Ductile tearing of cryogenic valve components

Abstract

The paper reports the result of an experimental investigation on the torsional failure mechanics of the rotating components of a cryogenic valve. The rotating assembly is composed of an AISI 316L shaft connected by two cold drawn pins of the same alloy to a disc made of cast CF3M stainless steel. The shaft presents a notch, in the region lying outside the pressure boundary, which has the scope of reducing the maximum torque that this can withstand in case of torsional overload, making so that the region within the pressure boundary is not damaged. Different notch designs are tested to failure in pure torsion in order to estimate the ideal geometry to guarantee this condition to be met. The results have then been used for the calibration of a shear damage material model, useful to explore different designs. Also, the shaft-disc connection has been tested, presenting a resistance superior to that of the shaft. Such condition is representative of an ideal design for safe operation.