Three-dimensional numerical analysis of out-of-plane creep crack-tip constraint in compact tension specimens

In this paper, the C (t) and C∗ integrals, stress redistribution time tred and creep crack-tip stress distributions in the compact tension (CT) specimens with various thicknesses have been calculated by the three-dimensional (3D) finite element method, and the out-of-plane creep crack-tip constraint induced by specimen thickness is quantitatively characterized and analyzed in detail. The results show that the out-of-plane creep crack-tip constraint in the CT specimens could be characterized and analyzed by the new constraint parameter R. The 3D creep crack-tip constraint increases with increasing specimen thickness, and the 3D effect becomes more pronounced with increasing the parameter C∗. There is a central region with higher creep constraint along the crack front, the size of the region increases with increasing specimen thickness, and decreases with increasing creep time and parameter C∗. The factors of influencing the out-of-plane creep crack-tip constraint are analyzed. ► Out-of-plane creep crack-tip constraint induced by specimen thickness was studied. ► The creep constraint could be characterized and analyzed by a new parameter R. ► Out-of-plane creep constraint increases with increasing specimen thickness. ► There is a central region with higher creep constraint along the crack front. ► Size of the central region decreases with increasing creep time and load level.