The impact of surface integrity by hard turning versus grinding on rolling contact fatigue ? Part I: Comparison of fatigue life and acoustic emission signals

2007 ◽  
Vol 30 (8) ◽  
pp. 698-711 ◽  
Author(s):  
A. W. WARREN ◽  
Y. B. GUO
Keyword(s):  
Acoustic Emission ◽  
Fatigue Life ◽  
Surface Integrity ◽  
Hard Turning ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
The Impact

The Impact of Surface Integrity by Hard Turning vs. Grinding on Rolling Contact Fatigue

2007 ◽  
Author(s):  
A. W. Warren ◽  
Y. B. Guo
Keyword(s):  
Acoustic Emission ◽  
Surface Integrity ◽  
Hard Turning ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Fatigue Tests ◽  
Rolling Contact ◽  
Polished Surface ◽  
Emission Signal ◽  
The Impact

Hard turning and grinding are finishing processes for the manufacture of precision components such as bearings, gears, and cams. However, the effects of distinct surface integrity by hard turning vs. grinding on rolling contact life are poorly understood. Four representative surface types were prepared: as-turned, as-ground, turned and polished, and ground and polished. Surface integrity was characterized by surface topography, microstructure, and micro/nanohardness. Fatigue tests were performed with an acoustic emission sensor and the signal processing software. The amplitude of acoustic emission signal is the most stable and sensitive signal to fatigue failure. The turned surface may have a longer life (>84%) than the ground one with equivalent surface finish.

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.

On Modeling the Rolling Contact Fatigue Performance Based on Residual Stresses Generated by Superfinish Hard Turning

2000 ◽  
Author(s):  
Salah R. Agha ◽  
C. Richard Liu
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Residual Stresses ◽  
Hard Turning ◽  
Rolling Contact Fatigue ◽  
Equivalent Stress ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Contact Fatigue Life ◽  
The Difference

Abstract It was shown earlier [Agha and Liu, 1998, 1999, 2000] that different cutting conditions, within superfinish hard turning, would lead to significantly different rolling contact fatigue lives. In this study, residual stresses were measured. The rolling contact fatigue life was then modeled using a maximum modified equivalent stress that takes residual stresses into account. It is seen that the maximum modified equivalent stress is a better predictor than the maximum Hertzian stress, but, still not accurate, given the consistent repeatability of the tested workpieces [Agha and Liu, 2000]. The difference in the nature of residual stresses produced by grinding and hard turning is used to show why the inclusion of the maximum modified equivalent stress, its location and the volume at risk, improves the power of the model to predict the rolling contact fatigue lives of the hard turned surfaces. This model is the best up to date for predicting the fatigue life of a surface, especially when residual stress is a factor.

Effect of Grain Flow Orientation on Rolling Contact Fatigue Life of AISI M-50

1982 ◽  
Vol 104 (3) ◽  
pp. 330-334 ◽  
Author(s):  
A. H. Nahm
Keyword(s):  
Fatigue Life ◽  
Flow Line ◽  
Flow Direction ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Vacuum Arc ◽  
Type I ◽  
Grain Flow ◽  
Contact Fatigue Life

Accelerated rolling contact fatigue tests were conducted to study the effect of grain flow orientation on the rolling contact fatigue life of vacuum induction melted and vacuum arc remelted (VIM-VAR) AISI M-50. Cylindrical test bars were prepared from a billet with 0, 45, and 90 deg orientations relative to billet forging flow direction. Tests were run at a Hertzian stress of 4,826 MPa with a rolling speed of 12,500 rpm at room temperature, and lubricated with Type I (MIL-L-7808G) oil. It was observed that rolling contact fatigue life increased when grain flow line direction became more parallel to the rolling contact surface.

scholarly journals Rolling Wear of Silicon Nitride Bearing Materials

1990 ◽  
Author(s):  
John W. Lucek
Keyword(s):  
Fatigue Life ◽  
Silicon Nitride ◽  
Failure Modes ◽  
Fatigue Testing ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Wear Performance ◽  
Wear Rates ◽  
Bearing Materials

Rolling-contact fatigue test methods were used to measure the wear performance of several silicon nitride materials. Sintered, hot pressed and hot isostatically pressed materials exhibited wear rates ranging over three orders of magnitude. Hot isostatically pressed materials had the lowest wear rates. Despite the disparity in wear performance, all materials tested had useful rolling-contact fatigue lives compared to steel. Fatigue life estimates, failure modes, and rolling wear performance for theses ceramics are compared to M-50 steel. This work highlights the rapid contact stress reductions that occur due to conformal wear in rolling-contact fatigue testing. Candidate bearing materials with unacceptably high wear rates may exhibit useful fatigue lives. Rolling contact bearing materials must possess useful wear and fatigue resistance. Proper performance screening of candidate bearing materials must describe the failure mode, wear rate, and the fatigue life. Guidelines for fatigue testing methods are proposed.

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