An Investigation of Cyclic Transient Behavior and Implications on Fatigue Life Estimates

1997 ◽  
Vol 119 (2) ◽  
pp. 161-170 ◽  
Author(s):  
Yanyao Jiang ◽  
Peter Kurath
Keyword(s):  
Stainless Steel ◽  
Fatigue Life ◽  
Cyclic Hardening ◽  
Transient Behavior ◽  
Fatigue Tests ◽  
304 Stainless Steel ◽  
Deformation History ◽  
Life Estimation ◽  
Fatigue Life Estimation ◽  
Track Deformation

Current research focuses on proportional cyclic hardening and non-Massing behaviors. The interaction of these two hardenings can result in the traditionally observed overall softening, hardening or mixed behavior exhibited for fully reversed strain controlled fatigue tests. Proportional experiments were conducted with five materials, 304 stainless steel, normalized 1070 and 1045 steels, and 7075-T6 and 6061-T6 aluminum alloys. All the materials display similar trends, but the 304 stainless steel shows the most pronounced transient behavior and will be discussed in detail. Existing algorithms for this behavior are evaluated in light of the recent experiments, and refinements to the Armstrong-Frederick class of incremental plasticity models are proposed. Modifications implemented are more extensive than the traditional variation of yield stress, and a traditional strain based memory surface is utilized to track deformation history. Implications of the deformation characteristics with regard to fatigue life estimation, especially variable amplitude loading, will be examined. The high-low step loading is utilized to illustrate the effect of transient deformation on fatigue life estimation procedures, and their relationship to the observed and modeled deformation.

scholarly journals Fatigue behavior of 316L austenitic stainless steel in air and LWR environment with and without mean stress

2018 ◽  
Vol 165 ◽  
pp. 03012 ◽  
Author(s):  
Wen Chen ◽  
Philippe Spätig ◽  
Hans-Peter Seifert
Keyword(s):  
Stainless Steel ◽  
Fatigue Life ◽  
Austenitic Stainless Steel ◽  
Fatigue Limit ◽  
Fatigue Behavior ◽  
Cyclic Hardening ◽  
Fatigue Tests ◽  
Mean Stress ◽  
Test Results ◽  
316L Austenitic Stainless Steel

The fatigue life design curves in nuclear codes are generally derived from uniaxial straincontrolled fatigue test results. Evidently, the test conditions are very different from the actual components loading context, which involves much more complex thermo-mechanical loading including mean stress, static load holding time and variation in water chemistry, etc. In this work, the mean stress and environmental effects on fatigue life of 316L austenitic stainless steel in air and light water reactor (LWR) environment were studied using hollow fatigue specimens and testing under load-controlled condition. Both positive (+50 MPa) and negative (-20 MPa) mean stresses showed beneficial effect on fatigue life in LWR environment and in air. This is tentatively attributed to mean stress enhanced cyclic hardening, which leads to smaller strain response at the same loading force. -20 MPa mean stress was found to increase fatigue limit, whereas the effect of +50 MPa mean stress on fatigue limit is still unclear. The preliminary results illustrate that the environmental reduction of fatigue life is amplified in load-controlled fatigue tests with tensile mean stress.

Assessment of Geometry Correction Functions of Tanker Knuckle Details Based on Fatigue Tests and Finite-Element Analysis

2003 ◽  
Vol 126 (3) ◽  
pp. 220-226 ◽  
Author(s):  
Y. Garbatov ◽  
S. Rudan ◽  
C. Guedes Soares
Keyword(s):  
Finite Element Analysis ◽  
Fatigue Life ◽  
Crack Growth ◽  
Fatigue Test ◽  
Fatigue Tests ◽  
Correction Function ◽  
Element Analysis ◽  
Life Estimation ◽  
Fatigue Life Estimation ◽  
Geometry Correction

The paper analyzes the fatigue crack growth of knuckle detail typical of tankers. An approach for evaluation of the fatigue life based on fracture mechanics is presented, where a Paris-Erdogan crack-growth law is applied. A geometry correction function is determined from fatigue test data. A closed-form equation is proposed for fatigue life estimation. The results obtained from a fatigue test and the calculated fatigue lives are compared.

Assessment of Geometry Correction Functions of Tanker Knuckle Details Based on Fatigue Tests and Finite Element Analysis

2002 ◽  
Author(s):  
Y. Garbatov ◽  
S. Rudan ◽  
C. Guedes Soares
Keyword(s):  
Finite Element Analysis ◽  
Fatigue Life ◽  
Crack Growth ◽  
Fatigue Test ◽  
Fatigue Tests ◽  
Correction Function ◽  
Element Analysis ◽  
Life Estimation ◽  
Fatigue Life Estimation ◽  
Geometry Correction

The paper analyses the fatigue crack growth of knuckle detail typical of tankers. An approach for evaluation of the fatigue life based on fracture mechanics is presented, where a Paris-Erdogan crack-growth law is applied. A geometry correction function is determined from fatigue test data. A closed-form equation is proposed for fatigue life estimation. The results obtained from a fatigue test and the calculated fatigue lives are compared.

