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.

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 suspensions 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 automotive applications, such as passenger cars, trucks and agricultural equipment. In this book, Dr. Bauer provides 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 and furthermore explains the design of the most important system components. Additionally he gives an overview of level control systems and various special functions. Finally the technology is illustrated by design examples and the outlook for future hydropneumatic suspensions is discussed.

This proceedings volume gathers the outcomes of the International Conference on Engineering Research and Applications (ICERA 2019), which was held at Thai Nguyen University of Technology, Vietnam, on December 1–2, 2019 and provided an international forum for disseminating the latest theories and practices in engineering research and applications. The conference focused on original research work in a broad range of areas, including Mechanical Engineering, Materials and Mechanics of Materials, Mechatronics and Micromechatronics, Automotive Engineering, Electrical and Electronics Engineering, and Information and Communication Technology. By sharing the latest advances in these fields, the book will help academics and professionals alike to revisit their thinking on sustainable development.

The International Conference on Engineering Research and Applications (ICERA 2022), held on December 1-2, 2022, at Thai Nguyen University of Technology in Thai Nguyen, Vietnam, provided an international forum to disseminate information on latest theories and practices in engineering research and applications. The conference focused on original research work in areas including mechanical engineering, materials and mechanics of materials, mechatronics and micro mechatronics, automotive engineering, electrical and electronics engineering, information and communication technology. By disseminating the latest advances in the field, the Proceedings of ICERA 2022, Advances in Engineering Research and Application, assists academics and professionals alike to reshape their thinking on sustainable development.

Off-road vehicles employed in agriculture, construction, forestry and mining sectors are known to exhibit comprehensive levels of terrain-induced ride vibration and relatively lower directional stability limits, especially for the articulated frame-steered vehicles (AFSV). The transmitted whole-body vibration (WBV) exposure levels to the human operators generally exceed the safety limits defined in ISO-2631-1 and the European Community guidelines. Moreover, the directional stability limits are generally assessed neglecting the contributions due to terrain roughness and kineto-dynamics of the articulated frame steering (AFS) system. Increasing demand for high load capacity and high-speed off-road vehicles raises greater concerns for both the directional stability limits and WBV exposure. The criterion for acceptable handling and stability limits of such vehicles do not yet exist and need to be established. Furthermore, both directional stability performance and ride vibration characteristics are coupled and pose conflicting vehicle suspension design requirements. This dissertation research focuses on enhancement of ride, and roll- and yaw-plane stability performance measures of frame-steered vehicle via analysis of kineto-dynamics of the AFS system and hydro-pneumatic suspensions. A roll stability performance measure is initially proposed for off-road vehicles considering magnitude and spectral contents of the terrain elevations. The roll dynamics of an off-road vehicle operating on random rough terrains were investigated, where the two terrain-track profiles were synthesized considering coherency between them. It is shown that a measure based on steady-turning root-mean-square lateral acceleration corresponding to the sustained period of unity lateral-load-transfer-ratio prior to the absolute-rollover, could serve as a reliable measure of roll stability of vehicles operating on random rough terrains. The simulation results revealed adverse effects of terrain elevation magnitude on the roll stability, while a relatively higher coherency resulted in lower terrain roll-excitation and thereby higher roll stability. The yaw-plane stability limits of an AFSV are investigated in terms of free yaw-oscillations as well as transient steering characteristics through field measurements and simulations of kineto-dynamics of the AFS system. It was shown that employing hydraulic fluid with higher bulk modulus and increasing the steering arm lengths would yield higher yaw stiffness of the AFS system and thereby higher frequency of yaw-oscillations. Greater leakage flows and viscous seal friction within the AFS system struts caused higher yaw damping coefficient but worsened the steering gain and articulation rate. A design guidance of the AFS system is subsequently proposed. The essential objective measures are further identified considering the AFSV's yaw oscillation/stability and steering performances, so as to seek an optimal design of the AFS system. For enhancing the ride performance of AFSV, a simple and low cost design of a hydro-pneumatic suspension (HPS) is proposed. The nonlinear stiffness and damping properties of the HPS strut that permits entrapment of gas into the hydraulic oil were characterized experimentally and analytically. The formation of the gas-oil emulsion was studied in the laboratory, and variations in the bulk modulus and mass density of the emulsion were formulated as a function of the gas volume fraction. The model results obtained under different excitations in the 0.1 to 8 Hz frequency range showed reasonably good agreements with the measured stiffness and damping properties of the HPS strut. The results showed that increasing the fluid compressibility causes increase in effective stiffness but considerable reduction in the damping in a highly nonlinear manner. Increasing the gas volume fraction resulted in substantial hysteresis in the force-deflection and force-velocity characteristics of the strut. A three-dimensional AFSV model is subsequently formulated integrating the hydro-mechanical AFS system and a hydro-pneumatic suspension. The HPS is implemented only at the front axle, which supports the driver cabin in order to preserve the roll stability of the vehicle. The validity of the model is illustrated through field measurements on a prototype vehicle. The suspension parameters are selected through design sensitivity analyses and optimization, considering integrated ride vibration, and roll- and yaw-plane stability performance measures. The results suggested that implementation of HPS to the front unit alone could help preserve the directional stability limits compared to the unsuspended prototype vehicle and reduce the ride vibration exposure by nearly 30%. The results of sensitivity analyses revealed that the directional stability performance limits are only slightly affected by the HPS parameters. Further reduction in the ride vibration exposure was attained with the optimal design, irrespective of the payload variations.