Exploiting intrinsic size effect to overcome specimen scaling limitations in fracture toughness characterisation of composite materials

This study investigates the use of an intrinsic size effect methodology for fracture toughness characterisation, beneficial in cases where geometrical specimen scaling is severely limited. The analytical formulation of the intrinsic method is validated both experimentally and numerically for intralaminar characterisation. Employing a woven carbon fibre-reinforced composite, the intrinsic methodology is able to increase the brittleness ratio of the tested size range without needing to test larger specimen sizes, by combining different types of notched geometries. The R -curve is successfully obtained through a bilogarithmic regression fit of the intrinsic strength data, accounting for the individual manufacturing tolerances of all tested specimens. This method also provides an easy way to compare the nominal strengths of the different notched geometries being employed.