National Repository of Grey Literature 2 records found  Search took 0.01 seconds. 
Stochastic stability of the generalized van der Pol system under random additive excitation
Náprstek, Jiří ; Fischer, Cyril
The paper is motivated by a series of wind tunnel experiments investigating aeroelastic SDOF and TDOF section models of various shape and aeroelastic properties. It reveals that most of them can be theoretically modeled by the van der Pol – Duffing type equations or their combination adjusting degree of individual nonlinear terms or their coefficients. It should be emphasized that this character of the system response is very stable and is obvious in linear as well as in weakly nonlinear domain when the post-critical effect emerges. Moreover, many special effects identified by an experimental way evoke properties recognized in the pure theory of differential equations.
Numerical assessment of stability of the ball vibration absorber
Fischer, Cyril ; Náprstek, Jiří
The ball vibration absorber (BVA) is in principle a heavy ball rolling inside a semi-spherical cavity. It is a convenient alternative to the usual pendulum-based dampers. The dynamics of the real ball absorber is significantly more complicated in comparison to the pendulum one. However, the numerical examination of the non-linear model of the BVA indicates that its resonance behaviour is similar to the spherical pendulum. Despite the theoretical differences, the resonance curves in both cases form similar patterns. It seems that detailed study of both separate cases can provide complementary results, whose parallels appear in the other model.

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