Plastic yielding of a film adhesive under multiaxial stresses

This article presents a study of the plastic yielding behaviour of a rubber -toughened film adhesive (FM73) subjected to triaxial stresses. Experiments were carried out using a bonded joint specimen similar to the Iosipescu sp ecimens originally designed for use with fibre composite materials. The exp erimental results reveal that the plastic yielding of the FM73 adhesive exh ibits a complex dependence on the hydrostatic stress, especially in the com pression regime. It is found that the conventional yield criteria widely em ployed to model adhesives, such as the modified Tresca criterion, the modif ied von Mises criterion, and the linear Drucker-Prager criterion, are unabl e to characterise the yield locus. To overcome this difficulty, the modifie d Drucker-Prager/cap plasticity model that is commonly associated with geol ogical materials is adopted in the present study, which provides a good cor relation with the experimental data. (C) 2000 Elsevier Science Ltd. All rig hts reserved.