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Filament-wound flexible pipes are widely used to transport fluid in pipeline systems, proved extremely useful in marine engineering. The hyperbolic flexible pipes have good vibration suppression performance, but they are easily deformed under internal pressure. This paper focuses on the stability of hyperbolic flexible pipes based on the composite Reissner shell theory and the transfer-matrix method. The nonlinear stretch of the reinforced filament and the fiber bridge effect are considered in the model. The calculation results show that a large winding angle reduces the deformation and the meridional stress. The available initial winding angle is limited by the geometry and the slippage coefficient of flexible pipe. The reinforced filament of high tensile modulus will reduce the deformation of the pipe. Compared with the geodesic winding trajectory, non-geodesic winding trajectories improves the stability of the pipe. The theoretical result is verified by the finite element analysis. The investigation method and results present in this paper will guide the design and optimization of more novel flexible pipes in the future.

In this article, the parametric model for the stiffness characteristic and burst pressure of cord-reinforced air spring with winding formation is developed. Based on the non-geostrophic winding model and the assumption of cord cross-stability, the cord winding trajectory model of the capsule is established. Then, the anisotropic and nonlinear mechanics model of the capsule with complex cord winding trajectory variation characteristics is constructed by the classical thin-shell theory. The capsule state vector is solved by the extended homogeneous capacity precision integration method. Due to the complex coupling relationship between the capsule state vector and the internal air pressure, the stiffness characteristic is solved by the iterative integration method. The burst pressure of the air spring is solved by the Tsai–Hill strength theory. Eventually, the accuracy and reliability of the proposed method are verified by the experimental results. The effects of the material properties, winding parameters, and geometric structure parameters on stiffness characteristics and burst pressure are discussed. The results of this article provide an important theoretical basis for the performance design of cord-reinforced air springs with winding formation.

Quasi-zero stiffness (QZS) vibration isolation system is composed of positive stiffness structure and negative stiffness structure. It can obtain high static stiffness and low dynamic stiffness near the static equilibrium position. The benefits of the QZS technology are to realize the low frequency vibration control and solve the contradiction of low natural frequency and small static deformation. In this paper, the research progress for QZS technology in recent years are introduced, and the outlooks are also proposed.

A hybrid isolator consisting of maglev actuator and air spring is proposed and developed for application in active-passive vibration isolation system of ship machinery. The dynamic characteristics of this hybrid isolator are analyzed and tested. The stability and adaptability of this hybrid isolator to shock and swing in the marine environment are improved by a compliant gap protection technique and a disengageable suspended structure. The functions of these new engineering designs are proved by analytical verification and experimental validation of the designed stiffness of such a hybrid isolator, and also by shock adaptability testing of the hybrid isolator. Finally, such hybrid isolators are installed in an engineering mounting loaded with a 200-kW ship diesel generator, and the broadband and low-frequency sinusoidal isolation performance is tested.

Maglev actuator is excellent for active vibration isolation, with non-contact form, low stiffness and rapid response. However, the actuators nonlinearity has to be restrained by the control algorithm. In this paper, the nonlinearity of maglev actuator was studied through theoretical analysis and experiment. An improved multi-channel FxLMS(filtered-x least mean square) algorithm was proposed, which considers the nonlinearity-induced harmonic frequency as extra line-spectrum excitation to control. Experiments showed that the improved FxLMS algorithm could efficiently compensate the nonlinearity of the actuators, thus had better effect when used in active vibration isolation system with non-linear actuators, compared with the traditional FxLMS method.

The paper presents a methodology to calculate the vertical stiffness of air spring. Investigation is focused on a convoluted air spring with one lobe. Based on the configuration of the membrane of the air spring and the geometry during its deflection, a stiffness expression dependant on the deflection is obtained. To have a good understanding of the performance of a single-degree-of-freedom system consisted of an air spring and a sprung mass, the paper provides an algorithm to simulate the motion of the system. The algorithm is a numerical step-by-step integration which combines explicit and implicit algorithms. A stiffness updating method based on the said stiffness expression is used in the dynamic simulation algorithm.Copyright © 2005 by ASME

The stress of curved rubber hose with inner pressure is analyzed. On the base of the spiraled geometrical configuration of fiber around the curved rubber hose, the formulation of its neutral angle and compression strength is derived. The theoretical analysis and experimental results indicate that the axial stress of curved rubber hose with inner pressure is the same as that of straight rubber hose, and the hoop stress of curved rubber hose with inner pressure reaches the maximum value on the inside of its camber line and the minimum value on its outside respectively. The compression strength of curved rubber hose is not only dependent on the strength, layer and spiraled density of reinforced materials, but also on its geometrical configuration.Copyright © 2005 by ASME

The characteristics of control parameters of air spring with rubber bellow are analyzed through finite element method and thermodynamic equation respectively. The analysis results indicate that the vertical stiffness of air spring is sensitive to the varying of vertical displacement and volume, and nonlinearly varies with vertical displacement. When the air spring is pressed down or pulled up under the exterior excitation, the height of air spring can be controlled to keep stable through adjusting the volume of air spring by the use of hydraulic transformer.Copyright © 2005 by ASME