Analytical Solutions to H∞ and H2 Optimization of Dynamic Vibration Absorbers Attached to Damped Linear Systems

2002 ◽  
Vol 124 (2) ◽  
pp. 284-295 ◽  
Author(s):  
Toshihiko Asami ◽  
Osamu Nishihara ◽  
Amr M. Baz
Keyword(s):  
Analytical Solutions ◽  
Series Solution ◽  
Numerical Solutions ◽  
Optimization Problems ◽  
Maximum Amplitude ◽  
Algebraic Solution ◽  
Primary System ◽  
Dynamic Vibration Absorber ◽  
Dynamic Vibration ◽  
H2 Optimization

H ∞ and H2 optimization problems of the Voigt type dynamic vibration absorber (DVA) are classical optimization problems, which have been already solved for a special case when the primary system has no damping. However, for the general case including a damped primary system, no one has solved these problems by algebraic approaches. Only the numerical solutions have been proposed until now. This paper presents the analytical solutions for the H∞ and H2 optimization of the DVA attached to the damped primary systems. In the H∞ optimization the DVA is designed such that the maximum amplitude magnification factor of the primary system is minimized; whereas in the H2 optimization the DVA is designed such that the squared area under the response curve of the primary system is minimized. We found a series solution for the H∞ optimization and a closed-form algebraic solution for the H2 optimization. The series solution is then compared with the numerical solution in order to check the accuracy in connection with the truncation error of the series. The exact solution presented in this paper is too complicated to handle by a hand-held calculator, so we proposed an approximate solution for the practical object.

Exact Algebraic Solution of an Optimal Double-Mass Dynamic Vibration Absorber Attached to a Damped Primary System

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
Toshihiko Asami
Keyword(s):  
Optimization Problems ◽  
Algebraic Solution ◽  
Vibration Absorber ◽  
Primary System ◽  
Dynamic Vibration Absorber ◽  
Excitation System ◽  
Double Mass ◽  
Series Type ◽  
Algebraic Solutions ◽  
H2 Optimization

Abstract This article presents exact algebraic solutions to optimization problems of a double-mass dynamic vibration absorber (DVA) attached to a viscous damped primary system. The series-type double-mass DVA was optimized using three optimization criteria (the H∞ optimization, H2 optimization, and stability maximization criteria), and exact algebraic solutions were successfully obtained for all of them. It is extremely difficult to optimize DVAs when there is damping in the primary system. Even in the optimization of the simpler single-mass DVA, exact solutions have been obtained only for the H2 optimization and stability maximization criteria. For H∞ optimization, only numerical solutions and an approximate perturbation solution have been obtained. Regarding double-mass DVAs, an exact algebraic solution could not be obtained in this study in the case where a parallel-type DVA is attached to the damped primary system. For the series-type double-mass DVA, which was the focus of the present study, an exact algebraic solution was obtained for the force excitation system, in which the disturbance force acts directly on the primary mass; however, an algebraic solution was not obtained for the motion excitation system, in which the foundation of the system is subjected to a periodic displacement. Because all actual vibration systems involve damping, the results obtained in this study are expected to be useful in the design of actual DVAs. Furthermore, it is a great surprise that an exact algebraic solution exists even for such complex optimization problems of a linear vibration system.

H 2 Optimization of the Three-Element Type Dynamic Vibration Absorbers

2002 ◽  
Vol 124 (4) ◽  
pp. 583-592 ◽  
Author(s):  
Toshihiko Asami ◽  
Osamu Nishihara
Keyword(s):  
Optimization Design ◽  
Random Excitation ◽  
Control Device ◽  
Algebraic Solution ◽  
Primary System ◽  
Dynamic Vibration Absorber ◽  
Dynamic Vibration ◽  
Optimum Parameters ◽  
Element Type ◽  
H2 Optimization

The dynamic vibration absorber (DVA) is a passive vibration control device which is attached to a vibrating body (called a primary system) subjected to exciting force or motion. In this paper, we will discuss an optimization problem of the three-element type DVA on the basis of the H2 optimization criterion. The objective of the H2 optimization is to reduce the total vibration energy of the system for overall frequencies; the total area under the power spectrum response curve is minimized in this criterion. If the system is subjected to random excitation instead of sinusoidal excitation, then the H2 optimization is probably more desirable than the popular H∞ optimization. In the past decade there has been increasing interest in the three-element type DVA. However, most previous studies on this type of DVA were based on the H∞ optimization design, and no one has been able to find the algebraic solution as of yet. We found a closed-form exact solution for a special case where the primary system has no damping. Furthermore, the general case solution including the damped primary system is presented in the form of a numerical solution. The optimum parameters obtained here are compared to those of the conventional Voigt type DVA. They are also compared to other optimum parameters based on the H∞ criterion.

