Nonlinear interface effects in multilayered structures: vibro-acoustic modeling and experimental analysis

TL;DR

This study investigates the nonlinear behavior of imperfect interfaces in multilayer structures through vibro-acoustic modeling and experimental laser vibrometry, revealing excitation-dependent stiffness variations.

Contribution

It introduces a combined theoretical and experimental framework for analyzing nonlinear interface effects in multilayer structures using an equivalent vibro-acoustic approach.

Findings

Dynamic response depends on excitation level.

Equivalent bending stiffness varies with excitation.

Nonlinear interfacial behavior affects structural response.

Abstract

This paper presents an experimental and theoretical study of the nonlinear behavior of imperfect interfaces in multilayer structures using an equivalent vibro-acoustic approach. The multilayer system is modeled through a Zig-Zag formulation, in which interfacial coupling conditions, stress continuity and displacement discontinuity, relate the kinematics of adjacent layers while preserving an independent description of each layer. This framework significantly reduces the number of kinematic unknowns without compromising the model accuracy. An equivalent Kirchhoff-Love plate formulation is then introduced to derive a frequency-dependent bending stiffness representative of the global structural response. Experimental measurements of the transverse displacement field are performed using laser vibrometry and processed via the Corrected Force Analysis Technique (CFAT).The results demonstrate that the dynamic response of a three-layer beam with imperfect interfaces depends on the excitation level. In particular, variations in the equivalent bending stiffness are observed, revealing the nonlinear nature of the interfacial behavior. The proposed methodology is applied to a glass-epoxy-glass multilayer beam under various excitation levels.