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US 4,923,057 AGranted
Electrorheological fluid composite structures
AssigneeLord Corporation
InventorsJ. David Carlson, John P. Coulter, Theodore G. Duclos
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AssigneeLord Corporation
InventorsJ. David Carlson, John P. Coulter, Theodore G. Duclos
Estimating the term…
Controllable electrorheological fluid composite structure elements incorporate electrorheological fluids as a structural component between opposing fluid containment layers to form at least a portion of any variety of extended mechanical systems such as plates, panels, beams and bars or structures including these elements. The electrorheological fluid is operatively contained in a region between the containment layers and has complex shear and tensile modulus properties which vary with the electric field applied thereto. A variable power source is utilized to create an electric potential between the layers of the structure element to create the electric field. An alternative power source may include the use of a piezoelectric material layer. In order to maintain the insulation and spacing between the containment layers, a fabric or separating layer having an open mesh is provided which permits the transportation of electrorheological fluid in the region between the layers. Multiple layers and regions are contemplated including orientation orthogonally to the long axis of the structure to take advantage of the elongational modulus of the fluid. The composite structures of the present invention may be incorporated in a wide variety of mechanical systems for control of vibration and other properties.
A flexible, laminar beam or panel for carrying lateral loads and bending movements comprising at least two flexible, electrically conductive containment layers configured in a parallel, spaced relationship and defining therebetween an enclosed space, an electrorheological fluid confined within said space, and an electric field generating means connected to each of said layers for applying a voltage potential between said layers thereby producing an electric field across said fluid, wherein the magnitude of said voltage potential is selected for determining the complex moduli of said fluid and the complex stiffness characteristics of said beam or panel.
A method for controlling the vibration characteristics of a laminar beam comprising the steps of providing at least two spaced, parallel flexible containment layers of conductive material for forming the upper and lower surfaces of said beam, enclosing an electrorheological fluid within said space between said layers, applying a voltage potential between said layers for producing an electric field across said fluid to select the complex moduli thereof, and varying the magnitude of said voltage potential to vary the complex stiffness characteristics of said beam.
A method for controlling the mechanical behavioral characteristics of laminated composite structures, comprising the steps of providing elastic containment layers of selected tensile modulus, thickness and distance therebetween to form at least a portion of said composite structure, enclosing an electrorheological fluid in one or more regions between said containment layers, selecting the overall loss factor and flexural rigidity of said structure by adjusting the complex shear modulus of said electrorheological fluid responsive to a variable electric field applied across said one or more regions, wherein the overall loss factor is determined by the expression ##EQU11## where .eta..sub.2 is equal to the imaginary portion of the complex shear modulus of said fluid divided by the real portion thereof, Y is the stiffness parameter, and X is the shear parameter.
A method for controlling the mechanical behavioral characteristics of laminated composite structures, comprising the steps of providing elastic containment layers of selected tensile modulus, thickness and distance therebetween to form at least a portion of the composite structure, enclosing an electrorheological fluid in one or more regions between said containment layers, and selecting the overall loss factor and flexural rigidity of the composite structure by adjustment of the complex elongational modulus of said electrorheological fluid responsive to a variable electric field applied across said one or more regions, wherein the overall loss factor .eta. of a simply supported laminated structure having said containment layers in series on either side of an elastic layer is determined by the expression ##EQU14## where, .eta..sub.2e is equal to the imaginary component of the complex tensile modulus E.sub.2 " divided by the real portion E.sub.2 ' thereof for said fluid, E.sub.1 is the tensile modulus of the elastic material, H.sub.1 is the thickness of the regions, and H.sub.12 is the distance between the midplanes of adjacent layers.
Apparatus for gripping objects comprising a base, at least two flexible, electrically conductive containment layers configured in a parallel, spaced relationship, and defining therebetween an enclosed space, wherein said layers are attached at a portion of the periphery thereof to said base, an electrorheological fluid confined within said space, and an electric field generating means connected to each of said layers for selectively immobilizing said fluid and said layers in a fixed position about said object.
Dependencies are inferred from the claim text.