Closed-Form Solutions to the Exact Optimizations of Dynamic Vibration Absorbers (Minimizations of the Maximum Amplitude Magnification Factors)

2002 ◽  
Vol 124 (4) ◽  
pp. 576-582 ◽  
Author(s):  
Osamu Nishihara ◽  
Toshihiko Asami
Keyword(s):  
Exact Solutions ◽  
Closed Form ◽  
Maximum Amplitude ◽  
Primary System ◽  
Magnification Factor ◽  
Dynamic Vibration Absorber ◽  
Dynamic Vibration ◽  
Classic Problem ◽  
Resonance Frequencies ◽  
Minimum Amplitude

A typical design problem for which the fixed-points method was originally developed is that of minimizing the maximum amplitude magnification factor of a primary system by using a dynamic vibration absorber. This is an example of usual cases for which their exact solutions are not obtained by the well-known heuristic approach. In this paper, more natural formulation of this problem is studied, and algebraic closed-form exact solutions to both the optimum tuning ratio and the optimum damping coefficient for this classic problem are derived under assumption of undamped primary system. It is also proven that the minimum amplitude magnification factor, resonance and anti-resonance frequencies are entirely algebraic.

OPTIMAL DESIGN OF DAMPED DYNAMIC VIBRATION ABSORBER FOR DAMPED PRIMARY SYSTEMS

2010 ◽  
Vol 34 (1) ◽  
pp. 119-135 ◽  
Author(s):  
Kefu Liu ◽  
Gianmarc Coppola
Keyword(s):  
Optimal Design ◽  
Optimum Design ◽  
Nonlinear Equations ◽  
Analytical Solutions ◽  
Vibration Absorber ◽  
Primary System ◽  
Dynamic Vibration Absorber ◽  
Classical Systems ◽  
Dynamic Vibration ◽  
Numerical Approaches

This study focuses on the optimum design of the damped dynamic vibration absorber (DVA) for damped primary systems. Different from the conventional way, the DVA damper is connected between the absorber mass and the ground. Two numerical approaches are employed. The first approach solves a set of nonlinear equations established by the Chebyshev’s equioscillation theorem. The second approach minimizes a compound objective subject to a set of the constraints. First the two methods are applied to classical systems and the results are compared with those from the analytical solutions. Then the modified Chebyshev’s equioscillation theorem method is applied to find the optimum damped DVAs for the damped primary system. Various results are obtained and analyzed.

scholarly journals Effect of Inerter in Traditional and Variant Dynamic Vibration Absorbers for One Degree-of-Freedom Systems Subjected to Base Excitations

2019 ◽  
Vol 23 (1) ◽  
pp. 9-16
Author(s):  
Dheepakram Laxmimala Barathwaaj ◽  
Sujay Yegateela ◽  
Vivek Vardhan ◽  
Vignesh Suresh ◽  
Devarajan Kaliyannan
Keyword(s):  
Damping Ratio ◽  
Maximum Amplitude ◽  
Vibration Absorber ◽  
Primary System ◽  
Base Excitation ◽  
Mass Ratio ◽  
Magnification Factor ◽  
Dynamic Vibration Absorber ◽  
Optimum Frequency ◽  
Dynamic Vibration

Abstract In this paper, closed-form optimal parameters of inerter-based variant dynamic vibration absorber (variant IDVA) coupled to a primary system subjected to base excitation are derived based on classical fixed-points theory. The proposed variant IDVA is obtained by adding an inerter alone parallel to the absorber damper in the variant dynamic vibration absorber (variant DVA). A new set of optimum frequency and damping ratio of the absorber is derived, thereby resulting in lower maximum amplitude magnification factor than the inerter-based traditional dynamic vibration absorber (traditional IDVA). Under the optimum tuning condition of the absorbers, it is proved both analytically and numerically that the proposed variant IDVA provides a larger suppression of resonant vibration amplitude of the primary system subjected to base excitation. It is demonstrated that adding an inerter alone to the variant DVA provides 19% improvement in vibration suppression than traditional IDVA when the mass ratio is less than 0.2 and the effective frequency bandwidth of the proposed IDVA is wider than the traditional IDVA. The effect of inertance and mass ratio on the amplitude magnification factor of traditional and variant IDVA is also studied.

