1,720,982 research outputs found
The Effect of Parametric Excitation on a Self-Excited Three-Mass System
No full textThis contribution deals with the quenching of self-excited vibrations by means of parametric excitation due to periodic variation of spring stiness. A three-mass chain system is investigated in detail. It is shown that the self-excitation can be fully or partly suppressed in a particular frequency interval
The Effect of Dynamic Absorbers for a Parametrically Excited Pendulum Type System: Numerical Results
No full textA Parametrically Excited System with Nonlinear Coupling
No full textA mechanical system consisting of two subsystems which are nonlinearly coupled is considered. The coupling terms in the differential equations of motion are of the second order. One subsystem is parametrically excited, the other being excited only through the nonlinear coupling. The vibration in the parametric resonance is analysed and the effect of nonexcited subsystem on this resonance is investigated
Multi-Frequency Oscillations in Self-Excited Systems
No full textOver the decades, the ISSC committee “Fatigue and Fracture” has been a major contributor to address the impertinence of good science work within the field. Fatigue and fracture mechanics have been an area with high focus on research the last 50 years with several books, publications and conferences covering these topics. Fatigue failure of structures has caused fatalities. The first known and highly addressed accident, which caused loss of several human lives, was the Versailles Railway accident in 1842. Almost 110 years after this accident, a meeting was held in London, U.K., with the most distinguished fatigue specialists at that time. They concluded that even in 1956 it was not a practical proposition to present a detail overview of the topics of metal fatigue since there was already “at least 4 books in the English language” addressing this topic. It is important to notice that the subject is vast and the committee can therefore not cover all topics related to fatigue and fracture. Hence, the topics in the current report have been selected based on the knowledge and interest of the members of the committee. The report is an overview and sometimes detailed description of recent activities within the offshore and ship industry with focus on the latest research on fatigue and fracture. More than 270 publications have been reviewed and referenced. The committee has been in contact with several of the other committees in order to prevent duplications of work within ISSC
Additional Contribution to the Problem of Self-Excited Systems having several Unstable Vibration Modes
No full textParametric Excitation in Nonlinear Dynamics
No full textConsider a one-mass system with two degrees of freedom, non-linearly coupled, with parametric excitation in one direction. Assuming the internal resonance 1:2 and parametric resonance 1:2 we derive conditions for stability of the trivial solution by using both the harmonic balance method and the normal form method of averaging. If the trivial solution becomes unstable, a stable periodic solution may emerge, there are also cases where the trivial solution is stable and co-exists with a stable periodic solution; if both the trivial solution and the periodic solution(s) are unstable, we find an attracting torus with large amplitudes by a Neimark–Sacker bifurcation. The results of the harmonic balance method and averaging are compared, as well as the results on the Neimark–Sacker bifurcation obtained by the numerical software package CONTENT and by averaging. In all cases we have good agreement
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