scholarly journals Probability Distribution Type for the Accumulated Damage from Miner’s Rule in Fatigue Design

2019 ◽  
pp. 205-212
Author(s):  
J. Hoole ◽  
P. Sartor ◽  
J. D. Booker ◽  
J. E. Cooper ◽  
X. V. Gogouvitis ◽  
...  
Keyword(s):  
Probability Distribution ◽  
Accumulated Damage ◽  
Fatigue Design ◽  
Miner’S Rule ◽  
Miner's Rule ◽  
Distribution Type

Fatigue Testing of Full Scale Girth Welded Pipes Under Variable Amplitude Loading

2012 ◽  
Author(s):  
Y.-H. Zhang ◽  
S. J. Maddox
Keyword(s):  
Fatigue Limit ◽  
Fatigue Damage ◽  
Fatigue Testing ◽  
Full Scale ◽  
Variable Amplitude Loading ◽  
Variable Amplitude ◽  
Fatigue Design ◽  
Miner’S Rule ◽  
Miner's Rule ◽  
Loading Spectrum

In the fatigue design of steel catenary risers there are concerns regarding the fatigue damage to girth welds from low stresses, below the constant amplitude fatigue limit, in the loading spectrum and the validity of Miner’s cumulative damage rule. In both cases there is increasing evidence that current design methods can be non-conservative. These fundamental issues were addressed in a recent JIP. A key feature was development of the resonance fatigue testing rigs to enable them to test full-scale pipes under variable amplitude loading. Such tests were performed under a loading spectrum representative of that experienced by some risers, with many tests lasting over 100 million cycles to investigate the fatigue damage due to small stresses as well as the validity of Miner’s rule. However, the resonance rigs are only capable of producing spectrum loading by gradually increasing or decreasing the applied load, whereas more ‘spiky’ random load sequences may be relevant in practice. Therefore the programme also included fatigue tests in conventional testing machines on strip specimens cut from pipes to compare the two types of loading sequence. This paper presents the results of these tests, conclusions drawn and recommendations for changes to current fatigue design guidance for girth welded pipes regarding the definition of the fatigue limit, allowance for the damaging effect of low stresses and the validity of Miner’s rule.

Fatigue Design of Machine Elements Under Cumulative Damage Effect, Using Bagci’s Fatigue Failure Surface Line

1984 ◽  
Vol 106 (4) ◽  
pp. 466-475
Author(s):  
C. Bagci
Keyword(s):  
Fatigue Life ◽  
Fatigue Strength ◽  
Material Properties ◽  
Cumulative Damage ◽  
Damage Effect ◽  
Stress Effect ◽  
Mean Stress ◽  
Fatigue Design ◽  
Miner’S Rule ◽  
Miner's Rule

A thorough review of the state-of-the-art of determining fatigue life of machine and structural members considering cumulative damage effect under varying stress amplitudes is given. Among the many proposed theories, Miner’s linear damage rule is seen to be as reliable as any other rule alleged to be an improvement for predicting fatigue life under cumulative damage effects. Its simplicity and amenability for easy modification have in fact been the basis for some other theories and used in design codes. In its original form, Miner’s rule, however does not account for fatigue strength reducing factors. Observing fatigue data on the effects of fatigue strength reducing factors, the article offers a modified form of the Miner’s rule to consider the effects of fatigue strength reducing factors, such as the notch, reliability, surface finish, size, and environmental factors. The mean stress effect and material properties are incorporated utilizing Bagci’s mean stress line and the S-N diagram. The safe fatigue life of a component subjected to stresses of varying magnitudes becomes Ns=df/∑i=1s(αi/10zi) where zi=A{B−log(pig/Rf)+log[1−(pi/mi)r]} in the ith block of stress range, Rf being the resultant of fatigue strength reducing factors; A, B, g are parameters defined by material properties, pi is the ratio of the basic alternating stress times the factor of safety (the failure value) to the yield strength of the material, and mi is the slope of the load line in the ith block of loading. Design charts for zi for steel and aluminum alloys for cases with and without basic mean stress for r=4 are given. Numerical examples are included. Therefore, the article offers the most general form of the Miner’s rule for designers’ use for fatigue design considering cumulative damage effect.

