scholarly journals Numerical Study of Coupled Electrical-Thermal-Mechanical-Wear Behavior in Electrical Contacts

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 955
Author(s):  
Fei Shen ◽  
Liao-Liang Ke
Keyword(s):  
Contact Pressure ◽  
Contact Stress ◽  
Electrical Contact ◽  
Numerical Approach ◽  
Electrical Contacts ◽  
Fretting Wear ◽  
Wear Depth ◽  
Surface Geometry ◽  
Contact Conductance ◽  
Mechanical Wear

Electrical contacts involve complicated electrical, thermal, and mechanical phenomena. Fretting wear as a surface damage mechanism significantly weakens the performance of electrical contact components. In this study, a numerical approach is developed to investigate the electrical-thermal-mechanical-wear coupling behavior of electrical contacts. An electrical contact conductance law is used with the current conservation model to evaluate the electrical behavior. A transient heat transfer model, including the Joule heating behavior and a thermal contact conductance law, is employed to calculate the temperature field. Both contact conductance laws are related to the contact pressure distribution obtained by the contact stress analysis. Based on the predicted contact stress and relative slip on contact surfaces, the energy wear model is used to study the evolution of fretting wear depth and contact surface geometry. The material properties in these models are temperature-dependent. The proposed numerical approach is implemented in a finite element modeling of electrical contacts, which is validated by comparing the predicted and experimental results of the wear scar profile. The effects of the fretting wear on the electric potential, current density, contact resistance, temperature, and contact pressure are numerically studied.

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.

Experimental and Theoretical Study of the Contact Mechanics of Five Total Knee Joint Replacements

1995 ◽  
Vol 209 (4) ◽  
pp. 225-231 ◽  
Author(s):  
T Stewart ◽  
Z M Jin ◽  
D Shaw ◽  
D D Auger ◽  
M Stone ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Knee Joint ◽  
Contact Pressure ◽  
Contact Stress ◽  
Linear Elasticity ◽  
Contact Area ◽  
Elasticity Analysis ◽  
Joint Replacements ◽  
Total Knee ◽  
Maximum Contact

The tibio-femoral contact area in five current popular total knee joint replacements has been measured using pressure-sensitive film under a normal load of 2.5 kN and at several angles of flexion The corresponding maximum contact pressure has been estimated from the measured contact areas and found to exceed the point at which plastic deformation is expected in the ultra-high molecular weight polyethylene (UHMWPE) component particularly at flexion angles near 90°. The measured contact area and the estimated maximum contact stress have been found to be similar in magnitude for all of the five knee joint replacements tested. A significant difference, however, has been found in maximum contact pressure predicted from linear elasticity analysis for the different knee joints. This indicates that varying amounts of plastic deformation occurred in the polyethylene component in the different knee designs. It is important to know the extent of damage as knees with large amounts of plastic deformation are more likely to suffer low cycle fatigue failure. It is therefore concluded that the measurement of contact areas alone can be misleading in the design of and deformation in total knee joint replacements. It is important to modify geometries to reduce the maximum contact stress as predicted from the linear elasticity analysis, to below the linear elastic limit of the plastic component.

Electrical contact performance of various electro-deposited graphene reinforced silver-based nanocomposites

2020 ◽  
Vol 62 (4) ◽  
pp. 401-407
Author(s):  
Ramazan Karslioglu ◽  
Lujain Al-Falahi
Keyword(s):  
Pulse Current ◽  
Electrical Contact ◽  
Reverse Current ◽  
Electrical Contacts ◽  
Test Device ◽  
Arc Erosion ◽  
Contact Test ◽  
Grain Sizes ◽  
Contact Erosion ◽  
Pulse Reverse

Abstract Silver and silver(Ag)-graphene(Gr) nanocomposite coatings were prepared via direct current, pulse current and pulse reverse current on copper electrical contacts for evaluating electrical contact performance. The effects of the addition of Gr and current types on microstructure, crystallographic orientation, mechanical properties and electrical contact performance were investigataed via a scanning electron microscope, an X-Ray diffractometer, microhardness test device and an electrical contact test device, respectively. The addition of Gr changed the Ag surface morphology and decreased grain sizes. Moreover, the addition of Gr significantly improved arc erosion resistivity and decreased the average working temperature during the contact test. In addition, pulse current and pulse reverse current provided a significant improvement in microhardness and electrical contact erosion resistance owing to increased embedded graphene amounts in silver layers.

