Engineering Fracture Mechanics, Vol. 73, No. 5, pp. 643-648, 2006
D.J. Shim, G.H. Paulino and R.H. Dodds Jr.
Department of Civil & Environmental Engineering, University of Illinois at Urbana-Champaign,
Newmark Laboratory, 205 North Mathews Avenue, Urbana, IL 61801, U.S.A.
Abstract
This note describes the effect of material gradation (parallel to the crack plane) on stress intensity factors and K-dominance, i.e. the dominance of the singular region, of fracture specimens; SE(T), SE(B) and C(T). The extent of K-dominance is investigated by comparing the actual stress field with the Williams’ asymptotic stress field. Linear-elastic finite element analyses are performed using graded elements which incorporate graded material properties at the element level. Material gradation and crack geometry are systematically varied to perform the parametric study. Results reveal that the effect of material gradation on KI is most pronounced when a short crack is located on the stiffer side of the fracture specimen. For a given specimen and crack geometry, the extent of K-dominance yields a curve with a peak point at a certain material gradation. Results of the present study provide valuable insight into the K-dominance of FGMs.
KEY WORDS: functionally graded material (FGM); K-dominance; stress intensity factor; fracture specimens; 3-D finite element analysis; graded element.