Steady state oscillations and stability of non-linear dynamic vibration absorbers

1992 ◽  
Vol 156 (2) ◽  
pp. 227-245 ◽  
Author(s):  
S. Natsiavas
Keyword(s):  
Steady State ◽  
Vibration Absorbers ◽  
Linear Dynamic ◽  
Dynamic Vibration ◽  
Non Linear ◽  
Dynamic Vibration Absorbers

Sequential design of two orthogonal dynamic vibration absorbers in a pendulum based on stability maximization

2012 ◽  
Vol 226 (11) ◽  
pp. 2645-2655 ◽  
Author(s):  
LD Viet
Keyword(s):  
Tangential Direction ◽  
Normal Direction ◽  
Vibration Absorber ◽  
Vibration Absorbers ◽  
Dynamic Vibration Absorber ◽  
Linear Dynamic ◽  
Dynamic Vibration ◽  
Dynamic Vibration Absorbers ◽  
Small Benefit ◽  
The Stability

A dynamic vibration absorber moving in the tangential or in the normal direction of a pendulum’s orbit can reduce the free vibration of the pendulum. This article discusses the problem of a pendulum structure attached with two dynamic vibration absorbers moving orthogonally at the same time. The analytical optimization is proposed to be done in two steps, in which the parameters of the linear dynamic vibration absorber moving in tangential direction and the non-linear dynamic vibration absorber moving in normal direction are chosen sequentially based on the stability maximization criterion. The analytical analysis shows that the two-dynamic vibration absorber scheme has small benefit in comparison with the single-dynamic vibration absorber scheme. The analytical conclusions are verified by numerical calculations. Although the conclusion of the article is unexpected, it is important in practice because the two-dynamic vibration absorber arrangement can be excluded in the design.

Structural Optimization of Cantilever Mechanical Elements

1986 ◽  
Vol 108 (4) ◽  
pp. 427-433 ◽  
Author(s):  
Eugene I. Rivin
Keyword(s):  
Structural Optimization ◽  
Natural Frequencies ◽  
Superior Performance ◽  
Vibration Absorbers ◽  
Stability Margins ◽  
Dynamic Vibration ◽  
Robot Arms ◽  
Limited Effectiveness ◽  
Mass Ratios ◽  
Dynamic Vibration Absorbers

Naturally limited stiffness of cantilever elements due to lack of constraint from other structural components, together with low structural damping, causes intensive and slow-decaying transient vibrations as well as low stability margins for self-excited vibrations. In cases of dimensional limitations (e.g., boring bars), such common antivibration means as dynamic vibration absorbers have limited effectiveness due to low mass ratios. This paper describes novel concepts of structural optimization of cantilever components by using combinations of rigid and light materials for their design. Two examples are given: tool holders (boring bars) and robot arms. Optimized boring bars demonstrate substantially increased natural frequencies, together with the possibility of greatly enhanced mass ratios for dynamic vibration absorbers. Machining tests with combination boring bars have been performed in comparison with conventional boring bars showing superior performance of the former. Computer optimization of combination-type robot arms has shown a potential of 10–60 percent reduction in tip-of-arm deflection, together with a commensurate reduction of driving torque for a given acceleration, and a higher natural frequencies (i.e., shorter transients). Optimization has been performed for various ratios of bending and joint compliance and various payloads.

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