial may be formed of steel or any other metal, fibreglass or other synthetic materials, or similar.
  • the tubular element may be a steel pipe which serves as a transverse beam, a vertical or near vertical upright or cylindrical column.
  • the tubular element may be part of a structure comprising other elements of the invention or other undamped elements.
  • Figure 2 is a cross-sectional view through the tubular element such as in Figure 1 showing the lead layer on the exterior.
  • the lead layer may typically be of a thickness 1 ⁇ m to 10 mm giving a total damping for the structure of from 1 to greater than 100% of critical damping.
  • the thickness of the lead layer may be typically in the range 1/1000 *1* of the wall thickness of the element up to or greater than the wall thickness of the element.
  • the lead layer may be applied by wrapping a thin lead sheet around the tubular element and bonding the lead sheet to the exterior surface of the element, extrusion coating of a thin lead layer over the element, spraying of a thin layer of lead over the element, or any other suitable application technique.
  • Figure 3 shows a similar tubular element, in this case with a lead layer 2 applied and bonded to the interior surface of the element
  • Figure 4 shows a similar tubular element having lead layers 2 applied both to the exterior and interior surfaces of the tubular element 1.
  • the lead layer(s) may be applied as a continuous layer over the exterior of the tubular elements, or in spaced bands around the circumference of the tubular elements, or as strips along the exterior or interior surfaces of the tubular elements, or similar, which may be positioned to shift the resonant frequency or points of resonance of the element.
  • the tubular element may be cylindrical or non-cylindrical such as oval or octagonal in cross-sectional shape for example.
  • the tubular element may be of constant or reducing or increasing cross- sectional dimension over its length.
  • Figures 7 and 8 show I beams 3 with lead layers 2 applied thereto in accordance with the invention.
  • a thin layer of lead is applied by bonding, coating or spraying or similar to each side of the vertical web of the I beam, to provide damping primarily against horizontal vibration in the beam.
  • lead layers 2 are applied to the top and bottom surfaces of the beam as shown, to enhance damping against vertical vibration.
  • lead layers may be applied to both the vertical and horizontal surfaces of the beams.
  • Figure 9 shows an L beam or angle 4 having lead 2 applied to one vertical face and one horizontal face of the element.
  • the lead may be applied in any thickness to provide the desired damping, by bonding thin sheets of lead to the beam surfaces, spraying or extrusion coating or similar.
  • Figure 10 shows a planar element 5 having lead applied to one side thereof to reduce vibration in the element.
  • the lead is shown applied as thin sheet strips but alternatively lead or other plastically deformable material may be applied over the whole of one or both surfaces of the planar element.
  • the planar element may be a complex planar shape such as the body panel of a motor vehicle, a hull or structural panel of a ship, a panel which is part of a wing or fuselage of an aircraft or similar, to reduce or damp vibration.
  • the damping material may be applied as strips or in specific regions to shift the resonant frequency or points of resonance of the element.
  • Figure 11 shows part of a blade 6 of a propeller or wind turbine.
  • a thin coating of lead 2 may be applied to the inside surface of the hollow blade 6.

Abstract

An element (3) such as cylindrical or non-cylindrical tubular element, a column, or a beam, comprises a layer of plastically deformable energy absorbing material such as lead (2) over at least part of an external and/or internal surface of the element. The layer is bonded to or integral with the surface(s) of the element (3), and is effective to reduce or damp motion or vibration induced in the element.

