Research in Nonlinear Dynamics and Friction

This is an experimental and theoretical study on systems with frictional damping and frictional excitation. Part of the project focuses on characterizing and modeling friction during oscillations. To this end, we have modeled hysteretic friction-velocity behavior in a mass spring system, and "developed" a decrement method for identifying friction parameters in a system with viscous and dry friction. (I say "developed" because we found later that Watari of Japan did something similar back in the 1960s.) The wavelet transform and geometric analyses have been helpful in the friction modeling. Another aspect of the project has focused on friction induced vibration, in effort to gain understanding of squeak and squeal problems. We are applying proper orthogonal decomposition in the study of friction induced vibration of distributed systems. We also are seeking experimental evidence of squeak mechanisms in automotive suspension parts in effort to find a squeak criterion for designers.

Support: National Science Foundation, CMS-9624347, 8/96-7/00; Ford Motor Company, 9/95-5/96.