Repeated Loading, Residual Stresses, Shakedown, and Tribology

1999 ◽  
Vol 14 (4) ◽  
pp. 1548-1559 ◽  
Author(s):  
J. A. Williams ◽  
I. N. Dyson ◽  
A. Kapoor
Keyword(s):  
Plastic Deformation ◽  
Residual Stresses ◽  
Pressure Distribution ◽  
Elastic Properties ◽  
Operating Conditions ◽  
Repeated Loading ◽  
Surface Layers ◽  
Near Surface ◽  
Coated Surfaces ◽  
Simple Stress

Protective residual stresses may be developed in the near surface layers of tribological contacts which enable loads sufficiently large to cause initial plastic deformation to be accommodated purely elastically in the longer term. This is the process of shakedown and, although the underlying principles can be demonstrated by reference to relatively simple stress systems, the situation is complex under a moving Hertzian pressure distribution. Bounding theorems can be used to generate appropriate load or shakedown limits not only for uniform half-spaces but also those with plastic and/or elastic properties which vary with depth. In this way, shakedown maps, which delineate the boundaries between potentially safe and unsafe operating conditions, can be generated for both hardened and coated surfaces.

The Effect of Interfacial Shear Strength on the Performance of Coated Surfaces in Repeated Sliding

1997 ◽  
Vol 119 (3) ◽  
pp. 541-548 ◽  
Author(s):  
A. Kapoor ◽  
J. A. Williams
Keyword(s):  
Plastic Deformation ◽  
Ceramic Coatings ◽  
Surface Layers ◽  
Surface Design ◽  
Near Surface ◽  
Coated Surfaces ◽  
Steel Substrates ◽  
Important System ◽  
Poor Adhesion ◽  
Interlayer Bond

When hard rough surfaces slide repeatedly on softer half-spaces, systems of protective residual stresses may be developed in the near surface layers of the softer material which enable loads sufficiently large to cause plastic deformation in the early cycles of loading to be accommodated purely elastically in the later stages of component life. This is the process of shakedown and limits on the intensity of the allowable Hertzian pressures consistent with the eventual cessation of plastic deformation for uniform half-spaces are now well established. In this paper, we produce shakedown maps for coated or treated surfaces, choosing principally to carry out the numerical calculations on a system which models the behavior of ceramic coatings on steel substrates. In addition to the relative hardnesses of coating and the substrate, important system parameters are shown to be the normalized thickness of the coating and the strength or integrity of the bond at the interface between the coating and substrate. It is quite possible for the production of a coating of less than the critical thickness, or one displaying poor adhesion, to reduce the shakedown performance to lower values than would be the case for an unprotected surface. Design curves are produced which illustrate how the improvement in shakedown performance of such coated surfaces varies with the normalized depth of coating and the strength of the interlayer bond.

TECHNOLOGY OF COMBINED ELECTROMECHANOULTRASONIC TREATMENT OF SURFACE LAYERS OF MACHINE PARTS

2020 ◽  
Vol 2 ◽  
pp. 26-33
Author(s):  
V.R. EDIGAROV
Keyword(s):  
Plastic Deformation ◽  
Surface Layer ◽  
Residual Stresses ◽  
Ultrasonic Treatment ◽  
Mechanical Treatment ◽  
Surface Plastic Deformation ◽  
Surface Plastic ◽  
Surface Layers ◽  
Machine Parts ◽  
Acoustic Treatment

The technology of combined electro–mechanical–acoustic treatment is presented, which is a combination of electro–mechanical treatment and surface plastic deformation by ultrasonic treatment. Microhardness and residual stresses in strengthened EMUzO surface layer of machine parts investigated.

New approach to stress analysis based on grazing-incidence X-ray diffraction

2001 ◽  
Vol 34 (4) ◽  
pp. 427-435 ◽  
Author(s):  
S. J. Skrzypek ◽  
A. Baczmański ◽  
W. Ratuszek ◽  
E. Kusior
Keyword(s):  
Residual Stresses ◽  
Grazing Incidence ◽  
Sample Surface ◽  
X Ray Diffraction ◽  
Surface Layers ◽  
Near Surface ◽  
X Ray ◽  
Tin Coatings ◽  
Diffraction Geometry ◽  
Destructive Measurement

A new development in the determination of residual stresses in thin surface layers and coatings is presented. The procedure, based on the grazing-incidence X-ray diffraction geometry (referred to here as the `g-sin2 ψ' geometry), enables non-destructive measurement at a chosen depth below the sample surface. The penetration depth of the X-ray radiation is well defined and does not change during the experiment. The method is particularly useful for the analysis of non-uniform stresses in near-surface layers. The g-sin2 ψ geometry was applied for measurements of the residual stresses in TiN coatings. Anisotropic diffraction elastic constants of textured material were used to determine the stress value from the measured lattice strains. A new method of data treatment enables reference-free measurements of residual stresses.