Description

A DAMPED ELEMENT
FIELD OF INVENTION
This invention relates to reducing the effects of induced motion or displacement in elements such as beams or columns of a structure, in aerials and masts, and in a variety of other applications.
BACKGROUND OF INVENTION
Tuned mass dampers are used to damp vibration or motion in structures which may be exposed to wind, vibration from other sources, seismic motion or similar. For example, tuned mass dampers may be used in telecommunications masts or aerials on top of buildings. Tuned mass dampers can be expensive to tune and are tuned to a particular frequency whereas the frequency of seismic motion is unpredictable.
The invention may be used in large structures such as buildings or bridges to reduce the effects of motion induced during earthquakes or from strong winds. The invention may also be used to damp vibration from industrial machinery or engines or the like for example, or in other applications where it is desired to isolate from or damp any motion, vibrations or similar.
SUMMARY OF INVENTION
The present invention provides an improved or at least alternative damping system. In broad terms in one aspect the invention comprises an element with a layer of a plastically deformable energy absorbing material over at least a part of an external and or internal surface of the element and bonded to or integral with the surface(s) of the element, which is effective to reduce or damp motion or vibration induced in the element.
The element may be a longitudinally extending element such as a cylindrical or non- cylindrical tube, a column, a beam of any configuration, a propeller or turbine blade, an aerial or mast, or similar. The element may also be a planar element in which it is desired to reduce or damp motion or vibration such as part of a piece of equipment such as a printed circuit board or metal wall of a casing for example. The planar element may be a complex planar element, such as the floor pan or other panel of a motor vehicle, a panel of an aeroplane fuselage or wing, part of a ship, or similar.
The plastically deformable energy absorbing material is preferably lead, but other plastically deformable energy absorbing materials which may be used include alloys of lead, aluminium at elevated temperature e.g. about 200°C, tin, zinc, brass, ion. super plastic alloys, or any other material having a low rate of work hardening.
Thin sheets of lead may be bonded to surfaces of the element, such as the internal and/or external surfaces of a cylindrical element, the sides and/or top and bottom surfaces of a beam, or similar. Alternatively the lead or other plastically deformable material may be applied by spraying, extrusion coating, electroplating, flux or electronic deposition, or other technique. Bonding of the lead to the surface(s) of the element may be by mechanical or chemical bonding. The lead or other plastically deformable material may be applied to the surface of the element, such as the entire external and/or internal surfaces of a cylindrical or non-cylindrical tube or column, the external surfaces of a solid column or similar, or to only part of the surface by applying the lead or similar in zones or regions so positioned to effectively reduce or damp any motion or vibration induced in the element. For example, strips of lead or other plastically deformable material may be bonded to a planar surface or similar. Lead may be applied by spraying or coating over selected regions.
Typically the element will be formed of a material which is elastic relative to the plastic damping material which is applied to the element, and the element will typically be formed of steel or similar, or fibreglass or other synthetic material having properties of elasticity which it is desired to damp.
Elements of the invention may be used in the construction of larger structures such as aerials or masts or pylons to isolate them from vibration or motion due to winds. They may also be used in the construction of large structures such as buildings or bridges to damp seismic motion. They may be used in any other application were it is desired to isolate from or damp any motion, vibrations, or similar. Small or miniature size elements of the invention may be used in sensitive electronic equipment such as the mechanism of a video recorder etc or in other similar applications. Numerous applications of elements of the invention are envisaged where damping or reduction of vibration or motion is required.
The layer of lead or other plastically deformable material may optionally comprise a further layer over or surrounding it, such as a layer of steel or other material to enhance or vary the mechanical properties of the element, or a protective layer such as a plastic or synthetic layer or similar.
The invention also comprises a method of manufacturing an element or reducing or damping motion or vibration induced in an element, comprising providing a layer of a plastically deformable energy absorbing material over at least a part of an external and/or internal surface of the element bonded to or integral with the surface(s) of the element, which is effective to reduce motion or vibration induced in the element.
BRIEF DESCRIPTION OF DRAWINGS
The invention will be further described with reference to the accompanying drawings, by way of example and without intending to be limiting. In the drawings:
Figure 1 shows a section of a tubular element having a lead layer on its exterior,
Figure 2 is a cross-sectional view of the tubular element of Figure 1 ,
