Buckling of Sharp Knuckle Torispheres Under External Pressure

The effect of knuckle size and length of the cylindrical flange on the buckling strength of externally pressurised torispheres with a sharp knuckle is examined numerically. Both elastic and elastic-perfectly plastic modelling is used. It is illustrated how sensitivity of the load-carrying capacity to the boundary conditions can be removed by the adoption of a large enough knuckle or a cylindrical flange of appropriate length.

Experimental results available for the sharp knuckle domes are collected and 10 new tests are carried out on machined steel domes. Two tests on spun torispheres are also included. The tests demonstrate that the safety margin as used for externally pressurised hemispheres and deep torispheres is inadequate for sharp knuckle torispheres with a 6% knuckle.