Magnetostrictive particulate actuator and its characterization for smart structure applications

Magnetostrictive Particulate Actuator (MPA), that take advantages of easy embedability and remote excitation capability of magnetostrictive particles is proposed as a new actuator for smart structure applications. MPA is configured as a rectangular polymeric beam with magnetostrictive particles dispersed uniformly. Based on the compatibility condition, a loading equation is derived that relates the free strain with the mechanical stress experienced by the magnetostrictive particles. The loading equation and the magnetoelastic property of the material are used to develop a macroscopic quasi-static model of MPA that includes the nonlinear relationship between the stress, Young's modulus and magnetic field of the magnetostrictive material. Parametric study shows how the parameters such as volume fraction, host material property, and orientation field affect the performance of MPA. A laboratory scale fabrication process is described. Characterization experiments are used to find the orientation factor and prestress. Experimental results show the nonlinear relationship between the parameters and performance as predicted by the model. The quasi-static model represents a first step toward a more sophisticated micromechanics model of the future.; A linearized dynamic model was developed since the dynamic parameters of the material are unavailable. Extensive experimental work was carried out to illustrate the effect of magnetic bias, orientation field, and volume fraction on the frequency response of MPA. The results differ from the predicted frequency response and the deviation increases with the amplitude of sinusoidal excitation current. Finally, experiment was conducted to study the feasibility of using MPA as an actuator in a simulated environment. The MPA was able to produce strain at the desired frequency while withstanding the reaction force of the host structure.; The magnetostrictive particulate actuators developed in this work are most suitable as distributed actuators to excite the host structure with a small strain while withstanding large force over a wide frequency range. For example, embedded in a laminated composite, MPA's can be used as micropositioners, vibration dampers, platform stabilizers, and motors.