USA As Represented by Secretary of the Navy

Marilyn Wun-Fogle

Arthur E Clark

James B Restorff

Lawrence T Kabacoff

Howard T Savage

Kristl B Hathaway

Antonio Hernando

Bruce Beihoff

Peter Finkel

Ahmed H Amin

Rick Allen Kellogg

Joseph J Stace

Colin J Murphy

Thomas A Lograsso

An energy harvesting device for harvesting energy from a moving structure includes a housing allowing transmission of magnetic fields therethrough. A piezoelectric material capable of a phase transition and a magnetostrictive material capable of a structural change when subjected to a magnetic field are mechanically coupled to each other in the housing. An adjustable pre-stress means is positioned between the housing and the combination of the piezoelectric and magnetostrictive materials. Electrical contacts are positioned on the piezoelectric material. A magnet is mounted on the moving structure. The housing is mounted in sufficient proximity to the magnet for the magnetic field of the magnet to induce the structural change in the magnetostrictive material.

Magnetoelectric energy harvesting

An alloy comprising: An alloy having a saturated magnetostriction of from about at least 150 ppm comprising:

Magnetostrictive materials, devices and methods using high magnetostriction, high strength FeGa and FeBe alloys

Disclosed are bimetallic strips that incorporate magnetostrictive materials to enhance and provide sensing, actuating and energy harvesting functions. The bimetallic strips include a positive magnetostrictive Fe-based alloy layer and a flexible layer. The flexible layer may be a negative magnetostrictive layer or a permanent magnet layer. One or more permanent magnet materials may also be used in the arrangement. The bimetallic strips are inexpensive and easily manufactured, and have characteristics that enhance sensing and actuator applications, and enables energy harvesting.

Bimetallic strips for energy harvesting, actuation and sensing

A method of using a magnetostrictive material to achieve a high magnetomechanical coupling factor comprising building an internal anisotropy energy into the magnetostrictive material and applying a tensile or compressive stress to the magnetostrictive material with the built-in internal anisotropy energy. The internal anisotropy energy is built into the magnetostrictive material by annealing the magnetostrictive material under an annealing stress or a suitable magnetic field. For a positive magnetostrictive material, when the annealing stress is compressive, the stress applied to the annealed material under operation is tensile, and when the annealing stress is the tensile, the stress applied to the annealed material under operation is compressive. For a negative magnetostrictive material, when the annealing stress is compressive, the stress applied to the annealed material under operation is tensile, and when the annealing stress is tensile, the stress applied to the annealed material under operation is compressive.

Method of achieving high transduction under tension or compression

An elongate structure having a magnetostrictive material composition is subjected to tensile stress in the longitudinal-axial direction, thereby generally orienting the magnetization of the elongate structure in the longitudinal-axial direction. Electrical current is conducted through the elongate structure and/or through at least one adjacent elongate conductor, thereby generally orienting the magnetization of the elongate structure in the transverse direction, generally in parallel with the transverse direction of the magnetic field concomitant the conduction of current through the elongate structure. The elongate structure magnetostrictively contracts due to the (generally 90&#xb0;) repositioning of the magnetization of the elongate structure. Examples of inventive configurational variants include: (i) an elongate structure itself conducting current; (ii) a hollow elongate structure accommodating placement therethrough of at least one elongate conductor; (iii) an elongate structure flanked by a pair of elongate conductors conducting current in opposite directions; (iv) plural elongate structures bordering a centralized elongate conductor.

High magnetostriction of positive magnetostrictive materials under tensile load

A positive magnetostrictive material such as a ferromagnetic alloy is subjected to a magnetic field during annealing treatment while being heated for a predetermined period of time at an elevated temperature below its softening temperature followed by cooling resulting in a treated ferromagnetic material having high tensile strength and positive magnetostriction properties for enhancing use thereof under tensile loading conditions. Such treatment of the ferromagnetic alloy may be augmented by application thereto of a compressive stress.

Preparation of positive magnetostrictive materials for use under tension

The efficiency of converting electrical energy into a mechanical output is maximized by alternatively matching selection of power supply for the drive coil applying a magnetic field to transducer element made of a magnetostrictive material having a near-zero magnetic anisotropy, or matching selection of the magnetostrictive material to the required magnetostriction for a given power supply.

Efficiency maximized conversion of electrical to mechanical energy by magnetostrictive transduction

A high power magnetostrictive transducer element comprising a material of the formula Tb,Dy,Ho,Fe,wherein 0.24&lE;x&lE;0.28, 0.52&lE;y&lE;0.56, 0.13&lE;z&lE;0.22, x&plus;y&plus;z&equals;1, and 0&lE;w&lE;0.20 and wherein the material is prestressed by a compressive force of from about 5 to about 100 MPa.

Hysteresis reduction in giant magnetostrictive materials

A magnetostrictive wire element made of amorphous ferromagnetic material is tailored for installation within a sensor by treatment which includes annealment by heating while a stress condition is imposed thereon, and applying a DC electric current thereto during said annealment to produce a cylindrical magnetic field relative to the wire element establishing spiral magnetic anistropy during cooldown after said heating.

Processing treatment of amorphous magnetostrictive wires

Magnetostrictive material such as Terfenol-D undergoes annealing treatment y heating for a limited period of time to an elevated temperature below the melting point, followed by cooling to a preferred magnetic state in which a compressive stress generated and applied during treatment is retained in the treated material as a built-in prestress.

Prestress imposing treatment of magnetostrictive material

Polycrystalline or single crystal magnetostrictive alloys of the formula Tb.sub.1-x Dy.sub.x Zn.sub.w (0&lt;x.ltoreq.0.7; 0.90.ltoreq.w.ltoreq.1.10) and Tb.sub.1-y Gd.sub.y Zn.sub.w (0&lt;y.ltoreq.0.4; 0.90.ltoreq.w.ltoreq.1.10) and magnetostrictive transducer elements made of these alloys.

Terbium-dysprosium-zinc and terbium-gadolinium-zinc magnetostrictive

A magnetostrictive element having a large magnetomechanical coupling factor long its axis, is selected to determine strain by measurement of changes in its electrical impedance along such axis. Such measurement is maximized by generation of current of a predetermined frequency conducted through the magnetostrictive element to correspondingly penetrate the magnetostrictive element to a substantial skin depth.

Strain sensing system including a magnetostrictive material having a

Magnetostrictive wire having a low surface-to-volume ratio established by a onstant non-planar cross-section, is helically deformed into contact with a shaft under a stress maintaining the wire in fixed relation to the shaft surface. Magnetic anisotropy is imparted to the wire by twist thereof about its cross-sectional axis while the wire is being helically deformed into contact with the shaft surface to form a torque sensor through which accurate torque detection is achieved.

Growing community of inventors

Potomac, MD, United States of America

Marilyn Wun-Fogle