Fatigue damage cumulation in materials under random loading based on an energy model

2020 ◽  
Author(s):  
Marta Kurek ◽  
Tadeusz Łagoda
Keyword(s):  
Fatigue Damage ◽  
Energy Model ◽  
Random Loading ◽  
Damage Cumulation

Different Fatigue Dynamics Under Statistically and Spectrally Similar Deterministic and Stochastic Excitations

2013 ◽  
Vol 81 (4) ◽  
Author(s):  
Son Hai Nguyen ◽  
Mike Falco ◽  
Ming Liu ◽  
David Chelidze
Keyword(s):  
Crack Growth ◽  
Fatigue Damage ◽  
Damage Accumulation ◽  
Growth Dynamics ◽  
Experimental System ◽  
Counting Method ◽  
Random Loading ◽  
Stochastic Excitations ◽  
Fatigue Damage Accumulation ◽  
System Coupling

Estimating and tracking crack growth dynamics is essential for fatigue failure prediction. A new experimental system—coupling structural and crack growth dynamics—was used to show fatigue damage accumulation is different under chaotic (i.e., deterministic) and stochastic (i.e., random) loading, even when both excitations possess the same spectral and statistical signatures. Furthermore, the conventional rain-flow counting method considerably overestimates damage in case of chaotic forcing. Important nonlinear loading characteristics, which can explain the observed discrepancies, are identified and suggested to be included as loading parameters in new macroscopic fatigue models.

Estimation of Cumulative Fatigue Damage Under Random Loading

1976 ◽  
Vol 98 (1) ◽  
pp. 348-353 ◽  
Author(s):  
A. K. Abu-Akeel
Keyword(s):  
Fatigue Damage ◽  
Computation Time ◽  
Straight Line Segment ◽  
Computer Applications ◽  
Accurate Estimation ◽  
Random Loading ◽  
Structural Element ◽  
Load Curve ◽  
Straight Line ◽  
Cumulative Fatigue Damage

A method is presented that leads to accurate estimation of the cumulative fatigue damage incurred in a randomly loaded structural element when loading is given in the form of spectral density load, or stress, plots. The load plots are here approximated by a series of straight lines and a closed formula is obtained to yield the damage incurred by the load within each straight line segment. The method avoids the errors that result from human misjudgment in the commonly used curve-stepping approach. It is also adaptable for computer applications and can be incorporated in a stress calculation program to save on computation time. In comparison to curve stepping, five straight-line segments may give the same accuracy as a hundred curve steps. This contrast, however, depends on the degree of irregularity of the load curve.

Accumulative Fatigue Damage Caused by Random Loading

1959 ◽  
Vol 26 (6) ◽  
pp. 394-395 ◽  
Author(s):  
H. C. Schjelderup
Keyword(s):  
Fatigue Damage ◽  
Random Loading

Analysis of Uncertainties in the Estimation of Fatigue Damage in Maritime Structures by the Bootstrap Technique

2010 ◽  
Author(s):  
Antonio Vasconcelos ◽  
Edison Castro Prates de Lima ◽  
Lui´s Volnei Sudati Sagrilo
Keyword(s):  
Standard Deviation ◽  
Fatigue Damage ◽  
Time Domain ◽  
Structural Damage ◽  
Time Domain Analysis ◽  
Relevant Information ◽  
Time Domain Simulation ◽  
Random Loading ◽  
Bootstrap Technique ◽  
Bootstrap Methodology

This work describes the application of the Bootstrap technique to assess relevant information about the structural damage due to the action of a random loading time domain simulation. The Bootstrap methodology allows the estimation of the standard deviation confident interval calculated over a single time domain analysis. Two numerical applications are presented to exemplify the using of the confident intervals to obtain information on the cumulative damage of a structure subject to these random loadings.

Fatigue Damage of the Locomotive Suspension Elements Under Random Loading

1981 ◽  
Vol 103 (4) ◽  
pp. 871-880 ◽  
Author(s):  
D. S. Garivaltis ◽  
V. K. Garg ◽  
A. F. D’Souza
Keyword(s):  
Probability Density ◽  
Fatigue Damage ◽  
Degrees Of Freedom ◽  
Probability Density Functions ◽  
Density Functions ◽  
Random Loading ◽  
Operational Stress ◽  
Operational Characteristics ◽  
Definition Of ◽  
Random Track Irregularities

Spectral analysis techniques are employed to analyze the fatigue damage to the suspension of a six-axle locomotive on tangent track with vertical and lateral random track irregularities. The locomotive is represented by a thirty-nine (39) degrees of freedom linear model. Spectral densities of forces and probability density functions for stress levels in suspension elements are generated. Using a modified definition of transmissibility, the probability density functions of the output/input and mean square values of outputs are obtained for various stiffness ratios. A cumulative linear damage criterion based on Miner’s theory is employed to predict fractional damage per operational second and mean life of the suspension elements. Operational stress cycles/sec. versus operational stress level are plotted for the suspension elements. These operational characteristics in conjunction with fatigue characteristics (S-N curve) can be effectively used as a tool for fatigue design.

