Precision controlled vibration isolation utilizing magnetorheological (MR) fluid technology for potential space optical applications, such as surveillance and directed energy, is addressed. This research includes the design, development and preliminary testing of a semi-active, proof-of-concept, MR vibration isolator. Base disturbances designed to produce payload vibration responses were employed in a single degree-of-freedom test apparatus. The MR vibration isolator served as the load-coupling element between the payload and the base disturbance input. The three-parameter isolator consists of two passive spring elements combined with one MR damping element. The MR damper control algorithm uses relative rate between damper cylinder and piston to dynamically vary the effective coefficient of damping. The result of this technology is ability to tune isolation frequency within a given range. Through intelligent modulation of the damping element alone, dynamic changes in both apparent stiffness and damping of the isolator are achieved. For applications where the ability to vary stiffness and damping would improve pointing accuracy and jitter control, this technology holds great appeal.

In this paper, an optimization study of partially covered beam with a constrained viscoelastic layer is presented. An energy approach and Lagrange’s method are used to establish the governing equation of motion of a CLD covered beam, and the assumed modes method is employed in solving the equation to obtain the modal loss factors which are used as the objective of optimal layout. A genetic algorithm of big mutation is employed to search for the optimum of the patch’s location, the thicknesses of both the constraining layer (CL) and the viscoelastic layer (VL) and the shear modulus of the viscoelastic material with the restriction of added volume of the total CLD treatment. Numerical results show that the optima of the design variables are highly relevant to each other. The thinner constraining layer requires a softer viscoelastic material for an optimal damping treatment. The variation of the CL thickness decreases slowly and that of the VL thickness increases with the increase of the thickness of the CLD treatment. One end of optimal damping treatment locates closely one end of base beam.

To efficiently reduce vibration and noise of a plate, an optimization of passive constrained layer damping (CLD) is presented. The dynamic equation of a sandwich plate with CLD treatment is derived using Lagrange’s method. The assumed modes method is employed to solve the equation and obtain the vibrational energy and sound power, which are used as the objective of optimal design. A genetic algorithm of big mutation is employed to search for the optimum of the location of CLD treatment, the thicknesses of both the constraining layer and the viscoelastic layer and the shear modulus of the viscoelastic material with the restriction of added mass of the total CLD treatment. Numerical results show that for a simply-supported plate with a transverse force (1Hz~200Hz) applied at (0.8La, 0.8Lb), the optimized CLD significantly reduce the vibrational energy and sound power.

In order to develop a compact and lightweight controllable damper for space truss structures vibration suppression, a novel double-piston magnetorheological (MR) damper is proposed. Working principle of this damper has been analyzed. One prototype damper have been designed and fabricated according to the analysis results. A series of experiments have been performed to get this prototype damper's dynamical properties. Hyperbolic tangent model have been used to describe damper's nonlinear hysteresis. After model optimization using the nonlinear least squares method, the relationship between damper force and drive currents have been acquired under different excitation conditions. Comparison between the reconstructed results and testing data indicates that the optimized model shows enough accuracy to not only present the experimental data, but also forecast the hysteretic properties of this damper.

A novel intelligent driver based on digital signal controller (DSC) has been put forward for magneto-rheological (MR) damper. The working principles of MR damper were described, as well as the hardware circuit scheme of signal condition and MR damper driver etc. on account of TMS320F28335 DSC. A hierarchical control algorithm was designed and the studies for the performance of the driver were conducted. The results suggest that the driver could provide accurate drive current for MR damper, and meanwhile the respond time is less than 2ms, which can meet the drive requirements of MR damper.