Numerical investigations of crack-tip constraint parameters in two-dimensional geometries

In this study, detailed finite element analyses have been carried out on co nventional laboratory specimens such as Centred Cracked Panel (CCP), Three Point Bend Bar (TPBB) and Compact Tension (CT) specimens to study the chara cteristics of crack-tip constraint parameters, Q and h. It is observed that the loss of constraint is gradual with increasing deformation for CCP, irr espective of crack depth and shallow cracked TPBB and CT geometries. Conver sely, deeply cracked TPBB and CT geometries maintain high constraint to fai rly high deformation levels. This paper also addresses the nature of crack- tip constraint conditions in axi-symmetric circumferentially flawed pipe (C FP). Two loading configurations are analysed: (a) CFP under axial pull only ; and (b) CFP under internal pressure with associated crack-face pressure a nd axial pull. It is found that the axi-symmetric CFP under internal pressu re exhibits lower constraint than those under pure axial pull. The radial c ompressive stresses resulting from internal pressure leads to stress biaxia lity, which reduces the constraint. (C) 2000 Elsevier Science Ltd. All righ ts reserved.