Damage indicators for early fatigue damage assessment in WC-Co hardmetals under uniaxial cyclic loads at a stress ratio of R = −1 at elevated temperatures

2021 ◽  
pp. 105749 ◽  
Author(s):  
Kathrin Maier ◽  
Thomas Klünsner ◽  
Philip Pichler ◽  
Stefan Marsoner ◽  
Werner Ecker ◽  
...  
Keyword(s):  
Fatigue Damage ◽  
Damage Assessment ◽  
Stress Ratio ◽  
Elevated Temperatures ◽  
Cyclic Loads ◽  
Damage Indicators

scholarly journals Internal Factors Affecting the Surface Rumpling of a β-NiAlHf Coating

Coatings ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 436
Author(s):  
Liang Liu ◽  
Jian He ◽  
Yaoge Dong ◽  
Hongbo Guo
Keyword(s):  
Physical Vapor Deposition ◽  
Elevated Temperatures ◽  
Coefficient Of Thermal Expansion ◽  
Dominant Role ◽  
Cyclic Loads ◽  
Internal Factor ◽  
Internal Factors ◽  
Factors Affecting ◽  
Mismatch Stress ◽  
Thermal Mismatch Stress

β-NiAl coatings on a superalloy substrate will inevitably result in severe rumpling at elevated temperatures; however, the associated rumpling mechanisms are not completely understood. The scale rumpling behavior of a β-NiAlHf coating deposited by electron beam physical vapor deposition (EB-PVD) on single crystal superalloy IC21 was investigated in this work. Some internal factors, including the mismatch in the coefficient of thermal expansion and the stress induced by the growth of oxide scale and the phase transformation, were taken into consideration. The thermal mismatch stress between the coating and substrate was the main internal factor responsible for rumpling behavior during thermal cyclic loads, while the phase degradation from β-NiAl to γ’-Ni3Al in the coating played a dominant role during static thermal loads.

High Cycle Fatigue Damage Evaluation of Steel Pipelines Based on Microhardness Changes During Cyclic Loads: Part II

2018 ◽  
Author(s):  
Geovana Drumond ◽  
Bianca Pinheiro ◽  
Ilson Pasqualino ◽  
Francine Roudet ◽  
Didier Chicot
Keyword(s):  
Fatigue Life ◽  
Fatigue Damage ◽  
High Cycle Fatigue ◽  
Steel Structures ◽  
New Method ◽  
Microplastic Deformation ◽  
Surface Phenomenon ◽  
Cyclic Loads ◽  
Cycle Fatigue ◽  
Indentation Tests

The hardness of a material shows its ability to resist to microplastic deformation caused by indentation or penetration and is closely related to the plastic slip capacity of the material. Therefore, it could be significant to study the resistance to microplastic deformations based on microhardness changes on the surface, and the associated accumulation of fatigue damage. The present work is part of a research study being carried out with the aim of proposing a new method based on microstructural changes, represented by a fatigue damage indicator, to predict fatigue life of steel structures submitted to cyclic loads, before macroscopic cracking. Here, Berkovich indentation tests were carried out in the samples previously submitted to high cycle fatigue (HCF) tests. It was observed that the major changes in the microhardness values occurred at the surface of the material below 3 μm of indentation depth, and around 20% of the fatigue life of the material, proving that microcracking is a surface phenomenon. So, the results obtained for the surface of the specimen and at the beginning of the fatigue life of the material will be considered in the proposal of a new method to estimate the fatigue life of metal structures.

Research on the Approach for the Assessment of Subsurface Rolling Contact Fatigue Damage

2013 ◽  
Vol 395-396 ◽  
pp. 845-851
Author(s):  
Xiao Feng Qin ◽  
Da Le Sun ◽  
Li Yang Xie
Keyword(s):  
Shear Stress ◽  
Friction Coefficient ◽  
Fatigue Damage ◽  
Stress Ratio ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Critical Stresses ◽  
Orthogonal Shear Stress

In this paper, the distribution of different critical stresses, which were used in previous correlation articles for the assessment of subsurface rolling contact fatigue damage, was analyzed. The rationality of orthogonal shear stress was selected as the key stress controlling the subsurface rolling contact fatigue damage was clarified. Base on the linear fatigue damage accumulative theory and the modification equation for the range of asymmetrical stress, the influence of friction on subsurface rolling contact fatigue damage was studied. The results show that the subsurface orthogonal shear stress is a completely symmetrical stress when the friction coefficient is zero, while it is an asymmetrical stress with considering the friction. The stress ratio of subsurface orthogonal shear stress and subsurface rolling contact fatigue damage is increased with the increasing of friction.

Early-Age Fatigue Damage Assessment of Cement-Treated Bases under Repetitive Heavy Traffic Loading

2018 ◽  
Vol 30 (6) ◽  
pp. 04018079 ◽  
Author(s):  
Arooran Sounthararajah ◽  
Ha Hong Bui ◽  
Nhu Nguyen ◽  
Peerapong Jitsangiam ◽  
Jayantha Kodikara
Keyword(s):  
Fatigue Damage ◽  
Damage Assessment ◽  
Heavy Traffic ◽  
Early Age ◽  
Traffic Loading
Sign in / Sign up

Export Citation Format

Share Document