Contact acoustic nonlinearity effect on the vibro-acoustic modulation of delaminated composite structures

•A novel 3D VAM generation theory based on modified GW model is proposed.•Proposed theory can conduct joint-analysis of nonlinear contact model and clapping/rubbing.•Mechanism of synchronous existence of AM&FM and difference of odd–even sidebands are explained.•The modified GW model is introduced into FEM by using UINTER subroutine.•The nonlinear DI’s damage imaging capability for different delamination is discussed in detail.