Cross Property Correlations for Metals Subjected to Fatigue Damage Accumulation

2002 ◽  
Author(s):  
Mahesh C. Bogarapu ◽  
Igor Sevostianov
Keyword(s):  
Electrical Resistance ◽  
Damage Accumulation ◽  
Fatigue Tests ◽  
Electric Resistance ◽  
Metal Structures ◽  
Accumulated Damage ◽  
Fatigue Damage Accumulation ◽  
Theoretical Predictions ◽  
Method Of Evaluation ◽  
Better Than

A new method of evaluation of elastic property deterioration due to accumulated damage is suggested and experimentally verified. It is based on the explicit correlations between two groups of anisotropic properties – conductivity and elasticity, recently established for porous/microcracked materials with anisotropic microstructures. An experimental study of fatigue has been done to verify the theoretical predictions. The electrical resistance and Young’s modulus are measured as functions of the number of loading cycles in the standard fatigue tests. The agreement between the theoretical predictions and the direct experimental data is better than 10% in all cases. The results allow one to use the measurement of electric resistance to estimate the damage accumulated in metal structures and decrease in the elastic modulus.

LCF Life Prediction Model of Coiled Tubing Based on Fatigue Damage Accumulation

2013 ◽  
Vol 699 ◽  
pp. 426-431
Author(s):  
Zong Yue Bi ◽  
Lin Yun Xian
Keyword(s):  
Fatigue Behavior ◽  
Cyclic Stress ◽  
Fatigue Tests ◽  
Coiled Tubing ◽  
Fatigue Damage Accumulation ◽  
Theoretical Predictions ◽  
Plastic Strain Energy ◽  
Cyclic Plastic Strain ◽  
Damage Rule ◽  
Life Prediction Model

This paper establishes a model to predict the fatigue behavior of coiled tubing subjected to variable total strain conditions. The approach based on nonlinear fatigue cumulative damage rule of effective hysteresis energy dissipation, but requires additional experimental results from fatigue tests that were performed under constant strain amplitude. Cyclic plastic strain energy is measured curve area of cyclic stress-strain curves. it is proved to be quite consistent between theoretical predictions and experimentl datas.

Applying a Stepwise Load for Calculation of the S-N Curve for Trabecular Bone Based on the Linear Hypothesis for Fatigue Damage Accumulation

2012 ◽  
Vol 726 ◽  
pp. 39-42 ◽  
Author(s):  
Tomasz Topoliński ◽  
Artur Cichański ◽  
Adam Mazurkiewicz ◽  
Krzysztof Nowicki
Keyword(s):  
Trabecular Bone ◽  
Fatigue Damage ◽  
Damage Accumulation ◽  
Applied Load ◽  
Fatigue Tests ◽  
Bone Sample ◽  
Linear Hypothesis ◽  
Fatigue Damage Accumulation

In this work were presented calculated fatigue curves based on fatigue tests of trabecular bone under stepwise load with the application of a linear hypothesis accumulation of fatigue damage. The investigation was performed on 61 cylindrical bone samples obtained from the neck of different femur heads. The bone sample fatigue tests were carried out under compression with stepwise increases of the applied load. The fatigue calculation assumed the Palmgren-Miner (P-M) linear hypothesis accumulation of fatigue damage and the associated modified formulae. The obtained mean fatigue curves were based on the modified stress σ/E0 (E0 – initial stiffnes) for the assumed rule-determined slope or y-intercept. The highest agreement with the literature was obtained for Σn/N=10.

Cyclic and Fatigue Behavior of the P355NL1 Steel Under Block Loading

2007 ◽  
Author(s):  
He´lder F. S. G. Pereira ◽  
Abi´lio M. P. De Jesus ◽  
Anto´nio A. Fernandes ◽  
Alfredo S. Ribeiro
Keyword(s):  
Fatigue Damage ◽  
Damage Accumulation ◽  
Fatigue Behavior ◽  
Fatigue Tests ◽  
Pressure Vessels ◽  
Cumulative Damage ◽  
Sequential Effects ◽  
Block Loading ◽  
Fatigue Damage Accumulation ◽  
Life Predictions

Current fatigue analyses of metallic structures undergoing variable amplitude loading, including pressure vessels, are mostly based on linear cumulative damage concepts, as proposed by Palmgren and Miner. This type of analysis neglects any sequential effects of the loading history. Several studies have shown that linear cumulative damage theories can produce inconsistent fatigue life predictions. In this paper, both fatigue damage accumulation and cyclic elastoplastic behaviors of the P355NL1 steel are characterized, using block loading fatigue tests. The loading is composed by blocks of constant strain-controlled amplitudes, applied according to two and multiple alternate blocks sequences. Also, loading composed by blocks of variable strain-controlled amplitudes are investigated. The block loading illustrates that fatigue damage evolves nonlinearly with the number of load cycles, as a function of the block strain amplitudes. These observations suggest a nonlinear damage accumulation rule with load sequential effects for the P355NL1 steel. However, the damage accumulation nonlinearity and load sequential effects are more evident for the two block loading rather than for multiple alternate block sequences, which suggests that the linear Palmgren-Miner’s rule tend to produce better results for more irregular loading histories. Some phenomenological interpretations for the observed trends are discussed under a fracture mechanics framework.

