Critical Evaluation of Frequency-Domain Approach for Fatigue Damage Estimation

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Gašper Vidic ◽  
Marko Nagode
Keyword(s):  
Frequency Domain ◽  
Fatigue Damage ◽  
Input Data ◽  
Critical Evaluation ◽  
High Amplitude ◽  
Damage Estimation ◽  
Accumulated Damage ◽  
Power Spectral ◽  
History Of ◽  
Frequency Domain Approach

Frequency-domain approach for fatigue damage estimation and lifetime prediction of mechanical components is often used for its computational efficiency and the capability to give a synthetic representation of a random process. The problem with the approach is that the input data, the stress power spectral density (PSD), may not include the information about potential small amount of high amplitude cycles which can substantially increase the accumulated fatigue damage. The paper investigates the scatter of the accumulated damage in generated random stress histories and compares them to the results obtained by a frequency-domain approach—the Dirlik method. The results show a possibility of a severe underestimation of accumulated damage when using frequency-domain approach. In case a typical stress, history of a certain mechanical component includes sporadic high amplitude cycles their effect shoud be taken into consideration when using frequency-domain approach.

Frequency Domain Fatigue Analysis for a Unbonded Flexible Riser: Damage Induced by Dynamic Bending

2020 ◽  
Author(s):  
Jiabei Yuan ◽  
Yucheng Hou ◽  
Zhimin Tan
Keyword(s):  
Tensile Stress ◽  
Frequency Domain ◽  
Fatigue Damage ◽  
Time Domain ◽  
Time History ◽  
Domain Analysis ◽  
Fatigue Analysis ◽  
Stress Spectrum ◽  
History Of ◽  
Frequency Domain Approach

Abstract The service life of flexible risers is a vital design parameter in offshore field development. The standard approach to calculate fatigue life is the nonlinear time-domain analysis. The approach uses time history of riser responses in local structure assessment to get the fatigue damage of tensile layers. Another approach is the linearized frequency-domain analysis. Instead of using time history of stress and rainflow counting technique, the approach uses stress spectrum and empirical mathematical terms to estimate the fatigue damage. The frequency domain approach is significantly faster. However, due to the whole system being linearized, the latter usually produces different results and is considered to be less accurate than the time domain approach. To address this issue, Baker Hughes previously developed an approach which uses the frequency domain technique as base solution and calibration factors from limited time domain cases. The approach is limited to tensile wires at the end fitting entrance where tension and tensile stress is directly linked. In this paper, a similar approach is proposed to be applied for tensile fatigue at all regions, whose tensile stress are induced by a combination of tension, pressure, bending and friction between layers. Since tensile stress is not directly related to any single riser response, the stress spectrum is predicted by using a transfer function. With the predicted stress spectrum, the fatigue damage of each case is calculated with Dirlik’s method and SN curves. The paper summarizes the development of the hybrid frequency domain approach. The fatigue damage of risers from several projects are acquired with both time domain and frequency domain approaches. The approach is significantly faster than traditional time domain approach and produces conservative results. Furthermore, discussions are made on options to improve the approach and reduce the conservatism in the frequency domain fatigue analysis.

FATIGUE DAMAGE ESTIMATION USING FREQUENCY DOMAIN APPROACH

2015 ◽  
Author(s):  
Walter Jesus Paucar Casas ◽  
Saul Camelo ◽  
Cesar Gonçalves dos Reis
Keyword(s):  
Frequency Domain ◽  
Fatigue Damage ◽  
Damage Estimation ◽  
Frequency Domain Approach

Fatigue Life Re-Assessment of FSO Spread Mooring System

2017 ◽  
Vol 862 ◽  
pp. 271-277
Author(s):  
Muhammad Irfan
Keyword(s):  
Fatigue Life ◽  
Frequency Domain ◽  
Fatigue Damage ◽  
Summation Method ◽  
Mooring System ◽  
Time Frequency ◽  
Irregular Wave ◽  
Operational Life ◽  
Frequency Domain Approach ◽  
Simple Summation

