Study on buckling of convex fillet welded joint

In the production of spherical vessels by using single-curvature polyhedron hydrobulging technology, one of the difficulties to be overcome is buckling of a convex fillet welded joint, which can make a polyhedron fracture along the fillet welded joint during hydrobulging, quality of the spherical vessel bulged from the polyhedron bad. In order to find measures to solve the problem, this paper studies the buckling mechanism of a convex fillet welded joint. It shows that the direct reason for buckling is the action of compressive stress along the tangential direction of the convex fillet welded joint, and the height of a buckle increases with the inside pressure of a bulged polyhedron during the bulging process after buckling occurs. Avoiding a convex fillet welded joint forming an enclosed ring or approximately enclosed ring in a section and outside the constant-area sphere of the polyhedron or increasing dihedral angle of cover fittet welded joints can decrease the compressive stress along the tangential direction of the convex fillet welded joint. So the measures can prevent buckling from occurring or decrease height of a buckle.