Physics Department colloquium will be Oct. 2 "A Model for Evaluating Friction Damping in Axisymmetric Structures will be presented by Annie Tangpong, North Dakota State University Department of Mechanical Engineering at 4 p.m. Friday, Oct. 2, in 211 Witmer Hall Abstract: A finite element method is developed to study the steady-state vibration of two axisymmetric structures-a base substructure and an attached damper substructure-that are driven by traveling wave excitation. The two structures couple through a spatially-distributed hysteretic friction interface. The base substructure is representative of a rotating brake rotor or gear, and the damper is a ring affixed to the base under preload and intended to control vibration through friction along the interface. Despite the nonlinearity and with contact occurring at an arbitrarily large number of nodal points, the response during sticking, or during a combination of sticking and slipping motions, can be determined from a low-order set of equation by the finite element model. The method is applicable to element types for both longitudinal and bending vibration, and to an arbitrary number of nodal degrees of freedom in each substructure. An example will be discussed using this method in the context of out-of-plane vibration of a coupled base-damper system. Coffee and Cookies will be served at 3:30 p.m. in 215 Witmer Hall. -- Connie Cicha, Assistant Professor, Physics Department Witmer Hall Room 211, connie_cicha@und.nodak.edu, 777-2911