scholarly journals Numerical Modeling of Electrical Contact Conductance of Rough Bodies

2015 ◽  
Vol 15 (01) ◽  
Author(s):  
Mikhail Murashov ◽  
Sergey Panin ◽  
Sergey Klimov
Keyword(s):  
Numerical Modeling ◽  
Electrical Contact ◽  
Contact Conductance

A Numerical Simulation of Fretting Wear considering the Dynamic Evolution of Debris for the Coated Contact Surface

2021 ◽  
pp. 1-49
Author(s):  
Li Xiao ◽  
Yingqiang Xu ◽  
Zhiyong Chen
Keyword(s):  
Fretting Wear ◽  
Contact Pair ◽  
Dynamic Evolution ◽  
Wear Depth ◽  
Wear Coefficient ◽  
Wear Model ◽  
Wear Process ◽  
Dlc Coating ◽  
Wear Life ◽  
Wear Calculation

Abstract In this paper, a multi-layer body model in which material properties and wear coefficient change with node coordinates is proposed, so that the wear profile is not restricted by the singularity of the interface of the coated contact pairs. The conversion rate of the adhered particles was obtained to describe the growth and expansion of the debris at the fretting interface based on experiments, and the wear model of coated contact pair considering the dynamic evolution of the debris layer was established. By comparing the previous experimental and computational results, the wear calculation method proposed in this paper is more reasonable to predict the wear profile of the coated contact pair. In addition, the influence of the debris layer on the wear depth, friction width, and contact pressure in the fretting process is analyzed, indicating that the existence of the debris layer can delay the wear process. Finally, the fretting wear life of the SCMV steel contact pair deposited with the W-DLC coating is estimated.

Numerical analysis of the transient wear and lubrication behaviors of misaligned journal bearings caused by linear shaft misalignment

2021 ◽  
pp. 1-17
Author(s):  
Tianyou Yang ◽  
Yanfeng Han ◽  
Yijia Wang ◽  
Guo Xiang
Keyword(s):  
Numerical Model ◽  
Film Thickness ◽  
Contact Pressure ◽  
Elastic Deformation ◽  
Journal Bearing ◽  
Fluid Pressure ◽  
Axial Direction ◽  
Wear Depth ◽  
Wear Process ◽  
Journal Misalignment

Abstract The purpose of this study is to investigate the role of the misalignment journal, caused by journal elastic deformation, on the transient wear and mixed lubrication performances using a numerical model. In the numerical model, the transient geometry lubrication clearance considering the journal misalignment, the transient elastic deformation and the transient wear depth are incorporated to evaluate the transient film thickness during wear process. The evolutions, under different external loads, of the wear depth, wear rate, elastic deformation, film thickness, fluid pressure and contact pressure are calculated by the numerical model. Furthermore, the calculated results of the misaligned journal bearing are compared with those of the aligned journal bearing. The results show that the distributions of the wear depth, film pressure and elastic deformation are asymmetric along the axial direction and the peak values of them shift toward the back end when the journal misalignment is considered. The maximum wear depth, maximum fluid pressure, maximum contact pressure and maximum elastic deformation of the misaligned journal condition are significantly larger than those of the aligned journal condition.

Evaluation of Electrical Contact Material Stability on Mercuric Iodide

1993 ◽  
Vol 302 ◽  
Author(s):  
A. Y. Cheng
Keyword(s):  
Free Energy ◽  
Room Temperature ◽  
Electrical Contact ◽  
Radiation Detection ◽  
Electrical Contacts ◽  
Contact Material ◽  
Mercuric Iodide ◽  
Energy Data ◽  
Contact Materials ◽  
Temperature Radiation

ABSTRACTMercuric iodide detectors are leading candidates for room-temperature radiation detection applications. The inherently reactive nature of mercuric iodide limits the number of materials suitable for fabrication of electrical contacts. The theoretical stabilities of elemental contact materials on mercuric iodide were evaluated at 25°C. Additionally, the stabilities of transparent conductive compounds, for photodetector applications, were studied. Calculations were based on Gibbs free energy data, estimates and a series of hypothesized reactions with mercuric iodide. Leading candidate materials were identified and compared to experimental results.

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