Evaluation of a modified Iosipescu shear test method for determining the shear properties of clear wood

A modified Iosipescu shear test method is proposed as an alternative for measuring the shear properties of clear wood. The method adopts four-point asymmetric loading procedure in the Iosipescu shear test but with the loading positions shifted to the neutral axis of the specimen. The original V-notched specimen is replaced by a combination of polyvinyl chloride blocks at two ends and a bow-tie-shaped wood specimen in the middle to provide a better stress pattern at failure. The measured shear strength and shear moduli are compared with results from compression test and off-axis tension test. Finite element analysis is also carried out to study the stress distribution in the wood specimen. Results show that the new shear test setup can provide close-to pure shear stress state in the specimen yielding better estimates of the shear properties of wood. The shear strength obtained by the new test setup is slightly lower than that from the off-axis tensile test which is probably due to the relatively thick specimen chosen in this study.