A general procedure for modified crack closure integral in 3D problems with cracks

✍ Scribed by K.Badari Narayana; B. Dattaguru; T.S. Ramamurthy; K. Vijayakumar

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 816 KB
• Volume: 48
• Category: Article
• ISSN: 0013-7944
• DOI: 10.1016/0013-7944(94)90076-0

✦ Synopsis

In linear elastic fracture mechanics (LEFM), Irwin's crack closure integral (CCI) is one of the sign&ant concepts for the estimation of strain energy release rates (SERR) G, in individual as well as mixed-mode configurations. For effective utilization of this concept in conjunction with the finite element method (FEM), Rybicki and Kanninen [Engng Fracture Neck 9,931-938 (1977)] have proposed simple and direct ~timations of the CC1 in terms of nodal forces and displacements in the elements forming the crack tip from a single finite element analysis instead of the conventional two configuration analyses. These modified CC1 (MCCI) expressions are basically element dependent. A systematic derivation of these expressions using element stress and displacement distributions is required. In the present work, a general procedure is given for the derivation of MCCI expressions in 3D problems with cracks. Further, a concept of sub-area integration is proposed which facilitates evaluation of SERR at a large number of points along the crack front without refining the finite element mesh. Numerical data are presented for two standard problems, a thick centre-cracked tension specimen and a semi-elliptical surface crack in a thick slab. Estimates for the stress intensity factor based on MCCI expressions corresponding to eight-noded brick elements are obtained and compared with available results in the literature.