Inelastic Stress-Strain Predictions for Multiaxial Fatigue Damage Evaluation

2009 ◽  
pp. 273-273-25 ◽  
Author(s):  
SM Tipton ◽  
JA Bannantine
Keyword(s):  
Fatigue Damage ◽  
Multiaxial Fatigue ◽  
Damage Evaluation ◽  
Stress Strain

Modal Velocity-Based Multiaxial Fatigue Damage Evaluation Using Simplified Finite Element Models

2020 ◽  
Vol 87 (11) ◽  
Author(s):  
Kurthan Kersch ◽  
Elmar Woschke
Keyword(s):  
Finite Element ◽  
Fatigue Damage ◽  
Cross Section ◽  
Multiaxial Fatigue ◽  
Finite Element Models ◽  
Damage Evaluation ◽  
Geometric Factors ◽  
The Relationship ◽  
General Method

Abstract This work proposes a new method for the fatigue damage evaluation of vibrational loads, based on preceding investigations on the relationship between stresses and modal velocities. As a first step, the influence of the geometry on the particular relationship is studied. Therefore, an analytic expression for Euler Bernoulli beams with a non-constant cross section is derived. Afterward, a general method for obtaining geometric factors from finite element (FE) models is proposed. In order to ensure a fast fatigue damage evaluation, strongly simplified FE-models are used for the determination of both factors and measurement locations. The entire method is demonstrated on three mechanical structures and indicates a better compromise between effort and accuracy than existing methods. For all examples, the usage of velocities and geometric factors obtained from simplified FE models enables a sufficient fatigue damage calculation.

OS2117 Multiaxial Fatigue Damage Evaluation of Ti-6Al-4V Based on Loading Path

2012 ◽  
Vol 2012 (0) ◽  
pp. _OS2117-1_-_OS2117-3_
Author(s):  
Masahiro TAKANASHI ◽  
Hiroshi NAKAMURA ◽  
Min WU ◽  
Takamoto ITOH
Keyword(s):  
Fatigue Damage ◽  
Multiaxial Fatigue ◽  
Loading Path ◽  
Damage Evaluation

scholarly journals Asynchronous Multiaxial Fatigue Damage Evaluation

2015 ◽  
Vol 101 ◽  
pp. 421-429 ◽  
Author(s):  
Vitor Anes ◽  
Luis Reis ◽  
Manuel Freitas
Keyword(s):  
Fatigue Damage ◽  
Multiaxial Fatigue ◽  
Damage Evaluation

scholarly journals Fatigue assessment of welded joints using multiaxial fatigue space theory with nominal stress approach

2020 ◽  
Author(s):  
Chun Lu ◽  
Jiliang Mo ◽  
Hongqin Liang
Keyword(s):  
Fatigue Damage ◽  
Welded Joints ◽  
Damage Assessment ◽  
Error Distribution ◽  
Multiaxial Fatigue ◽  
Nominal Stress ◽  
Damage Evaluation ◽  
Space Theory ◽  
Welding Defects ◽  
Nominal Stress Approach

Welded joints are widely employed in engineering field and they are always the starting points of fatigue damage. Because of the unfavorable material and geometry characters, as well as initial welding defects, the fatigue damage evaluation of welded joints is an important and troublesome issue for engineers. In this article, multiaxial fatigue space theory proposed by the first author for smooth specimens is extended for the fatigue damage assessment of welded joints, by adopting nominal stress approach. The fatigue test data with different materials, loading paths, and welded joints geometries are used to validate the capability of this theory. The result indicates a strong parallelization between predicted life and experimental life, with a favorable prediction error and beneficial error distribution. It can be concluded that multiaxial fatigue space theory is a useful method for fatigue damage assessment of welded joints with the help of nominal stress approach.

Modeling Multiaxial Fatigue Damage Using Polar Equations

2017 ◽  
Author(s):  
Jafar Albinmousa ◽  
Syed Haris Iftikhar ◽  
Mustafa Al-Samkhan
Keyword(s):  
Fatigue Damage ◽  
Fatigue Cracks ◽  
Closed Form Solution ◽  
Damage Parameter ◽  
Multiaxial Fatigue ◽  
Loading Path ◽  
Shear Stresses ◽  
Critical Plane ◽  
Stress Strain ◽  
Loading Paths

It is estimated that more than 70% of failures in engineering components are associated with fatigue loading. Therefore, fatigue is a major design tool for mechanical components. These components are usually subjected to multiaxial cyclic loading. In fact, multiaxial state is very common as tension specimen is under triaxial strain state even though its stress state is uniaxial. There are three approaches to modeling fatigue damage: stress, strain and energy. Critical plane concept is established based on the fact that fatigue cracks initiate at specific plane(s), therefore, multiaxial fatigue damage parameter is evaluated at these plane(s). Critical plane fatigue models such as Fatemi-Socie is among the popular strain-based models. Because it was shown to provide estimation mostly within two factors of life for different materials and different multiaxial loading conditions. This paper presents a new method for analyzing critical plane damage parameters. Using plane stress-strain transformation, maximum values of normal and shear stresses and strains from hysteresis loops are obtained at 360 planes. Plotting these values on polar diagrams shows that multiaxial cyclic responses represent polar curves that can successfully be fitted with definitive known polar equations. In principle, this means that both critical plane and fatigue damage can be determined analytically for a given loading path. However, fitting constants must first be determined. A systematic analysis is performed on different experimental data that were obtained by testing two extruded magnesium alloys at proportional and 90° out of phase loading paths. A closed-form solution for Fatemi-Socie damage parameter is presented for these two loading paths.

scholarly journals Investigation of Changes in Fatigue Damage Caused by Mean Load under Block Loading Conditions

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2738
Author(s):  
Roland Pawliczek ◽  
Tadeusz Lagoda
Keyword(s):  
Fatigue Life ◽  
Fatigue Damage ◽  
Strain Curve ◽  
Mean Value ◽  
Fatigue Properties ◽  
Stress Strain ◽  
Reference Case ◽  
Block Loading ◽  
The Mean ◽  
Mean Strain

The literature in the area of material fatigue indicates that the fatigue properties may change with the number of cycles. Researchers recommend taking this into account in fatigue life calculation algorithms. The results of simulation research presented in this paper relate to an algorithm for estimating the fatigue life of specimens subjected to block loading with a nonzero mean value. The problem of block loads using a novel calculation model is presented in this paper. The model takes into account the change in stress–strain curve parameters caused by mean strain. Simulation tests were performed for generated triangular waveforms of strains, where load blocks with changed mean strain values were applied. During the analysis, the degree of fatigue damage was compared. The results of calculations obtained for standard values of stress–strain parameters (for symmetric loads) and those determined, taking into account changes in the curve parameters, are compared and presented in this paper. It is shown that by neglecting the effect of the mean strain value on the K′ and n′ parameters and by considering only the parameters of the cyclic deformation curve for εm = 0 (symmetric loads), the ratio of the total degree of fatigue damage varies from 10% for εa = 0.2% to 3.5% for εa = 0.6%. The largest differences in the calculation for ratios of the partial degrees of fatigue damage were observed in relation to the reference case for the sequence of block n3, where εm = 0.4%. The simulation results show that higher mean strains change the properties of the material, and in such cases, it is necessary to take into account the influence of the mean value on the material response under block loads.

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