Dynamic Vibration Absorber

About: Dynamic Vibration Absorber is a research topic. Over the lifetime, 4764 publications have been published within this topic receiving 49429 citations.

A Robust Adaptive Tuned Vibration Absorber Using Semi-Passive Shunt Electronics

Abstract: An adaptive tuned vibration absorber containing an electromagnet with an adaptive synthetic shunt impedance is described. The system is designed to self-tune to retain optimal tuning under the presence of changes in excitation frequency, the properties of the host structure or environmental conditions. The control system comprises both feedforward (FF) and feedback (FB) elements. The FF controller is model based and adapts both the shunt resistance and capacitance. It is designed and implemented to provide a controllable effective mechanical stiffness and damping. The FB controller compensates for errors in model parameters, estimates of the excitation frequency or environmental changes. Three different FB algorithms are implemented and tested, namely linear, nonlinear polynomial, and fuzzy logic control. Experimental results show that the linear controller is unreliable, but the polynomial and fuzzy controllers work effectively. The adaptive controller can successfully adapt the system to track a variable excitation frequency while being robust to errors or changes in system parameters and provides guaranteed stability in operation.

Elastomeric tuned vibration absorber

Abstract: A tuned vibration absorber (40) includes a mounting plate (42) having at least two (46, 56), and alternatively four, mounting holes (46, 50) in spaced relationship from a longitudinal center axis of the plate (42). An elastomeric spring (60) is bonded to the mounting plate (42). A main tuning mass (70) is bonded to the elastomeric spring (60) opposite the mounting plate (42), and fine tuning masses (72) are riveted directly onto the main tuning mass (70). The elastomeric spring (60) and main mass (70) both have a rectangular profile to maintain a low profile height from the mounting plate (42). A cover (50) is formed of a single sheet of metal bent to form a rectangular box with one open side. The cover (50) includes mounting flanges (54) with holes (56) that align with the mounting holes (46) on the mounting plate (42). For mounting the vibration absorber on a stiffening ring (10) of an aircraft frame, a spacing plate (90) is positionable between a portion of the mounting plate (42) and the stiffening rib (10) of an aircraft frame, and adjacent to an overlapping secondary stiffening (14, 16) ring to provide a flat mounting surface.

Electrically-tunable vibration absorbers

Abstract: An ETVA (electrically-tunable vibration absorber) has a vibratable mass with a mechanical spring suspension supplemented by an electromagnetic spring simulation that can be adjusted electrically to vary the self-resonant frequency of the vibratable mass and tune it to a disturbing frequency that is to be suppressed. A flux path from the electromagnet traverses an air gap between a pair of oppositely-facing matching magnetic pole arrays, one of which is attached to the vibratable mass while the other pole array is substantially attached to the object structure that is being treated to suppress vibration. The two interfacing arrays are configured in mirror-image relationship as seen in cross-section, and are held by the spring suspension so as to be mutually aligned under a quiescent condition and to move relative to each other under vibration only in a designated direction so that the gap separation distance remains substantially constant and thus the flux density at the poles remains substantially constant and unmodulated, resulting in high efficiency due to minimal eddy current losses.

Experimental studies on active control of a dynamic system via a time-delayed absorber

Abstract: The traditional passive absorber is fully effective within a narrow and certain frequency band. To solve this problem, a time-delayed acceleration feedback is introduced to convert a passive absorber into an active one. Both the inherent and the intentional time delays are included. The former mainly comes from signal acquiring and processing, computing, and applying the actuation force, and its value is fixed. The latter is introduced in the controller, and its value is actively adjustable. Firstly, the mechanical model is established and the frequency response equations are obtained. The regions of stability are delineated in the plane of control parameters. Secondly, the design scheme of control para- meters is performed to help select the values of the feedback gain and time delay. Thirdly, the experimental studies are conducted. Effects of both negative and positive feedback control are investigated. Experimental results show that the proper choices of control parameters may broaden the effective frequency band of vibration absorption. Moreover, the time-delayed absorber greatly suppresses the resonant response of the primary system when the passive absorber totally fails. The experimental results are in good agreement with the theoretical predictions and numerical simulations. A time-delayed acceleration feedback is introduced to convert a passive absorber into an active one. The design scheme of control parameters is performed for selection guidance of the values of feedback gain and time delay. Experimental results show the effectiveness of the time-delayed absorber on suppressing the vibration of the primary system.

Shock and vibration damping arrangement for vehicles

Abstract: not available for EP0027869Abstract of corresponding document: US4368900A mass such as a vehicle or craft, for example an aircraft, is cushioned against landing shocks and vibrations by an electronically controlled shock and vibration absorber system. For this purpose an electrical control signal is produced which takes into account several coefficients through the adjustment of potentiometers in a control circuit which continuously controls the damping characteristic curve of the shock and vibration absorber system.