Vehicle suspension design and dynamics analysis play a key role in enhancement of automotive system performance. Despite extensive developments in actively-controlled suspensions, their commercial applications have been limited due to the associated high cost and weight. Alternative designs in either passive or semi-active suspensions are highly desirable to achieve competitive vehicle performance with relatively lower cost and greater reliability. This dissertation research proposes two hydro-pneumatic suspension strut designs, including a twin-gas-chamber strut, and systematically investigates various concepts in roll- and pitch-coupled suspensions employing hydraulic, pneumatic and hybrid fluidic interconnections between the wheel struts. The proposed strut designs, including single- and twin-gas-chamber struts, offer larger working area and thus lower operating pressure, and integrate damping valves. Nonlinear mathematical models of the strut forces due to various interconnected and unconnected suspension configurations are formulated incorporating fluid compressibility, floating piston dynamics, and variable symmetric and asymmetric damping valves, which clearly show the feedback damping effects of the interconnections between different wheel struts. The properties and dynamic responses of the proposed concepts in roll- and pitch-coupled suspension struts are evaluated in conjunction with in-plane and three-dimensional nonlinear vehicle models. The validity of the vehicle models is demonstrated by comparing their responses with the available measured data. The analyses of the proposed coupled suspensions are performed to derive their bounce-mode, anti-roll, anti-pitch and warp-mode properties, and vehicle dynamic responses to external excitations. These include road roughness, steering and braking, and crosswinds. The results suggest that the fluidically-coupled passive suspension could yield considerable benefits in enhancing vehicle ride and handing performance. Furthermore these offer superior design flexibility. The suspension struts offer a large number of coupling possibilities in the three-dimensions, some of which however would not be feasible, particularly for commercial vehicles where suspension loads may vary considerably. A generalized analytical model for a range of interconnected suspensions is thus developed, and a performance criterion is formulated to assess the feasibility of a particular interconnection in a highly efficient manner. The handling and directional responses of a three-dimensional vehicle model employing X-coupled hydro-pneumatic suspension are evaluated under split-? straight-line braking and braking-in-a-turn maneuvers. The results clearly show that the X-coupled suspension offers enhanced anti-roll and anti-pitch properties while retaining the soft vertical ride and warp properties. Fundamental pitch and vertical dynamics of a road vehicle are also considered to derive a set of essential design rules for suspension design and tuning for realizing desirable pitch performance.

Design of a vehicle suspension involves a difficult compromise among the ride, handling and directional control performance characteristics. While a soft suspension is desired to enhance ride quality, hard suspension springs are required to achieve good handling and directional control performance. Auxiliary roll stiffeners, in conjunction with soft suspension, are frequently used to attain an acceptable compromise between ride and handling performance of a vehicle. Alternatively, an improved compromise between ride and handling can be realized by interconnecting hydro-pneumatic suspension struts in the roll plane. The interconnected suspension can provide soft suspension rate for improved ride quality, and firm roll stiffness and damping for adequate handling and control performance. In this dissertation, a hydro-pneumatic suspension, interconnected in the roll plane, is analytically investigated for its ride and handling performance potentials. A highway bus equipped with the interconnected hydro-pneumatic suspension system is modeled in the roll plane as a four-degrees-of-freedom dynamical system subject to excitations arising from road irregularities and roll moment caused by directional maneuvers. The static and dynamic properties of the interconnected suspension are derived and discussed in terms of its load-carrying capacity, suspension rate, roll stiffness, and damping forces. The ride and handling performance characteristics of the interconnected suspension are deterministic excitations. A passive variable damping mechanism is proposed and investigated to achieve improved vehicle ride quality. The vibration isolation performance characteristics of the interconnected suspension employing the variable damping valves are further investigated for deterministic and random excitations. From the computer simulation results, it is concluded that the interconnected hydro-pneumatic suspension with inherent enhanced anti-roll stiffness and damping characteristics can provide an improved compromise between ride comfort and handling performance of a vehicle.

Hydropneumatic suspension systems combine the excellent properties of gas springs with the favourable damping properties of hydraulic fluids. The advantages of these systems are particularly appropriate for mobile applications, such as agricultural and construction equipment as well as passenger cars, trucks and busses. Based on his 20 years of experience with this technology, Dr. Bauer provides in this book an extensive overview of hydropneumatic suspension systems. Starting with a comparison of different types of suspension systems, the author subsequently describes the theoretical background associated with spring and damping characteristics of hydropneumatic systems. Furthermore, he explains the design of the most important system components and gives an overview of level control systems, various special functions, patents and design examples. Finally, an outlook for future hydropneumatic suspension systems is discussed. Compared to the first edition, this new edition puts an additional focus on damping functions as well as applications / projects and contains various additional details such as proportional valves, all-wheel suspension or dediated power supply. Furthermore, suspension testing has been added as a new chapter.

