A new criterion for mixed mode fracture initiation based on the crack tip plastic core region

In this work, we propose a new criterion for mixed mode I-II crack initiation angles based on the characteristics of the plastic core region surrounding the crack tip. The shape and size of the plastic core region are thoroughly analyzed under different loading conditions and a new formulation for the non-dimensional variable radius of the core region is presented for mixed mode (KI−KII) fracture. The proposed criterion states that the crack extends in the direction of the local or global minimum of the plastic core region boundary depending on the resultant stress state at the crack tip. The results show a well-defined correlation between the plastic core region characteristics and crack extension angles predicted by other criteria. The proposed criterion is formulated for various loading conditions and is compared with other available criteria against the limited available experimental data. It is shown that the proposed criterion provides a better agreement with the experimental data.

[1]  P. Theocaris.  Discussion of “on the use of the T-criterion in fracture mechanics” by N.A.B. Yehia, engineering fracture mechanics 1985 , 1986 .

[2]  Masahiro Kinoshita,et al.  Dynamic fracture-path prediction in impact fracture phenomena using moving finite element method based on Delaunay automatic mesh generation , 2001 .

[3]  N. P. Andrianopoulos,et al.  The mises elastic-plastic boundary as the core region in fracture criteria , 1982 .

[4]  N. P. Andrianopoulos,et al.  Experimental study of the T-criterion in ductile fractures , 1983 .

[5]  S. K. Maiti,et al.  Comparison of the criteria for mixed mode brittle fracture based on the preinstability stress-strain field Part I: Slit and elliptical cracks under uniaxial tensile loading , 1983 .

[6]  Mark S. Shephard,et al.  The NT-criterion for predicting crack growth increments , 1987 .

[7]  Du Shanyi,et al.  Mixed-mode fracture criteria for the materials with different yield strengths in tension and compression , 1992 .

[8]  N. P. Andrianopoulos,et al.  On the use of the T-criterion in fracture mechanics , 1986 .

[9]  J. Rice,et al.  Elementary engineering fracture mechanics , 1974 .

[10]  Nabil A.B. Yehia,et al.  Distortional strain energy density criterion: the , 1991 .

[11]  S. Basu,et al.  A thermo-mechanical study of mode I, small-scale yielding crack-tip fields in glassy polymers , 2002 .

[12]  N. Chandra,et al.  Analysis of crack growth and crack-tip plasticity in ductile materials using cohesive zone models , 2003 .

[13]  Luis E. Vallejo.  The Brittle And Ductile Behavior Of A Material Containing A Crack Under Mixed-Mode Loading , 1987 .

[14]  N. Merah,et al.  Experimental characterization of the elastic-plastic strain fields at the crack tip due to cyclic loading , 1994 .

[15]  N. Merah,et al.  Effect of Thickness on Elasto-Plastic Deformation and Hysteretic Energy Dissipated at Crack Tip , 1991 .

[16]  J. Williams,et al.  The fracture of spherical shells under pressure and circular tubes with angled cracks in torsion , 1974 .

[17]  J. Lambros,et al.  Role of plasticity in heat generation during high rate deformation and fracture of polycarbonate , 2002 .

[18]  F. Erdogan,et al.  On the Crack Extension in Plates Under Plane Loading and Transverse Shear , 1963 .

[19]  S. M. Khan,et al.  Analysis of mixed mode crack initiation angles under various loading conditions , 2000 .

[20]  T. K. Paul,et al.  A centrally cracked thin circular disk, Part II: mixed mode fatigue crack propagation , 1998 .

[21]  N. P. Andrianopoulos,et al.  The T-criterion applied to ductile fracture , 1982 .

[22]  X. Kong,et al.  Effect of triaxial stress on mixed-mode fracture , 1995 .

[23]  V. G. Ukadgaonker,et al.  A new criterion for fracture initiation , 1995 .

[24]  E. Orowan,et al.  Fracture and strength of solids , 1949 .

[25]  S. K. Maiti,et al.  Comparison of the criteria for mixed mode brittle fracture based on the preinstability stress-strain field , 1984 .

[26]  P. Theocaris,et al.  Lefm brittle and ductile fractures as described by the T-criterion , 1988 .

[27]  G. Sih.  Strain-energy-density factor applied to mixed mode crack problems , 1974 .

[28]  J. G. Williams,et al.  Fracture under complex stress — The angled crack problem , 1984 .

[29]  G. Sih.  SOME BASIC PROBLEMS IN FRACTURE MECHANICS AND NEW CONCEPTS , 1973 .