Understanding Damage Initiation and Propagation Mechanisms in Polyurethane Foam Core Sandwich Panels Using Acoustic Emission Monitoring

Abstract

Comprehending the damage initiation and propagation mechanisms in sandwich materials is crucial for optimizing their design. We employ a passive approach based on three-point bending tests on prismatic sandwich beam specimens with polyurethane foam cores. During these tests, the acoustic emission (AE) signals generated by the materials under mechanical loading are recorded. AE is defined as the release of energy in the form of transient elastic waves accompanying a dissipative process in the material. These signals are then analyzed based on parameters such as amplitude, energy and number of events to study the influence of support span length and core thickness. Classification of the acoustic signatures allows identification of the different damage modes (core shear, delamination, indentation, etc.). This acoustic activity is correlated with the deformation phases (load-displacement curve) and the damage modes observed in real-time. This correlation enables evaluation of the collected signals and improves understanding of the damage mechanisms in sandwich materials.