Reliability-Based Fatigue Design for Piping Using Spectrum Characteristics

2012 ◽  
Author(s):  
Shinsuke Sakai ◽  
Jyunki Maeda ◽  
Masahiro Takanashi ◽  
Izumi Satoshi
Keyword(s):  
Fatigue Damage ◽  
Limit State ◽  
Equivalent Stress ◽  
Random Wave ◽  
State Function ◽  
Counting Method ◽  
Random Loading ◽  
Analytical Treatment ◽  
Fatigue Design ◽  
Spectrum Characteristics

A reliability-based approach can play an important role in avoiding excessive conservative design for piping. We showed a formulation for applying the limit state function method to reliability-based fatigue design at the previous PVP conference. Using this method, the reliability can be expressed by two dominant parameters: the distribution of equivalent stress and the distribution of fatigue life. If the equivalent stress under stationary random loading can be related to some specific spectrum parameters, it is expected that reliability-based fatigue design can be achieved under random loading. Fatigue damage under random loading is usually estimated using Miner’s law together with the SN diagram. In applying Miner’s law, the random wave is decomposed to the fatigue range using some counting method. The rainflow cycle counting (RFC) method is widely used as a counting method. In view of design application, however, the estimation of fatigue damage from spectrum characteristics is important, and the RFC method is not necessarily suitable for this purpose because it is rather difficult to use in the analytical treatment. Fortunately, it has been shown that the level crossing counting (LCC) method provides a more conservative estimation when compared with the RFC method and the analytical treatment for the evaluation is available. In this paper, we will show a procedure for reliability-based fatigue design which evaluates fatigue damage using the LCC method, spectrum characteristics and Miner’s law.

Numerical study of fatigue damage under random loading using Rainflow cycle counting

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Tayeb Kebir ◽  
José A.F.O. Correia ◽  
Mohamed Benguediab ◽  
Abilio M.P. De Jesus
Keyword(s):  
Fatigue Damage ◽  
Numerical Study ◽  
Scientific Work ◽  
Stress Effect ◽  
Mean Stress ◽  
Random Loading ◽  
Content Type ◽  
Rainflow Cycle Counting ◽  
The Mean ◽  
Rainflow Counting

PurposeThe purpose of this scientific work is to simulate the fatigue damage under random loading, taking into account the mean stress effect on fatigue lifetime and using the Rainflow counting technique to assess the fatigue damage by the Ansys software. The used material is aluminum alloy 6082-T6. A comparison with literature results has confirmed this investigation in this paper.Design/methodology/approachThe study of fatigue under random loading is based on the same concepts as constant loading with the addition of damage summation. The proportion of damage caused by a stress cycle depends not only on the alternating stress but also on the mean stress.FindingsAnalysis of the fatigue damage shows that the number of relative damage due to each cycle.Originality/valueThis paper aims to simulate the fatigue damage under random loading for aluminum alloys.

A method for estimating rainflow fatigue damage of narrowband non-Gaussian random loadings

2014 ◽  
Vol 228 (14) ◽  
pp. 2459-2468 ◽  
Author(s):  
HW Cheng ◽  
JY Tao ◽  
X Chen ◽  
Y Jiang
Keyword(s):  
Fatigue Damage ◽  
Fourth Order ◽  
Analytical Solutions ◽  
Estimation Methods ◽  
Accurate Estimation ◽  
Damage Estimation ◽  
Random Loading ◽  
New Approach ◽  
Computational Errors ◽  
Non Gaussian

We describe efforts to improve the accuracy of fatigue damage estimation methods of narrowband non-Gaussian random loading. The available analytical solutions are reviewed and briefly summarized, and the reasons for the occurrence of computational errors during nonlinear transformation-based methods are determined. The computational errors are mainly due to inconsistencies in the statistical moments above fourth order. A new approach is proposed for the evaluation of rainflow fatigue damage. This approach avoids the problem of transformation-based methods and provides accurate estimation for fatigue damage of narrowband leptokurtic non-Gaussian random loading. Additionally, the applicability of the proposed method to Gaussian random loading is investigated. Finally, two examples are carried out and comparisons are made to more commonly used methods to demonstrate the capabilities and brevity of the proposed algorithm.

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