Life Prediction of Notched Components

1995 ◽  
Vol 117 (1) ◽  
pp. 50-55 ◽  
Author(s):  
M. Giglio ◽  
L. Vergani
Keyword(s):  
Strain Energy ◽  
Fem Analysis ◽  
Fatigue Tests ◽  
Pressure Vessel Steel ◽  
Total Strain Energy ◽  
Vessel Steel ◽  
Number Of Cycles ◽  
Experimental Values ◽  
Cycles To Failure ◽  
Notched Components

In this study, keyhole and smooth specimens, made from a low alloy pressure vessel steel (ASTM A-533 grade B), were subjected to monoaxial fatigue tests. The results show the influence of the stress concentration factor, Kt, on the number of cycles to failure, Nf. Total strain energy per cycle, ΔWt = ΔWp + ΔWe, was proved to be a good parameter for predicting the life of notched components. Elasto-plastic FEM analysis, utilizing the cyclic and monotonic curve of the material, showed close agreement with the experimental values.

In-Phase and Out-of-Phase Multiaxial Fatigue

1991 ◽  
Vol 113 (1) ◽  
pp. 112-118 ◽  
Author(s):  
F. Ellyin ◽  
K. Golos ◽  
Z. Xia
Keyword(s):  
External Pressure ◽  
Damage Parameter ◽  
Multiaxial Fatigue ◽  
Pressure Vessel Steel ◽  
Proportional Loading ◽  
Vessel Steel ◽  
Total Strain Energy Density ◽  
Number Of Cycles ◽  
Life Predictions ◽  
Cycles To Failure

In this investigation, thin-walled circular cylindrical specimens fabricated from a low alloy pressure vessel steel (ASTM A-516 Gr. 70) were subjected to various multiaxial loading conditions. The tests were conducted under strain-controlled condition, and loading was provided through an axial actuator and internal and external pressure across the specimen wall. Four in-plane strain ratios (ρ = Δεt/Δεa) were tested, and the most damaging case was the equi-biaxial in-plane straining, ρ = 1. For the latter condition, 90 deg out-of-phase loading was also investigated. These tests indicated a dramatic decrease in the number of cycles to failure, Nf, as a result of out-of-phase loading. The influence of the plastic strain path on life is thus clearly demonstrated. It is shown that the total strain energy density, ΔWt = ΔWe+ + ΔWp, correlates with both the in-phase and out-of-phase cyclic tests, and therefore is a proper damage parameter to be used for life predictions. A brief description of how ΔWt can be calculated is given for the case of proportional loading. The predicted results are compared with the experimental data, and the agreement is found to be very good indeed.

An Experimental Study on Low Cycle Fatigue of Inconel 617 Super Alloy

2006 ◽  
Vol 306-308 ◽  
pp. 163-168 ◽  
Author(s):  
Jae Hoon Kim ◽  
Duck Hoi Kim ◽  
Young Shin Lee ◽  
Young Jin Choi ◽  
Hyun Soo Kim ◽  
...  
Keyword(s):  
Strain Energy ◽  
Low Cycle Fatigue ◽  
Cyclic Hardening ◽  
Fatigue Tests ◽  
Cyclic Behavior ◽  
Cycle Fatigue ◽  
Inconel 617 ◽  
Number Of Cycles ◽  
Cycles To Failure ◽  
Super Alloy

Low cycle fatigue tests are performed on the Inconel 617 super alloy that be used for structural material of hot gas casing for gas turbine. The relations between strain energy density and number of cycles to failure are examined in order to predict the low cycle fatigue life of Inconel 617 super alloy. The lives predicted by strain energy methods are found to coincide with experimental data and results obtained from the Coffin-Manson method. And, the cyclic behavior of the Inconel 617 super alloy is characterized by cyclic hardening with increasing number of cycles.

A Total Strain Energy Density Theory for Cumulative Fatigue Damage

1988 ◽  
Vol 110 (1) ◽  
pp. 36-41 ◽  
Author(s):  
K. Golos ◽  
F. Ellyin
Keyword(s):  
Energy Density ◽  
Strain Energy Density ◽  
Strain Energy ◽  
Elastic Strain Energy ◽  
Cumulative Damage ◽  
Total Strain ◽  
Pressure Vessel Steel ◽  
Total Strain Energy ◽  
Vessel Steel ◽  
Total Strain Energy Density

A unified theory based on the cyclic strain energy density criterion is presented first. It is shown that the fatigue failure in both low and high-cycle regimes, and cumulative damage and loading sequence, can all be expressed in terms of a single damage parameter. The damage criterion is based on the total strain energy density per cycle (sum of the plastic and tensile elastic strain energy). Both the crack initiation and propagation phases of the fatigue life are embodied in this approach. A systematic investigation into the cyclic, fatigue and cumulative damage behavior of the pressure vessel steel, A-516 Gr. 70, is subsequently presented. The comparison between the predicted and experimental results is found to be good.

