文档介绍：ARTICLE IN PRESS
Journal of Fluids and Structures 25 (2009) 617–628
ate/jfs
Monitoring VIV fatigue damage on marine risers
H. MukundanÃ, Y. Modarres-Sadeghi, . Dahl, . Hover, . Triantafyllou
Center for Ocean Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139-4307, USA
Received 15 April 2008; accepted 21 March 2009
Available online 7 May 2009
Abstract
Long flexible cylinders (., risers, tendons and mooring lines) exposed to the marine environment encounter ocean
currents leading to vortex-induced vibration (VIV). These oscillations, often driven at high frequencies over extended
periods of time, may result in structural failure of the member due to fatigue damage accumulation. Recent
developments in instrumentation and installation of data acquisition systems on board marine risers have made
accurate measurement of riser responses possible. This paper aims at using the data from these data acquisition devices
(typically strain gages and accelerometers) in order to understand the evolution of the riser VIV, with the final aim of
estimating the fatigue damage. For this purpose we employ systematic techniques to reconstruct riser VIV response
using the data from the available sensors. The reconstructed riser response allows estimation of the dynamic axial
stresses due to bending and consequently the estimates of the fatigue damage along the entire riser. The above methods
can take into account the fatigue damage arising plicated riser motions involving the presence of traveling
waves even with the use of very few sensors. An alternate approach using a Van der Pol wake oscillator model is also
explored to obtain fatigue life estimates caused by riser VIV.
r 2009 Elsevier Ltd. All rights reserved.
Keywords: Vortex-induced vibration; Marine risers; Response reconstruction; Fatigue life estimation; Scalograms; Van der Pol wake
oscillator
1. Introduction
The move to deeper waters in sear