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The frictional vibration generated in water-lubricated rubber bearings operating under low speed, heavy load, startup and shutdown conditions can severely degrade the reliability and the sheltered performance of underwater vehicles. The rubber layer of the ship stern tube water-lubricated rubber bearings is easily elastically deformed under certain loads, which affects the damping performance of the bearing system. To explore the effects of thickness, hardness, and concavo-convexity on the damping property of water-lubricated rubber stern bearings, frictional force, vibration, noise, and displacement and deformation of the contact area were studied using a test rig with a transparent glass cylinder. An orthogonal L9(3)4 test design was applied accordingly to determine the optimum construction and material parameters of the rubber layer. Orthogonal test results indicate that among rubber layer hardness, thickness, and test block concavo-convexity, the former is most significant in terms of the frictional vibration, followed by the thickness and, finally, the radius of the surface. When the hardness is 65 A, the thickness is 12 mm, and the plate type is concave, the frictional vibration performance of the rubber layer is optimal. More important, based on the static deformation and the dynamic displacement of the rubber, the causes of the frictional vibration and the influence of different materials and structural parameters on frictional vibration were visually analyzed. The overall trends and the mechanism discussed in this research may be considered as a guideline for the design, optimization, and manufacture of water-lubricated bearings. [ABSTRACT FROM AUTHOR]

High-levelab initiocalculations have been performed on the PBr radical by using multi-reference configuration interaction method plus Davidson correction (+Q) with correlation-consistent quadruple-ζ quality basis set. The potential energy curves (PECs) of the 22 Λ–S states of PBr have been obtained, most of which are reported for the first time. From the PECs of the bound states, the spectroscopic constants have been determined, in good agreement with the experimental results where available. Due to the large state density, there exhibits complicated interactions in the electronic excited states of PBr. The possible interactions by the spin–orbit coupling (SOC) effect have been discussed based on the evaluatedR-dependent spin–orbit matrix elements. The 51 Ω states, generating from the 22 Λ–S states after taking SOC into account, have been computed. The Λ–S component analysis of the wavefunctions for the Ω states indicates the strong interaction of the Λ–S states especially at the avoided crossing points and near the dissociation limits. Finally, the transition dipole moments of several transitions arising from upper Ω states to the X10+and X21 states and the corresponding radiative lifetimes have been studied. Our calculation results provide new information that should be valuable for further experimental studies on the electronic excited states of the PBr radical. [ABSTRACT FROM AUTHOR]