scholarly journals Determination of Residual Fatigue Life of Welded Structures at Bucket-Wheel Excavators through the Use of Fracture Mechanics

2018 ◽  
Vol 13 ◽  
pp. 79-84 ◽  
Author(s):  
M. Arsić ◽  
S. Bošnjak ◽  
N. Gnjatović ◽  
S.A. Sedmak ◽  
D. Arsić ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Fracture Mechanics ◽  
Welded Structures ◽  
Residual Fatigue Life ◽  
Residual Fatigue

Integrity assessment and determination of residual fatigue life of vital parts of bucket-wheel excavator operating under dynamic loads

2019 ◽  
Vol 105 ◽  
pp. 182-195 ◽  
Author(s):  
Dušan Arsić ◽  
Nebojša Gnjatović ◽  
Simon Sedmak ◽  
Aleksandra Arsić ◽  
Milan Uhričik
Keyword(s):  
Fatigue Life ◽  
Dynamic Loads ◽  
Integrity Assessment ◽  
Residual Fatigue Life ◽  
Residual Fatigue

A Model for the Determination of Residual Fatigue Life of a Nickel-Based Superalloy

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
Duyi Ye ◽  
Jinyang Zheng
Keyword(s):  
High Temperature ◽  
Fatigue Life ◽  
Fatigue Damage ◽  
Strain Energy ◽  
Damage Mechanics ◽  
Residual Fatigue Life ◽  
Mechanics Model ◽  
Plastic Strain Energy ◽  
Residual Fatigue

In this paper, both the dissipation of the plastic-strain energy and the exhaustion of the static toughness during high-temperature low-cycle fatigue of GH4145/SQ superalloy were investigated. Together with the analysis of the microscopic aspects of the material, an energy-based damage mechanics model was developed for the prediction of the residual fatigue life of the high-temperature fastened parts in power plant. Experimental results show that the static toughness is a parameter that is highly sensitive to the fatigue damage process. The deterioration of the static toughness during fatigue process reveals the exhaustion of the materials’s ability to absorb energy, which is essentially associated with the irreversible energy dissipation process of the fatigue failure. Based on the dissipation of the plastic-strain energy and the exhaustion of the static toughness during fatigue, a damage variable is defined that is consistent with the fatigue damage mechanism. The variable is sensitive to the fatigue process and can be measured with a simple experimental procedure. A fatigue damage evolution equation is derived on the basis of Lemaitre’s potential of dissipation in the framework of continuum damage mechanics. Furthermore, an equation for the determination of the residual fatigue life is deduced. The fatigue damage mechanics model is verified by comparing the predicted results with the experimental observations. The fatigue damage mechanics model developed may provide a feasible approach to determining the residual fatigue life of the high-temperature fastened parts in power plant.

Uncertainties of Crack Propagation Analysis in Ship Structures

2016 ◽  
Author(s):  
Wengang Mao ◽  
Jingxia Yue ◽  
Da Wu ◽  
Luis De Gracia ◽  
Naoki Osawa
Keyword(s):  
Fatigue Life ◽  
Fracture Mechanics ◽  
Crack Propagation ◽  
Fatigue Cracks ◽  
Estimation Methods ◽  
Ship Structures ◽  
Residual Fatigue Life ◽  
Propagation Analysis ◽  
Structural Details ◽  
Residual Fatigue

Fatigue cracks can be observed quite frequently on today’s ocean crossing vessels. To ensure the safety of ship structures sailing in the sea, it is important to know the residual fatigue life of these damaged ship structures. In this case, the fracture mechanics theory is often employed to estimate how fast these cracks can propagate along ship structures. However, large uncertainties are always associated with the crack prediction and residual fatigue life analysis. In this study, two uncertainties sources will be investigated, i.e. the reliability of encountered wave environments connected with shipload determinations and different fracture estimation methods for crack propagation analysis. Firstly, different available codes based on fracture mechanic theory are used to compute the stress intensity factor related parameters for crack propagation analysis. The analysis is carried out for both 2D and 3D cases of some typical ship structural details. The comparison is presented to illustrate the uncertainties of crack propagation analysis related with different codes. Furthermore, it is assumed that the structural details will undertake dynamic loading from a containership operated in the North Atlantic. A statistical wave model is used to generate wave environments along recorded ship routes for different years. The uncertainties of crack growth analysis related with encountered weather environments is also investigated in the study. The comparison of these two uncertainties indicated the requirement of further development for the fracture mechanics theory and associated numerical codes, as well as the reliable life-cycle encountered weather environments.

Residual Fatigue Life Determination of Anchor Bolts

1979 ◽  
Vol 101 (1) ◽  
pp. 47-52 ◽  
Author(s):  
B. Mukherjee
Keyword(s):  
Growth Rate ◽  
Fatigue Life ◽  
Crack Growth Rate ◽  
Fracture Mechanics ◽  
Crack Growth ◽  
Effect Of Temperature ◽  
Transmission Tower ◽  
Residual Fatigue Life ◽  
Anchor Bolts ◽  
Residual Fatigue

A project was conducted to determine residual fatigue life of transmission tower anchor bolts. Notched and fatigue precracked round bar specimens were used to simulate anchor bolt fatigue and to determine fatigue life experimentally. Fatigue precracked compact tension specimens were used to determine fatigue crack growth rate properties using a fracture mechanics approach. The effect of temperature on crack growth rate was also investigated. A method to estimate fatigue life of surface cracked round bars was developed and predictions were compared against experimental results. This paper shows how a fracture mechanics approach can be used to estimate residual fatigue life of cracked anchor bolts.

scholarly journals Effect of Pre-Corrosion Pits on Residual Fatigue Life for 42CrMo Steel

Materials ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2130 ◽  
Author(s):  
Dezheng Liu ◽  
Yan Li ◽  
Xiangdong Xie ◽  
Jing Zhao
Keyword(s):  
Stress Intensity Factor ◽  
Fatigue Life ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Research Work ◽  
Residual Fatigue Life ◽  
42Crmo Steel ◽  
Regression Formula ◽  
Residual Fatigue ◽  
Corrosion Pits

The effect of pre-corrosion pits on residual fatigue life for the 42CrMo steel (American grade: AISI 4140) is investigated using the accelerated pre-corrosion specimen in the saline environment. Different pre-corroded times are used for the specimens, and fatigue tests with different loads are then carried out on specimens. The pre-corrosion fatigue life is studied, and the fatigue fracture surfaces are examined by a surface profiler and a scanning electron microscope (SEM) to identify the crack nucleation sites and to determine the size and geometry of corrosion pits. Moreover, the stress intensity factor varying with corrosion pits in different size parameters is analyzed based on finite element (FE) software ABAQUS to derive the regression formula of the stress intensity factor. Subsequently, by integrating the regression formula with the Paris formula, the residual fatigue life is predicted and compared with experimental results, and the relationship of the stress intensity factor, pit depth, and residual fatigue life are given under different corrosion degrees. The fatigue life predicted by the coupled formula agrees well with experiment results. It is observed from the SEM images that higher stress amplitude and longer pre-corroded time can significantly decrease the residual fatigue life of the steel. Additionally, the research work has brought about the discovery that the rate of crack extension accelerates when the crack length increases. The research in this paper also demonstrates that the corrosion pit size can be used as a damage index to assess the residual fatigue life.

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