Analysis for interior stress in various curvature radiuses on D-ring seal using hybrid photoelastic experimental method

When the seal is suffered from defected damage, it initiates a little leakage and finally becomes the critical abnormal condition. Sealing ring has very small than neighbored other components, it has to be considered as the most important thing due to intensity of its function. Sealing rings are designed with many kinds of cross-sections: O-ring, Square-ring, D-ring, X-ring etc. according to its different usage. The cross-section of D-ring is included with cross-sections of O-ring and Square-ring partially, in a other word, D-ring has both advantages of O-ring and Square-ring. In order to reduce the stress concentration, D-ring should be prepared with curvature radius in both sides of the lower square corner. In this work, the analyses on the interior stresses, and the behavior of D-ring with various curvature radius under uniform squeeze rate 20 % and various internal pressures of 0~20 MPa were studied by using the stress frozen photoelastic experiment and the photoelastic experimental hybrid method. From this research, it was founded that the geometrically optimal condition for curvature radius of D-ring under uniform squeeze rate and various internal pressures is r/D = 0.3.