Orthogonal Shear Stress Amplitude as a Function of Rolling Contact Ellipticity and Depth

1997 ◽  
Vol 119 (4) ◽  
pp. 883-886 ◽  
Author(s):  
G. J. Moyar ◽  
V. Sharma
Keyword(s):  
Shear Stress ◽  
Stress Amplitude ◽  
Rolling Contact ◽  
Orthogonal Shear Stress

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.

scholarly journals Investigating the Contact Responses of the Roller Cavity Surfaces in the Compressor Blade Rolling Process

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Qichao Jin ◽  
Wenhu Wang ◽  
Ruisong Jiang
Keyword(s):  
Shear Stress ◽  
Contact Pressure ◽  
Rolling Process ◽  
Compressor Blade ◽  
Rolling Contact ◽  
Slip Zone ◽  
Sliding Velocity ◽  
Forward Slip ◽  
Forming Process ◽  
Forward Slip Zone

The investigation of the contact responses is the key for evaluating the local wear of dies in the plastic forming process. This paper investigated the contact load distributions and evolutions of the roller cavities in the compressor blade rolling process by the FEM. It was the first study to quantify the distributions and evolutions of the contact responses for rolling irregular components. The results indicated that the maximum contact pressure is generally present at the center of the contact interfaces, and the magnitudes of contact pressure decreased with evolution of the blade rolling process. The rolling contact interfaces can be divided into the backward slip zone, the stick zone, and the forward slip zone based on the shear stress distributions. The stick zone was a narrow belt which separated the forward and the backward slip zone, and the shear stress in the stick zone was nearly zero. The shear stress magnitudes in the forward slip zone were smaller than those in the backward slip zone, and the directions of shear stress in forward and backward slip zones were adverse. The magnitudes of shear stress over the forward and backward slip zones decreased with evolution of the blade rolling process. The distributions of local sliding were in a V-shape, the local sliding in the stick zone was nearly zero, and the bigger sliding in backward and forward slip zones was present at the boundaries of rolling entrance and exit sections. The local sliding velocity magnitudes in the backward slip zones were always bigger than those in the forward slip zones, and the magnitudes of local sliding at the rolling entrance sections were bigger than those at the rolling exit sections. In general, the local sliding velocity magnitudes increased firstly and decreased sharply at 2T/3. The current paper develops the distributions and evolutions of contact responses in the blade rolling process. The contact responses can be used for studying the wear of roller cavities to avoid the accuracy inconsistency of the shaped blade.

scholarly journals A Fatigue Life Prediction Model Based on Modified Resolved Shear Stress for Nickel-Based Single Crystal Superalloys

Metals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 180 ◽  
Author(s):  
Jialiang Wang ◽  
Dasheng Wei ◽  
Yanrong Wang ◽  
Xianghua Jiang
Keyword(s):  
Shear Stress ◽  
Fatigue Life ◽  
Prediction Model ◽  
Single Crystal ◽  
Life Prediction ◽  
Stress Amplitude ◽  
Damage Parameter ◽  
Fatigue Life Prediction ◽  
Model Based ◽  
Life Prediction Model

In this paper, the viewpoint that maximum resolved shear stress corresponding to the two slip systems in a nickel-based single crystal high-temperature fatigue experiment works together was put forward. A nickel-based single crystal fatigue life prediction model based on modified resolved shear stress amplitude was proposed. For the four groups of fatigue data, eight classical fatigue life prediction models were compared with the model proposed in this paper. Strain parameter is poor in fatigue life prediction as a damage parameter. The life prediction results of the fatigue life prediction model with stress amplitude as the damage parameter, the fatigue life prediction model with maximum resolved shear stress in 30 slip directions as the damage parameter, and the McDiarmid (McD) model, are better. The model proposed in this paper has higher life prediction accuracy.

