J-R CURVES FROM CIRCUMFERENTIALLY THROUGH-WALL-CRACKED PIPE TESTS SUBJECTED TO COMBINED BENDING AND TENSION - PART I - THEORY AND NUMERICAL-SIMULATION

One of the key aspects in leak-before-break analyses is to predict the maximum load-carrying capacity of a circumferentially cracked pipe. S uch analyses require the fracture resistance of the material using the J-integral parameter, typically using small-scale laboratory specimen s, such as compact tension, C(T), or three-point bend specimens, To ev aluate the similitude between the laboratory specimens and a circumfer entially through-wall-cracked pipe, the toughness can be evaluated dir ectly from the pipe using an analysis typically called an eta-factor a pproach. The fracture resistance from the pipe tests can then be compa red to laboratory specimen toughness values to assess similitude issue s Additionally: several analysis methods (i.e., LBB.NRC, LBB.ENG, LBB. GE, etc.) that predict maximum load capability of through-wall-cracked pipes have eta-factor analyses embedded in them. Hence, the evaluatio n of the J-R curve accuracy or consistency with small-scale specimens is a verification of one step in such predictive analyses. This paper presents extensions to the earlier eta-factor solutions for circumfere ntially through-wall-cracked pipes where the previous analyses were fo r cracks in pipes under either pure bending or pure tension, The impro vements investigated account for loading under combined bending and te nsion due to internal pressure, The application of these methods to fu ll-scale pipe tests is presented in part II (Miura and Wilkowski, 1998 ) of this paper.