Fatigue Testing of Full Scale Girth Welded Pipes Under Variable Amplitude Loading

2014 ◽  
Vol 136 (2) ◽  
Author(s):  
Y.-H. Zhang ◽  
S. J. Maddox
Keyword(s):  
Fatigue Limit ◽  
Fatigue Damage ◽  
Fatigue Testing ◽  
Full Scale ◽  
Variable Amplitude Loading ◽  
Variable Amplitude ◽  
Fatigue Design ◽  
Miner’S Rule ◽  
Miner's Rule ◽  
Loading Spectrum

In the fatigue design of steel catenary risers, there are concerns regarding the fatigue damage to girth welds from low stresses, below the constant amplitude fatigue limit, in the loading spectrum and the validity of Miner's cumulative damage rule. These fundamental issues were addressed in a recent joint-industrial project (JIP). A key feature was development of the resonance fatigue testing rigs to enable them to test full-scale pipes under variable amplitude loading. Such tests were performed under a loading spectrum representative of that experienced by some risers, with many tests lasting over 100 million cycles to investigate the fatigue damage due to small stresses as well as the validity of Miner's rule. However, the resonance rigs are only capable of producing spectrum loading by gradually increasing or decreasing the applied load whereas more “spiky” random load sequences may be relevant in practice. Therefore, the program also included fatigue tests in conventional testing machines on strip specimens cut from pipes to compare the two types of loading sequence. This paper presents the results of these tests, conclusions drawn, and recommendations for changes to current fatigue design guidance for girth welded pipes regarding the definition of the fatigue limit, allowance for the damaging effect of low stresses, and the validity of Miner's rule.

Fatigue Strength Study on Different Structure Type of Hatch Corner

2011 ◽  
Vol 233-235 ◽  
pp. 2580-2583
Author(s):  
Yong He Xie ◽  
Wei Wang ◽  
Heng Zhang
Keyword(s):  
Fatigue Strength ◽  
Scale Effect ◽  
Hot Spot ◽  
Structure Type ◽  
Cumulative Damage ◽  
Hot Spot Stress ◽  
Fatigue Design ◽  
Miner’S Rule ◽  
Curve Method ◽  
Miner's Rule

The fatigue strength study of the hatch corner is carried out ,based on the S-N curve method and the assumption of the linear cumulative damage of Palmgren-Miner's rule, using the hot spot stress method. Study on the effect of the structure different type to the fatigue strength of the hatch corner is carried out through changing its construction details and thickness. By comparing, the reasonable structure is obtained, and the scale effect should be put into consideration in fatigue design.

Improved Fatigue Design of SCR Modified Miner’s Rule

2019 ◽  
Author(s):  
Hans Olav Knagenhjelm ◽  
Mons Hauge ◽  
Bård Nyhus
Keyword(s):  
Carbon Steel ◽  
Stress Distribution ◽  
Fatigue Testing ◽  
Wave Spectrum ◽  
Fatigue Crack Initiation ◽  
Steel Pipe ◽  
Variable Amplitude ◽  
Fatigue Design ◽  
Miner’S Rule ◽  
Miner's Rule

Abstract The Aasta Hansteen floating production system is the first SPAR platform with steel catenary risers (SCR) at the Norwegian Continental Shelf (NCS). The water depth is 1300 msw. The weather conditions with respect to wave loading are more severe than any offshore installation completed so far. Under such environmental conditions, it is vital to verify the design of the SCR’s with respect to extreme loading and fatigue life. A fatigue verification program has been executed for ground OD welds of both clad and carbon steel riser materials. The objective was to determine the effect of weld defects in combination with the effect of variable amplitude loading using the actual fatigue stress distribution experienced by critical parts of the SCR. The stress distribution is based on the local wave spectrum and estimated from hydrodynamic analysis of the riser and the long-term wave statistics. Two clad pipes and one carbon steel pipe was exposed to rotation bending fatigue testing with artificially imposed defects. One clad pipes gave fracture after more than 1.0 × 109 cycles. The carbon steel pipe gave fracture after 4.56 × 108 cycles. A modified Miner’s summation rule is proposed for variable amplitude fatigue design. The procedure is based on a verification of variable amplitude testing against constant amplitude testing. The results indicate that load amplitudes below a fatigue limit defined at 107 cycles are not contributing significantly to fatigue crack initiation and growth from a weld defect. The proposed method suggests an engineering approach to this by a modification of the Miner’s rule for VA loading.

