Effects of weld strength mismatch on J and CTOD estimation procedure for SE(B) specimens

This work examines the effect of weld strength mismatch on fracture toughness measurements defined by J and CTOD fracture parameters using single edge notch bend (SE(B)) specimens. A central objective of the present study is to enlarge on previous developments of J and CTOD estimation procedures for welded bend specimens based upon plastic eta factors (η) and plastic rotational factors (rp). Very detailed non-linear finite element analyses for plane-strain models of standard SE(B) fracture specimens with a notch located at the center of square groove welds and in the heat affected zone provide the evolution of load with increased crack mouth opening displacement required for the estimation procedure. One key result emerging from the analyses is that levels of weld strength mismatch within the range ±20% mismatch do not affect significantly J and CTOD estimation expressions applicable to homogeneous materials, particularly for deeply cracked fracture specimens with relatively large weld grooves. The present study provides additional understanding on the effect of weld strength mismatch on J and CTOD toughness measurements while, at the same time, adding a fairly extensive body of results to determine parameters J and CTOD for different materials using bend specimens with varying geometries and mismatch levels.

[1]  Eberhard Roos,et al.  A procedure for the experimental assessment of the J-integral by means of specimens of different geometries , 1986 .

[2]  C. Shih,et al.  Elastic-Plastic Analysis of Cracks on Bimaterial Interfaces: Part I—Small Scale Yielding , 1988 .

[3]  Yun-Jae Kim,et al.  Mismatch effect on plastic yield loads in idealised weldments , 2001 .

[4]  John R. Rice,et al.  Some further results of J-integral analysis and estimates. , 1973 .

[5]  Claudio Ruggieri,et al.  Failure assessments of corroded pipelines with axial defects using stress-based criteria: Numerical studies and verification analyses , 2009 .

[6]  Api Standard,et al.  Welding of Pipelines and Related Facilities , 2006 .

[7]  Hyungyil Lee.  Estimation of crack driving forces on strength-mismatched bimaterial interfaces , 2002 .

[8]  W. Drugan,et al.  Theory of plasticity , 1987 .

[9]  Yun-Jae Kim,et al.  Compendium of yield load solutions for strength mis-matched DE(T), SE(B) and C(T) specimens , 2001 .

[10]  D. M. Parks,et al.  Advances in Characterization of Elastic-Plastic Crack-Tip Fields , 1992 .

[11]  Robert A. Ainsworth,et al.  Simplified J-estimations based on the Engineering Treatment Model for homogeneous and mismatched structures , 2001 .

[12]  Yun-Jae Kim,et al.  Mismatch effect on plastic yield loads in idealised weldments: II. Heat affected zone cracks , 2001 .

[13]  John D. Landes,et al.  The load separation criterion and methodology in ductile fracture mechanics , 1991 .

[14]  B. Moran,et al.  A general treatment of crack tip contour integrals , 1987 .

[15]  Robert A. Ainsworth,et al.  Assessment of the integrity of structures containing defects , 1987 .

[16]  H. W. Kerr.  A review of factors affecting toughness in welded steels , 1976 .

[17]  C. F. Shih,et al.  Elastic-Plastic Analysis of Cracks on Bimaterial Interfaces: Part II—Structure of Small-Scale Yielding Fields , 1989 .

[18]  J. Hutchinson.  Fundamentals of the Phenomenological Theory of Nonlinear Fracture Mechanics , 1983 .

[19]  Y-Y Wang,et al.  PAPER 28 – The limits of applicability of J and CTOD estimation procedures for shallow-cracked SENB specimens , 1993 .

[20]  Robert H. Dodds,et al.  Numerical investigation of 3-D constraint effects on brittle fracture in SE(B) and C(T) specimens , 1996 .

[21]  C. Turner,et al.  Method for Laboratory Determination of J c , 1976 .

[22]  Uwe Zerbst,et al.  Basic principles of analytical flaw assessment methods , 2000 .

[23]  Yun-Jae Kim,et al.  Plastic η factor solutions of homogeneous and bi‐material SE(T) specimens for toughness and creep crack growth testing , 2001 .