scholarly journals Strain ratcheting limit stresses as a function of microstructure of WC-Co hardmetals under uniaxial cyclic loads under a stress ratio of R = −∞ at elevated temperatures

2021 ◽  
pp. 105699
Author(s):  
Kathrin Maier ◽  
Thomas Klünsner ◽  
Philip Pichler ◽  
Stefan Marsoner ◽  
Werner Ecker ◽  
...  
Keyword(s):  
Stress Ratio ◽  
Elevated Temperatures ◽  
Cyclic Loads

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.

Effect of stress ratio and mean stress on high cycle fatigue behavior of the superalloy IN718 at elevated temperatures

2019 ◽  
Vol 6 (9) ◽  
pp. 0965a6 ◽  
Author(s):  
Dhananjay Pradhan ◽  
G S Mahobia ◽  
K Chattopadhyay ◽  
D C Fernando ◽  
N Paulose ◽  
...  
Keyword(s):  
Stress Ratio ◽  
High Cycle Fatigue ◽  
Elevated Temperatures ◽  
Fatigue Behavior ◽  
Mean Stress ◽  
Cycle Fatigue

Experimental Research on Dynamic Poisson’s Ratio of Silty Clay

2010 ◽  
Vol 168-170 ◽  
pp. 286-292
Author(s):  
Hua Pan ◽  
Guo Xing Chen ◽  
Tian Sun
Keyword(s):  
Shear Strain ◽  
Poisson’S Ratio ◽  
Stress Ratio ◽  
Confining Pressure ◽  
Poisson's Ratio ◽  
Cyclic Loads ◽  
Silty Clay ◽  
Shear Tests ◽  
Torsional Shear ◽  
Hollow Cylinder Apparatus

Cyclic triaxial and cyclic torsional shear tests were performed on undisturbed marine silty clay by the hollow cylinder apparatus, and the Young’s modulus and shear modulus were obtained respectively. Furthermore, the influence of effective confining pressure and stress ratio on dynamic Poisson’s ratio was investigated on this basis. It was found that the dynamic Poisson’s ratio increases with generalized shear strain, but decreases with increasing effective confining pressure and stress ratio. The effect of effective confining pressure and stress ratio on dynamic Poisson’s ratio was weakened as the generalized shear strain was increasing. The dynamic Poisson’s ratio was about 0.48 when the Poisson’s ratio was increased to 1.8E-2 or so, and the test was terminated. There was no shear dilatation during all tests because the Poisson’s ratios were smaller than 0.5. It indicates that the marine silty clay tested in this paper has a good stability under cyclic loads.

Effect of Stress Ratio on Fatigue Behaviour of Non-Crimp Fabric Composites at Room and Elevated Temperatures

2020 ◽  
Vol 27 (5) ◽  
pp. 575-596 ◽  
Author(s):  
Trevor Sabiston ◽  
Bin Li ◽  
Jidong Kang ◽  
Jie Liang ◽  
David Wilkinson ◽  
...  
Keyword(s):  
Stress Ratio ◽  
Elevated Temperatures ◽  
Fatigue Behaviour ◽  
Fabric Composites

Study on Equivalent Stress to Control Average Inelastic Behavior of Perforated Plates

2014 ◽  
Author(s):  
Yeldos Kultayev ◽  
Naoto Kasahara
Keyword(s):  
Stress Ratio ◽  
Elevated Temperatures ◽  
Equivalent Stress ◽  
Perforated Plate ◽  
Estimation Method ◽  
Inelastic Behavior ◽  
Perforated Plates ◽  
Inelastic Analysis ◽  
Solid Plate ◽  
Simple Models

Next generation reactors which are subjected to elevated temperatures must be designed to account for inelastic deformation along with elastic one. In order to simplify design analysis of perforated portions, conventionally axisymmetric models with equivalent elastic materials are employed. To extend to inelastic analysis, a method of Effective Stress Ratio (ESR) has been studied in recent years. Previous studies have shown that perforated plates have their own ESR and it is a function of geometry and is independent from their materials. In this study the only geometry dependence and physical meaning of ESR were clarified. ESR results were compared with Reference Stress Method (RSM) results for unit-ligaments with various ligament efficiencies. It was revealed that RSM results coincide with ESR. First meaning of ESR is stress ratio between solid plate and perforated plate at the same reference stresses. Second meaning of this ratio is how plasticity properties of equivalent solid plate have to be changed to give the same steady state deformation rate at the same mean boundary stress. Moreover, to clarify stress redistribution control mechanism at different ligament efficiencies, simple models were developed and an estimation method based on simple models was proposed for engineering use.

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