Parametric stability in a silicon model of the leech swim oscillator

Author(s):  
S. Wolpert
Keyword(s):  
Author(s):  
Tyler J. Selstad ◽  
Kambiz Farhang ◽  
David Chelidze

Abstract Electrorheological (ER) fluids are known to exhibit damping and stiffness properties which are highly dependent on the induced electrical field strength within the ER medium. Incorporation of ER fluid within a structural member then provides a means of stiffness and damping variation of the member. A structural member with embedded ER fluid is considered. Equations governing the axial and transverse motions of the member are reduced to a system of linear ordinary differential equations with time-varying coefficients. Application of the multiple time scales method results in amplitude-frequency relations. A control method is considered in which the effect of embedded ER fluid damping modulation using a simple harmonic excitation voltage on the parametric stability boundaries of the member is examined. Results indicate that the parametric stability boundaries can change effecting various modulation amplitudes and frequencies.


2018 ◽  
Vol 10 (28) ◽  
pp. 50-63
Author(s):  
mina moghaddaszadeh ◽  
Rasool Asghari Zakaria ◽  
Davoud Hassanpanah ◽  
naser zare ◽  
◽  
...  

2019 ◽  
Vol 286 ◽  
pp. 01008
Author(s):  
A. Azrar ◽  
N. Fakri ◽  
A.A. Aljinaidi ◽  
L. Azrar

The dynamic analysis instability of axially moving rectangular composite graphene sheets with visco elastic foundation is modeled and numerically simulated for various boundary conditions based on the differential quadrature method (DQM). The partial differential equation of motion based on the nonlocal elasticity and the Kirchhoff plate theories is given. The Galerkin and harmonic balance methods are used for the linear and parametric vibration analysis. The influences of nonlocal parameter, the fibers orientation and the viscoelastic foundation effects on the dynamic behaviors of the rectangular graphene sheet as well as the instabilities induced by the time dependent axial speed and its excitation frequency are investigated.


2011 ◽  
Vol 134 (1) ◽  
Author(s):  
Li-Qun Chen ◽  
You-Qi Tang

In this paper, the parametric stability of axially accelerating viscoelastic beams is revisited. The effects of the longitudinally varying tension due to the axial acceleration are highlighted, while the tension was approximately assumed to be longitudinally uniform in previous studies. The dependence of the tension on the finite support rigidity is also considered. The generalized Hamilton principle and the Kelvin viscoelastic constitutive relation are applied to establish the governing equations and the associated boundary conditions for coupled planar motion of the beam. The governing equations are linearized into the governing equation in the transverse direction and the expression of the longitudinally varying tension. The method of multiple scales is employed to analyze the parametric stability of transverse motion. The stability boundaries are derived from the solvability conditions and the Routh-Hurwitz criterion for principal and sum resonances. In terms of stability boundaries, the governing equations with or without the longitudinal variance of tension are compared and the effects of the finite support rigidity are also examined. Some numerical examples are presented to demonstrate the effects of the stiffness, the viscosity, and the mean axial speed on the stability boundaries. The differential quadrature scheme is developed to numerically solve the governing equation, and the computational results confirm the outcomes of the method of multiple scales.


Author(s):  
Qingbin Gao ◽  
Umut Zalluhoglu ◽  
Nejat Olgac

The stability boundaries of LTI time-delayed systems with respect to the delays are studied in two different domains: (i) delay space (DS) and (ii) spectral delay space (SDS), which contains pointwise frequency information as well as the delay. SDS is the preferred domain due to its advantageous boundedness properties and simple construct of stability transition boundaries. These transitions at the mentioned boundaries, however, present some conceptual challenges in SDS. This transition property enables us to extract the corresponding local stability variation properties in the DS, while it does not have any implication in the preferred SDS. The novel aspect of the investigation is to introduce a comparison mechanism between these two domains, DS and SDS, from the stability transition perspective. Interestingly, we are able to prove their equivalency, which provides complementary insight to the parametric stability variations.


2017 ◽  
Vol 30 (2) ◽  
pp. 719-742
Author(s):  
Gerson Cruz Araujo ◽  
Hildeberto E. Cabral

Sign in / Sign up

Export Citation Format

Share Document