Acoustic emission description from a damage and failure scenario of rotomoulded polyolefin sandwich structure subjected to internal pressure for storage applications

The aim of this paper is to study the damage mechanisms in a sandwich polymer structure that contains three layers: two polyolefin skins and the foam core (skin–foam–skin). Specific tests on structure associated with the acoustic emission (AE) technique and tomographic observations (RX) are used to identify the damage. Initially, a conventional tensile test was performed to correlate the acoustic emission with the initiation of plasticity and damage to a polyethylene sample. The results obtained are close to those observed in other studies and it is possible to separate the signal from cavitation and propagation of necking. The technique is then employed to capture the rupture of a polymer skin on a multilayer rotomoulded structure (bottle). Tests were carried out on this bottle under internal water pressure. Three tests are performed with more or less early interruptions in order to identify the first damage and understand their evolution. Different quantities (average frequency, RA value, etc.) are observed in order to quantify and understand the perceived damage. With the AE/RX correlation and mechanical behaviour, a scenario of structural damage is proposed.