Acoustic Emission Monitoring for Rolling Contact Fatigue Damage of Machined Components by Hard Turning vs. Grinding

2007 ◽  
Author(s):  
A. W. Warren ◽  
Y. B. Guo
Keyword(s):  
Shear Stress ◽  
Acoustic Emission ◽  
Fatigue Damage ◽  
Surface Integrity ◽  
Rolling Contact Fatigue ◽  
Real Life ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Second Phase ◽  
Surface Cracks

The fundamental knowledge of fatigue damage mechanism is necessary for understanding manufacturing process effects. However, the artificial defects on the test samples in traditional fatigue tests will change the surface integrity and therefore may not reflect the nature of fatigue damage. This paper studies the fatigue damage resulting from real-life rolling contact tests and finite element analysis of AISI 52100 steel and identifies the possible mechanisms for fatigue failure in the presence of process induced surface integrity. Rolling contact fatigue damage was real-time monitored using an acoustic emission (AE) sensor. Surface and subsurface fatigue damage of the samples was then characterized using optical and scanning electron microscopy (SEM) and surface profiling. The results suggest that shear stress induced Mode II crack is the dominant fatigue mechanism. Two types of subsurface cracks were observed: main cracks that propagate parallel to the surface due to subsurface shear stress induced fracture/debonding of inclusions or second phase particles. Shear stress induced surface cracks propagate at shallow angles (∼35°) from the surface. Branching cracks eventually form and connect the main crack to surface. The formation of main cracks and surface cracks may be parallel processes, and spalling occurs as a combined effect of the main, surface, and branching cracks. The relationship between AE signals and fatigue damage was been established.

Effect of Mean Stress on 2A12-T4 Aluminum Alloy under Tension-Torsion Constant Amplitude Loading

2016 ◽  
Vol 713 ◽  
pp. 334-337
Author(s):  
Tian Qing Liu ◽  
Xin Hong Shi ◽  
Jian Yu Zhang
Keyword(s):  
Shear Stress ◽  
Aluminum Alloy ◽  
Fatigue Life ◽  
Phase Angle ◽  
Stress Amplitude ◽  
Maximum Shear Stress ◽  
Fatigue Tests ◽  
Mean Stress ◽  
Normal Mean ◽  
Fracture Appearance

Fatigue tests have been carried out to investigate the effects of mean-stress and phase-difference on the tension-torsion fatigue failure of 2A12-T4 aluminum alloy. The results show that for fully reversed tension-torsion loading, the fatigue life increases with the increase of phase angle, but the fatigue life decreases with the increase of phase angle, when mean-stress exists, both for shear mean-stress and normal mean-stress. Fracture appearance shows that the crack initiation is on the direction of maximum shear stress amplitude plane. Critical plane criteria based on the linear combination of the maximum shear stress amplitude and maximum normal stress are studied and further discussion on the drawbacks of this kind of criteria are performed.

ASME Sec VIII Div 3 Fatigue Life Predictions Using Critical Plane Approach

2015 ◽  
Author(s):  
Kumarswamy Karpanan ◽  
William Thomas
Keyword(s):  
Shear Stress ◽  
Fatigue Life ◽  
Principal Stress ◽  
Stress Amplitude ◽  
Maximum Shear Stress ◽  
Fe Model ◽  
Critical Plane ◽  
Principal Stress Direction ◽  
Stress Direction ◽  
Surface Node

ASME VIII Div 3 fatigue evaluation is based on the theory that cracks tend to nucleate along the slip lines oriented in the maximum shear stress planes. This code provides methods to calculate the fatigue stresses when the principal stress direction does not change (proportional loading) and axes change (nonproportional loading). When principal stress direction does not change within a fatigue cycle, shear stress amplitude is calculated only on the three maximum shear stress planes. But when the principal stress directions do change within a loading cycle, the plane carrying the maximum shear stress amplitude (also known as critical plane) cannot be easily identified and all planes at a point needs to be searched for the maximum shear stress amplitude. This paper describes the development of an ANSYS-APDL macro to predict the critical plane at each surface node of an FE model using the FEA stress results. This macro searches through 325 planes (at 10° increments along two angles) at each surface node and for each load step to identify the maximum shear stress and the corresponding normal stress for each surface node. The fatigue life is calculated for each surface node and is plotted as a color contour on the FEA model. This macro can be extended to calculate the fatigue life using other critical plane approaches such as the Findley and Brown-Miller models.

