Extension of Surface Cracks During Cyclic Loading

There is a dramatic change in the shape of the semi-elliptical cracks growing due to combined cyclic bending and tensile loading of plates. The growing cracks change their shape such that they follow preferred propagation patterns (PPPs). It is observed that computation of strain energy release rate (G) in surface cracks plays an important role in determining the preferred propagation pattern (PPP). Numerical integration techniques have been employed to compute total strain energy (TSE) release rate. The variation of TSE with crack depth (a/t) for different bending ratios (Rb) is presented and discussed. A program in BASIC is written to directly simulate the propagation of crack on the screen. It is shown that for a given cyclic loading field, the PPP represents an upper limit on the aspect ratio of any surface crack growing due to this cyclic loading.

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Fatigue propagation of surface cracks under cyclic loading

Low Cycle Fatigue and Elasto-Plastic Behaviour of Materials ◽

10.1016/b978-008043326-4/50118-5 ◽

1998 ◽

pp. 709-714

Author(s):

T. Boukharouba ◽

J. Gigert ◽

K. Azouaoui ◽

G. Pluvinage

Keyword(s):

Cyclic Loading ◽

Surface Cracks

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Comparative study of the effective parameters on residual stress relaxation in welded aluminum plates under cyclic loading

Mechanics & Industry ◽

10.1051/meca/2020061 ◽

2020 ◽

Vol 21 (5) ◽

pp. 505

Author(s):

Yousef Ghaderi Dehkordi ◽

Ali Pourkamali Anaraki ◽

Amir Reza Shahani

Keyword(s):

Residual Stress ◽

Cyclic Loading ◽

Stress Relaxation ◽

Stress Amplitude ◽

Cyclic Plasticity ◽

Mean Stress ◽

Effective Parameters ◽

Perfect Plasticity ◽

Residual Stress Relaxation ◽

Aluminum Plates

The prediction of residual stress relaxation is essential to assess the safety of welded components. This paper aims to study the influence of various effective parameters on residual stress relaxation under cyclic loading. In this regard, a 3D finite element modeling is performed to determine the residual stress in welded aluminum plates. The accuracy of this analysis is verified through experiment. To study the plasticity effect on stress relaxation, two plasticity models are implemented: perfect plasticity and combined isotropic-kinematic hardening. Hence, cyclic plasticity characterization of the material is specified by low cycle fatigue tests. It is found that the perfect plasticity leads to greater stress relaxation. In order to propose an accurate model to compute the residual stress relaxation, the Taguchi L18 array with four 3-level factors and one 6-level is employed. Using statistical analysis, the order of factors based on their effect on stress relaxation is determined as mean stress, stress amplitude, initial residual stress, and number of cycles. In addition, the stress relaxation increases with an increase in mean stress and stress amplitude.

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On The Dynamic Behaviour of Automobile Pulleys Under Cyclic Loading

Karbala International Journal of Modern Science ◽

10.33640/2405-609x.1603 ◽

2020 ◽

Vol 6 (2) ◽

Author(s):

Haval Kamal Asker ◽

Thaker Saleh Dawood

Keyword(s):

Cyclic Loading ◽

Dynamic Behaviour

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Effect of Incremental Displacement on the Fracture Resistance Curve of Nuclear Piping Materials under Reverse Cyclic Loading

Korean Journal of Metals and Materials ◽

10.3365/kjmm.2017.55.2.85 ◽

2017 ◽

Vol 55 (2) ◽

pp. 85-90

Author(s):

Sang-Young Kim

Keyword(s):

Cyclic Loading ◽

Fracture Resistance ◽

Resistance Curve

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Evaluation of System Effectiveness of Multifunctional Hydrogen Complex at Nuclear Power Plants

Alternative Energy and Ecology (ISJAEE) ◽

10.15518/isjaee.2019.13-15.24-39 ◽

2019 ◽

pp. 24-39

Author(s):

R. Z. Aminov ◽

A. N. Bayramov ◽

M. V. Garievskii

Keyword(s):

Cyclic Loading ◽

Nuclear Power ◽

Power Plants ◽

Nuclear Power Plants ◽

Frequency Control ◽

Economic Effect ◽

Current Frequency ◽

Main Equipment ◽

Primary Frequency ◽

Primary Frequency Control

The paper gives the analysis of the problem of the primary current frequency regulation in the power system, as well as the basic requirements for NPP power units under the conditions of involvement in the primary regulation. According to these requirements, the operation of NPPs is associated with unloading and a corresponding decrease in efficiency. In this regard, the combination of nuclear power plants with a hydrogen complex is shown to eliminate the inefficient discharge mode which allows the steam turbine equipment and equipment of the reactor facility to operate in the basic mode at the nominal power level. In addition, conditions are created for the generation and accumulation of hydrogen and oxygen during the day, as well as additionally during the nighttime failure of the electrical load which allows them to be used to generate peak power. The purpose of the article is to assess the systemic economic effect as a result of the participation of nuclear power plants in combination with the hydrogen complex in the primary control of the current frequency in the power sys-tem, taking into account the resource costs of the main equipment. In this regard, the paper gives the justification of cyclic loading of the main equipment of the hydrogen complex: metal storage tanks of hydrogen and oxygen, compressor units, hydrogen-oxygen combustion chamber of vapor-hydrogen overheating of the working fluid in the steam turbine cycle of a nuclear power plant. The methodological foundations for evaluating the working life of equipment under cyclic loading with the participation in the primary frequency control by the criterion of the growth rate of a fatigue crack are described. For the equipment of the hydrogen complex, the highest intensity of loading is shown to occur in the hydrogen-oxygen combustion chamber due to high thermal stresses. The system economic effect is estimated and the effect of wear of the main equipment under cyclic loading is shown. Under the conditions of combining NPP power units with a hydrogen complex, the efficiency of primary reg-ulation is shown to depend significantly on: the cost of equipment subjected to cyclic loading; frequency and intensity of cyclic loading; the ratio of the tariff for peak electricity, and the cost of electricity of nuclear power plants. Based on the developed methodology for assessing the effectiveness of the participation of nuclear power plants with a hydrogen complex in the primary frequency control, taking into account the damage to the equipment, the use of the hydrogen complex is shown to provide a tangible economic effect compared with the option of unloading nuclear power plants with direct participation in frequency control.

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