The Strumming Vibrations of Marine Cables: 

 State of the Art 



1. INTRODUCTION 



1.1 Objectives. At the beginning of Fiscal Year 1975, technical management of the NAVFAC cable 

 dynamics research program was undertaken by the Civil Engineering Laboratory, Naval Construction 

 Battalion Center. The overall objective of this program, as stated in a research plan put forward by 

 CEL/NCBC, is: 



".|. . to provide for the development of effective methods for the analysis of the dynamic response 

 of 3-dimensional, moored cable structures which undergo dynamic motions generated by various 

 natural or man-produced causes. Failure to predict this dynamic behavior by suitable analytical tech- 

 niques will affect the confidence in the adequacy of the system design as well as the estimated reliability 

 of the system's performance." 



"[One aspect of this problem] is the small-displacement, "high frequency" response generated by 

 shedding vortices as water flows past the cable-this response is commonly referred to as cable strum- 

 ming. The objective of the plan for this specific area is twofold: (1) development of a capability to 

 predict the strumming response (i.e., deflection, frequency, generated acoustic energy, and drag force) 

 of cable networks which have horizontally or vertically oriented cable segments, in taut or catenary 

 configuration subjected to a current which may vary along the cable length, and (2) development of 

 techniques which can be used to suppress cable strumming." 



This report considers the problem of marine cable design against strumming vibrations. The 

 suppression of these vibrations is dealt with in a separate CEL-sponsored report.t 



tJ.E. Kline, A, Brisbane and E.M. Fritzgerald, "Cable Strumming Suppression" MAR Inc., Technical Report 249, July 1980. 



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