On Ratchetting-Based Models of Wear and Rolling Contact Fatigue (RCF)

2003 ◽  
Author(s):  
M. Ciavarella ◽  
L. Afferrante
Keyword(s):  
Shear Stress ◽  
Plastic Material ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Longitudinal Direction ◽  
Surface Flow ◽  
Rolling Contact ◽  
Stress Cycle ◽  
Shakedown Theory ◽  
Number Of Cycles

Recent efforts to develop simple unified models of both wear and RCF (Kapoor & Franklin, 2000, Franklin et al., 2001) are discussed, in view of previous theoretical and experimental results on ratchetting in rolling contact. At sufficiently high contact pressures, surfaces deform plastically with unidirectional cumulation of “ratchetting” strains (Johnson, 1985, Ch.9). However, the modelling of ratchetting strains as a function of plastic material properties has turned out more complicated than what originally suggested by the first attempts (Merwin & Johnson, 1963), as recently discussed by Ponter et al. (2003). Wear due to surface ratchetting occurs for sufficiently high friction, whereas RCF is mainly due to ratchetting subsurface. It appears that experimental data on ratchetting strains in the literature unfortunately do not show a clear and unique trend, and various proposed fitting equations differ significantly in quantitative and qualitative terms, particularly at large number of cycles. It is shown that ratchetting in rolling contact is a combination of “structural ratchetting” (that modelled with the perfect plasticity model) and “material ratchetting”, and the latter is very sensitive to the hardening behaviour of the material. Also, the surface and subsurface flow regimes are very different: in pure rolling, a simplified model of the stress cycle condition is a fully reversed cycle of shear superposed to an out-of-phase pulsating compression in a extended region below the surface (neglecting other two components also of pulsating compression); increasing the friction coefficient, a mean shear stress is induced as well as a tensile component in the direct stress, and for friction f > 0.3 the maximum moves at the surface, but the highly stressed zone becomes a thin surface layer which suffers uniquely of “material ratchetting”. In the limit of very high friction, we have the critical condition on the surface which obviously gives a pulsating shear stress cycle in phase with a pulsating compression, but in addition we have a nearly fully reversed cycle of tension-compression (although the tensile peak is very localized also in the longitudinal direction). Such multiaxial stress fields and their largely different features introduced cause a response of the material which has not been studied enough, perhaps both in terms of ratchetting rates and in terms of the failure condition. In particular, the ductility for ratchetting surface flow as used in wear models seems apparently much higher than that for RCF ratchetting models. Also, RCF at large number of cycles in the C&S experiments (Clayton & Su, 1996, Su & Clayton, 1997) seems not well correlated with shakedown theory, and accordingly, simple ratchetting equations based on excess of shakedown such as that of Tyfoor et al (1996), do not seem well suited a Wohler SN life curve. However, these conclusions are only very qualitative as the materials in the two tests are different, and at present empirical separate models for wear and RCF based on hardness of materials and a posteriori data fitting seem the only quantitative way forward for engineering purposes.

Internal Shear Stress Distribution and Subsurface Cracks of PPS Thrust Bearings under Rolling Contact Fatigue in Water

2020 ◽  
Vol 858 ◽  
pp. 101-105
Author(s):  
Syunsuke Mizozoe ◽  
Katsuyuki Kida
Keyword(s):  
Shear Stress ◽  
Stress Distribution ◽  
Crack Propagation ◽  
Contact Stress ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Subsurface Crack ◽  
Thrust Bearings ◽  
Subsurface Cracks

In this study, crack propagation in PPS thrust bearings under rolling contact fatigue (RCF) in water was observed, and relation between subsurface crack and internal shear stress parallel to the surface was investigated. It was found the cause of flaking was subsurface crack. They were evaluated in terms of contact stress and friction between their faces. It was discovered that subsurface cracks distributed around shear stress peak, and flaking failure was dominated by subsurface shear stress.

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