Active vibration control

About: Active vibration control is a research topic. Over the lifetime, 6770 publications have been published within this topic receiving 76599 citations. The topic is also known as: active vibration damping.

The formulation of a refined hybrid enhanced assumed strain solid shell element and its application to model smart structures containing distributed piezoelectric sensors/actuators

Abstract: In the present paper, a novel refined hybrid piezoelectric element formulation is developed for mechanical analysis and active vibration control of laminated structures bonded to piezoelectric sensors and actuators. By invoking the electrical field potential equation, a 'quasi-decoupling' method for treating the coupling electromechanical effects is presented and a modified generalized variational principle with a weaker interelement continuity condition is proposed. On the basis of this functional, a general formulation for a refined hybrid piezoelectric element method is established by incorporating an orthogonal interpolation approach and enhanced assumed strain (EAS) modes. A linearly distributed transverse EAS in the thickness direction is adopted to overcome the thickness locking of solid shell elements. Compared with the conventional incompatible brick element approach, the present formulation is very reliable, more accurate, computationally efficient and can be used to model the response of thin plates and shell structures.

Dynamic modeling and adaptive vibration control study for giant magnetostrictive actuators

Abstract: Giant magnetostrictive actuators (GMA) used in vibration control and high precision positioning control have been studied widely in last decade. Recently, although many researchers commit themselves to modeling giant magnetostrictive actuators, there is still lack of simplified model of analyzing nonlinear properties to deal with the problems on active vibration control with giant magnetostrictive actuators. In this paper, a nonlinear constitutive model of a giant magnetostrictive actuator is put forward for the application of effectively suppressing vibration. The nonlinear constitutive model is established not only by combining linear constitutive equations with the Bouc–Wen equations but also by using Hamilton's principle and the assumed mode method to analyze the hysteresis phenomena and quadric frequency property in the giant magnetostrictive actuator. In addition, a minimum variance self-turning regulator (MVSTR) is incorporated into the design of a controller, which may be used in suppressing low frequency (≤5 Hz) and micron-level (≤5 μm) disturbances. In the end of this paper, some simulations are performed in LABVIEW and experimental control tests are implemented using a giant magnetostrictive actuator prototype. Both the numerical simulations and experimental tests results show that the amplitudes of disturbances may be reduced up to no less than 90% averagely in the whole sampling processes. This proves that the giant magnetostrictive actuator has not only the capacity of controlling low-frequency and micro-level vibration but also the notable effectiveness of active control by the adaptive regulator. Moreover, the minimum variance self-tuning regulator is testified as a feasible controller for vibration control in the paper.

Minimization of the residual vibrations of ultra-precision manufacturing machines via optimal placement of vibration isolators

Abstract: Ultra-precision manufacturing (UPM) machines are used to fabricate and measure complex parts having micrometer-level features and nanometer-level tolerances/surface finishes. Consequently, low-frequency residual vibrations that occur during the motion of the machines’ axes must be mitigated. A long-standing rule of thumb in vibration isolation system design is to locate the isolators in such a way that all vibration modes are decoupled. This paper uses the 2D dynamics of a passively isolated system to show that coupling the vibration modes of the isolated system by altering the location of the isolators provides conditions which allow for the drastic reduction of residual vibrations. An objective function which minimizes residual vibration energy is defined. Perturbation analyses of the objective function reveal that the recommended practice of decoupling the vibration modes more often than not leads to sub-optimal results in terms of residual vibration reduction. The analyses also provide guidelines for correctly locating the isolators so as to reduce residual vibrations. Simulations and experiments conducted on a passively isolated ultra-precision machine tool are used to validate the findings of the paper; a 5-fold reduction of the dominant residual vibrations of the machine tool is achieved without sacrificing vibration isolation quality (i.e., transmissibility).