Scrutinized and revised stress intensity factor formulas for double cleavage drilled compression specimens

First, we critically review the stress intensity factor formulas for double cleavage drilled compression (DCDC) specimens, and prove the highly acclaimed analytical formulas for the DCDC were erroneously formulated in Plaisted et al. (2006), we detail the reasons for the errors in several integrals with a short-crack model, and in expressions for bending moment and moment of inertia with a long-crack mode, extending the brief argument in Wang et al. (2016). Then, revised stress intensity factor formulas for DCDC derived by curve-fitting the results from finite element analysis are given, which are applicable to wide-ranging specimen geometries beyond that prescribed in He et al. (1995). Finally, it is shown that even with a load-controlled loading, crack growth stability for DCDC is guaranteed for the whole fracturing process in the experiment, excluding only the DCDC with very small crack length, this is a unique and useful feature pertaining to the DCDC for testing brittle materials.