Rate effects in mode-II fracture of plastically deforming, adhesively bonded structures
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Results from a combined experimental and numerical investigation into the effects of rate on mode-II fracture of a plastically deforming, adhesively bonded joint are presented. It is shown that a cohesive-zone model has to be modified to include coupling between normal and shear modes of deformation when there is extensive shear deformation of the adhesive layer. A suitable cohesive-zone modeling strategy is described, and the mode-II cohesive parameters determined from the model are presented as a function of loading rate. Previous studies of the same system showed that the effects of rate in mode-I were limited to the probability that a crack growing in a toughened quasi-static mode would spontaneously make a transition to a brittle mode of fracture. No such transitions were found for mode-II fracture. Crack growth always occurred in a quasi-static fashion. While there was some evidence that rate might affect the mode-II fracture parameters, these effects were very limited even up to crack velocities of about 1,000 mm/s. Any possible effects was limited to a very minor increase in toughness and strength with increased loading rates. However, the magnitude of these possible increases were comparable to the magnitude of the uncertainties in the measured values.
KeywordsCohesive zone Bonded joint Finite elements Experiments
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