Frictional shakedown in a complete contact

2003 ◽  
Vol 38 (4) ◽  
pp. 329-338 ◽  
Author(s):  
R Saez ◽  
A Mugadu ◽  
J Fuenmayor ◽  
D. A Hills
Keyword(s):  
Normal Load ◽  
Partial Slip ◽  
Shearing Force ◽  
Slip Regime ◽  
Contact Configuration ◽  
Bound Theorem ◽  
Oscillatory Shearing ◽  
Constant Normal Load ◽  
Complete Contact ◽  
Plastic Shakedown

The phenomenon of frictional shakedown is investigated by considering a complete contact configuration for which a stable partial slip regime exists; a tilted square-ended rigid punch is pressed against an incompressible half-plane by an offset constant normal load and subject to an oscillatory shearing force. The analysis shows that analogies might be drawn with conventional plasticity nomenclature and that, under certain conditions, Melan's lower bound theorem of plastic shakedown may be invoked, leading to the elimination of steady state slip. The implications of these results to fretting contacts are discussed.

scholarly journals Tangential Loading of General Three-Dimensional Contacts

1998 ◽  
Vol 65 (4) ◽  
pp. 998-1003 ◽  
Author(s):  
M. Ciavarella
Keyword(s):  
Pressure Distribution ◽  
Poisson’S Ratio ◽  
Normal Load ◽  
Complete Solution ◽  
Tangential Force ◽  
Three Dimensional ◽  
Poisson's Ratio ◽  
Partial Slip ◽  
Normal Contact ◽  
Slip Regime

A general three-dimensional contact, between elastically similar half-spaces, is considered. With a fixed normal load, we consider a pure relative tangential translation between the two bodies. We show that, for the case of negligible Poisson’s ratio, an exact solution is given by a single component of shearing traction, in the direction of loading. It is well known that, for full sliding conditions, the tangential force must be applied through the center of the pressure distribution. Instead, for a full stick case the tangential force must be applied through the center of the pressure distribution under a rigid flat indenter whose planform is the contact area of the problem under consideration. Finally, for finite friction a partial slip regime has to be introduced. It is shown that this problem corresponds to a difference between the actual normal contact problem, and a corrective problem corresponding to a lower load, but with same rotation of the actual normal indentation. Therefore for a pure translation to occur in the partial slip regime, the point of application of the tangential load must follow the center of the “difference” pressure. The latter also provides a complete solution of the partial slip problem. In particular, the general solution in quadrature is given for the axisymmetric case, where it is also possible to take into account of the effect of Poisson’s ratio, as shown in the Appendix.

Torsional Friction Behavior of Contact Interface Between PEEK and CoCrMo in Calf Serum

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Dongliang Liu ◽  
Qingliang Wang ◽  
Dekun Zhang ◽  
Jian Wang ◽  
Xiao Zhang
Keyword(s):  
Plastic Deformation ◽  
Normal Load ◽  
Angular Displacement ◽  
Calf Serum ◽  
Partial Slip ◽  
Torsional Angle ◽  
Friction Behavior ◽  
Cocrmo Alloy ◽  
Slip Regime ◽  
Marginal Region

Polyether ether ketone (PEEK) and its composites are recognized as alternative bearing materials for use in arthroplasty because of their excellent mechanical properties. In this paper, torsional friction tests of PEEK against the CoCrMo alloy, simulating the contact mode between the prosthesis tibia and femur, were carried out under a 25% calf serum solution in a Leeds Prosim knee simulator. The torsional friction behavior of PEEK against the CoCrMo alloy was investigated under various normal loads (1000 N, 1600 N and 2200 N), torsional angular displacement amplitudes (±1 deg, ±3 deg, and ±5 deg), and the number of cycles (7500, 15,000, and 30,000). The torsional friction characteristics and damage mechanism are discussed. The results show that PEEK exhibited low friction coefficient under the different conditions. With increases in the torsional angle and normal load, three types of torque/angular displacement amplitude (T–θ) curves (i.e., linear, parallelogram, and elliptical loops) were observed and analyzed during the process of torsional friction. With the increase of the torsional angle, the coefficient of friction decreases. And the contact states change from the partial slip regime to the slip regime. The greater the torsional angle displacement, the more severe the damage to the PEEK surface. With an increase in the normal load, the wear scars increased. The wear depth is deepened and the width is widened, and the wear gradually becomes serious with an increase in the load. The small load is more likely to cause damage to the central area of PEEK, and the larger load causes more serious damage to the marginal region. The central and marginal regions of the PEEK sample have different wear characteristics. The worn surfaces of the central regions were characterized by convex ridges resulting from plastic deformation, while curved ploughs and fatigue peeling appeared in the marginal region. The wear mechanism of PEEK in the central region is plastic deformation, while fatigue wear and abrasive wear mainly appeared in the marginal region.