Residual stresses in rolling contact

1969 ◽  
Vol 4 (3) ◽  
pp. 208-218 ◽  
Author(s):  
R J Pomeroy ◽  
K L Johnson
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Surface Region ◽  
Rolling Contact ◽  
Surface Layers ◽  
Friction Forces ◽  
Near Surface ◽  
Contact Loads ◽  
Pure Rolling ◽  
Theoretical Predictions

The paper reports an experimental investigation into the residual strsses induced into cylndrical discs by the action of rolling-contact loads sufficiently high to cause some plastic deformation in the near-surface layers. A general method is first described for finding both circumferential and axial components of residual stress in cylindrical bodies in circumstances where the stresses vary with the radial co-ordinate only. This method is believed to be an improvement on previous methods for separating the two components of residual stress, particularly where only specimens of restricted length are available. For example, the method could be applied to thick-walled tubes. Measurements have been made of the residual stresses due to rolling contact, in pure rolling and in combined rolling and sliding. In all cases both components of residual stress were compressive and reached a maximum value below the surface at about the depth of the maximum Hertz shear stress. The measured residual stresses in the sub-surface region were roughly in agreement with the theoretical predictions of Merwin, Johnson, and Jefferis. A subsidiary peak of compressive stress was found at the surface itself. Neither the surface nor the subsurface stresses were found to be greatly influenced by the presence of friction forces when sliding accompanied rolling.

scholarly journals Quality improvement of calibrated steelby surface deformation. Part 2. Effect of enveloping surface deformation on residual stresses in cylindrical bars

2021 ◽  
Vol 64 (5) ◽  
pp. 330-336
Author(s):  
S. A. Zaides ◽  
Van Anh Pham ◽  
L. G. Klimova
Keyword(s):  
Residual Stress ◽  
Plastic Deformation ◽  
Residual Stresses ◽  
Surface Deformation ◽  
High Surface ◽  
Surface Plastic Deformation ◽  
Surface Plastic ◽  
Surface Layers ◽  
Tensile Stresses ◽  
Enveloping Surface

Cold-drawn metal has a number of undeniable advantages over the hot-rolled one. Increased hardness, high surface quality, stability of the diametrical dimension along the length of the workpiece are the basis for choosing calibrated metal as effective workpieces for the manufacture of long parts such as shafts, axles, and rods. In some cases, such workpieces require a small amount of machining, for example, threading or making necks at the ends of a bar. The wider use of the calibrated metal is hindered by residual stresses that are formed during its manufacture. In the first part of this article, it was proposed to use small plastic deformations to control residual stresses. By the example of a new process of surface plastic deformation, which is called orbital burnishing, the working and residual stresses in cylindrical workpieces are determined. In the second part of the article, the process of enveloping surface plastic deformation is considered, which, at high productivity, makes it possible to reduce the residual tensile stresses in the calibrated metal or form the surface layers of the workpiece compressive stress. A technique for the experimental determination of residual stresses in the volume of a body is based on layer-by-layer removal of the inner and outer layers of cylindrical samples. Influence of the main parameters of the enveloping deformation process on the components of the residual stress tensor is established. A range of relative compressions (0.1 – 1.0 %) is revealed, at which residual compressive stresses are formed in the surface layers of the workpiece. It was found that at a relative compression of 0.5 %, the maximum residual compression stresses are created. Enveloping surface deformation has a positive effect on the residual stress state and on colddrawn metal – the residual tensile stresses can be reduced, removed or converted into compressive ones.

scholarly journals Shear cutting induced residual stresses in involute gears and resulting tooth root bending strength of a fineblanked gear

2021 ◽  
Author(s):  
Daniel Müller ◽  
Jens Stahl ◽  
Anian Nürnberger ◽  
Roland Golle ◽  
Thomas Tobie ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Residual Stresses ◽  
Carrying Capacity ◽  
Bending Strength ◽  
Tooth Root ◽  
Load Carrying Capacity ◽  
Near Surface ◽  
Load Carrying ◽  
Involute Gears ◽  
Cut Surface

AbstractThe manufacturing of case-hardened gears usually consists of several complex and expensive steps to ensure high load carrying capacity. The load carrying capacity for the main fatigue failure modes pitting and tooth root breakage can be increased significantly by increasing the near surface compressive residual stresses. In earlier publications, different shear cutting techniques, the near-net-shape-blanking processes (NNSBP’s), were investigated regarding a favorable residual stress state. The influence of the process parameters on the amount of clean cut, surface roughness, hardness and residual stresses was investigated. Furthermore, fatigue bending tests were carried out using C-shaped specimens. This paper reports about involute gears that are manufactured by fineblanking. This NNSBP was identified as suitable based on the previous research, because it led to a high amount of clean cut and favorable residual stresses. For the fineblanked gears of S355MC (1.0976), the die edge radii were varied and the effects on the cut surface geometry, hardness distribution, surface roughness and residual stresses are investigated. The accuracy of blanking the gear geometry is measured, and the tooth root bending strength is determined in a pulsating test rig according to standardized testing methods. It is shown that it is possible to manufacture gears by fineblanking with a high precision comparable to gear hobbing. Additionally, the cut surface properties lead to an increased tooth root bending strength.

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