The Penn State Research Foundation

George A Lesieutre

Christopher L Davis

Jeremy Frank

Gary H Koopmann

Chen Weicheng

Eric Mockensurm

Jeffrey J Dosch

The present invention is actuator having a shaft delivering mechanical power to a load, a first active element adapted to be driven by an oscillating signal, and at least one mechanical diode operatively connected to the shaft in the act of development. A plurality of mechanical diodes may also be used. Mechanical diodes can be either rotary mechanical diodes or linear mechanical diodes. The mechanical diodes can also be bi-directional.

Smart material motor with mechanical diodes

A coupling coefficient is a measure of the effectiveness with which a shape-changing material (or a device employing such a material) converts the energy in an imposed signal to useful mechanical energy. Device coupling coefficients are properties of the device and, although related to the material coupling coefficients, are generally different from them. This invention describes a class of devices wherein the apparent coupling coefficient can, in principle, approach 1.0, corresponding to perfect electromechanical energy conversion. The key feature of this class of devices is the use of destabilizing mechanical pre-loads to counter inherent stiffness. The approach is illustrated for piezoelectric and thermoelectrically actuated devices. The invention provides a way to simultaneously increase both displacement and force, distinguishing it from alternatives such as motion amplification, and allows transducer designers to achieve substantial performance gains for actuator and sensor devices.

Transfer having a coupling coefficient higher than its active material

A piezoceramic vibration control device in which stiffness is established by a capacitor in shunt with piezoceramic element of the device. The device can be formed of a stack of piezoceramic elements bonded to one another and precompressed by a spring. A control system is arranged to tune the natural frequency of the vibration control device to a disturbance frequency or s primary structural response frequency by varying the capacitance of the capacitor.

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State College, PA, United States of America

George A Lesieutre