An Innovative System for Fretting Wear Testing Under Oscillating Normal Force

2000 ◽  
Vol 15 (7) ◽  
pp. 1591-1599 ◽  
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.

scholarly journals In-Situ Fretting Wear Analysis of Electrical Connectors for Real System Applications

2019 ◽  
Vol 3 (2) ◽  
pp. 47 ◽  
Author(s):  
Arpith Siddaiah ◽  
Ashish K. Kasar ◽  
Vishal Khosla ◽  
Pradeep L. Menezes
Keyword(s):  
Contact Resistance ◽  
Coefficient Of Friction ◽  
Electrical Contact ◽  
Electrical Contacts ◽  
Fretting Wear ◽  
Electrical Contact Resistance ◽  
Contact Loads ◽  
High Degree ◽  
Electrical Connectors

The tribological behavior of electrical contacts, especially separable type electrical connectors at low contact loads, are considered. The reliability of these connectors has been a major concern due to the fretting phenomenon that can lead to an unacceptable increase in contact resistance. This study analyzes various aspects of the fretting mechanism from a tribological perspective where friction and wear are the primary cause of degradation in electrical components. With the use of precise tribological equipment (high data acquisition rate of 5000 Hz), the electrical contact resistance and coefficient of friction at the contact interface are measured. The measurements were made in-situ for a simulated fretting environment under various constant loading conditions. It was observed that low contact loads (1 N) and low fretting frequency (1 Hz) leads to a high degree of fluctuation in the coefficient of friction. However, for the same conditions, the lowest wear rate and electrical contact resistance were observed. The reason behind this could be due to the lack of continuous electrical contact and a high degree of fretting frequency under low contact loads, ultimately leading to extended periods of an open circuit. Experimental analysis indicates the existence of an optimum loading condition at which the fretting wear effect is at its minimum. Detailed analysis of post fretting surface roughness, coating wear, and wear debris is conducted, as well as transfer film formations to explain the mechanism of fretting observed.

Electrical Contact Resistance Between Gas Diffusion Layers and Bipolar Plates for Applications to PEM Fuel Cells

2004 ◽  
Author(s):  
V. Mishra ◽  
F. Yang ◽  
R. Pitchumani
Keyword(s):  
Fuel Cells ◽  
Contact Resistance ◽  
Electrical Contact ◽  
Pem Fuel Cells ◽  
Gas Diffusion ◽  
Surface Geometry ◽  
Electrical Contact Resistance ◽  
Gas Diffusion Layers ◽  
Diffusion Layers ◽  
Wide Range

The electrical contact resistance between gas diffusion layers and bi-polar flow channel plates is one of the important factors contributing to the operational voltage loss in fuel cells. Effective analysis and design of fuel cells therefore need to account for the contact resistance in deriving the polarization curve for the cell. Despite its significance, relatively scant work is reported in the open literature on the measurement and modeling of the contact resistance in fuel cell systems, and the present work aims to fill this void. Experimental data are reported for the first time to show the effects of different gas diffusion layer materials and contact pressure on the electrical contact resistance. A fractal asperity based model is adopted to predict the contact resistance as a function of pressure, material properties, and surface geometry. Good agreement is observed between the data and the model predictions for a wide range of contacting pressures and materials.

Measurement and Prediction of Electrical Contact Resistance Between Gas Diffusion Layers and Bipolar Plate for Applications to PEM Fuel Cells

2004 ◽  
Vol 1 (1) ◽  
pp. 2-9 ◽  
Author(s):  
V. Mishra ◽  
F. Yang ◽  
R. Pitchumani
Keyword(s):  
Fuel Cells ◽  
Contact Resistance ◽  
Electrical Contact ◽  
Pem Fuel Cells ◽  
Gas Diffusion ◽  
Surface Geometry ◽  
Electrical Contact Resistance ◽  
Gas Diffusion Layers ◽  
Diffusion Layers ◽  
Wide Range

The electrical contact resistance between gas diffusion layers and bipolar flow channel plates is one of the important factors contributing to the operational voltage loss in polymer electrolyte membrane (PEM) fuel cells. Effective analysis and design of fuel cells therefore need to account for the contact resistance in deriving the polarization curve for the cell. Despite its significance, relatively scant work is reported in the open literature on the measurement and modeling of the contact resistance in fuel cell systems, and the present work aims to fill this void. Experimental data are reported for the first time to show the effects of different gas diffusion layer materials and contact pressure on the electrical contact resistance. A fractal asperity based model is adopted to predict the contact resistance as a function of pressure, material properties, and surface geometry. Good agreement is observed between the data and the model predictions for a wide range of contacting pressures and materials.

scholarly journals Friction and electrical contact resistance in reciprocating nano-scale wear testing of metallic materials

Wear ◽  
2021 ◽  
pp. 203866
Author(s):  
Ben D. Beake ◽  
Adrian J. Harris ◽  
Tomasz W. Liskiewicz ◽  
Jérémie Wagner ◽  
Sam J. McMaster ◽  
...  
Keyword(s):  
Contact Resistance ◽  
Electrical Contact ◽  
Wear Testing ◽  
Metallic Materials ◽  
Electrical Contact Resistance ◽  
Nano Scale
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