Life Prediction Techniques for Variable Amplitude Multiaxial Fatigue—Part 1: Theories

1996 ◽  
Vol 118 (3) ◽  
pp. 367-370 ◽  
Author(s):  
C. H. Wang ◽  
M. W. Brown
Keyword(s):  
Fatigue Damage ◽  
Life Prediction ◽  
Local Strain ◽  
Multiaxial Fatigue ◽  
Critical Plane ◽  
Random Loading ◽  
Variable Amplitude ◽  
Fatigue Damage Accumulation ◽  
Prediction Techniques ◽  
Searching Method

Fatigue life prediction under multiaxis random loading is an extremely complex and intractable topic; only a few methods have been proposed in the literature. In addition, experimental results under multiaxis random loading are also scarce. In part one of this two-part paper, a multiaxial non-proportional cycle counting method and fatigue damage calculation procedure are proposed, which is compared with one published damage-searching method. Both theories are based on critical plane concepts, one being an extension of the local strain approach for uniaxial variable amplitude loading and the other employing a new counting algorithm for multiaxis random loading. In principle, these two methods can be considered as bounding solutions for fatigue damage accumulation under multiaxis random loading.

Life Prediction Techniques for Variable Amplitude Multiaxial Fatigue—Part 2: Comparison With Experimental Results

1996 ◽  
Vol 118 (3) ◽  
pp. 371-374 ◽  
Author(s):  
C. H. Wang ◽  
M. W. Brown
Keyword(s):  
Fatigue Test ◽  
Life Prediction ◽  
Room Temperature ◽  
Multiaxial Fatigue ◽  
Experimental Results ◽  
Prediction Methods ◽  
Variable Amplitude ◽  
Prediction Techniques ◽  
Tubular Specimens ◽  
Random Fatigue

An extensive multiaxial random fatigue test programme was conducted at room temperature using tubular specimens. Experiments were performed under combined tension/torsion and triaxial loading, covering proportional and nonproportional variable amplitude loading cases. The two proposed life prediction methods discussed in Part 1 are evaluated using the experimental results, demonstrating that these two methods provide satisfactory predictions.

Evaluation of Multiaxial Fatigue Life Prediction Methodologies for Ti-6Al-4V

2002 ◽  
Vol 124 (2) ◽  
pp. 229-237 ◽  
Author(s):  
Alan R. Kallmeyer ◽  
Ahmo Krgo ◽  
Peter Kurath
Keyword(s):  
Fatigue Damage ◽  
Life Prediction ◽  
Equivalent Stress ◽  
Multiaxial Fatigue ◽  
Critical Plane ◽  
Proportional Loading ◽  
Biaxial Fatigue ◽  
Fatigue Data ◽  
Stress States ◽  
Mean Stresses

Many critical engineering components are routinely subjected to cyclic multiaxial stress states, which may include non-proportional loading and multidimensional mean stresses. Existing multiaxial fatigue models are examined to determine their suitability at estimating fatigue damage in Ti-6Al-4V under complex, multiaxial loading, with an emphasis on long-life conditions. Both proportional and non-proportional strain-controlled tension/torsion experiments were conducted on solid specimens. Several multiaxial fatigue damage parameters are evaluated based on their ability to correlate the biaxial fatigue data and uniaxial fatigue data with tensile mean stresses (R>−1) to a fully-reversed (R=−1) uniaxial baseline. Both equivalent stress-based models and critical plane approaches are evaluated. Only one equivalent stress model and two critical plane models showed promise for the range of loadings and material considered.

Taking Full Advantage of Nominal Stresses to Design Notched Components against Variable Amplitude Multiaxial Fatigue

2011 ◽  
Vol 488-489 ◽  
pp. 747-750 ◽  
Author(s):  
Luca Susmel ◽  
David Taylor
Keyword(s):  
Experimental Investigation ◽  
Shear Stress ◽  
Fatigue Damage ◽  
Fatigue Loading ◽  
Multiaxial Fatigue ◽  
Critical Plane ◽  
Variable Amplitude ◽  
Maximum Variance ◽  
Curve Method ◽  
Notched Components

The present paper is concerned with the use of the Modified Wöhler Curve Method (MWCM), applied in terms of nominal stresses, to estimate lifetime of notched components subjected to variable amplitude multiaxial fatigue loading. The MWCM is applied by defining the critical plane through that direction experiencing the maximum variance of the resolved shear stress: since the shear stress resolved along the above direction is a monodimensional quantity, fatigue cycles are directly counted by the classical Rain-Flow method. The performed validation exercise, based on an extensive experimental investigation, seems to strongly support the idea that the MWCM applied along with the classical nominal stress based approach is capable of accurately estimating fatigue damage also in notched components subjected to variable amplitude multiaxial load histories.

