Low Cycle Fatigue Life Prediction Using Unified Mechanics Theory in Ti-6Al-4V Alloys

Fatigue in any material is a result of continuous irreversible degradation process. Traditionally, fatigue life is predicted by extrapolating experimentally curve fitted empirical models. In the current study, unified mechanics theory is used to predict life of Ti-6Al-4V under monotonic tensile, compressive and cyclic load conditions. The unified mechanics theory is used to derive a constitutive model for fatigue life prediction using a three-dimensional computational model. The proposed analytical and computational models have been used to predict the low cycle fatigue life of Ti-6Al-4V alloys. It is shown that the unified mechanics theory can be used to predict fatigue life of Ti-6Al-4V alloys by using simple predictive models that are based on fundamental equation of the material, which is based on thermodynamics associated with degradation of materials.

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Fatigue Life Prediction Using Unified Mechanics Theory in Ti-6Al-4V Alloys

10.20944/preprints201911.0317.v1 ◽

2019 ◽

Author(s):

Noushad Bin Jamal M ◽

Aman Kumar ◽

Lakshmana Rao Chebolu ◽

Cemal Basaran

Keyword(s):

Fatigue Life ◽

Life Prediction ◽

Cyclic Load ◽

Computational Models ◽

Low Cycle Fatigue ◽

Three Dimensional ◽

Fundamental Equation ◽

Degradation Process ◽

Fatigue Life Prediction ◽

Degradation Of Materials

Fatigue in any material is a result of continuous irreversible degradation process. Traditionally, fatigue life is predicted by extrapolating experimentally curve fitted empirical models. In the current study, unified mechanics theory is used to predict fatigue life of Ti-6Al-4V under monotonic tensile, compressive and cyclic load conditions. The unified mechanics theory is used to derive constitutive model for fatigue life prediction using a three-dimensional computational model. The proposed analytical and computational models have been used to predict the low cycle fatigue life of Ti-6Al-4V alloys. It is shown that the unified mechanics theory can be used to predict fatigue life of Ti-6Al-4V alloys by using simple predictive models that are based on fundamental equation of the material, which is based on thermodynamics associated with degradation of materials.

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

The Journal of Strain Analysis for Engineering Design ◽

10.1177/0309324718763671 ◽

2018 ◽

Vol 53 (4) ◽

pp. 197-209 ◽

Cited By ~ 2

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.

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