KK تعيين تحليلي ضرايب تمركز اتصالات لوله اي چند صفحه اي

Analytical Determination Of Stress Concentration Factors For KK Multiplanar Tubular Joints

Fatigue analysis is one of the most important case studies in marine structures design in which stress concentration factor is used as a parameter including the structural specifications. Codes and standards present different formula for determination of stress concentration factors at offshore structures joints that their accuracies and validations are not clear. This study is an attempt to create a 3-dimensional model, using finite element method and employ appropriate elements, as to discuss stress concentration factors. At current research, the finite element model of unplanned and multiplanar K joints, including the weld, was produced using ANSYS-5.4 general-purpose Finite element software and related stress concentration factors were compared. A simple and relatively accurate method is used to simulate the weld. It was shown that the common methods for determination of stress concentration factors of multiplanar joints, in which an equivalent planar approach is employed, are not economical. Comparing the results of numerical method and those of parametric equations, some suitable equations were derived and their validation range was discussed. With respect to parametric studies of K & KK joints, optimum geometrical dimensions for an economical design were determined. At the end, two equations for determination of stress concentration factors of K & KK joints were presented as research result.