Abstract:
Pressure vessels used in industries usually incorporate openings in the main shell that
causes local stress concentration around the opening which in turn reduces the
pressure carrying capacity of the vessel. Therefore the aim of the present work is to
investigate the stress concentration factor and also the stress distribution around the
elliptical radial and offset holes having blended features at the intersection using
finite element method. Two different orientations of the cross holes are investigated,
one with the major axis of the hole along the longitudinal axis of the cylinder and
another along the circumferential direction of the cylinder A finite element package
ANSYS is used for the present computation. The cylindrical pressure vessels of
different ratios of outer to inner diameter are analyzed using three dimensional solid
isoparametric finite elements. After imposing boundary conditions and loading the
vessel with internal pressure, the stress concentration factors (SCF) are obtained for
some noticeable configurations of cross hole and cylinder. The comparison of
principal and von Mises SCFs between equivalent circular (obtained by Hamilton et
al. [11]) and elliptical radial cross holes show that elliptical cross holes reduce the
SCFs around 30% and 28% respectively compared to the circular ones. Elliptical
holes of circumferential orientation show about 55% reduction in SCF values than
the longitudinal orientation, thus establishing that the circumferential orientation of
the hole must be preferred over the longitudinal orientation. Again, the smaller offset
cross holes provide a maximum reduction in principal and von Mises SCF values
around 15% ad 9% respectively in comparison with the radial cross holes; thus
making offset cross holes a better proposition than the radial ones.