The International Conference on Mechanical Design and Production has over the years established itself as an excellent forum for the exchange of ideas in these established fields. The first of these conferences was held in 1979. The seventh, and most recent, conference in the series was held in Cairo during February 15-17, 2000. International engineers and scientists gathered to exchange experiences and highlight the state-of-the-art research in the fields of mechanical design and production. In addition a heavy emphasis was placed on the issue of technology transfer. Over 100 papers were accepted for presentation at the conference. Current Advances in Mechanical Design & Production VII does not, however, attempt to publish the complete work presented but instead offers a sample that represents the quality and breadth of both the work and the conference. Ten invited papers and 54 ordinary papers have been selected for inclusion in these proceedings. They cover a range of basic and applied topics that can be classified into six main categories: System Dynamics, Solid Mechanics, Material Science, Manufacturing Processes, Design and Tribology, and Industrial Engineering and its Applications.

This second volume is a compilation of 43 articles representing the scientific and technical advances in various aspects of system dynamics, instrumentation, measurement techniques, simulation and controls, which would serve as an important resource in the field. The articles represent state-of-the-art contributions in the fields of dynamics and control of nonlinear, hybrid and stochastic systems; nonlinear control theory; and adaptive, model predictive and real-time controls with applications involving fault diagnostics, manufacturing systems, vehicular dynamics, simulator designs, smart actuators, etc.

This book consists of 113 selected papers presented at the 2015 International Conference on Mechanical Engineering and Control Systems (MECS2015), which was held in Wuhan, China during January 23-25, 2015. All accepted papers have been subjected to strict peer review by two to four expert referees, and selected based on originality, ability to test ideas and contribution to knowledge.MECS2015 focuses on eight main areas, namely, Mechanical Engineering, Automation, Computer Networks, Signal Processing, Pattern Recognition and Artificial Intelligence, Electrical Engineering, Material Engineering, and System Design. The conference provided an opportunity for researchers to exchange ideas and application experiences, and to establish business or research relations, finding global partners for future collaborations. The conference program was extremely rich, profound and featured high-impact presentations of selected papers and additional late-breaking contributions.

The design of a vehicle suspension involves complex compromises due to conflicting ride comfort and handling requirements. High load capacity and high mass center commercial vehicles, especially, impose greater design challenges due to their relatively low rollover immunity. Road vehicles, invariably, employ auxiliary roll stiffeners such as antiroll bars to realize a better compromise among the roll dynamic and ride comfort performance. The anti-roll bars, however, add considerable weight, exhibit negligible damping and cause stronger coupling between the roll and vertical modes. Alternatively, roll-connected hydro-pneumatic suspensions offer superior anti-roll performance, while preserving the soft vertical ride characteristics. Reported studies have shown that such suspensions can provide anti-roll characteristics similar to an antiroll bar but with considerable roll damping and less weight. The feedback effects of the hydraulic couplings in such suspensions yield negative damping force in the vertical mode, which have not yet been explored. This thesis research presents a systematic study of negative damping features of the roll-coupled hydro-pneumatic suspensions and its significance for realizing variable damping properties. Three different configurations of hydro-pneumatic struts were conceived for realizing hydraulic couplings in the roll plane. Analytical models of the roll-coupled suspensions were formulated considering ideal gas law, turbulent flows through orifices and damping valves, laminar flows through interconnections, floating piston dynamics and fluid compressibility. The analytical formulations were used to describe the negative damping feature attributed to the flow feedbacks. The vertical and roll mode damping and stiffness properties of the proposed configurations were derived via analytical relations, which showed that hydraulic couplings yield high roll stiffness and damping with only minimal effect on the vertical mode properties. The simulation results demonstrated two negative damping force components of a strut attributed to flows through the interconnecting pipes and flows through orifices in the connected strut. These negative damping force components, however, contributed to only positive roll damping moment. A methodology to enhance negative damping force of the connected struts was proposed for realizing variable damping properties similar to those of the conventional damping valves. Deployments of small size multiple interconnections or the flow-control valves across the struts resulted in comprehensive magnitudes of negative damping force components. Simulation results were obtained under lateral acceleration excitation idealizing the centrifugal force encountered during a steady-turn maneuver, a road bump, and in-phase and out-of-phase harmonic road excitations. The results were obtained for unconnected and connected struts with and without the damping valves and interconnection flow valves. Comparisons of the results revealed that interconnection valves can provide variable damping properties similar to the damping valves. The interconnection valves, however, offer greater design/tuning flexibility since these are mounted externally. The results suggested that further efforts in parameterization of the coupling flows will be worthy for realizing optimal damping properties of the roll-coupled hydro-pneumatic suspensions.