BROWN UNIVERSITY -
Joint Materials/Solid Mechanics Seminar Series
Aerospace Engineering and Engineering Mechanics | |
Abstract: Polymeric self-assembled monolayers (SAMs) are used to minimize friction in MEMs devices and control adhesion in composites. Nanomechanical models of friction, adhesion and fracture require the properties of these SAMs. This talk examines the use of molecular dynamics and continuum analyses and a novel scanning probe microscope for this purpose. An interfacial force microscope (IFM) is used to probe self-assembled monolayers of octadeciletrichlorosilane (OTS) on silicon. Its unique self-balancing force sensor allows the full attractive and repulsive portions of the force-displacement response of the tip/surface interactions to be obtained without the usual instabilities that are encountered in AFM. The measured force profiles are used to judge the validity of linear and nonlinear elastic models of the OTS behaviour in continuum analyses that include surface interactions. The nonlinear behavior is motivated by molecular dynamics analyses of OTS subjected to simple stress states. The linear elastic analyses yield high Young's moduli, corresponding to the high degree of order but did not provide very good agreement with the measured force profiles. The nonlinear analysis is more promising.
Center for Fluid Mechanics Seminar
Abstract: We present a prototype of a patient-specific analysis of cardiovascular lesions. The methodology uses an image-based computational fluid dynamics (CFD) and includes the following steps: (a) reconstruction of anatomically realistic continuous geometric model of a stenosed artery from magnetic resonance angiography (MRA) images; (b) generating a computational mesh; (c) direct numerical simulations (DNS) of an arterial flow; (d) POD (proper orthogonal decomposition) analysis of DNS- driven data in order to extract meaningful clinical information.
PDE Seminar
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