A numerical study of T-stress in dynamically loaded fracture specimens

The objective of this paper is to study the evolution of T-stress in dynamically loaded fracture specimens. To this end, two-dimensional plane strain, elastodynamic finite element analyses of single edge notched (tension) specimens, and three point bend specimens subjected to time varying loads are performed. The T-stress is computed using an accurate and computationally efficient domain representation of the interaction integral. The results demonstrate that dynamically loaded specimens are subjected to a large negative T-stress during the early stages of loading as compared to that under static loading. The above phenomenon can satisfactorily explain the strong elevation in the dynamic fracture toughness at high loading rates, which has been reported in numerous experimental studies.

[1]  A. J. Carlsson,et al.  Influence of non-singular stress terms and specimen geometry on small-scale yielding at crack tips in elastic-plastic materials , 1973 .

[2]  R. H. Dodds,et al.  Constraint effects on fracture toughness of impact-loaded, precracked Charpy specimens , 1996 .

[3]  Guandong Wang,et al.  Two Parameter Fracture Mechan-ics: Theory and Applications , 1993 .

[4]  R. Narasimhan,et al.  Constraint effects on ductile fracture processes near a notch tip under mixed-mode loading , 1999 .

[5]  O. C. Zienkiewicz,et al.  The finite element method, fourth edition; volume 2: solid and fluid mechanics, dynamics and non-linearity , 1991 .

[6]  L. Freund,et al.  Analysis of a dynamically loaded three-point-bend ductile fracture specimen , 1986 .

[7]  J. Kalthoff.  Fracture behavior under high rates of loading , 1986 .

[8]  R. Narasimhan,et al.  A finite element investigation of the effect of crack tip constraint on hole growth under mode I and mixed mode loading , 1999 .

[9]  F. J. Belzunce,et al.  A two parameter fracture criterion for high strength low carbon steel , 1996 .

[10]  S. Basu,et al.  Finite Element Simulation of Mode I Dynamic, Ductile Fracture Initiation , 1996 .

[11]  M. F. Kanninen,et al.  Research challenges arising from current and potential applications of dynamic fracture mechanics to the integrity of engineering structures , 1995 .

[12]  Ares J. Rosakis,et al.  Dynamic fracture initiation and propagation in 4340 steel under impact loading , 1990 .

[13]  J. Duffy,et al.  The Effect of Loading Rate and Temperature on the Initiation of Fracture in a Mild, Rate-Sensitive Steel , 1979 .

[14]  S. Basu,et al.  A numerical investigation of loss of crack tip constraint in a dynamically loaded ductile specimen , 2000 .

[15]  S. Basu,et al.  A comparative study of dynamic, ductile fracture initiation in two specimen configurations , 2000 .

[16]  R. Narasimhan,et al.  An experimental investigation of constraint effects on mixed mode fracture initiation in a ductile aluminium alloy , 1999 .

[17]  John W. Hutchinson,et al.  Dynamic Fracture Mechanics , 1990 .

[18]  James W. Dally,et al.  Dynamic measurements of initiation toughness at high loading rates , 1988 .

[19]  J. Z. Zhu,et al.  The finite element method , 1977 .

[20]  K. Ravi-Chandar,et al.  An experimental investigation into dynamic fracture: I. Crack initiation and arrest , 1984 .

[21]  C. Shih,et al.  Family of crack-tip fields characterized by a triaxiality parameter—II. Fracture applications , 1992 .

[22]  A. Rosakis,et al.  Dynamic Failure Mechanisms in Beryllium-Bearing Bulk Metallic Glasses , 1998 .

[23]  M. Williams,et al.  On the Stress Distribution at the Base of a Stationary Crack , 1956 .

[24]  Vladimir Sladek,et al.  Integral formulation for elastodynamic T-stresses , 1997 .

[25]  A. Rosakis,et al.  Dynamic measurement of the J integral in ductile metals: Comparison of experimental and numerical techniques , 1990 .

[26]  C. Shih,et al.  Effect of Constraint on Specimen Dimensions Needed to Obtain Structurally Relevant Toughness Measures , 1993 .

[27]  S. Basu,et al.  A finite element study of the effects of material characteristics and crack tipconstraint on dynamic ductile fracture initiation , 1999 .

[28]  J. W. Hancock,et al.  J-Dominance of short cracks in tension and bending , 1991 .

[29]  Ares J. Rosakis,et al.  Experimental Determination of Dynamic Crack Initiation and Propagation Fracture Toughness in Thin Aluminum Sheets , 1998 .

[30]  J. Hancock,et al.  Two-Parameter Characterization of Elastic-Plastic Crack-Tip Fields , 1991 .

[31]  A. Kfouri.  Some evaluations of the elastic T-term using Eshelby's method , 1986 .

[32]  A. Rosakis,et al.  Loading Rates and the Dynamic Initiation Toughness in Brittle Solids , 1998 .

[33]  J D G Sumpter,et al.  Constraint based analysis of shallow cracks in mild steel , 1992 .