*Midwest Mechanics Seminar* * April 4^th , 2012 4:30 ARMS Room 1010* *Eliot Fried*** *D**epartment of Mechanical Engineering, McGill University* ** *Stability of a thin elastic film close to a rigid plate* ** *Abstract:* ** *We introduce and study a variational model for the formation of patterns induced by bringing the surface of a rigid plate into contact proximity with the surface of a polymeric film strongly bonded to a substrate. We treat the film as a homogeneous, isotropic, hyperelastic solid and account for both attractive and repulsive van der Waals interactions between the film surface and the proximate contractor. Aside from confiming the intuitive expectation that the presence of a repulsive contribution to the van der Waals potential should stabilize patterns that form on the film surface, we elucidate the role of repulsive interactions at the onset of instability. For a recently proposed van der Waals potential involving two parameters, the Hamaker constant **A **and the equilibrium spacing **d**e**, our results include estimates for the critical gap **d**c **at which undulations appear on the _lm surface, the corresponding wavenumber **k**c **of the undulations, and a lower bound **f **for the attractive force needed to induce the undulations. To leading order, **d**c **~ **(**Ah /**)****1**=**4**, **k**c **~ **1**=h**, and **f**m **~ **(**3**A=h**3**)**1**=**4**, where **h **and ****denote the thickness and infinitesimal shear modulus of the film. Correction terms due to repulsive interactions indicate that, while **k**c **may be influenced by ****and **A**, **d**c **may also be influenced by **d**e**. Granted knowledge of ****and **A**, our results also suggest a simple experimental protocol for determining **d**e**.*** ** *Bio:* ** *Eliot Fried obtained his Ph.D. in Applied Mechanics from the California Institute of Technology in 1991. He received an NSF Mathematical Sciences Postdoctoral Fellowship, a Japan Society for the Promotion of Science Postdoctoral Research Fellowship, and an NSF Research Initiation Award. Currently he is a Professor of Mechanical Engineering and the Tier 1 Canada Research Chair in Interfacial and Defect Mechanics at McGill University. He previously held positions at Carnegie Mellon University, the Pennsylvania State University, College Park, the University of Illinois at Urbana-Champaign, and Washington University in St. Louis. At Illinois, he was a Fellow of the Center of Advanced Study and was awarded a Critical Research Initiative Grant. His research focuses on the mechanics and thermodynamics of novel materials, including liquid crystals, surfactant solutions, hydrogels, and nanocrystalline alloys.*** **