Modelling and mesh generation of weld profile in tubular Y-joint

This paper describes a systematic method of modelling the weld thickness of a tubular Y joint. The intersection between the chord and the brace member s is defined precisely. This intersection curve will then be used to evalua te the dihedral angle gamma, which is the angle between the chord and the b race surfaces along the intersecting line. As the dihedral angle gamma is a n important parameter used to determine the weld thickness, its variation a long the intersection curve and its relationship with the weld thickness is investigated first. It is shown that the smoothness of the weld path may n ot always be maintained if the minimum weld thickness, as specified in the American Welding Society (AWS) Codes D1.1-96, is to be followed strictly. T hus in some cases, modification of the intersection curve is necessary in o rder to model the weld path along the joint. Two scale factors FOSouter and FOSinner for the outer and inner intersection curves, and two constants m and n are introduced and proposed in this study. They are used to control t he parameter k(TW), which in turn controls the minimum weld thickness T-W. Based on this model, an automatic mesh generator is developed to produce a well-graded finite element mesh. The stress concentration factors (SCFs) ar e shown to converge when the mesh is doubled and then tripled. Finally, som e tubular welded specimens are fabricated. and the outer weld profiles are measured physically. It is shown that scale factors FOSouter = 0.3, FOSinne r = 0.25 and constants m = 2.0, n = 0.4. are adequate to satisfy the requir ed minimum outer weld profile. Therefore, the proposed method to model the weld size is both consistent and accurate for any tubular Y-joints. (C) 200 1 Elsevier Science Ltd. All rights reserved.