Multiple Equilibria and Their Effects on Impact Damage in an Air-Handling Assembly

Nonlinear dynamic systems can have multiple equilibriumstates, which together with the system properties,initial conditions, input. and nonlinear feedback dictatehow nonlinear systems respond. In systems with impacts,stiffness discontinuitiescan lead to deterioration in function and eventual failureafter many vibration cycles. This article demonstrateshow multiple static equilibria can potentially accelerate impactdamage. Based on experimental data and observations froman air-handling assembly with clearance and Coulomb frictionnonlinearities, a low-order model is developed to describethe observed behavior. It is demonstrated that motion inthe neighborhood of an equilibriumpoint causes more severe vibration impact damage due to aloss of tolerance away from the design point.