Constant Amplitude and Cumulative Damage Fatigue Tests on Bailey Bridges

2009 ◽  
pp. 15-15-25 ◽  
Author(s):  
D Webber
Keyword(s):  
Fatigue Tests ◽  
Cumulative Damage ◽  
Constant Amplitude

Cumulative Damage in Push-Pull Fatigue of Fillet-Welded Mild Steel Plate Subjected to Narrow Band Random Loading

1970 ◽  
Vol 185 (1) ◽  
pp. 339-351 ◽  
Author(s):  
D. J. White ◽  
J. Lewszuk
Keyword(s):  
Mild Steel ◽  
Steel Plate ◽  
Narrow Band ◽  
Fatigue Tests ◽  
Cumulative Damage ◽  
Mean Stress ◽  
Constant Amplitude ◽  
Random Loading ◽  
The Relationship ◽  
Made In

Push-pull fatigue tests have been made in constant amplitude loading and in narrow band random loading on fillet-welded cruciforms made from 3/8 in thick mild steel plate to B.S. 1501-151 Grade 28. The test frequency was 250 Hz, mean tensile stresses of 0, 5 and 10 tonf/in2were employed and tests were extended for endurances of up to 108cycles. Curves have been fitted to the S-N results using the relationship N( S — So)α= C and on the assumption that this may be extrapolated beyond 108cycles, curves showing the effect of mean stress are given for both constant amplitude loading and narrow band random loading for endurances up to 1012cycles. Suitable factors of safety should be applied to these stresses before use in design. For endurances beyond 107cycles, an increase in tensile mean stress from 0 to 10 tonf/in2reduced the fatigue strength by about 50 per cent in both constant amplitude loading and random loading. Reasonable agreement was found at all mean stresses between the experimental random loading S-N curves and those predicted using the constant amplitude results and the Palmgren-Miner cumulative damage hypothesis.

Cumulative Damage in Fretting Fatigue of Pinned Joints Subjected to Narrow Band Random Loading

1970 ◽  
Vol 21 (4) ◽  
pp. 400-408 ◽  
Author(s):  
D. J. White ◽  
J. Lewszuk
Keyword(s):  
Tensile Stress ◽  
Narrow Band ◽  
Fatigue Tests ◽  
Cumulative Damage ◽  
Mean Square ◽  
Test Frequency ◽  
Constant Amplitude ◽  
Random Loading ◽  
Good Agreement ◽  
Made In

SummaryFatigue tests have been made in constant amplitude loading and in narrow band random loading on FV520B steel lugs of width 27 mm loaded by means of a pin 12·7 mm in diameter. The test frequency was 220 Hz, a mean tensile stress of 309 N/mm2 was used and tests extended for endurances of up to 109 cycles.For endurances up to 106 cycles there was good agreement between constant amplitude and random loading results with both stresses expressed in root mean square values. Beyond this endurance, the random loading results lay below those obtained in constant amplitude loading. Predictions made using the Palmgren-Miner cumulative damage hypothesis in conjunction with the endurance curve in constant amplitude loading gave good agreement with the results in random loading over the whole range of endurances tested.

scholarly journals Fatigue Characteristic of Designed T-Type Specimen under Two-Step Repeating Variable Amplitude Load with Low-Amplitude Load below the Fatigue Limit

2021 ◽  
Vol 9 (2) ◽  
pp. 107
Author(s):  
Jin Gan ◽  
Di Sun ◽  
Hui Deng ◽  
Zhou Wang ◽  
Xiaoli Wang ◽  
...  
Keyword(s):  
Stress Ratio ◽  
Type Specimen ◽  
Fatigue Tests ◽  
Cumulative Damage ◽  
Cyclic Loads ◽  
Constant Amplitude ◽  
Type Specimens ◽  
Variable Amplitude ◽  
Non Linear ◽  
Low Amplitude

