An Investigation Of Vibration Isolation Systems Using Active Semi Active And Tunable Passive Mechanisms With Applications To Vehicle Suspensions

In this dissertation, an analytical investigation on active, semi-active and passive vibration control mechanisms is presented in order to achieve improved shock and vibration isolation of mechanical systems, especially ground vehicle applications. A hybrid active vibration isolation system, incorporating an electro-magnetic force generator along with passive damping and spring elements, is mathematically modeled based on fundamental physical laws and taking into account the generator dynamics. Complete vibration isolation characteristics of the hybrid active control system are evaluated for various feedback variables and control schemes, using numerical simulations. Influence of the force generator dynamics on vibration isolation performance is illustrated through the simulation results. A concept of tunable pressure limiting modulation is proposed in hydraulic damper systems. A hydraulic orifice damper is modified by using the proposed tunable pressure limiting modulation to achieve variable damping in vibration isolation systems, without requiring any external energy source, sophisticated control devices and feedback instrumentation that are essential for active and semi-active isolators. The fluid flow equations are employed to develop the nonlinear mathematical model of the hydraulic damper, incorporating the fluid and mechanical compliance, and the dynamics of the pressure limiting mechanism. The computer simulation reveals that the shock and vibration isolation performance of the tunable pressure limited hydraulic damper systems is comparable to that of the semi-active 'on-off' vibration control systems. A generalized harmonic linearization technique, based on a principle of energy similarity of dynamic elements, is proposed to derive equivalent linear representations of both nonlinear damping and spring elements, in the frequency domain. An analysis of the nonlinear in-plane vehicle model, with air-springs, orifice damping and pressure limiting modulation due to tunable hydraulic shock absorbers, is carried out to establish the stochastic response to random road inputs in terms of power spectral density, and to illustrate the improved vehicle ride performance due to tunable shock absorbers. An interconnected hydro-pneumatic suspension with tunable pressure limiting mechanism is presented to achieve improved vehicle ride and handling performance. Analysis of a roll plane model of a vehicle employing the tunable interconnected suspension shows that the connections of fluid flow within the interconnected suspension provide an enhanced static roll stability; while the tunable pressure limiting modulation between the strut and the accumulator of each suspension unit offers an improved vehicle ride performance.

This book discusses efforts to control the low-frequency vibration transmission of typical power equipment and pipeline systems of ships, exploring the use of active and passive hybrid vibration isolation and adjustable dynamic vibration absorption technologies. It also proposes an adaptive feed-forward control strategy and studies a distributed feed-forward control hardware system. In addition, the book presents a three-way dynamic vibration absorption theory used to design a pipeline-system adjustable dynamic vibration absorber, which offers a number of advantages, such as compact structure, easy assembly and disassembly, low power consumption, excellent vibration control effect and wide frequency band adjustable ability, etc. This book is a valuable resource for researchers and engineers in the fields of noise and vibration control, active control systems, active vibration isolation and adaptive dynamic vibration absorption.

This book contains the select papers presented at the International Conference on Progressive Research in Industrial & Mechanical Engineering (PRIME 2021), held at the National Institute of Technology (NIT) Patna, India. The book discusses various aspects related and relevant to core areas of mechanical engineering including engineering design, production engineering, industrial engineering, automobile engineering, thermal and fluids engineering, mechatronics, control and robotics and other inter-disciplinary emerging topics for potential use in a spectrum of applications. The book will be a valuable reference for students, researchers and professionals interested in mechanical engineering and allied fields.

Researchers have studied many methods of using active and passive control devices for absorbing vibratory energy. Active devices, while providing significant reductions in structural motion, typically require large (and often multiply-redundant) power sources, and thereby raise concerns about stability. Passive devices are fixed and cannot be modified based on information of excitation or structural response. Semiactive devices on the other hand can provide significant vibration reductions comparable to those of active devices but with substantially reduced power requirements and in a stable manner. Technology of Semiactive Devices and Applications in Vibration Mitigation presents the most up-to-date research into semiactive control systems and illustrates case studies showing their implementation and effectiveness in mitigating vibration. The material is presented in a way that people not familiar with control or structural dynamics can easily understand. Connecting structural dynamics with control, this book: Provides a history of semiactive control and a bibliographic review of the most common semiactive control strategies. Presents state-of-the-art semiactive control systems and illustrates several case studies showing their implementation and effectiveness to mitigate vibration. Illustrates applications related to noise attenuation, wind vibration damping and earthquake effects mitigation amongst others. Offers a detailed comparison between collocated and non-collocated systems. Formulates the design concepts and control algorithms in simple and readable language. Includes an appendix that contains critical considerations about semiactive devices and methods of evaluation of the original damping of a structure. Technology of Semiactive Devices and Applications in Vibration Mitigation is a must-have resource for researchers, practitioners and design engineers working in civil, automotive and mechanical engineering. In addition it is undoubtedly the key reference for all postgraduate students studying in the field.

This book presents the research results of advanced vibration control technology, based on two types of typical equipment in industrial engineering of China: power equipment and vibration-sensitive equipment. The main contents of this book include optimized active control strategy research, semi-active control research that can track and equivalently achieve active control effects, refined analysis of active control based on finite element method, research on the impact of vibration isolator layout on vibration isolation performance, passive and active control research based on system freedom decoupling and load decoupling, realized passive and active control research using quasi-zero stiffness system based on positive and negative stiffness, intelligent sensors optimization deployment of plane and space structure, and related key technology application cases in engineering applications. This book provides useful references for engineers and researchers in industrial engineering and technical support for practitioners in the development of China's high-end industry.