Effect of Mechanical Property Mismatch on Failure Assessment Curve for Welded Joint With a Semi-Elliptical Crack

Abstract

Elastic-plastic finite element analysis was performed to study the welded joints with a semi-elliptical crack. This research includes the effects of crack depth, strength mismatch ratio, and weld width on the crack driving force J-integral and the constraint parameter A 2 at the crack tip. A two-parameter J-A 2 fracture criterion based on the present results of crack tip stress field in the welded joints was established. The corresponding failure assessment diagrams were investigated in detail, from which the reliability and safety margin of the welded structures were discussed.

Quantification of crack tip constraint effect based on the critical distance

“…The parameters Q and A 2 were widely applied in the quantification of in-plane crack tip constraints in flawed structures. [11][12][13] The two constraint parameters were also used to approximately quantify the three-dimensional crack front constraint by neglecting the difference in stress distribution along the throughthickness direction of specimens. [14][15][16] Referring to the derivation of the J-A 2 approach, Nikishkov, 17, 18 Nikishkov, and Matvienko 19 developed the J-A approach, which was mathematically equivalent to the J-A 2 approach.…”

“…To eliminate the effect of global bending stress on the stress fields ahead of the crack tip, the bending‐corrected J‐Q‐M 9 and J‐A 2 ‐M 10 approaches were developed to describe the stress fields for bending specimens under large‐scale yielding conditions. The parameters Q and A 2 were widely applied in the quantification of in‐plane crack tip constraints in flawed structures 11–13 . The two constraint parameters were also used to approximately quantify the three‐dimensional crack front constraint by neglecting the difference in stress distribution along the through‐thickness direction of specimens 14–16 .…”

Procedimento de avaliação de integridade estrutural de juntas soldadas circunferenciais em tubulações submarinas rígidas submetidas à flexão.

“…Diversos compêndios de carga limite utilizando ferramentas numéricas foram desenvolvidos, para uma vasta gama de geometrias e estruturas[57,66,67,68].O processo de soldagem é indispensável para fabricação de componentes na área de tubulações e vasos de pressão. Apesar de amplamente utilizada para promover a união localizada de metais, a soldagem é um procedimento que introduz níveis significativos de heterogeneidade na estrutura que, por sua vez, tornam o componente suscetível ao surgimento de trincas e aumentam a complexidade dos procedimentos de estimativa de força motriz, pois alteram os padrões de deformação na ponta da trinca e sua relação com o carregamento global aplicado.A heterogeneidade introduzida pela soldagem pode ser dividida em dois grupos: mecânica 1 e geométrica[69]. A heterogeneidade mecânica corresponde às diferenças entre as propriedades do material de solda e de base (tensão de escoamento e coeficiente de encruamento).…”