Magnetostrictive material

6 is the angle between the direction of M and the direction the strain is measured in 

A is the average of the saturated magnetostrictive constants Aioo and Am for the material 

This average may be positive or negative, meaning the material may contract in one direction and expand in another, or the volume may contract or expand, depending on the material. The 60 Hz hum associated with power transformers is a result of the expansion and contraction of the laminations in the core. 

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This class of smart materials is the mechanical equivalent of electrostrictive and magnetostrictive materials. Elastorestrictive materials exhibit high hysteresis between strain and stress (14,15). This hysteresis can be caused by motion of ferroelastic domain walls. This behavior is more compHcated and complex near a martensitic phase transformation. At this transformation, both crystal stmctural changes iaduced by mechanical stress and by domain wall motion occur. Martensitic shape memory alloys have broad, diffuse phase transformations and coexisting high and low temperature phases. The domain wall movements disappear with fully transformation to the high temperature austentic (paraelastic) phase. 

A] As a result of applying a magnetic field, the poles of tiny magnetic particles in a magnetostrictive material line up, which alters the shape of the material. [B] The application of an electric field aligns particles in an electrorheological fluid. 

Applications of magnetostriction include sensors and actuators. Magnetostrictive materials can perform many of the same functions as piezoelectric materials, though specific properties vary. Production of ultrasound, for instance, can be done with magnetostriction, but this effect tends to be limited to lower frequencies than piezoelectric materials. 

National Aeronautics and Space Administration—Ames Education Division Smart Materials. Available online. URL http //virtualskies.arc. nasa.gov/research/youDecide/smartMaterials.html. Accessed May 28, 2009. As part of an educational activity in which students plan an aviation research project, this Web site provides links to pages discussing piezoelectric materials, electrorheological and magnetorheological fluids, shape-memory alloys, and magnetostrictive materials. 

The present chapter deals with the magnetoelasticity of heterogeneous materials. Generally, the dimensions of a magnetostrictive material change when the material is... 

This class of smart materials is the mechanical equivalent of electrostrictive and magnetostrictive materials. Elastorestrictive materials exhibit high hysteresis between strain and stress. This hysteresis can be caused by motion of fenoelastic domain walls. Tins behavioi is mote complicated and complex near a martensitic phase transformation. 

Magnetostrictive materials are analogs of electrostrictive materials that change shape when exposed to a magnetic field. The phenom-... 

Source Properties of Chosen Magnetostrictive Materials, SmartSITE, http // smartsite.immt.pwr.wroc.pl/index/gmm 02 mag mat. 

The first practical device to make use of magnetostrictive technology, a sonar system developed by researchers at NSWC, used this property. The system consisted of magnetostrictive materials... 

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