scholarly journals Parameters Optimization for a Kind of Dynamic Vibration Absorber with Negative Stiffness

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Yongjun Shen ◽  
Xiaoran Wang ◽  
Shaopu Yang ◽  
Haijun Xing
Keyword(s):  
Analytical Solution ◽  
Fixed Points ◽  
Numerical Solutions ◽  
Negative Stiffness ◽  
Vibration Absorber ◽  
Primary System ◽  
Stiffness Ratio ◽  
Dynamic Vibration Absorber ◽  
Dynamic Vibration ◽  
Frequency Curves

A new type of dynamic vibration absorber (DVA) with negative stiffness is studied in detail. At first, the analytical solution of the system is obtained based on the established differential motion equation. Three fixed points are found in the amplitude-frequency curves of the primary system. The design formulae for the optimum tuning ratio and optimum stiffness ratio of DVA are obtained by adjusting the three fixed points to the same height according to the fixed-point theory. Then, the optimum damping ratio is formulated by minimizing the maximum value of the amplitude-frequency curves according toH∞optimization principle. According to the characteristics of negative stiffness element, the optimum negative stiffness ratio is also established and it could still keep the system stable. In the end, the comparison between the analytical and the numerical solutions verifies the correctness of the analytical solution. The comparisons with three other traditional DVAs under the harmonic and random excitations show that the presented DVA performs better in vibration absorption. This result could provide theoretical basis for optimum parameters design of similar DVAs.

scholarly journals Attenuation of Motorcycle Handle Vibration Using Dynamic Vibration Absorber

2018 ◽  
Vol 217 ◽  
pp. 01006
Author(s):  
Muhammad Iyad Al-Maliki Saifudin ◽  
Nabil Mohamad Usamah ◽  
Zaidi Mohd Ripin
Keyword(s):  
Vibration Absorber ◽  
Primary System ◽  
Additional Source ◽  
Dynamic Vibration Absorber ◽  
Vibration Absorption ◽  
The Road ◽  
Dynamic Vibration ◽  
Attenuation Level ◽  
Road Surface Roughness ◽  
Extended Exposure

Motorcycle riders are exposed to hand-transmitted vibration of the hand-arm system due to the vibration of the handle and extended exposure can result in numbness and trembling. One feasible solution to attenuate the handle vibration is by using a dynamic vibration absorber (DVA). In this work a DVA is designed and mounted on the motorcycle handle in order to reduce the vibration at the handle by transferring the vibration from the primary system handle to the secondary mass. Removal of elastomeric material at the DVA mounting locations, symmetry of secondary mass and the direction of DVA attachment influence the vibration absorption. A series of tests conducted show that the vibration on the handle is mainly induced by the engine and there is additional source of vibration from the road surface roughness. Installation of DVA at different locations on the handle resulted in various attenuation levels at different speed in the x and z directions. the attenuation level is between 59-68 % in the biodynamic x-directions for speed at 30-50 kmh-1.

Exact Optimization of a Three-Element Dynamic Vibration Absorber: Minimization of the Maximum Amplitude Magnification Factor

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Osamu Nishihara
Keyword(s):  
Maximum Amplitude ◽  
Resonance Curve ◽  
Element Model ◽  
Optimality Criteria ◽  
Simultaneous Equations ◽  
Vibration Absorber ◽  
Magnification Factor ◽  
Dynamic Vibration Absorber ◽  
Dynamic Vibration ◽  
Numerical Computing

In this study, the maximum amplitude magnification factor for a linear system equipped with a three-element dynamic vibration absorber (DVA) is exactly minimized for a given mass ratio using a numerical approach. The frequency response curve is assumed to have two resonance peaks, and the parameters for the two springs and one viscous damper in the DVA are optimized by minimizing the resonance amplitudes. The three-element model is known to represent the dynamic characteristics of air-damped DVAs. A generalized optimality criteria approach is developed and adopted for the derivation of the simultaneous equations for this design problem. The solution of the simultaneous equations precisely equalizes the heights of the two peaks in the resonance curve and achieves a minimum amplitude magnification factor. The simultaneous equations are solvable using the standard built-in functions of numerical computing software. The performance improvement of the three-element DVA compared to the standard Voigt type is evaluated based on the equivalent mass ratios. This performance evaluation is highly accurate and reliable because of the precise formulation of the optimization problem. Thus, the advantages of the three-element type DVA have been made clearer.

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