Effect of Temperature Changes on the Waveform of Fatigue Damage Accumulation

2014 ◽  
Vol 598 ◽  
pp. 160-167 ◽  
Author(s):  
Stanisław Mroziński ◽  
Michał Piotrowski
Keyword(s):  
Fatigue Life ◽  
Temperature Change ◽  
Damage Accumulation ◽  
Low Cycle Fatigue ◽  
Fatigue Tests ◽  
Effect Of Temperature ◽  
Cycle Fatigue ◽  
Temperature Changes ◽  
Fatigue Damage Accumulation ◽  
Two Temperatures

In this paper there have been presented the results of low-cycle fatigue tests of steel P91 samples in the conditions of isothermal fixed amplitude loads as well as loads with a temperature change. Fixed amplitude isothermal loads were conducted on five levels of full strain and in two temperatures T1=20°C and T2=600°C. In the paper there has been found a significant influence of the sequence of temperature changes on the cyclic properties after the temperature change and on the fatigue life. The conducted experimental verification of the Palmgren-Miner hypothesis proved its influence on the temperature changes during the tests.

Cyclic and Fatigue Behavior of the P355NL1 Steel Under Block Loading

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
Hélder F. S. G. Pereira ◽  
Abílio M. P. De Jesus ◽  
Alfredo S. Ribeiro ◽  
António A. Fernandes
Keyword(s):  
Fatigue Damage ◽  
Damage Accumulation ◽  
Fatigue Behavior ◽  
Fatigue Tests ◽  
Pressure Vessels ◽  
Cumulative Damage ◽  
Sequential Effects ◽  
Block Loading ◽  
Fatigue Damage Accumulation ◽  
Life Predictions

Current fatigue analyses of metallic structures undergoing variable amplitude loading, including pressure vessels, are mostly based on linear cumulative damage concepts, as proposed by Palmgren and Miner. This type of analysis neglects any sequential effects of the loading history. Several studies have shown that linear cumulative damage theories can produce inconsistent fatigue life predictions. In this paper, both fatigue damage accumulation and cyclic elastoplastic behaviors of the P355NL1 steel are characterized using block loading fatigue tests. The loading is composed of blocks of constant strain-controlled amplitudes, applied according to two and multiple alternate blocks sequences. Also, loading composed by blocks of variable strain-controlled amplitudes are investigated. The block loading illustrates that fatigue damage evolves nonlinearly with the number of load cycles, as a function of the block strain amplitudes. These observations suggest a nonlinear damage accumulation rule with load sequential effects for the P355NL1 steel. However, the damage accumulation nonlinearity and load sequential effects are more evident for the two block loading rather than for multiple alternate block sequences, which suggests that the linear Palmgren–Miner rule tends to produce better results for more irregular loading histories. Some phenomenological interpretations for the observed trends are discussed under a fracture mechanics framework.

Construction of a Generalized Fatigue Diagram of Metallic Materials

2019 ◽  
Vol 945 ◽  
pp. 563-568 ◽  
Author(s):  
O.V. Bashkov ◽  
A.A. Popkova ◽  
G.A. Gadoev ◽  
Tatiana I. Bashkova ◽  
Denis B. Solovev
Keyword(s):  
Acoustic Emission ◽  
Damage Accumulation ◽  
Fatigue Tests ◽  
Separate Analysis ◽  
Emission Sources ◽  
Fatigue Damage Accumulation ◽  
Fatigue Rupture ◽  
Ae Signal ◽  
Accumulation Of Damage ◽  
Ae Signals

The paper presents the results of the study of the stage of accumulation of damage and fatigue rupture of titanium alloys (using the method of acoustic emission). The main object of research was the development of a method for designing a generalized fatigue diagram characterizing the stage of fatigue damage accumulation. The studies aimed at experimental verification of the hypothesis of the stage of damage accumulation, which can be established only by the registered parameters of acoustic emission with separate analysis by types of acoustic emission sources. In contrast to the method of research, which is carried out fractographic analysis, the use of acoustic emission method can significantly reduce the amount of testing. The types of acoustic emission sources on the distribution plane of two-parameter “AE signal energy EAE vs. frequency parameter Kf” are considered. Fatigue stages in the tests of trial alloys were determined by the activity of the AE signals emitted by different types of AE sources (dislocation, micro - and macro-cracks). A generalized diagram of fatigue developed according to the specified stages. The developed method significantly reduces the volume of fatigue tests and fractographic studies.

scholarly journals Assessment of residual fatigue life of metal beam of reinforced concrete superstructures of road bridges

