Development of a methodology for measuring fracture toughness using sub size test specimens

To obtain real data of mechanical properties-fracture toughness-to describe the behaviour of cracks in the material, standard 1T-CT test specimens are usually used that, according to the standard, have the dimensions of 50x62.5 and a thickness of 25 mm. In the case of lack of material obtained for example by 3D printing, SPD methods, or by semi-destructive sampling from a real component to evaluate its residual life, these tests cannot be performed using a standard sample, but can be performed using a designed miniaturized test specimen marked as 0.16T-CT with dimensions 10x10 and thickness 4 mm. This paper contains the development of a methodology for testing fracture toughness using a sub-sized test specimens and a comparison of the obtained results with the results of tests obtained using a standard specimen. The techniques based on miniaturized test specimens for determining fracture toughness have been shown here as a tool to provide a deeper insight into the fracture behaviour of a material and to understand better the behaviour of the material in cases where a limited number of experiments are available.