engleski

On the occurrence of vibro-impact-regimes in the dynamical system with clearances

Vibration of mechanical systems with clearances can result in relative motion across the clearance space and impacting between the components. Repeated impacts (vibro-impacts) may lead to excessive noise and large changes in the dynamic stiffness. An analysis of such systems is a complex problem which includes an abrupt variation of stiffness, usually modelled as piecewise linear. Vibro-impacts can be separated into three different regimes: a no-impact regime, a single-sided impact and a two-sided impact. A no-impact case occurs whenever the displacement is entirely inside one of the stage stiffness regions. A single-sided impact or a two-sided impact will occur when the displacement exceeds the stiffness breakpoint at one or both sides, respectively [1]. A two-degree-of-freedom system with clearances can be viewed as two coupled nonlinear oscillators. Each oscillator may undergo any of the impact regimes, so the system may be experienced to a total of 3 x 3 = 9 different impact regimes. The objective of this paper is to find the frequency range whether a given impact regime, in the two-degree-of-freedom system with two clearances, exists and to investigate the motivation of impact regime changes. The harmonic balance method and the time finite element method [2] are used for obtaining approximate analytical and numerical frequency responses. The stability of numerical solutions is examined using Poincare` map [3]. Considering the obtained responses, the amplitude ranges of different impact regimes can be determined, as well as, the frequencies at which the transition between impact regimes will occur. Close agreement is found between the solutions resulting from both approaches.

Nonlinear Vibrations; Clearances; Vibro-Impact Regimes

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