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

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

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.

scholarly journals Heat Input Influence on the Fatigue Life of Welds from Steel S460MC

Metals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1288 ◽  
Author(s):  
Jaromir Moravec ◽  
Jiri Sobotka ◽  
Pavel Solfronk ◽  
Robin Thakral
Keyword(s):  
Fatigue Life ◽  
Heat Input ◽  
Strengthening Mechanism ◽  
Dynamic Loads ◽  
Microalloyed Steels ◽  
Fine Grained ◽  
Weld Fatigue ◽  
Static And Dynamic Loads ◽  
Fine Grained Steels

Fine-grained steels belong to the progressive materials, which are increasingly used in the production of welded structures subjected to both static and dynamic loads. These are unalloyed or microalloyed steels hardened mainly by the grain-boundary strengthening mechanism. Such steels require specific welding procedures, especially in terms of the heat input value. At present, there are studies of the welding influence on the change of thermomechanically processed steels’ mechanical properties, however mainly under static loading. The paper is therefore focused on the assessment of the welding effect under dynamic loading of welded joints. In the experimental part was determined the influence of five different heat input values on the change of weld fatigue life. As a result, there is both determination of five S-N curves for the double-sided fillet welds from the thermomechanically processed fine-grained steel S460MC and the quantification of the main influences reducing the fatigue life of the joint.

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.

Effects of Variable Loading on Residual Fatigue Life of the Railway Wheelset

2013 ◽  
Vol 577-578 ◽  
pp. 121-124 ◽  
Author(s):  
Pavel Pokorný ◽  
Luboš Náhlík ◽  
M. Ševčík ◽  
Pavel Hutař
Keyword(s):  
Growth Rate ◽  
Fatigue Life ◽  
Life Time ◽  
Interaction Effects ◽  
Classical Approach ◽  
Variable Loading ◽  
Know How ◽  
Residual Fatigue Life ◽  
Residual Fatigue ◽  
Account Interaction

The paper deals with the effects of variable loading on residual fatigue life of the railway wheelset. The railway wheelsets can include some cracks created during manufacturing process or during previous operation. Therefore, it is important to know how the existing cracks will behave during further service of the train. The experiments show that the fatigue crack growth rate depends not only on size of the load amplitudes in a loading spectrum, but it depends also on the sequence of load amplitudes. Taking into account interaction effects of overloading cycles requires use a method that calculates increments of crack length in each cycle, i.e. cycle-by-cycle. One of such methods represents generalized Willenborg model. This model was used for residual fatigue life time estimations of railway wheelset and results obtained were compared with classical approach, which did not take into account interaction effects. Results obtained can be used for establishing of service intervals of railway wheelsets.

Sign in / Sign up

Export Citation Format

Share Document