scholarly journals Influence of Gaseous Hydrogen on Fatigue Behavior of Ferritic Stainless Steel – A Fatigue-life Estimation

2015 ◽  
Vol 133 ◽  
pp. 362-378 ◽  
Author(s):  
Georg Schauer ◽  
Jens Roetting ◽  
Malte Hahn ◽  
Simone Schreijaeg ◽  
Manfred Bacher-Höchst ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Fatigue Life ◽  
Ferritic Stainless Steel ◽  
Fatigue Behavior ◽  
Gaseous Hydrogen ◽  
Life Estimation ◽  
Fatigue Life Estimation

scholarly journals Effect of Quenching Media and Tempering Temperature on Fatigue Property and Fatigue Life Estimation Based on RBF Neural Network of 0.44 % Carbon Steel

2019 ◽  
Vol 10 (1) ◽  
pp. 273-286
Author(s):  
Song Guo ◽  
Changyou Li ◽  
Jingang Shi ◽  
Fangjun Luan ◽  
Xiaoyu Song
Keyword(s):  
Neural Network ◽  
Fatigue Life ◽  
Rbf Neural Network ◽  
Fatigue Tests ◽  
Tempering Temperature ◽  
Life Estimation ◽  
Mineral Oils ◽  
Quenching Media ◽  
Fatigue Life Estimation ◽  
The Mean

Abstract. In this work, the effect of the quenching media (brine, water, and two types of naphthenic mineral oils) and the tempering temperature (200, 400, 600 ∘C) on the static mechanical properties and the fatigue life has been investigated using 300 fatigue and 36 static tension tests. S–N curves and standard deviations of fatigue life under each heat treatment condition were calculated and shown. The fracture surfaces of the selected 11 specimens were observed by the scanning electron microscope and the reasons of affecting the fatigue life were discussed. To estimate the mean fatigue life under the conditions of any given tempering temperature and cycle stress amplitude based on 300 fatigue tests, the mean fatigue life estimation method based on RBF neural network was presented and verified by 12 other fatigue tests. The test results have shown that (1) the mean fatigue life decreases with the increase of tempering temperature for the same quenching media, (2) the mean fatigue life using brine is more than water which is more than naphthenic mineral oils for the same tempering temperature, and (3) the proposed method based on RBF neural network could accurately estimate the mean fatigue life when the tempering temperature and cyclic stress amplitude are given for each quenching medium.

The Effect of Hydrogen on the Fatigue Properties of Austenitic Stainless Steel

2013 ◽  
Vol 1545 ◽  
Author(s):  
Adam L. Nekimken ◽  
Patrick D. Ferro ◽  
John A. Sousa ◽  
Christine K. Ngan ◽  
Michael D. Phillips ◽  
...  
Keyword(s):  
High Pressure ◽  
Stainless Steel ◽  
Fatigue Life ◽  
Maximum Stress ◽  
Fatigue Tests ◽  
304 Stainless Steel ◽  
Fatigue Properties ◽  
Bending Fatigue ◽  
Cyclic Stresses ◽  
Pressure Hydrogen

ABSTRACTHydrogen can be used as an environmentally friendly fuel to power vehicles, electric devices, and spacecraft with water vapor as the only emission. One associated challenge is the development of safe hydrogen storage systems. Hydrogen tanks and other hydrogen infrastructure elements will be exposed to both high-pressure hydrogen and cyclic stresses. In our work, 304 stainless steel specimens were precharged with hydrogen and subjected to rotational bending fatigue with a maximum stress amplitude of 90 ksi. A diffusion model was solved to approximate the concentration of hydrogen in the specimen at the time of the test. Contrary to our previous work with simple bending fatigue tests, hydrogen precharging actually increased rotational bending fatigue life from 28,074 (Sx = 7,430, N = 103) cycles to 91,513 (Sx = 40,209, N=32) cycles, a factor of approximately 3.25. This result demonstrates that the effect of hydrogen on fatigue life can be highly situational, and great care should be taken when designing systems that will be exposed to high-pressure hydrogen under fatigue conditions.

The Use of a Power Law Function for Fatigue Life Estimation for Block Loads

2016 ◽  
Vol 250 ◽  
pp. 1-9
Author(s):  
Ewelina Böhm ◽  
Marta Kurek ◽  
Tadeusz Łagoda ◽  
Karolina Łagoda
Keyword(s):  
Fatigue Life ◽  
Power Law ◽  
Fatigue Tests ◽  
Life Estimation ◽  
Fatigue Life Estimation ◽  
Calculation Results ◽  
Power Law Function ◽  
Damage Accumulation Model ◽  
Model Derivation

A new damage accumulation model based on a power law for fatigue life estimation is presented. The model has been created on the basis of functions of memory taken from psychology. The model derivation is presented as well as its basic properties. It takes into account the loading sequence. The experimental verification of the model is performed for experimental results taken from the literature for four material groups tested with block loading programs. The obtained calculation results are compared with results obtained with the use of Palmgren-Miner model. The model can be used for the determination of fatigue life, especially for block load fatigue tests.

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