Mode II critical stress intensity factor of solid wood obtained from the asymmetric four-point bend fracture test using groove-free and side-grooved samples

•KIIc of solid wood was obtained by AFPBF tests of groove-free and grooved samples.•The KIIc values were compared with those obtained from the 3ENF tests.•The AFPBF test was effective when considering the additional crack length. Asymmetric four-point bend fracture (AFPBF) tests and three-point bend end-notched flexure (3ENF) tests were performed on groove-free and side-grooved samples of western hemlock, and the Mode II fracture critical stress intensity factor (KIIc) was obtained. Differences in the KIIc values obtained from the AFPBF and 3ENF tests were significant. However, these differences were effectively reduced when the additional crack length Δ was introduced into the data reduction process. These results indicate that the KIIc value can be determined by considering the Δ value and the results obtained from previous Mode II fracture mechanics tests.