Design and analysis of novel compression fracture specimen with constant form factor: Edge cracked semicircular disk (ECSD)

Inspired by the Brazilian disk geometry we examine the utility of an edge cracked semicircular disk (ECSD) specimen for rapid assessment of fracture toughness of brittle materials using compressive loading. It is desirable to optimize the geometry towards a constant form factor F for evaluating KI. In this investigation photoelastic and finite element results for KI evaluation highlight the effect of loading modeled using a Hertzian. A Hertzian loading subtending 4° at the center leads to a surprisingly constant form factor of 1.36. This special case is further analyzed by applying uniform pressure over a chord for facilitating testing.

► New fracture specimen ECSD under Hertzian compression is analyzed.
► Compressed SD along straight edge experiences tension at circular end.
► KI is found from photoelastic isochromatic fringe pattern of ECSD.
► KI found from FEA shows form factor constancy for a particular load angle.
► More convenient design ECSD(Ch) also shows form factor constancy.