Figure 3 shows a section of a tubular element having a lead layer on its interior,
Figure 4 is a cross-sectional view of the tubular element of Figure 3,
Figure 5 shows a section of a tubular element having lead layers on the exterior and interior of the element, Figure 6 is a cross-sectional view of the tubular element such of Figure 5,
Figure 7 shows an I beam having lead layers applied to both sides of the vertical web of the I beam,
Figure 8 shows an I beam having lead layers applied to the top and bottom horizontal surfaces of the I beam,
Figure 9 shows an L beam or element having a lead layer applied to the vertical and horizontal surfaces on one side of the element,
Figure 10 shows part of a hollow blade of a propeller or turbine having a lead coated layer applied to the interior, and
Figure 11 shows a planar element having lead applied to a part of one side of the planar element.
DETAILED DESCRIPTION OF PREFERRED FORMS
Referring to the drawings, the tubular element 1 of Figure 1 has a thin layer of lead 2 applied to the exterior of the tubular element. The tubular element 1 may be a telecommunications aerial on top of a building for example, which may be subjected to buffeting from high winds, which it is desired to damp against motion or vibration. The aerial may be formed of steel or any other metal, fibreglass or other synthetic materials, or similar. Alternatively the tubular element may be a steel pipe which serves as a transverse beam, a vertical or near vertical upright or cylindrical column. The tubular element may be part of a structure comprising other elements of the invention or other undamped elements.
Figure 2 is a cross-sectional view through the tubular element such as in Figure 1 showing the lead layer on the exterior. The lead layer may typically be of a thickness 1 μm to 10 mm giving a total damping for the structure of from 1 to greater than 100% of critical damping. The thickness of the lead layer may be typically in the range 1/1000*1* of the wall thickness of the element up to or greater than the wall thickness of the element. Depending on the thickness of the lead layer in any particular application, the lead layer may be applied by wrapping a thin lead sheet around the tubular element and bonding the lead sheet to the exterior surface of the element, extrusion coating of a thin lead layer over the element, spraying of a thin layer of lead over the element, or any other suitable application technique.
Figure 3 shows a similar tubular element, in this case with a lead layer 2 applied and bonded to the interior surface of the element, while Figure 4 shows a similar tubular element having lead layers 2 applied both to the exterior and interior surfaces of the tubular element 1. In each case the lead layer(s) may be applied as a continuous layer over the exterior of the tubular elements, or in spaced bands around the circumference of the tubular elements, or as strips along the exterior or interior surfaces of the tubular elements, or similar, which may be positioned to shift the resonant frequency or points of resonance of the element. The tubular element may be cylindrical or non-cylindrical such as oval or octagonal in cross-sectional shape for example. The tubular element may be of constant or reducing or increasing cross- sectional dimension over its length. Figures 7 and 8 show I beams 3 with lead layers 2 applied thereto in accordance with the invention. In the I beam shown in Figure 7, a thin layer of lead is applied by bonding, coating or spraying or similar to each side of the vertical web of the I beam, to provide damping primarily against horizontal vibration in the beam. In the beam of Figure 8 lead layers 2 are applied to the top and bottom surfaces of the beam as shown, to enhance damping against vertical vibration. In other forms of I beams or other beams lead layers may be applied to both the vertical and horizontal surfaces of the beams.
Figure 9 shows an L beam or angle 4 having lead 2 applied to one vertical face and one horizontal face of the element. Again the lead may be applied in any thickness to provide the desired damping, by bonding thin sheets of lead to the beam surfaces, spraying or extrusion coating or similar.
Figure 10 shows a planar element 5 having lead applied to one side thereof to reduce vibration in the element. In Figure 10 the lead is shown applied as thin sheet strips but alternatively lead or other plastically deformable material may be applied over the whole of one or both surfaces of the planar element. As stated previously, the planar element may be a complex planar shape such as the body panel of a motor vehicle, a hull or structural panel of a ship, a panel which is part of a wing or fuselage of an aircraft or similar, to reduce or damp vibration. The damping material may be applied as strips or in specific regions to shift the resonant frequency or points of resonance of the element.
Figure 11 shows part of a blade 6 of a propeller or wind turbine. In the case of wind turbines in particular, it is desirable to damp vibration or flexing in a blade formed of fibreglass or other similar material. As shown in Figure 11, a thin coating of lead 2 may be applied to the inside surface of the hollow blade 6.
The foregoing describes the invention including preferred forms thereof. Alterations and modifications as will be obvious to those skilled in the art are intended to be incorporated within the scope hereof, as defined in the accompanying claims.

