Crack propagation paths in four point bend Aluminium–PMMA specimens

•SIF’s solutions for sub interface crack FPB bi-material specimen loaded asymmetric.•CTTM was developed and used to measure real crack length using DIC technique.•The presence of interface influences the crack propagation paths.•Crack propagation paths are influenced by the applied mixed mode load.•The interface produces shielding in FPB Al–PMMA bi-material specimens.

The presence of cracks has a major impact on the reliability of advanced materials, like fiber or particle reinforced composites, layered composites, laminated composites. For engineering application, it is very important to estimate the crack path, and the influence of the interface on the fracture parameters. This paper presents the crack propagation paths of a sub-interface crack in a four point bend bi-material specimen made half of Aluminium half of PMMA. Experimental crack paths were obtained using fatigue tests and are compared with the simulated ones by finite element analysis code FRANC2D/L. It has been obtained a good correlation between curvilinear trajectories of experimentally observed and numerically simulated cracks. An estimation of crack growth rates of a sub-interface crack is also presented.