Deep-sea floating platforms are one of the most important large structures for ocean energy exploitation. A new energy-absorbing device named S-shaped Tuned Liquid Column Damper (TLCD) has been invented for the suppression of the horizontal motion and vertical in-plane rotation of a deep-sea floating platform. A conventional tuned liquid column damper has a U-shaped water tunnel to absorb the excessive energy of the main structure. The application of U-shaped dampers in deep-sea floating platforms is difficult due to the restriction of a large horizontal length. A novel S-shaped damper is proposed to retain the same amount of liquid using a shorter S-shaped tunnel. Theoretical and experimental works are conducted and prove that an S-shaped damper needs less than half the horizontal length to provide the same suppression as a U-shaped damper. A coupling calculation model is proposed and followed by the sensitivity analysis. The study demonstrates the applicability of the novel S-shaped damper for the motion suppression in deep-sea floating platforms.

Dual-chamber air springs are used as a key component for vibration isolation in some industrial applications. The working principle of the dual-chamber air spring device as applied to motion suppression of marine structures is similar to that of the traditional air spring, but they differ in their specific characteristics. The stiffness and damping of the dual-chamber air spring device determine the extent of motion suppression. In this article, we investigate the stiffness and damping characteristics of a dual-chamber air spring device applied to marine structure motion suppression using orthogonal analysis and an experimental method. We measure the effects of volume ratio, orifice ratio, excitation amplitude, and frequency on the stiffness and damping of the dual-chamber vibration absorber. Based on the experimental results, a higher-order non-linear regression method is obtained. We achieve a rapid calculation model for dual-chamber air spring stiffness and damping, which can provide guidance to project design.

The compressor is the primary source of noise in a refrigeration system. Most compressors are wrapped with multi-layer sound insulation cotton for noise reduction and sound insulation. We explore the sound insulation law of different polyvinyl chloride thicknesses and non-woven fibers. Polyvinyl chloride with varying thicknesses and non-woven fibers are then combined by bonding to study the sound insulation characteristics of a two-layer composite structure. A sound insulation prediction model is established using the multi-parameter nonlinear regression method. An optimal cost mathematical model is established based on experimental and mathematical methods that can quickly determine the optimal cost scheme for different designs with the same effect.

In the current analysis, an attempt is made to extend a two-dimensional model for absorbed energy capability, and wave dispersion information of the functionally graded graphene nanoplatelets reinforced composite (FG-GPLRC) doubly curved panel coupled with a piezoelectric patch. The material properties of GPLRC layer are modeled by considering viscoelastic relations between stress and strain as well as Halpin-Tsai, and the role of mixture assumptions. FSDT and Hamilton’s principle are taken into consideration for the exact derivation of the general governing equations and boundary conditions of the FG-GPLRC panel coupled with a piezoelectric patch. For developing a precise solution approach, the analytical solution procedure is eventually used. The results demonstrate that viscoelastic parameter, wave number, applied voltage, and thickness of the piezoelectric patch have an important role in the absorbed energy capability, and wave dispersion in the FG-GPLRC panel coupled with a piezoelectric patch. The golden and fundamental result of this research is that, when the applied voltage to the piezoelectric patch increases, the energy absorption by the system decreases. Also, at the higher value of the viscoelastic factor, there is not any effect from applied voltage on the phase velocity of the system. For the design and application of the current research, some inspiration and guidance are provided by theory and simulation results.