International Journal
of Computational Engineering Science, Vol. 5, No. 4, pp. 833-861, 2004
Special issue on "Modeling of Functionally Graded Materials"
G.H. Paulino and J.H. Kim
Department of Civil and Environmental Engineering, University of Illinois
at Urbana-Champaign, Newmark
Laboratory, 205 North Mathews Avenue, IL
61801, U.S.A.
Abstract
Poisson's ratio is important for fracture behavior of functionally graded materials, while its effect on stress intensity factors and T-stress (i.e. non-singular stress) is negligible in homogeneous materials. It has a significant influence on stress intensity factors and T-stress for a crack in such materials under mixed-mode loading conditions. For the applied loads parallel to material gradation, the compliant part of materials shows more significant contraction than the stiff part of materials. This behavior affects the near crack-tip fields which are characterized by stress intensity factors and T-stress. This paper makes use of an accurate scheme, i.e. the interaction integral method, to evaluate stress intensity factors and T-stress, and it presents an example where a center crack is oriented perpendicular to material gradation, and the applied load is parallel to material gradation. The example is investigated for both constant and linearly varying Poisson's ratios.
Keywords: functionally graded material (FGM), fracture mechanics, stress
intensity factor (SIF), T-stress, interaction
integral, finite element method (FEM).