# US 5,703,553 A · Magnetostrictive active strut > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,703,553 A - Document ID: US5703553A - Status: Granted - Kind: A - Application number: 08/653,522 - Filed: 1996-05-24 - Granted: 1997-12-30 - Earliest claimed: 1996-05-24 - Assignees: SatCon Technology Corporation - Inventors: Dariusz Antoni Bushko; Kevin Michael Avakian; Bruce Graham Johnson; Michael Jonathan Gerver - Web page: https://patentgrep.com/patent/US5703553A ## CPC - B60G 17/0157: {non-fluid unit, e.g. electric motor} - F16F 15/005: {using electro- or magnetostrictive actuation means (generating of mechanical vibrations operating with electrostriction B06B1/06, with magnetostriction B06B1/08; vehicle suspension arrangements characterised by use of piezoelectric elements B60G17/01941; piezoelectric, electrostrictive and magnetostrictive devices per se H10N30/00)} - B60G 2300/16: Aeroplanes - B60G 2401/10: Piezoelectric elements - B60G 2600/604: low pass - F16F 2230/16: used in a strut, basically rigid - B60G: VEHICLE SUSPENSION ARRANGEMENTS (air-cushion vehicles B60V; {cycle suspensions B62K25/00}) - F16F: SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION ## Abstract A magnetostrictive active member configured to withstanding significant bending moments and having a prestress mechanism that is adjustable for maintaining optimal performance of an integral magnetostrictive element. The magnetostrictive active member includes a magnetostrictive actuator and parallel flexures incorporated in a housing to create a load path for bending moments to be carried by the housing, through the parallel flexures, as opposed to being carried by the magnetostrictive actuator. A plurality of ball-joints are integrated with the flexures and magnetostrictive actuator, receiving compressire forces and ensuring that no moments are applied to the magnetostrictive actuator. A prestress or preload mechanism is incorporated which provides a compressire preload to the magnetostrictive actuator internal to the housing. The preload mechanism includes an adjustable nut than is externally accessible to adjust the preload and facilitate optimal performance of the magnetostrictive actuator. Sensors integral to the active member housing include a load cell which measures both the internally generated preload and the external axial load, as well as the force produced by the actuator. A plurality of non-contact capacitive displacement sensors are contained in the housing and used in generating a displacement output signal. An integral flux sensor accurately measures the magnetic field applied to the magnetostrictive actuator. Modular end fittings are implemented to facilitate use of the same fittings as passive members that may be used in a mechanical structure, so that an active member can be easily installed in a location that may have contained a passive member. ## Claims ### Claim 1 A magnetostrictive active member, comprising: a housing configured to contain elements of said magnetostrictive active member; a magnetostrictive actuator member disposed within said housing and being configured for actuation in a first and second direction; a preload mechanism at least partially disposed within said housing, applying preload to said actuator member, said preload mechanism including a portion accessible from the exterior of said housing and being adjustable to change the preload applied to said actuator member; and a load path system substantially shielding said actuator member from at least bending moments to avoid excessive tensile stresses in said actuator member, said load path system comprising parallel flexures directing bending moments to said housing. ### Claim 2 (depends on 1) The magnetostrictive active member of claim 1 wherein said actuator member is a Terfenol-D rod. ### Claim 3 (depends on 1) The magnetostrictive active member of claim 1 wherein said housing contains a permanent magnet and said actuator member is biased using said permanent magnet. ### Claim 4 (depends on 1) The magnetostrictive active member of claim 1 wherein said load path system further comprises at least one ball joint. ### Claim 5 (depends on 1) The magnetostrictive active member of claim 1 wherein said preload mechanism comprises a spring member abutting a threaded adjuster having external threads thereon, and a nut portion having threads on an internal surface thereof, said nut portion being accessible from exterior of said housing and being actuatable to actuate said threaded adjuster to increase compression on said spring member. ### Claim 6 (depends on 1) The magnetostrictive active member of claim 1 further including a load cell internal to said housing configured to measure compressive forces exerted by and on said magntostrictive actuator member. ### Claim 7 (depends on 1) The magnetostrictive active member of claim 1 further including a flux sensor internal to said housing measuring magnetic flux of the magnetostrictive actuator member. ### Claim 8 (depends on 1) The magnetostrictive active member of claim 1 further including at least one displacement sensor configured to measure axial motion of said magnetostrictive actuator member. ### Claim 9 (depends on 8) The magnetostrictive active member of claim 8 wherein said at least one displacement sensor comprises two non-contact, capacitive sensors disposed substantially equally spaced from a center-line of said magnetostrictive actuator member and output from said two non-contact, capacitive sensors is averaged to provide a measurement of axial motion of said magnetostrictive actuator member. ### Claim 10 A magnetostrictive active member, comprising: a housing configured to contain elements of said magnetostrictive active member; a magnetostrictive actuator member disposed within said housing and being biased by permanent magnetic biasing for actuation in a first and second direction; at least one magnetic coil disposed in said housing and configured to selectively apply a magnetic field to said magnetostrictive actuator member to effect said actuation in said first and second direction; and a load path system substantially shielding said magnetostrictive actuator member from at least bending moments to avoid excessive tensile stresses in said actuator member, said load path system comprising at least one flexure configured to direct bending moments to said housing. ### Claim 11 (depends on 10) The magnetostrictive active member of claim 10 further including a preload mechanism at least partially disposed within said housing, applying preload to said actuator member, said preload mechanism including a portion accessible from the exterior of said housing and being adjustable to change the preload applied to said actuator member. ### Claim 12 (depends on 11) The magnetostrictive active member of claim 11 wherein said preload mechanism comprises a spring member abutting a threaded adjuster having external threads thereon, and a nut portion having threads on an internal surface thereof, said nut portion being accessible from exterior of said housing and being actuatable to actuate said threaded adjuster to increase compression on said spring member. ### Claim 13 (depends on 10) The magnetostrictive active member of claim 10 wherein said actuator member is a Terfenol-D rod. ### Claim 14 (depends on 10) The magnetostrictive active member of claim 10 wherein said load path system further comprises at least one ball joint. ### Claim 15 (depends on 10) The magnetostrictive active member of claim 10 further including a load cell internal to said housing configured to measure compressire forces exerted by and on said magntostrictive actuator member. ### Claim 16 (depends on 10) The magnetostrictive active member of claim 10 further including a flux sensor internal to said housing measuring magnetic flux of the magnetostrictive actuator member. ### Claim 17 (depends on 10) The magnetostrictive active member of claim 10 further including at least one displacement sensor configured to measure axial motion of said magnetostrictive actuator member. ### Claim 18 (depends on 17) The magnetostrictive active member of claim 17 wherein said at least one displacement sensor comprises two non-contact, capacitive sensors disposed substantially equally spaced from a center-line of said magnetostrictive actuator member and output from said two non-contact, capacitive sensors is averaged to provide a measurement of axial motion of said magnetostrictive actuator member.