In-time fatigue monitoring using neural networks

Abstract This paper presents a new methodology for fatigue monitoring of fixed offshore structures. The accumulated fatigue damage on selected joints, caused by actual loading conditions, will be assessed through a data acquisition and processing system installed on board. Based on measurements of upward jacket displacements and feedforward backpropagation neural networks, the calculation of fatigue damage is performed in-time. This information, along with inspection reports, could be used to improve further inspection and repair of the platform jacket. A simplified structural numerical model takes into account, as much as possible, the dynamical structural conditions of a platform installed on Campos Basin, RJ, Brazil, in order to match the paper's conclusions to the actual behaviour of fixed offshore structures.

[1]  John E. Mottershead,et al.  Model Updating In Structural Dynamics: A Survey , 1993 .

[2]  P Carr,et al.  A UNIFIED PROBABILISTIC APPROACH TO DESIGN AND INSPECTION OF OFFSHORE STEEL STRUCTURES , 1987 .

[3]  T A Lopes,et al.  EVALUATION OF FATIGUE DAMAGE ON FIXED JACKET PLATFORMS , 1991 .

[4]  C. H. Wells,et al.  A probabilistic structure life prediction system for container ship repair and inspection , 1992 .

[5]  A. U. Levin,et al.  Recursive identification using feedforward neural networks , 1995 .

[6]  P. Werbos,et al.  Beyond Regression : "New Tools for Prediction and Analysis in the Behavioral Sciences , 1974 .

[7]  J Wolfram.  REVISION OF FATIGUE LIFE CALCULATIONS AND ASSOCIATED UNCERTAINTIES IN THE LIGHT OF IN SERVICE DATA , 1985 .

[8]  Bart Kosko,et al.  Neural networks and fuzzy systems: a dynamical systems approach to machine intelligence , 1991 .

[9]  Gary G. R. Green,et al.  Neural networks, approximation theory, and finite precision computation , 1995, Neural Networks.

[10]  J. K. Vandiver,et al.  The Determination of Modal Damping Ratios From Maximum Entropy Spectral Estimates , 1982 .

[11]  James H. Garrett,et al.  Use of neural networks in detection of structural damage , 1992 .

[12]  Geoffrey E. Hinton,et al.  Learning representations by back-propagating errors , 1986, Nature.

[13]  T. K. S. Murthy.  Computer Methods in Marine and Offshore Engineering , 1991 .

[14]  W. D. Dover,et al.  Fatigue analysis of offshore platforms subject to sea wave loadings , 1985 .

[15]  W D Dover,et al.  STRUCTURAL INTEGRITY OF WELDED TUBULAR JOINTS IN RANDOM LOAD FATIGUE COMBINED WITH SIZE EFFECT , 1987 .

[16]  Laurene V. Fausett,et al.  Fundamentals Of Neural Networks , 1993 .

[17]  Kurt Hornik,et al.  Multilayer feedforward networks are universal approximators , 1989, Neural Networks.