Fatigue Life Prediction Under Multiaxial Variable Amplitude Loading Using A Stress-Based Criterion

2020 ◽  
Vol 10 (1) ◽  
pp. 33-53
Author(s):  
Quoc Huy VU ◽  
Dinh Quy VU ◽  
Thi Tuyet Nhung LE
Keyword(s):  
Fatigue Life ◽  
Life Prediction ◽  
Prediction Method ◽  
Fatigue Loading ◽  
Multiaxial Fatigue ◽  
Fatigue Life Prediction ◽  
Random Loading ◽  
Variable Amplitude Loading ◽  
Variable Amplitude ◽  
1045 Steel

This article presents fatigue life calculations for metals under different multiaxial variable amplitude loading patterns. Developed from a stress-based multiaxial fatigue criterion, a damage parameter used in the fatigue life prediction method can capture correctly different damage mechanisms (proportional and non-proportional multiaxiality, mean stress, asynchronous and variable amplitude) of fatigue loading in the high cycle fatigue domain. The method is based on a reference S-N curve and a cumulative damage law. Assessment of the accuracy of the proposed method is carried out with three different materials from literature (EN-GS800-2 cast iron, 39NiCrMo3 steel and SAE 1045 steel) subjected to different patterns of variable amplitude loading (blocks, non-proportional asynchronous and proportional random loading). Results reveal that the prediction method is in good accordance with the experimental data.

scholarly journals Multiaxial high-cycle fatigue modelling for random loading

2019 ◽  
Vol 300 ◽  
pp. 12005
Author(s):  
Haoyang Wei ◽  
Jie Chen ◽  
Patricio Carrion ◽  
Anahita Imanian ◽  
Nima Shamsaei ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Normal Stress ◽  
Life Prediction ◽  
Equivalent Stress ◽  
Multiaxial Fatigue ◽  
Fatigue Life Prediction ◽  
Load Spectrum ◽  
Critical Plane ◽  
Random Loading ◽  
Random Load

In this paper, a multiaxial fatigue life prediction model is proposed under general multiaxial random loadings. First, a brief review for existing multiaxial fatigue models is given and special focus is on the LiuMahadevan critical plane concept, which can be applied to both brittle and ductile materials. Next, new model development based on the Liu-Mahadevan critical plane concept for random loading is presented. The key concept is to use two-steps to identify the critical plane: identify the maximum damage plane due to normal stress and calculate the critical plane orientation with respect to the maximum damage plane due to normal stress. Multiaxial rain-flow cycle counting method with mean stress correction is used to estimate the damage on the critical plane. Equivalent stress transformation is proposed to convert the multiaxial random load spectrum to an equivalent constant amplitude spectrum. The equivalent stress is used for fatigue life prediction. Following this, experimental design and testing is performed for Al 7075-T6 under various different random uniaxial and multiaxial spectrums. The developed model is validated with both literature and in-house testing data. Very good agreement is observed for the investigated material. Finally, conclusion and future work is given based on the proposed study.

A weight function method for multiaxial low-cycle fatigue life prediction under variable amplitude loading

2018 ◽  
Vol 53 (4) ◽  
pp. 197-209 ◽  
Author(s):  
Xiao-Wei Wang ◽  
De-Guang Shang ◽  
Yu-Juan Sun
Keyword(s):  
Fatigue Life ◽  
Weight Function ◽  
Life Prediction ◽  
Function Method ◽  
Low Cycle Fatigue ◽  
Fatigue Life Prediction ◽  
Cycle Fatigue ◽  
Critical Plane ◽  
Variable Amplitude ◽  
Weight Function Method

A weight function method based on strain parameters is proposed to determine the critical plane in low-cycle fatigue region under both constant and variable amplitude tension–torsion loadings. The critical plane is defined by the weighted mean maximum absolute shear strain plane. Combined with the critical plane determined by the proposed method, strain-based fatigue life prediction models and Wang-Brown’s multiaxial cycle counting method are employed to predict the fatigue life. The experimental critical plane orientation and fatigue life data under constant and variable amplitude tension–torsion loadings are used to verify the proposed method. The results show that the proposed method is appropriate to determine the critical plane under both constant and variable amplitude loadings.

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.

Sign in / Sign up

Export Citation Format

Share Document