Fatigue Damage Prediction in Metallic Materials Based on Multiscale Modeling

AIAA Journal ◽  
2009 ◽  
Vol 47 (11) ◽  
pp. 2567-2576 ◽  
Author(s):  
Chuntao Luo ◽  
Jun Wei ◽  
Manuel Parra-Garcia ◽  
Aditi Chattopadhyay ◽  
Pedro Peralta
Keyword(s):  
Fatigue Damage ◽  
Multiscale Modeling ◽  
Metallic Materials ◽  
Damage Prediction

On the Vortex-Induced Vibration Response of a Model Riser and Location of Sensors for Fatigue Damage Prediction

2010 ◽  
Author(s):  
C. Shi ◽  
L. Manuel ◽  
M. A. Tognarelli ◽  
T. Botros
Keyword(s):  
Fatigue Damage ◽  
Traveling Waves ◽  
Wavelet Transforms ◽  
Cross Flow ◽  
Waveform Analysis ◽  
Flexible Cylinder ◽  
Vortex Induced Vibration ◽  
Damage Prediction ◽  
Time Frequency ◽  
Damage Rate

This study is concerned with vortex-induced vibration (VIV) of deepwater marine risers. Riser response measurements from model tests on a densely instrumented long, flexible riser in uniform and sheared currents offer an almost ideal set-up for our work. Our objectives are two-fold: (i) we use the measured data to describe complexities inherent in riser motions accompanying VIV; and (ii) we discuss how such data sets (and even less spatially dense monitoring) can be used effectively in predicting fatigue damage rates which is of critical interest for deepwater risers. First, we use mathematical tools including Hilbert and wavelet transforms to estimate instantaneous amplitudes and phases of cross-flow (CF) and in-line (IL) displacements for the model riser as well as scalograms to understand time-frequency characteristics of the response; this work confirms that the motion of a long flexible cylinder is far more complex than that of a rigid cylinder, and that non-stationary characteristics, higher harmonics, and traveling waves are evident in the riser response. Second, a well-established empirical procedure, which we refer to as Weighted Waveform Analysis (WWA), is employed to estimate the fatigue damage rate at various locations along the length of the riser from strain measurements at only eight sensors. By iterating over numerous different combinations of these eight strain sensors as inputs (from among all the twenty-four available locations on the riser), optimal locations for the eight sensors on the riser are identified by cross-validation, whereby predicted strains and fatigue damage rates at locations of instrumented sensors are compared with strains and fatigue damage rates based on actual recorded measurements there. We find that, if properly placed, as few as eight sensors can provide reasonably accurate estimates of the fatigue damage rate over the entire riser length. Finally, we demonstrate how more accurate fatigue damage prediction can result when non-stationary response characteristics are considered and a modified WWA method (that more effectively accounts for traveling waves than the WWA method alone does) is employed.

Fatigue Damage Prediction as a Part of Technical Systems Reliability Assessment

2017 ◽  
Vol 755 ◽  
pp. 131-138 ◽  
Author(s):  
Bohuš Leitner ◽  
Mária Lusková ◽  
Zdeněk Dvořák ◽  
Eva Sventekova
Keyword(s):  
Fatigue Damage ◽  
Operating Conditions ◽  
Practical Application ◽  
Civil Structures ◽  
Damage Prediction ◽  
Damage Level ◽  
Material Fatigue ◽  
Boundary States ◽  
Technical Systems ◽  
Damage Processes

Material fatigue of different technical systems parts belongs to the most frequent causes of boundary states occurrence and relating operation breakdowns. An extraordinary attention is dedicated to the prediction of fatigue damage processes in structures elements all over the world because breakdowns, caused by a fatigue failure, have often a character of catastrophe. There should be a dominant effort to bring conditions of calculation or experimental measures near to the working conditions in which the investigated system is exploited. A modern way of calculation of any technical systems (e.g. large mechanical or civil structures) therefore demands to respect dynamic and stochastic nature of all influencing working factors and related working loads. The main reason for it is prevention from their working breakdowns. The objective of the paper is general formulation of reliability of technical systems assessment, brief characteristic of basic areas to be taken into account as input into calculated prediction of technical systems fatigue damage level and analysis of risk items by its practical application in real operating conditions.

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