Nonlinear response of a flanged fastened joint due to acoustical sine sweep excitation

Abstract

Fastened joints can significantly complicate the prediction of damping and resonance frequencies of built-up systems. This complexity often leads to over-designing for safety, which drives up manufacturing and operational costs. To improve understanding of the dynamic response of fastened joints, impact hammer and acoustically driven excitation of fastened plates at a flange have been measured. These findings add experimental data that are not well represented in the literature for such joints. The structure was excited acoustically, and acceleration was measured at multiple locations on the flange and plate. Backbone curves were generated with sinusoidal sweeps of acoustic input energy. These curves highlight the nonlinearity of the system, which varies according to fastener preload. Generally, as preload torque values decrease, nonlinearity increases with shifts observed in damping, stiffness, and resonance frequency. Data presented will be used to create a model for better predicting the global dynamic properties of built-up structures.