Re-assessment fatigue life on spread moored system of Floating Storage and Offloading (FSO) vessel moored in irregular wave has been carried out based on hybrid time-frequency domain approach. Previous assessment work result obtained the fatigue life very conservative about thousands of year, whilst existing mooring system was designed for the operational life of 10 years. Different method from previous work was used in fatigue damage calculation approach for undertaking a fatigue mooring analysis in present work. Present works aim to show that the simple summation method used for previous assessment that cause the large variation in fatigue life obtained by comparing different methods of combining fatigue damage. Comparison between the result of fatigue life both previous assessment and present work (re-assessment) of fatigue life are made and discussed.

Frequency Domain Fatigue Analysis for a Unbonded Flexible Riser: Damage Induced by Dynamic Tension

2019 ◽  
Author(s):  
Jiabei Yuan ◽  
Yucheng Hou ◽  
Zhimin Tan
Keyword(s):  
System Design ◽  
Frequency Domain ◽  
Fatigue Damage ◽  
Deep Water ◽  
Computational Time ◽  
Flexible Riser ◽  
Dynamic Tension ◽  
Irregular Wave ◽  
Unbonded Flexible Riser ◽  
Frequency Domain Approach

Abstract Evaluation of fatigue damage of offshore flexible risers is critical in flexible riser system design. For deepwater application, irregular wave time domain approach is often adopted as the state of practice to avoid excessive conservatism due to its better representation of the stochastic offshore environment. The approach can indeed fully capture the non-linear behaviors of the system at a significant cost of computational time. For example, computational time typically takes over 3∼4 weeks for a deep water free hanging riser system with thousands of fatigue load-cases and the full 3-hour simulations. On the other hand, the same scope of simulation can be completed in frequency domain within day(s), which will enable the designer to accelerate the optimization of riser system design. This paper presents an analysis method in frequency domain for assessing the fatigue damage of tensile armour wires inside the top end fitting (EF), which is induced by dynamic tension variation and often governs the riser service life in deep water applications. A validation measurement is also implemented to ensure the accuracy and practicability of this frequency domain approach in riser system design.

Fatigue damage assessment of a car body-in-white using a frequency-domain approach

2007 ◽  
Vol 30 (1/2/3) ◽  
pp. 172 ◽  
Author(s):  
Kamel Bel Knani ◽  
Denis Benasciutti ◽  
Alberto Signorini ◽  
Roberto Tovo
Keyword(s):  
Frequency Domain ◽  
Fatigue Damage ◽  
Damage Assessment ◽  
Car Body ◽  
Body In White ◽  
Frequency Domain Approach

Simple Method for Evaluation of Fatigue Damage of Structures in Wide-Band Random Vibrations

1994 ◽  
Vol 208 (1) ◽  
pp. 65-68 ◽  
Author(s):  
J J Kim ◽  
H Y Kim
Keyword(s):  
Spectral Density ◽  
Frequency Domain ◽  
Power Spectral Density ◽  
Fatigue Damage ◽  
Time Domain ◽  
Wide Band ◽  
Simple Method ◽  
Density Data ◽  
Power Spectral ◽  
The Time Domain

The note describes a simple method for evaluation of fatigue damage of structures in wide-band vibrations from response power spectral density data in the frequency domain. The method is applied to three sample cases and the results are compared with those of the damage calculation in the time domain.

Spectral analysis of sine-sweep vibration: A fatigue damage estimation method

2021 ◽  
Vol 157 ◽  
pp. 107698
Author(s):  
M. Palmieri ◽  
F. Cianetti ◽  
G. Zucca ◽  
G. Morettini ◽  
C. Braccesi
Keyword(s):  
Spectral Analysis ◽  
Fatigue Damage ◽  
Estimation Method ◽  
Damage Estimation ◽  
Sine Sweep
Sign in / Sign up

Export Citation Format

Share Document