0
Safety and Reliability

Time-Domain Hydroelastic Analysis of a Flexible Marine Structure Using State-Space Models

[+] Author and Article Information
Reza Taghipour1

Centre for Ships and Ocean Structures, Department of Marine Technology, Norwegian University of Science and Technology, Otto Nielsens vei 10, Trondheim N-7491, Norwayreza@ntnu.no

Tristan Perez

Centre for Ships and Ocean Structures, Department of Marine Technology, Norwegian University of Science and Technology, Otto Nielsens vei 10, Trondheim N-7491, Norway; Centre for Complex Dynamic Systems and Control, The University of Newcastle, Callaghan, NSW 2304, Australia

Torgeir Moan

Centre for Ships and Ocean Structures, Department of Marine Technology, Norwegian University of Science and Technology, Otto Nielsens vei 10, Trondheim N-7491, Norway

It is indeed possible to formulate the problem with forward speed.

1

Corresponding author.

J. Offshore Mech. Arct. Eng 131(1), 011603 (Dec 11, 2008) (9 pages) doi:10.1115/1.2979800 History: Received March 03, 2007; Revised December 18, 2007; Published December 11, 2008

This article deals with time-domain hydroelastic analysis of a marine structure. The convolution terms associated with fluid memory effects are replaced by an alternative state-space representation, the parameters of which are obtained by using realization theory. The mathematical model established is validated by comparison to experimental results of a very flexible barge. Two types of time-domain simulations are performed: dynamic response of the initially inert structure to incident regular waves and transient response of the structure after it is released from a displaced condition in still water. The accuracy and the efficiency of the simulations based on the state-space model representations are compared to those that integrate the convolutions.

FIGURES IN THIS ARTICLE
<>
Copyright © 2009 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 1

Snapshots of the barge during test (from Ref. 7)

Grahic Jump Location
Figure 2

Barge underwater geometry and sketch of the foremost floating section

Grahic Jump Location
Figure 3

Schematic of calculations

Grahic Jump Location
Figure 4

Measured and interpolated initial deformation in the barge

Grahic Jump Location
Figure 5

2D dry mode shapes obtained by Eqs. 11,12

Grahic Jump Location
Figure 6

Total damping ratio modeled in the hydroelastic calculations

Grahic Jump Location
Figure 7

Mode shape sensitivity of the response in the regular waves by plotting the largest amplitude of the response contributed by each mode. Mode Nos. 1, 2,... and 6 correspond to heave, pitch,... and fourth flexible mode. The values are normalized with respect to the largest data.

Grahic Jump Location
Figure 8

RAOs of the vertical displacements for the points in Table 2. Markers are the experimental results from Ref. 7 and solid lines are the results from the hydroelastic calculations.

Grahic Jump Location
Figure 9

Retardation functions (a) hr(13) and (b) hr(51), excitation force impulse response functions (c) hf(2) and (d) hf(3), and their approximation by state-space models using realization theory technique

Grahic Jump Location
Figure 10

Time series of the vertical displacements for the points in Table 2 at a wave frequency of 4rad∕s. Marker-dotted lines are the harmonic response generated from motion RAOs and solid lines are the simulated results where convolution integrals are replaced by state-space models.

Grahic Jump Location
Figure 11

Transient response of the barge at the points in Table 2 due to the initial deformation in Fig. 4. Dashed lines are the measured response from experiments reported in Ref. 7 and solid lines are the dynamic response simulations by using state-space models. The dotted lines are the simulation results by directly integrating the convolutions. Note that the results of simulation using state-space models are plotted on top of the simulations using direct integration of the convolutions.

Grahic Jump Location
Figure 12

Mode shape sensitivity of the dynamic response due to initial deformation of the barge by plotting the largest response contributed by each mode. Mode Nos. 1, 2,... and 6 correspond to heave, pitch,... and fourth flexible mode. The values are normalized with respect to the largest data.

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In