Analysis of the Influence of Hydrostatic Stress on the Behaviour of an Adhesive in a Bonded Assembly

摘要

Generally, adhesives are viscoelastic-plastic materials, for which the development of viscosity and plasticity varies depending on the type of adhesive and the stress state. Various models exist to represent the yield surface or the so-called elastic limit, taking into account the two stress invariants, hydrostatic stress and von Mises equivalent stress. Moreover, to develop precise pressure-dependent constitutive models, it is necessary to have a large experimental database in order to accurately represent the adhesive strains which are strongly dependent on the tensile-shear loading combination. Under quasi-static loadings, for a given strain rate range viscous effects can be neglected, but only a few experimental results are available to model the behaviour of the adhesive in a bonded assembly accurately under realistic loadings. Moreover, edge effects often have a large influence on the mechanical response. This paper presents the possibility of combining the use of an experimental device, which strongly limits the influence of the edge effects, with a pressure vessel especially designed to study the influence of hydrostatic stress. The latter allows pressures up to 100 MPa to be applied during mechanical testing. Comparisons with results obtained with a modified Arcan device are presented. Such results are useful for the development of 3D pressure-dependent models for the yield function and for the analysis of more complex loading.