2019 ◽  
Vol 6 (3) ◽  
Author(s):  
Elena Feoktistova
Keyword(s):  
Reinforced Concrete ◽  
Fatigue Life ◽  
Fatigue Damage ◽  
Damage Accumulation ◽  
Steel Structures ◽  
Asymmetry Factor ◽  
Residual Fatigue Life ◽  
Fatigue Damage Accumulation ◽  
Residual Fatigue ◽  
Method Of Evaluation

The article proposes a method of evaluation of residual fatigue life of metal beam of reinforced concrete superstructures of road bridges. In the calculations of residual fatigue life were implemented statistical data of endurance characteristics of steel structures that mostly fully corresponds to the given junctions by design, material, production technology and force impact. Fatigue life is determined based on the hypothesis of linear addition of fatigue damage accumulation. The critical damage amount providing the target reliability considered equal to one. Residual fatigue life of metal beams is calculated based on endurance characteristics of different groups of welded joints.For the life period assessment the motor transport load including prospective is reduced to the estimated. The reduction factor is defined based on the stress level, asymmetry factor of stress cycle and steel grade according to the conditions of equality of fatigue damage accumulation. The method allows determining of the remaining fatigue life of welded metal beams according to the transport load. Service limit and usage mode are predicted based on the structural calculations taking into account defects and damages using actual size and considering manufacturing, constructing and operational defects. Moreover, changes of strength and fatigue characteristics should be taken into account. The method of evaluation of residual fatigue life of metal beam of reinforced concrete superstructures of road bridges proposed by the auther requires clarification of te current and future load impact. The fatigue life mostly depends on the performance of superstructures maintanance and repair works.

Method of Determining the Initial Stiffness Modulus for Trabecular Bone under Stepwise Load

2012 ◽  
Vol 726 ◽  
pp. 84-89 ◽  
Author(s):  
Tomasz Topoliński ◽  
Artur Cichański ◽  
Adam Mazurkiewicz ◽  
Krzysztof Nowicki
Keyword(s):  
Trabecular Bone ◽  
Damage Accumulation ◽  
Applied Load ◽  
Bone Structure ◽  
Fatigue Tests ◽  
Statistical Relationship ◽  
Initial Stiffness ◽  
Stiffness Modulus ◽  
Unsuccessful Attempt ◽  
Fatigue Damage Accumulation

In this work was presented method of initial stiffness modulus E0 calculation based on fatigue tests of trabecular bone under stepwise load. The investigation was performed on 61 cylindrical bone samples obtained from the neck of different femur heads. The bone sample fatigue tests were carried out under compression with stepwise increases of the applied load. The obtained values of the initial stiffness modulus E0 were consistent with literature data and can be used to determine the S-N curve for trabecular bone using the hypotheses of fatigue damage accumulation. It was also an unsuccessful attempt to find a statistical relationship between the values of the initial stiffness modulus E0 and indices of bone structure.

Fatigue of Unidirectional Cord-Rubber Composites

1999 ◽  
Vol 27 (1) ◽  
pp. 48-57 ◽  
Author(s):  
Y. Liu ◽  
Z. Wan ◽  
Z. Tian ◽  
X. Du ◽  
J. Jiang ◽  
...  
Keyword(s):  
Damage Accumulation ◽  
Fatigue Testing ◽  
Fatigue Behavior ◽  
Constant Load ◽  
Testing System ◽  
Rubber Composites ◽  
Cycle Frequency ◽  
Periodic Loading ◽  
Fatigue Damage Accumulation ◽  
Rubber Composite

Abstract A fatigue testing system is established with which the real-time recording of stress, strain, temperature, and hysteresis loss of rubbers or cord-rubber composite specimens subjected to periodic loading or extension can be successfully carried out. Several problems are connected with the experimental study of the fatigue of rubber composites. In constant extension cycling, the specimen becomes relaxed because of the viscoelasticity of rubber composites, and the imposed tension-tension deformation becomes complex. In this method, the specimen is unlikely to fail unless the imposed extensions are very large. Constant load cycling can avoid the shortcomings of constant extension cycling. The specially designed clamps ensure that the specimen does not slip when the load retains a constant value. The Deformation and fatigue damage accumulation processes of rubber composites under periodic loading are also examined. Obviously, the effect of cycle frequency on the fatigue life of rubber composites can not be ignored because of the viscoelasticity of constituent materials. The increase of specimen surface temperature is relatively small in the case of 1 Hz, but the temperature can easily reach 100°C at the 8 Hz frequency. A method for evaluating the fatigue behavior of tires is proposed.

Fatigue damage accumulation around notches

2004 ◽  
Vol 46 (6) ◽  
pp. 309-313
Author(s):  
Yutaka Iino ◽  
Hideo Yano
Keyword(s):  
Fatigue Damage ◽  
Damage Accumulation ◽  
Fatigue Damage Accumulation
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