In order to investigate the non-linear fatigue cumulative damage of joints in ocean structural parts, one type of low carbon steel Q345D was employed to prepare designed T-type specimens, and a series of fatigue experiments were carried out on the specimens under two-step repeating variable amplitude loading condition. The chosen high cyclic loads were larger than the constant amplitude fatigue limit (CAFL) and the chosen low cyclic loads were below the CAFL. Firstly, the S-N curve of designed T-type specimen was obtained via different constant amplitude fatigue tests. Then, a series of two-step repeating variable load were carried out on designed T-type specimens with the aim of calculating the cumulative damage of specimen under the variable fatigue load. The discussions about non-linear fatigue cumulative damage of designed T-type specimens and the interaction effect between the high and low amplitude loadings on the fatigue life were carried out, and some meaningful conclusions were obtained according to the series of fatigue tests. The results show that fatigue cumulative damage of designed T-type specimens calculated based on Miner’s rule ranges from 0.513 to 1.756. Under the same cycle ratio, the cumulative damage increases with the increase of high cyclic stress, and at the same stress ratio, the cumulative damage increases linearly with the increase of cycle ratio. Based on the non-linear damage evaluation method, it is found that the load interaction effect between high and low stress loads exhibits different damage or strengthening effects with the change of stress ratio and cycle ratio.

RC Beam Bridge’s Fatigue Cumulative Damage Rule Research

2013 ◽  
Vol 787 ◽  
pp. 829-832
Author(s):  
Hong Bing Zhu ◽  
Bo Xia ◽  
Yao Zhao
Keyword(s):  
Fatigue Damage ◽  
Fatigue Tests ◽  
Cumulative Damage ◽  
Rc Beam ◽  
Constant Amplitude ◽  
Advantages And Disadvantages ◽  
Damage Theory ◽  
Theory Research ◽  
Beam Bridge ◽  
Damage Rule

Fatigue damage is the RC beam bridge is facing a big problem, for the RC beam bridge fatigue tests and fatigue cumulative damage theory research is very meaningful. Summarizes the research achievements of the RC beam bridge fatigue test, from constant amplitude fatigue, luffing fatigue and stochastic fatigue, etc, are discussed in this paper. Analyses the existing linear, nonlinear and probability fatigue cumulative damage theory and its applicable conditions, advantages and disadvantages. RC fatigue tests were discussed and the problems that exist in the fatigue cumulative damage theory research.

Fatigue of Stabilized SS and 316 NG Alloy in PWR Environment

2006 ◽  
Author(s):  
Jussi P. Solin
Keyword(s):  
Stainless Steels ◽  
Fatigue Tests ◽  
Test Results ◽  
Constant Amplitude ◽  
Low Oxygen ◽  
Variable Amplitude ◽  
Variable Amplitude Fatigue ◽  
Reduction Factors

Strain controlled constant and variable amplitude fatigue tests for 316NG and Titanium stabilized stainless steels in low oxygen PWR waters were performed. The stabilized steel has been plant aged for 100 000 hours. Constant amplitude test results at 0,01 Hz sinusoidal straining comply with predicted lives according to the Fen approach for both materials. Spectrum straining both in air and in environment caused predicted life reduction factors (about 3) for the stabilized steel, but for the 316NG steel spectrum straining in environment resulted to a larger reduction in life.

scholarly journals Effects of Actual Marine Atmospheric Pre-Corrosion and Pre-Fatigue on the Fatigue Property of 7085 Aluminum Alloy

Metals ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 81
Author(s):  
Laixin Shi ◽  
Lin Xiang ◽  
Jianquan Tao ◽  
Jun Liu ◽  
Qiang Chen ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Life ◽  
Pitting Corrosion ◽  
Atmospheric Corrosion ◽  
Fatigue Property ◽  
Outdoor Exposure ◽  
Fatigue Tests ◽  
Constant Amplitude ◽  
Fatigue Fractography ◽  
Corrosion Mode

