Evaluating the stresses of a stepped unrounded D-ring under uniform squeeze rate and internal pressure by photoelastic experimental hybrid method

The stresses that develop in a stepped unrounded D-ring loaded with internal pressures at a 20% squeeze rate are analyzed using the photoelastic experimental hybrid method. The analysis demonstrated that the contact stresses on both the upper and front sides of the Dring increased as the applied internal pressure increased, with the magnitudes of σX/pi and σY/pi being considerably higher than those of τXY/pi. Moreover, as applied internal pressure increased, the semi-circular portion of the D-ring moved to fill the space ahead of the step before contacting the restraining wall of the front side. The order of magnitude of stresses in region 1 of the front side of the D-ring was lower than those in region 2. At an internal pressure of 3.92 MPa, the contact stresses on the upper side decreased before increasing again at points away from the region of extrusion. The study further showed that a sharp corner in the geometry of the D-ring does not contribute to the generation of detrimental stresses that may lead to failure of the D-ring before extrusion.