An ad-hoc fretting wear tribotester design for thin steel wires

Steel wire ropes experience fretting wear damage when the rope runs over a sheave promoting an oscillatory motion between the wires. Consequently, wear scars appear between the contacting wires leading to an increase of the stress field and the following rupture of the wires due to fatigue. That is why the understanding and prediction of the fretting wear phenomena of thin wires is fundamental in order to improve the performance of steel wire ropes. The present research deals with the design of an ad-hoc fretting wear test machine for thin wires. The test apparatus is designed for testing thin wires with a maximum diameter of 1.0 mm, at slip amplitudes ranging from 5 to 300 μm, crossing angle between 0-90°, and contacting force ranging from 0,5 to 5 N. The working principle of displacement amplitude and contacting force as well as the crossing angle between the wires are described. Preliminary studies for understanding the fretting wear characteristics are presented, analysing 0.45 mm diameter cold-drawn eutectoid carbon steel (0.8% C) wires (tensile strength higher than 3000 MPa).

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An Innovative System for Fretting Wear Testing Under Oscillating Normal Force

Journal of Materials Research ◽

10.1557/jmr.2000.0228 ◽

2000 ◽

Vol 15 (7) ◽

pp. 1591-1599 ◽

Cited By ~ 11

Author(s):

M. Z. Huq ◽

C. Butaye ◽

J-P. Celis

Keyword(s):

Contact Resistance ◽

Normal Force ◽

Electrical Contact ◽

Wear Test ◽

Fretting Wear ◽

Wear Testing ◽

Mode Ii ◽

Test Machine ◽

Electrical Contact Resistance ◽

Wide Range

Material damage caused by fretting wear is of significant concern in many engineering applications. This paper describes the design and performance of a new machine for the laboratory investigation of fretting wear under oscillating normal force (fretting mode II). The test machine uses an electromagnetic actuator to impose an oscillating normal force between the contacting bodies at a constant force amplitude over a wide range of frequencies. The principle of the actuation mechanism and the fretting wear induced with this particular wear test configuration are outlined in detail. Normal force and electrical contact resistance were measured on-line during fretting mode II wear tests. The performance of the wear test machine is illustrated by data obtained for different materials combinations, namely, hard materials, such as high-speed steel and (Ti,Al)N coatings oscillating against alumina ball counterbodies, and soft materials, such as a tin coating oscillating against the same. In general, wearing of the counterbodies was observed in the slip region. It has been observed that hard coatings and bulk ceramics are prone to fretting fatigue cracking. The evolution of electrical contact resistance in the case of the self-mated soft tin coatings tested under fretting mode II conditions is also reported.

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Steam Generator Fretting-Wear Damage: A Summary of Recent Findings

Journal of Pressure Vessel Technology ◽

10.1115/1.2883707 ◽

1999 ◽

Vol 121 (3) ◽

pp. 304-310 ◽

Cited By ~ 27

Author(s):

F. M. Gue´rout ◽

N. J. Fisher

Keyword(s):

Steam Generator ◽

Wear Test ◽

Operating Conditions ◽

Fretting Wear ◽

Measuring System ◽

Effect Of Temperature ◽

Design Parameters ◽

Wear Depth ◽

Alloy 800 ◽

Wear Damage

Flow-induced vibration of steam generator (SG) tubes may sometimes result in fretting-wear damage at the tube-to-support locations. Fretting-wear damage predictions are largely based on experimental data obtained at representative test conditions. Fretting-wear of SG materials has been studied at the Chalk River Laboratories for two decades. Tests are conducted in fretting-wear test machines that simulate SG environmental conditions and tube-to-support dynamic interactions. A new high-temperature force and displacement measuring system was developed to monitor tube-to-support interaction (i.e., work-rate) at operating conditions. This improvement in experimental fretting-wear technology was used to perform a comprehensive study of the effect of various environment and design parameters on SG tube wear damage. This paper summarizes the results of tests performed over the past 4 yr to study the effect of temperature, water chemistry, support geometry and tube material on fretting-wear. The results show a significant effect of temperature on tube wear damage. Therefore fretting-wear. The results show a significant effect of temperature or tube wear damage. Therefore, fretting-wear tests must be performed at operating temperatures in order to be relevant. No significant effect of the type of water treatment on tube wear damage was observed. For predominantly impacting motion, the wear of SG tubes in contact with 410 stainless steel is similar regardless of whether Alloy 690 or Alloy 800 is used as tubing material or whether lattice bars or broached hole supports are used. Based on results presented in this paper, an average wear coefficient value is recommended that is used for the prediction of SG tube wear depth versus time.

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