INVESTIGATION OF MODE II IN FOUR POINT BENDING BEAM TEST

A Finite Element Analysis has been applied to a type of four-point bending specimen with S/W=3 to determine which condition a pure mode II can be constructed. The ANSYS simulation results have demonstrated that conditions l1 = l4 and l2 = l3 could not guarantee a pure mode II case be generated. The ratio W/D and ratio a/W have a remarkable contribution to the formation of pure mode II. At W/D = 3.75 and a/W from 0.25 to 0.35, an almost perfect shear mode II can be achieved at the single crack tip region. When a/W varies 0.2 to 0.6, the specimen can also be treated as in pure shear mode II case if a 6 percent of the ratio KI/KII is acceptable. A KII expression in fifth-degree polynomials has been calibrated.