Single-curvature polyhedron hydrobulging technology for manufacturing
spherical vessels can be adopted to build spherical pressure vessels w
ithout using heavy presses and large-size dies. It has been proved tha
t the cost and production time is greatly reduced. When using the tech
nology, one of the difficulties to be overcome is buckling of a straig
ht fillet welded joint that can increase the pressure under which the
polyhedron is bulged into a spherical vessel and makes the straight fi
llet welded joint split along the tangential direction of the fillet w
elded joint. This paper studies the buckling mechanism of a latitudina
l straight fillet welded joint of an orange polyhedron. The result sho
ws that the buckling process of a straight fillet welded joint can be
divided into three stages: (a) single-buckle stage; (b) multiple-buckl
e stage; (c) circularizing stage. A direct reason for buckling of a st
raight fillet welded joint is the action of unevenly distributed tensi
le stress perpendicular to the fillet welded joint. Avoiding serious g
eometry discontinuity on a polyhedron wall, adopting a polyhedron stru
cture with greater dihedral angles or increasing loading capability of
the polyhedron can decrease the height of buckles although using thes
e measures can not prevent buckles from emerging. (C) 1997 Elsevier Sc
ience Ltd.