Dynamics and Control of Machines

摘要

Machine dynamics is the fundamental basis for optimal machine design. Based on dynamic analysis of the system special control, damping and counterbalance arrangements can be foreseen, which would simplify operations, adjustment and maintenance during the lifetime of the machine. According to the authors’ preface, the aim of writing the book has been to provide practitioners and graduate students with the basic principles of contemporary machine dynamics with emphasis on the qualitative understanding of machine operations. Accordingly, the approach of the book is analytical rather than numerically oriented with the mathematical analysis kept at a minimum. Dynamic equations of machines with a single driver and a single mechanism (two-degree-of-freedom systems) are thoroughly analyzed in steady state and transient operation modes. The non-linear equations of motion are derived based on classical analytical (Lagrangian) mechanics. The level of generalization of the formulation is relatively high. Illustrative examples representing the derivation of some simple machines with or without compliance would have been useful. The equation of motion is generalized to multi-degree-of-freedom chained systems. The analytical treatment of the equations of motion is based on a 1st order perturbation technique, where the 0th and 1st order problems are solved by classical linear modal analysis. The book provides an instructive treatment of the principles for control of unintended machine vibrations and performance error reduction. Both passive (tuned mass dampers) and active (feed-back) control strategies are outlined for a number of specific case studies. The approach to control theory is the classical one (cascade of single-input single-output control elements, stability criterion based on Nyquist plots, etc.), although the particular dynamic features of digital control are emphasized. Modern approaches for multi-degree-of-freedom systems (optimal control, adaptive strategies, etc.) based on state vector formulations are not dealt with. Because a variety of control problems have been worked, the book may be useful for practitioners with basic knowledge in structural dynamics in analyzing machine dynamics and associated control problems. However, it can hardly stand alone as a postgraduate textbook in the field. First, the number of illustrative examples is relatively small, especially in the first half of the book, and exercises are totally lacking. Secondly, the book is based on concepts developed by the authors, previously published in Russian sources. This is reflected by the bibliography, which is dominated by older Russian references. Here an updated literature review of more recent developments in the field would be desirable. Finally, the English translation deviates in several cases from common practice in mechanics. For example, the principle of virtual work is referred to as the equation of elementary work, and perturbation analysis is designated as the method of successive approximations. There are many good books on mechanical vibrations, and on impact dynamics. But this seems to be the only monograph in English dealing thoroughly with vibro-impact systems and processes. Such processes involve colliding elements, and vibrations with abrupt changes in velocity and force during each cycle. Applications include devices to crush, grind, forge, rivet, drill, punch, tamp, print, tighten, pile, cut, and surface treat a variety of materials and objects, at frequencies ranging from sub-Hz to ultrasonic. Typically, to minimize input force and energy, these systems are driven at resonance, and utilize impacts to maximize output force. How can such processes be described, quantified, modeled, analyzed, controlled, suppressed, enhanced, and synthesized? Prof. Babitsky’s Theory of Vibro-Impact Systems and Applications answers these questions with unquestionable authority, reflecting the author’s position as a leading expert and main contributor