Effect of length-to-height ratio on fracture properties of asymmetrical single-edge notched beam (ASENB) specimen made of ceramic under full range mixed mode I/II loading state

Abstract

Asymmetrical single-edge notched beam (ASENB) specimen is among the suitable specimens for measuring full mode I/II fracture parameters. However, in lack of a standard or common method, researchers used this specimen with different geometers, which have proven can affect the results. This research evaluated the effect of ASENB’s geometry on fracture parameters numerically and experimentally. First, the finite element method determined the geometry factors (Y_I and Y_II) and non-singular (T-stress) fracture parameters. Then, the experimental fracture tests were conducted using ceramic material. Results show it is more reasonable to express the Y_I and Y_II based on S₁/L and S₂/H, instant S₁/L, and S₂/L. In other words, the geometry factors can be expressed better based on the height of the specimen and not length. So, for ASENB specimens tested in conventional S₁/L of 0.7 to 0.9, the pure mode-II condition was generated in 0.05 < S₂/H < 0.14. The modeling showed that the non-singular term of fracture (T-stress) was significant compared to fracture toughness, so the Biaxiality was measured as 0.5 to −2.5, more significant for pure mode-II and almost regardless of the a/H ratio. As experimental tests show, the relative length of the ASENB specimen has an insignificant effect on measured fracture toughness, so a more compact specimen with L/H of about 2 to 4 can suggested for tests.