Claims

1. An element comprising with a layer of plastically deformable energy absorbing material over at least part of an external and/or internal surface of the element and bonded to or integral with the surface(s) of the element, which is effective to reduce or damp motion or vibration induced in the element.
2. An element according to claim 1 wherein the element is a longitudinally extending element.
3. An element according to claim 2 wherein the element is a cylindrical or non- cylindrical tubular element, a column, or a beam.
4. An element according to claim 2 wherein the element is a propeller or turbine blade.
5. An element according to claim 2 wherein the element is an aerial or mast.
6. An element according to claim 1 wherein the element is a planar element including a complex planar element.
7. An element according to any one of claims 1 to 6 wherein the plastically deformable energy absorbing material is lead or an alloy of lead.
8. An element according to any one of claims 1 to 7 wherein the plastically deformable energy absorbing material comprises thin sheets of the material bonded to surfaces of the element.
9. An element according to any one of claims 1 to 7 wherein the plastically deformable energy absorbing material has been applied to the element by spraying, extrusion coating, electroplating, flux or electronic deposition, or chemical bonding.
10. An element according to any one of claims 1 to 9 wherein the plastically deformable energy absorbing material is applied to selected zones or regions of the external or internal surfaces of the element.
11. An element according to any one of claims 1 to 11 wherein the layer of plastically deformable material is a continuous layer.
12. An element according to any one of claims 1 to 11 wherein the element is formed of a material which is elastic relative to the plastically deformable, energy absorbing material.
13. An element according to claim 12 wherein the element is formed of steel or fibreglass.
14. An element according to any one of claims 1 to 13 wherein the thickness of the layer of plastically deformable energy absorbing material is between 1 micrometer and 1 millimetre.
15. An element according to any one of claims 1 to 14 wherein a layer of the plastically deformable energy absorbing material is applied over at least part of both an external and internal surface of the element.
16. An method of manufacturing an element or reducing or damping motion or vibration induced in an element, comprising providing a layer of a plastically deformable energy absorbing material over at least a part of an external and/or internal surface of the element bonded to or integral with the surface(s) of the element, which is effective to reduce motion or vibration induced in the element.
PCT/NZ1996/000055 1995-06-02 1996-05-31 A damped element WO1996038639A1 (en)

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NZ272281 1995-06-02

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WO2009034292A2 (en) * 2007-09-11 2009-03-19 Blade Dynamics Limited A root end joint for a wind turbine blade
EP3453904A1 (en) * 2017-09-08 2019-03-13 China Communications Construction Company Limited Bearing structural member, support, joint assembly and tube section assembly
CN111810355A (en) * 2020-08-05 2020-10-23 中国华能集团清洁能源技术研究院有限公司 Blade torsion vibration damping device and method for horizontal-axis wind generating set
USD984032S1 (en) * 2022-05-06 2023-04-18 Linhai Ruichen Lighting Co., Ltd. LED light string insulation core

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WO2009034292A2 (en) * 2007-09-11 2009-03-19 Blade Dynamics Limited A root end joint for a wind turbine blade
WO2009034292A3 (en) * 2007-09-11 2009-09-03 Blade Dynamics Limited A root end joint for a wind turbine blade
US8425195B2 (en) 2007-09-11 2013-04-23 Blade Dynamics Limited Wind turbine blade
EP3453904A1 (en) * 2017-09-08 2019-03-13 China Communications Construction Company Limited Bearing structural member, support, joint assembly and tube section assembly
CN111810355A (en) * 2020-08-05 2020-10-23 中国华能集团清洁能源技术研究院有限公司 Blade torsion vibration damping device and method for horizontal-axis wind generating set
WO2022027827A1 (en) * 2020-08-05 2022-02-10 中国华能集团清洁能源技术研究院有限公司 Blade torsion vibration damping apparatus and method for horizontal-axis wind power generator set
USD984032S1 (en) * 2022-05-06 2023-04-18 Linhai Ruichen Lighting Co., Ltd. LED light string insulation core

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