Studying Of Engineering Treatment Method Of Assessing The Integrity And Designing Of Auxiliary System Of Welded Structures Containing Defects

In order to study the influence of inheterogeneity of weld joints on the assessment methods of welded structures, by using the finite element method, the J-integral single parameter and the incompleteness of the HRR field, which is used to describ the crack tip stress-strain fields of welded joint on the condition of different stress state has been carefully investigated. The result show that it is incorrect to analyzing the mechanical inheterogeneity of welded joints with the fracture mechanics concept which has been used before. On the plane strain condition, considering the J-integral single parameter can not show the nature of the crack tip stress-strain fields of welded joint completely, the Q parameter of stress-triaxiality is used and the double-parameter J~Q failure assessment curve of welded joints containing defect has been first building in this paper. Forthermore, by the finite element method, the effect rules of welded joints under different geometrical dimensions and mis-matched materials on the J~Q failure assessment curves are analyzed. Considering the engineering treatment method of various factors in the double-paiameter J~O failure assessment curve of welded joints and the measurement and computation, the various critical parameters have been systematically studied. As a result, an evaluation method, which is rather complete and easy in use for the practical engineering for the integrity of welded structures is obtained.Fracture toughness and its measurement technique is another important aspect for the defect assessment of welded structures. The load-displacement curves of welded joints under different geometrical dimensions and mismatched strength on the condition of plane strain are discussed by finite element method. And more, the fracture properties of each stress-strain condition of mismatched welded joints are analyzed in the use of the compliance-changing-rate method. In the end, the engineering treatment method of the fracture factors and toughness of welded joints is realized to using engineering practices.Finally, an auxiliary program, which can be used to assess the integrity of welded-structure containing defects, is developed by utilizing the Visual C++ 6.0 in this paper.