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Xin Xu

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Full-Text Articles in Nanoscience and Nanotechnology

Multiscale Contact Mechanics Model For Rf-Mems Switches With Quantified Uncertainties, Hojin Kim, Nurul Shaik, Xin Xu, Arvind Raman, Alejandro Strachan Sep 2014

Multiscale Contact Mechanics Model For Rf-Mems Switches With Quantified Uncertainties, Hojin Kim, Nurul Shaik, Xin Xu, Arvind Raman, Alejandro Strachan

Xin Xu

We introduce a multiscale model for contact mechanics between rough surfaces and apply it to characterize the force-displacement relationship for a metal-dielectric contact relevant for radio frequency micro-electromechanicl system (MEMS) switches. We propose a mesoscale model to describe the history-dependent force-displacement relationships in terms of the surface roughness, the long-range attractive interaction between the two surfaces, and the repulsive interaction between contacting asperities (including elastic and plastic deformation). The inputs to this model are the experimentally determined surface topography and the Hamaker constant as well as the mechanical response of individual asperities obtained from density functional theory calculations and large-scale …

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Atomic Force Microscopy Characterization Of Cellulose Nanocrystals, Roya Lahiji, Xin Xu, R. Reifenberger, Arvind Raman, Alan Rudie, Robert Moon Sep 2014

Atomic Force Microscopy Characterization Of Cellulose Nanocrystals, Roya Lahiji, Xin Xu, R. Reifenberger, Arvind Raman, Alan Rudie, Robert Moon

Xin Xu

Cellulose nanocrystals (CNCs) are gaining interest as a "green" nanomaterial with superior mechanical and chemical properties for high-performance nanocomposite materials; however, there is a lack of accurate material property characterization of individual CNCs. Here, a detailed Study of the topography, elastic and adhesive properties of individual wood-derived CNCs is performed using atomic force microscopy (AFM). AFM experiments involving high-resolution dynamic mode imaging and jump-mode measurements were performed on individual CNCs under ambient conditions with 30% relative humidity (RH) and under a N-2 atmosphere with 0.1% RH. A procedure was also developed to calculate the CNC transverse elastic modulus (E-T) by …

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