Measurement of the shear modulus of wood by the square-plate twist method

In this research, square-plate twist test methods for obtaining the shear modulus of wood were examined. Square plates of western hemlock (Tsuga heterophylla Sarg.) were used as specimens. Twist tests were conducted according to three different methods for various length/thickness and span/plate diagonal ratios, and the shear modulus corresponding to each test condition was obtained. To examine the validity of shear modulus obtained by these tests, asymmetric four-point bending tests and finite element calculations were independently conducted and the results were compared. Specimens had a length/thickness ratio greater than 47 and were supported at two or three points close to each corner while applying a load to the remaining corner. Under these conditions, the shear modulus could be properly obtained over a wide range of span/plate diagonal ratios.