Many types of electrical connectors are used in traditional and emerging technology sectors such as electric vehicles, traditional automobiles, and aircraft, in which they need to maintain a stable and low electrical contact resistance (ECR). However, external shock and vibration can cause a sudden increase in ECR, which can lead to system failures due to electrical discontinuities or power transfer loss. In this study, the impact of structural dynamics on the ECR response is investigated using an analytical modeling and simulation. A structural vibration of 100 Hz with a surface displacement amplitude of 3 nm is applied to an electrical connector system, and the dynamic ECR response is analyzed with respect to the structural stiffness and damping ratio. At the onset of structural vibration, the system shows a high frequency ECR response with large amplitude variation, which decays over the elapsed time. From the parametric simulations and statistical data analysis, it is observed that the magnitude of ECR fluctuation decreases with the structural stiffness and damping ratio. Within the tested range of structural properties, the ECR fluctuation is more sensitive to the stiffness than the damping ratio.
Hydrogen atoms are doped to diamond-like carbon (DLC) to improve its thermomechanical properties and tribological performance as a surface protective coating. In this study, molecular dynamics (MD) simulations are performed to investigate the impacts of diffused H atoms on the mechanical stiffness, surface energy, specific heat, and thermomechanical contact behavior of DLC. The hydrogenated DLC (a-C:H) is prepared by adding H atoms to a fixed amount of C atoms (method 1) and by replacing C atoms in DLC with H atoms (method 2). The atomic percentage of hydrogen (at. % H) in DLC is varied from 0 to 8.6%. From the systematic MD simulation results, it is observed that the DLC's mechanical stiffness increases with at. % H due to the increasing density with a higher sp3%, but it shows a decreasing trend for method 2 due to the decreasing density. During the sliding contact with a hemispherical diamond tip, the a-C:H samples show a lower coefficient of friction (COF) than the hydrogen-free DLC (ta-C) sample for method 1 but a higher COF for method 2, which can be attributed to the changes in density and surface energy with respect to hydrogen contents in DLC.
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