RETRACTION: Fracture investigation of U-notch made of tungsten-copper functionally graded materials by means of strain energy density (Retraction of Vol 40, Pg 1984, 2017)

The averaged strain energy density over a well-defined control volume was employed to assess the fracture of U-notched specimens made of tungsten-copper functionally graded materials under prevalent mode II loading. The boundary of control volume was evaluated by using a numerical method. Power law function was employed to describe the mechanical properties (elasticity modulus, Poisson's ratio, fracture toughness and ultimate tensile stress) through the specimen width. The effect of notch tip radius and notch depth on notch stress intensity factors and mode mixity parameter were assessed. In addition, a comparison based on fracture load between functionally graded and homogeneous W-Cu was made. Furthermore, in this research, it was shown that the mean value of the strain energy density over the control volume can be accurately determined using coarse meshes for functionally graded materials.