Effects of actual marine atmospheric precorrosion and prefatigue on the fatigue property of 7085-T7452 aluminum alloy were investigated by using the methods of marine atmospheric outdoor exposure tests and constant amplitude axial fatigue tests. Marine atmospheric corrosion morphologies, fatigue life, and fatigue fractography were analyzed. After three months of outdoor exposure, both pitting corrosion and intergranular corrosion (IGC) occurred, while the latter was the dominant marine atmospheric corrosion mode. Marine atmospheric precorrosion could result in a dramatical decrease in the fatigue life of the as-received 7085-T7452 aluminum alloy, while selective prefatigue can improve the total fatigue life of the precorroded specimen. The mechanism of the actual marine atmospheric corrosion and its effects on the fatigue life of the 7085-T7452 aluminum alloy were also discussed.

The Effects of Periodic High Loads on Fretting Fatigue

1981 ◽  
Vol 103 (3) ◽  
pp. 223-228 ◽  
Author(s):  
A. Kantimathi ◽  
J. A. Alic
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Life ◽  
Growth Retardation ◽  
Fretting Fatigue ◽  
Fatigue Tests ◽  
Constant Amplitude ◽  
Axial Loads ◽  
Prolonged Fatigue ◽  
Stress Ratios ◽  
Crack Growth Retardation

Fretting fatigue tests have been conducted on 7075-T7351 aluminum alloy coupons with fretting pads of the same material. Three different stress ratios were used, the otherwise constant amplitude axial loads being interrupted every 1000 cycles by either tensile overloads to 400 MPa or compressive underloads to −200 MPa. Tensile overloads greatly prolonged fatigue life for low stresses where the overload ratios were 1.6 and above; compressive underloads had comparatively little effect. The results are discussed in terms of crack growth retardation phenomena.

Energy Accumulation in Steel, in the Conditions of Constant-Amplitude

2015 ◽  
Vol 240 ◽  
pp. 114-121
Author(s):  
Stanisław Mroziński ◽  
Michał Piotrowski
Keyword(s):  
Crack Initiation ◽  
Strain Energy ◽  
Fatigue Tests ◽  
Constant Amplitude ◽  
P91 Steel ◽  
Energy Accumulation ◽  
Different Order ◽  
Different Levels

This work presents results of fatigue tests of P91 steel specimens under constant-amplitude and programmed loading in temperature T=600°C. Two strain levels, applied in different order, were used for programmed loading. The loading program level changes were introduced for different levels of damage. The tests provided the basis for analysis of strain energy ΔWpl in the function of the number of load cycles under constant-amplitude and programmed loading. It has been found that that the form of a loading program has an influence on the life and value of energy cumulated in the specimen until crack initiation. Verification of Palmgren Miner hypothesis revealed that its effectiveness depends on the loading program and temperature.

Exploratory Tests on the Effects of Random Loading and Corrosive Environment on the Fatigue Strength of Fillet-Welded Lap Joints

1975 ◽  
Vol 17 (4) ◽  
pp. 181-185 ◽  
Author(s):  
K. J. Marsh ◽  
T. Martin ◽  
J. McGregor
Keyword(s):  
Fatigue Strength ◽  
Mild Steel ◽  
Narrow Band ◽  
Fatigue Tests ◽  
Lap Joints ◽  
Corrosive Environment ◽  
Test Frequency ◽  
Constant Amplitude ◽  
Random Loading ◽  
Loading Tests

Fatigue tests on simple, fillet-welded, mild steel lap joints have been carried out to determine the effects of a corrosive environment and random loading. At normal testing frequencies, a brine-drip environment had no effect on the constant-amplitude fatigue strength at short endurances. At stresses less than the in-air fatigue limit, the corrosive environment was sufficient to allow crack growth at very low stress levels. In these corrosive environment tests, reducing the test frequency by a factor of 50 halved the life. The results of narrow-band random loading tests could be predicted reasonably accurately either by a fracture mechanics method or by Miner's rule.

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