Magnetostrictive active strut

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.