Analysis of pressure vessel steel fatigue tests in air

1989 ◽  
Vol 115 (1) ◽  
pp. 23-30 ◽  
Author(s):  
E.D. Eason ◽  
S.P. Andrew ◽  
S.B. Warmbrodt ◽  
E.E. Nelson ◽  
J.D. Gilman
Keyword(s):  
Pressure Vessel ◽  
Fatigue Tests ◽  
Pressure Vessel Steel ◽  
Vessel Steel

Combination of Cyclic Fatigue Testing and Materials Characterisation to Investigate Ageing of Elastomers

2017 ◽  
Vol 44 (4) ◽  
pp. 1-8 ◽  
Author(s):  
T. Kroth ◽  
D. Lellinger ◽  
I. Alig ◽  
M. Wallmichrath
Keyword(s):  
Fatigue Life ◽  
Molecular Mass ◽  
Fatigue Testing ◽  
Cyclic Fatigue ◽  
Chain Scission ◽  
Thermal Ageing ◽  
Fatigue Tests ◽  
Additive Package ◽  
Number Of Cycles ◽  
Cycles To Failure

Cyclic fatigue testing and elastomer characterisation were combined to study changes in material properties and network structure of elastomers during thermal ageing. Natural rubber containing a typical additive package with carbon black was studied as a model material. The samples were aged at different temperatures in air or under a nitrogen atmosphere. The fatigue life in number of cycles to failure (S-N curves) was determined from force- and displacement-controlled fatigue tests on tensile bar specimens after different thermal ageing times. Changes in mechanical properties and crosslink density were studied by tensile tests, dynamic mechanical analysis, stress relaxation experiments, compression set measurements, swelling measurements and solid-state NMR. Changes in network density during thermal ageing are related to the interplay between the formation of new crosslinks and chain scission. The average molecular mass of the network chains was found to be a suitable parameter for comparing different characterisation methods. An initial decrease in the molecular mass between two crosslinking points due to post-curing is followed by an increase due to chain scission. A similar trend was found for fatigue life in number of cycles to failure (N) in force-controlled fatigue tests: an increase in N for short ageing times is followed by a decrease after longer ageing times.

Effect of Creep in Low-Cycle Fatigue of Pressure Vessel Steel

1970 ◽  
Vol 92 (1) ◽  
pp. 67-73 ◽  
Author(s):  
J. Dubuc ◽  
A. Biron
Keyword(s):  
Pressure Vessel ◽  
Low Cycle Fatigue ◽  
Strain Range ◽  
Fatigue Tests ◽  
Pressure Vessel Steel ◽  
Cycle Fatigue ◽  
Total Strain Range ◽  
Vessel Steel ◽  
The Mean ◽  
Mean Strain

Low-cycle fatigue tests have been carried out at 2 cpm on a pressure vessel steel at 350 deg C (662 deg F). The total strain range was fixed for each test and the minimum (or mean) strain in some cases was constant (zero minimum value), in others increased uniformly in time at a predetermined rate. It was found that variations in the mean strain up to 0.5 percent/hour had no significant influence on the results.

Evaluation of Durability of Haulage System Based on Low Fatigue Cycle Test and FEM Analysis

2015 ◽  
Vol 237 ◽  
pp. 227-232
Author(s):  
Jarosław Piekło ◽  
Maria Maj ◽  
Robert Żuczek ◽  
Adam Zachura
Keyword(s):  
Gear Tooth ◽  
Experimental Studies ◽  
Fem Analysis ◽  
Basic Research ◽  
Strength Properties ◽  
Fatigue Tests ◽  
Steel Alloy ◽  
Number Of Cycles ◽  
Highly Loaded ◽  
Haulage System

The use of the innovative design of gears segments of drivetrain engine of a longwall shearer’s haulage system with highly loaded components has improved tribological pairs of gear-tooth. The elimination of structurally complex sets of gears allowed to reduce the cost of individual component of the system, reduction of the failure rate and significantly improve the processes of repair and maintenance. The article presents the results of experimental and numerical analysis of stress and strain variables in highly loaded gear element of haulage system. The experimental studies of L20HGSNM steel alloy from which the casting was produced included basic research of strength properties of the material and two types of fatigue tests: in the range of a small number of cycles - a classic LFC and modified MLCF test. Acquired material properties of the steel alloy allowed to create material characteristics and fatigue strength curve, which were used in FEM calculations. Based on the results of numerical calculations and multiaxial criteria the fatigue life of the casting gears were evaluated.

