DYNACOLLE

Adhesive failure mechanisms are sensitive to loading speed. Moreover, failure generally occurs under mixed loading between tension and shear. However, current cohesive zone models do not take into account the possible coupling between mixing and loading speed. The aim of this work is therefore to characterize the fracture behavior of an adhesive under multiaxial dynamic loading. To this end, a new experimental protocol is developed.

With the same set-up, slight variations in specimen geometry enable the entire fracture envelope to be covered, from tension to shear. Dynamic loading is performed using a servohydraulic tensile machine. The validity of the protocol under quasi-static loading is experimentally demonstrated by comparison with an existing reference test. Mode II and Mode III fractures were found to be equivalent. Moreover, toughness decreases at high loading speeds, whatever the mode mix.

Finally, a fracture criterion is defined to take into account both the influence of mode mixing, and that of loading speed, on toughness.