Notes on vibration

摘要

While the International Standards Organisation has produced criteria that cover vibration levels in ship accommodation spaces (ISO 6954), for reciprocating engines (ISO 10816-1 and ISO 10816-6), and for generating sets (ISO 8258-9 and ISO10816-3), most major classification societies have established their own guidelines for the measurement, reporting and evaluation of vibration. From the perspective of crew and passenger comfort, noise and vibration has been on the class agenda for many years. Since countermeasures can be more effectively implemented during the vessel design phase, research has primarily been channelled into developing new predictive methods and tools. Analytical predictions typically used today cover: 1. Fundamental hull natural frequencies and estimates of resonant responses 2. Fundamental longitudinal natural frequencies of the tower block superstructure 3. Panel natural frequencies to assess the impact of propeller excitation at blade and twice blade rates, and 4. Propeller shaft systems, including alignment, oil film dynamics and any relevant transient effects, especially looking at lateral, axial and torsional vibration.