Моделювання коливальних процесів віброударних систем

Abstract

In order to improve the efficiency of methods and means of mathematical modeling of vibro-impact systems, a generalized function of the periodic mode of movement of the executive body has been developed. It is presented in the form of the dependence of the shock impulse on the ratio of the angular velocities of the linear conservative system and its own. When obtaining this function, the Heaviside integral jump function and the periodic Green's function were used. The function of the dependence of the oscillation frequency on the impact impulse is determined from the impact conditions for the function of the system's response to a periodic sequence of impulses. The design model of a vibroimpact system is considered, both with one impact element and a motion limiter, and with a double-sided impact pair with alternate impact interactions with the limiters. In the intervals between impacts, there is a linear force interaction. When developing the mathematical model, a stereomechanical impact model was used, which is characterized by the velocity recovery coefficient after the impact. The analysis of the dependence function of the oscillation frequency on the shock impulse made it possible to obtain skeletal diagrams of resonant and quasi-resonant oscillations of vibro-impact systems with one and many degrees of freedom. Based on the obtained phase diagrams of the state of vibro-impact systems, it was determined: in a system with a gap, an increase in the impact speed increases the oscillation frequency, and the vibro-impact nonlinearity is «hard»; in a system with tension, with an increase in the value of the shock impulse, the oscillation frequency decreases (nonlinearity is «soft»). In the absence of a gap, the system is isochronous. Depending on the initial energy reserve and the location of the limiters in an asymmetric oscillatory system, with one degree of freedom, there can be vibro-impact modes with both one (closer located) and both limiters. In a linear conservative system with several degrees of freedom, a single-impact T-periodic regime is realized. If the dissipation during motion and impact is very small, then a regime close to resonant can exist in the system. In this case, periodic oscillations are supported by a weak external periodic force. The developed mathematical model makes it possible to fully describe the process of changing the relative coordinate of the movement of the working body, both in transient and in the established modes of movement of the system.