Development of a Fatigue Damage and Lifing Assessment Method for Inconel 625 and Aluminum 6061-T6

2017 ◽  
Author(s):  
Dino Celli ◽  
M.-H. Herman Shen ◽  
Tommy George ◽  
Onome Scott-Emuakpor ◽  
Casey Holycross
Keyword(s):  
Fatigue Damage ◽  
Strain Energy ◽  
Room Temperature ◽  
Assessment Method ◽  
Fatigue Tests ◽  
Inconel 625 ◽  
Total Strain Energy ◽  
Mechanical Fatigue ◽  
Energy Dissipated ◽  
Good Agreement

An energy based fatigue damage and lifing assessment method is developed for a high temperature material, Inconel 625, and Aluminum 6061-T6. A newly developed experimental method is used for interrogating accumulated fatigue damage and evolution for low and high cycle fatigue (LCF/HCF) at continuum scales. The proposed fatigue lifing assessment method is based on assessing the total strain energy dissipated to cause fatigue failure of a material, known as the fatigue toughness. From the fatigue toughness and experimentally determined fatigue lives at two different stress amplitudes, the cyclic parameters of the Ramberg-Osgood constitutive equation that describes the hysteresis stress-strain loop of a cycle are determined. Stress controlled mechanical fatigue tests are performed to construct room temperature stress-life (S-N) curves and to determine damage progression based on accumulated fatigue damage. The predicted fatigue life obtained from the present energy based approach is found in good agreement with experimental data.

Fatigue Tests on Aluminum Specimens Subjected to Constant and Random Amplitude Loadings

2016 ◽  
Vol 138 (4) ◽  
Author(s):  
Morteza Rahimi Abkenar ◽  
David P. Kihl ◽  
Majid T. Manzari
Keyword(s):  
Fatigue Life ◽  
Aluminum Alloys ◽  
Cyclic Stress ◽  
Fatigue Tests ◽  
Test Results ◽  
Number Of Cycles ◽  
Mechanical Devices ◽  
Cycles To Failure ◽  
Amplitude Versus ◽  
Weight Structures

Increasing interest in using aluminum as the structural component of light-weight structures, mechanical devices, and ships necessitates further investigations on fatigue life of aluminum alloys. The investigation reported here focuses on characterizing the performance of cruciform-shaped weldments made of 5083 aluminum alloys in thickness of 9.53 mm (3/8 in.) under constant, random, and bilevel amplitude loadings. The results are presented as S/N curves that show cyclic stress amplitude versus the number of cycles to failure. Statistical procedures show good agreements between test results and predicted fatigue life of aluminum weldments. Moreover, the results are compared to the results obtained from previous experiments on aluminum specimens with thicknesses of 12.7 mm (1/2 in.) and 6.35 mm (1/4 in.).

A Strain-Based Fatigue Reliability Analysis Method

1995 ◽  
Vol 117 (2A) ◽  
pp. 229-234 ◽  
Author(s):  
J. D. Baldwin ◽  
J. G. Thacker
Keyword(s):  
Laboratory Data ◽  
Strain Analysis ◽  
Strain Range ◽  
Distribution Model ◽  
Fatigue Reliability ◽  
Gaussian Random Process ◽  
Rainflow Cycle Counting ◽  
Number Of Cycles ◽  
Cycles To Failure ◽  
Notched Components

A new fatigue reliability technique has been developed using a strain-based analysis. A probabilistic strain-life curve, where the variability in cycles to failure at constant strain range has been modeled with a three-parameter Weibull distribution, has been incorporated into the strain-based fatigue analysis. This formulation, which includes a notch strain analysis, rainflow cycle counting and damage accumulation according to Miner’s rule, is used to estimate fatigue life to crack initiation for notched components using smooth specimen laboratory data. Unlike other probabilistic fatigue models, the technique developed here does not include a distribution model for stress peaks such as the commonly-used stationary narrow band Gaussian random process assumption but rather uses strain histories directly. Using this model, techniques have been developed to estimate the number of cycles to failure at a specified reliability and to predict the reliability and failure rate at a specified time in the analysis.

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