Excessive shipboard vibrations can cause structural and machinery failures, crew discomfort and fatigue, and increased maintenance requirements for shipboard systems. In many cases ship construction specifications require the shipyard to demonstrate "acceptable " levels of vibration using measurements completed during sea trials. This paper provides an overview of standards for these measurements and modern techniques used to collect and analyze the specified vibration data. A brief discussion of the types of vibrations found on ships and their causes is followed by a review of codes, guides and standards for vibration measurement. Instrumentation suitable for measurement of each type of vibration response is described and the design of a typical trial measurement system is presented. Techniques for analyzing and presenting trial results are reviewed and compared with analysis methods specified by SNAME, ISO and NAVSEA. Finally, a discussion of potential problems faced by an owner and shipyard in developing and meeting a vibration measurement specification is offered.
Electric Motor Noise for Small Quadcopters: Part 1 – Acoustic Measurements
