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The paper explains a concept of a vehicle molecular spring suspension whose stiffness in middle stage can be as low as 13 N/mm. The design of this suspension spring on the basis of a hydrophobic nanoporous material is introduced. The test methods of determining the static and dynamic mechanical properties of the novel suspension spring are described. The rationality of experimental design and the accuracy of theoretical analysis is proved by the negligible error between experimental results and theoretical analysis. The vibration isolation test results show that the natural frequency of the suspension can be as low as 1.06 Hz. [ABSTRACT FROM AUTHOR]

A molecular spring isolator comprising ZIF-8 with hydrophobic micropores, water, and a cylinder/piston unit is introduced. Liquid water can be intruded into the micropores of ZIF-8 under critical pressure. In the meantime, mechanical energy is stored. And once the external pressure is withdrawn, spontaneous capillary evaporation will occur. The stored energy, meanwhile, is released. This behavior is similar to a coil spring. The Laplace–Washburn equation is used to describe the force equilibrium of a single water column in a micropore. After that, the result of water infiltrating a great deal of hydrophobic pores is revealed by theoretical analysis and an experiment. An averaging method is devoted to computing the primary resonance response and its accuracy is proved by the fourth-order Runge–Kutta method. Furthermore, the energy transmissibility is used to estimate its vibration isolation capability. Finally, a vibration isolation test indicated that the inherent frequency of the isolator is as low as 1.3 Hz. [ABSTRACT FROM AUTHOR]

The research on the control mechanism of a covering layer on self-noise of the interior hull field remains underdeveloped. Because the detection function of sonar is greatly affected by the self-noise of the platform area, the sonar dome of composite material exhibits significant self-noise suppression while ensuring sufficient sound penetration. Based on an infinite flat model of a point-force excitation combined with a simplified two-degree-of-freedom system coupled with shell and flexible composite covering layer, the structure of the shell plate with or without a covering layer is analysed, and the expressions for the insertion loss and the degree of isolation of the covering layer in response to the shell vibration are deduced according to mechanical properties. In addition, this paper presents an influence law of a covering layer on the shell system vibration response under different stiffness, mass and damping parameters when the load is on a shell plate or covering layer. The most important contributions of this paper are the interior noise and vibration performance tests of a typical local carbon/glass hybrid reinforced sheet-beam structure with or without an overlying rubber blanket, where the layered material is on the interior of the structure. The experiment was implemented in air. The test model, filled with water, was hung by a flexible rubber band. In addition, the comparison of the structural vibration suppression and noise reduction performance of covering layers was made under different load types. [ABSTRACT FROM AUTHOR]