A four-point bending test to study both failure initiation and crack propagation at the interface of an adhesive joint
Résumé
In this study the authors propose a test specimen developed to study both failure
initiation and crack propagation at the interface with the aim to determine its strength and
toughness. The two-substrate specimen used were bonded with a thin joint of structural
adhesive, to conform to most of the industrial applications. Then, geometry of the specimen and
parameters of the four-point bending were designed to localize failure initiation at one interface
and in order to have a stable evolution of the crack propagation at this interface. This
optimization work was performed using 3D Finite Element Model for an interface of metallic
substrates and an industrial epoxy based adhesive. An experimental campaign was carried out
on the optimized configuration of the specimen and the four-point bending flexural loading. The
failure properties identified at the interface for a specific surface preparation are compared to
the one characterized for “cohesive” failures on the structural adhesive