Structural damage identification in plates via nonlinear structural intensity maps

A nonlinear structural intensity concept is presented as an approach for the identification of defects displaying nonlinear vibration behavior. The nonlinear structural dynamic response exhibited by a riveted joint with loosened fasteners connecting a stiffener with a flat panel is investigated. The excitation, generating elastic waves with dominant bending components, triggers the nonlinear contact between the plate and the stiffener inducing a dynamic response rich with nonlinear harmonics. Experimental structural intensity maps are evaluated at the super-harmonic frequencies. This technique provides an experimental approach for the characterization and two dimensional visualization of nonlinear types of defects.