Resumen de CCC specimen: A novel specimen for FCG studies under plane strain conditions
F. V. Antunes, Alonso Camacho Reyes, E. R. Sérgio, José Manuel Vasco Olmo, Francisco Alberto Díaz Garrido, D.M. Neto
Fatigue crack growth is usually studied using CT or MT specimens, which have through-thickness cracks. Plane strain conditions are assumed to exist for relatively thick specimens (t10 mm), while plane stress state is studied considering thin specimens (t<4 mm). However, the crack front has always corner points, even in thick specimens, and interior regions even in thin specimens, therefore pure stress states are never reached. A novel specimen is proposed here, able to simulate pure plane strain conditions. It is a cylindrical specimen with central crack, obtained by additive manufacturing. There are no corner points along crack front, which propagates keeping a circular shape. Therefore, all the complexities associated with crack shape, corner points and variation of crack closure along crack front are avoided. The specimens may be used to develop comparative studies in air and vacuum, avoiding expensive vacuum chambers. Ti6Al4V titanium alloy specimens were produced by SLM with a diameter of 10 mm, and the effectiveness of the concept was proved.
However, the measurement of crack length inside the specimen is a challenging task. A numerical approach was followed to determine crack length from compliance measurements.
