Novel test method for evaluating the accelerated fatigue performance of adhesive bonded joints

A novel adhesive joint test is proposed and evaluated for enhanced adhesive system selection. This method employs a simple joint geometry specimen adaptable to standard dynamic mechanical thermal analysis (DMTA) equipment. The joint configuration enables versatile mixed loading under controlled environmental conditions (temperature and humidity), whilst subject to cyclic loading. Its compact size facilitates accelerated aging studies compared to conventional methods. Comparative analysis with single lap shear (SLS) joint testing demonstrates the new method's potential for superior or equivalent load and mode discrimination, while offering accelerated testing and deeper insights into substrate-adhesive interactions, i.e., variable stress states can be imposed on the adhesive layer, based on the location of the adhesive bondline, to tailor the stresses acting in the adhesive layer to better match stresses produced by service loads. Additionally, the new accelerated fatigue test method should provide complimentary data, such as the stiffness of adhesive joints, to traditional (and often simplistic) performance indicators, such as SLS performance. This parameter is particularly relevant to bonded engineering components, as the stiffness of adhesive joints is related with the fatigue performance of engineering components.