Viscoelastic foundation analysis of Single Cantilevered Beam (SCB) test under stationary loading

A simple, Maxwell type foundation model has been derived for analysis of the Single Cantilever Beam (SCB) fracture test, used for evaluating adhesively bonded joints under stationary loading conditions. Crack initiation tests, under constant force loading, are presented to introduce the effective λeff concept, which can be extended to the wedge test configuration (viz. constant deflection/relaxation loading). A simple Maxwell model is used to approximate relaxation/creep behaviour of the bondline. Analytical solutions are found in the Laplace domain. Numerical inversion techniques are proposed to calculate the evolution of macroscopic quantities, such as deflection or applied force, but also stress and strain along the bondline. This analysis gives some insight into the crack nucleation process and indications for better prediction of threshold values for ‘infinite life’ (no crack initiation).