scholarly journals Fretting Behavior of Thermoplastic Polyurethanes

Lubricants ◽  
2019 ◽  
Vol 7 (9) ◽  
pp. 73
Author(s):  
Chao Wang ◽  
Andreas Hausberger ◽  
Michael Berer ◽  
Gerald Pinter ◽  
Florian Grün ◽  
...  
Keyword(s):  
Coefficient Of Friction ◽  
Normal Load ◽  
Dynamic Mechanical Properties ◽  
Mechanical Analysis ◽  
Partial Slip ◽  
Dissipated Energy ◽  
Dynamic Mechanical ◽  
Thermoplastic Polyurethanes ◽  
Slip Regime ◽  
The Coefficient Of Friction

Fretting tests were conducted with five different thermoplastic polyurethanes against a steel ball. Their fretting behaviors were investigated under various test parameters, such as normal load and displacement amplitude. In order to test the sliding performances, tribological tests were conducted using a ring-on-disc setup. The results show that their fretting behaviors can be related to the dynamic mechanical properties, which were characterized by dynamic mechanical analysis (DMA). The three fretting regimes were identified by means of hysteresis and wear scar analysis. In addition, investigations were carried out until the transition regimes occurred. Different wear processes were revealed for each of the three regimes. Differences were identified using dissipated energy. The profiles of wear scars and the counterparts were analyzed using a microscope. The coefficient of friction was calculated separately for the partial slip and gross slip regimes. In the mixed fretting regime, the coefficient of friction is almost at the same level among the five materials. In the partial slip regime, however, it can be distinguished. Temperature measurements were conducted on the counterparts during the tests. Overall, the material that showed the best tribological properties also performed the best in the fretting tests.

Rotational Fretting Wear of Ion Nitrided Medium Carbon Steel

2010 ◽  
Vol 97-101 ◽  
pp. 1532-1541
Author(s):  
J. Luo ◽  
Y.D. Wang ◽  
C. Song ◽  
J.L. Mo ◽  
Min Hao Zhu
Keyword(s):  
Carbon Steel ◽  
Friction Coefficient ◽  
Normal Load ◽  
Angular Displacement ◽  
Nitrided Layer ◽  
High Hardness ◽  
Fretting Wear ◽  
Partial Slip ◽  
Slip Regime ◽  
Substrate Steel

The nitrided layer on the surface of LZ50 (0.50% C) carbon steel was prepared by ion nitriding technique and its characterizations were detected by using Vickers hardness tester, profilometer, scanning electric microscope (SEM), optical microscope (OM) and X-ray diffraction (XRD). Rotational fretting is one of basic running modes in contact configuration of ball-on-flat, to which was paid little attention. The rotational fretting wear behaviors of the nitrided layer and its substrate steel were comparatively studied in dry condition under varied angular displacement amplitudes (θ) in range of 0.125º-1º, imposed normal load (Fn) of 20 N and a constant rotational speed of 0.2º/s. The experimental results showed that the nitrided layer presented rough and porous surface and high hardness was mainly consist of ε-Fe2-3N and γ׳-Fe4N phases. Compared with the substrate steel, the nitrided layer had a significant effect on reducing the friction coefficient and improving the fretting wear resistance, though the nitrided layer almost didn’t change the fretting running regimes of the substrate steel. In the partial slip regime, lower friction coefficients and slight damage appeared for the nitrided layer due to the coordination of elastic deformation of contact zones. In the slip regime, the friction coefficient of the nitrided layer was lower than that of the substrate in the initial stage as a result of the preventing plastic deformation by its high hardness surface. The rotational fretting wear mechanism of the nitrided layer in the slip regime was mainly identified as abrasive wear, oxidative wear and delamination. As a result, the nitrided layer presented a better capability for alleviating rotational fretting wear.

Frictional complete contacts subject to shear and bulk tension

2008 ◽  
Vol 222 (12) ◽  
pp. 2301-2309 ◽  
Author(s):  
N Banerjee ◽  
D Dini ◽  
D A Hills
Keyword(s):  
Normal Load ◽  
Cyclic Shear ◽  
Edge Angle ◽  
Subsequent Application ◽  
Constant Normal Load

This paper provides a set of ‘maps’ showing the response of three example frictional complete contacts (with edge angle of 60°, 90°, and 120°) subject to a constant normal load and the subsequent application of cyclic shear and bulk tension, the latter present in only one body. The maps define the region of full adhesion, the nature of violations, and conditions under which they arise.

Sign in / Sign up

Export Citation Format

Share Document