scholarly journals Non-Linear Probabilistic Modification of Miner’s Rule for Damage Accumulation

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7335
Author(s):  
Łukasz Blacha
Keyword(s):  
Fatigue Life ◽  
Probability Distribution ◽  
Damage Accumulation ◽  
Normal Distributions ◽  
Damage Degree ◽  
Non Linear ◽  
Miner’S Rule ◽  
The Mean ◽  
Fatigue Life Analysis ◽  
Miner's Rule

A non-linear modification to Miner’s rule for damage accumulation is proposed to reduce the scatter between experimental fatigue life and fatigue life predicted according to the original Miner’s sum. Based on P-s-n probability distribution and design s-n curves, the modification satisfies the assumption of equality between the mean damage degree (at the critical level) and fatigue life random variables, which is not covered in the original formulation. The adopted formulation shows the discrepancies between the fatigue lives predicted according to the design s-n curves and the estimated probability distribution. It also proves that it is inappropriate to apply a normal distribution to fatigue life analysis and that the model becomes non-linear only for non-normal distributions. The predictions according to the established model were compared to the predictions obtained with Miner’s rule.

Treatment of Low Stresses in Fatigue Design of Girth Welds Under Spectrum Loading

2008 ◽  
Author(s):  
Stephen J. Maddox
Keyword(s):  
Fatigue Tests ◽  
Test Results ◽  
Welded Steel ◽  
Steel Pipes ◽  
Fatigue Design ◽  
Conflicting Evidence ◽  
Miner’S Rule ◽  
Miner's Rule ◽  
Girth Welds ◽  
Spectrum Loading

Although the use of Miner’s rule for calculating the cumulative damage due to spectrum loading is well established, there is conflicting evidence as to how stresses below the constant amplitude fatigue limit (CAFL) should be assessed. They are known to be damaging under spectrum loading, but the extent of that damage is not clear. Since such stress levels potentially contribute the majority of the fatigue damage from wave motion and vortex-induced vibration in risers, this issue is highly significant both economically and with respect to safety. Therefore, fatigue tests were performed on strip specimens cut from girth-welded steel pipes under constant and variable amplitude loading to investigate this issue. The test results were assessed on the basis of Miner’s rule used in conjunction with various methods of extrapolating the S-N curve beyond the CAFL to establish the most suitable for correctly representing the damaging effect of stress ranges below it. A fracture mechanics fatigue crack growth analysis was also performed to calculate the fatigue lives expected under the test loading spectrum.

A Comparison of Fracture Mechanics and S–N Curve Approaches in Designing Drill Pipe

1992 ◽  
Vol 114 (3) ◽  
pp. 205-211 ◽  
Author(s):  
A. Ertas ◽  
G. Mustafa ◽  
O. Cuvalci
Keyword(s):  
Fracture Mechanics ◽  
Fatigue Damage ◽  
Drill Pipe ◽  
Ball Joint ◽  
Marine Riser ◽  
Deep Drilling ◽  
Miner’S Rule ◽  
Miner's Rule ◽  
Total Damage ◽  
Dynamic Fatigue

It is well known that the upper ball joint in a marine riser, in deep drilling, can cause fatigue damage in the drill pipe passing through it. A study of fracture mechanics and S–N curve approaches has been undertaken to determine the dynamic fatigue damage in the drill pipe. Miner’s rule is utilized in both methods to determine the total damage. The results of both methods are compared.

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