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Structural adhesives have been increasingly used in automotive industries in conjunction with lightweight structural components to maximize weight reduction in modern car design. They are used to bond various kind of lightweight materials such as FRP composites or metallic alloys and provide a good distribution of force across joining area without damaging the substrates. For automotive applications, bonded components have been often used in complex loading environments which brings failure prediction of adhesive joints a key of success for this technology. As polymer-based materials, hydrostatic pressure can have a major impact on adhesive joint failure in addition to temperature and strain rate. Its influence can be investigated using a specific test fixture known as a modified-Arcan fixture. This article presents the characterization of epoxy-based adhesive using a series of modified-Arcan tests to apply different loading taking in account effect of hydrostatic pressure onto adhesive joints. A high-order exponential Drucker-Prager failure criterion is chosen to interpret the yield and failure surface. Finally, the non-linear behaviour of adhesive is identified via 0° and 90° Arcan tests which correspond respectively to tri-axial and shear modes and the validation of this behaviour is carried out by mix-mode 60° and 120° Arcan tests. The simulation shows a good agreement only with the result in direction 60° while in direction 120° the divergence is obvious due to the different in damage mechanism of this mode.

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National audienceThis study deals with the characterization of two adhesive joints under quasi static and fatigue loading. Different testing systems were involved. For quasi static loading, the complex behaviour model based on modified Drucker-Prager criterion taken into account hydrostatic stress and rate dependence was proposed to describe the elasto-visco-plastic behaviour of adhesives. The model’s parameters were determined and validated from experiments with the aid of finite element simulations (FEM). For fatigue loading, the lifetime of adhesives was studied. S-N curves was established and extended a failure criterion for any number of cycles. Endurance limit was determined for any combination of applied load for one adhesive, while another adhesive showed the endurance limit only in shear loading