Stress analysis of a stepped rounded D‐ring with a ratio of H1/H2 = 3.0 under uniform squeeze rate and internal pressure by photoelastic experimental hybrid method

Stresses occurring in a stepped rounded D‐ring designed to have a ratio of H₁/H₂ = 3.0 and compressed to 20% squeeze and pressurized with internal pressures of 0 MPa, 0.98 MPa, 1.96 MPa, 3.92 MPa, 4.9 MPa and 5.89 MPa are analyzed using photoelastic experimental hybrid method. It was observed that when a pressure of 0 MPa and 20% compression are applied, the photoelastic isochromatic fringes of the stepped rounded D‐ring with a ratio of H₁/H₂ = 3.0 were almost symmetrical. However, as the applied internal pressure increased, the circular portion of the D‐ring moved over the step on the front side along the points 1_r–2_r towards the restraining wall of the front side of the groove. During the motion of the circular portion, the space between the restraining wall and the step on the front side was slowly filled; but unlike the D‐ring with a ratio of H₁/H₂ = 1.0 where complete filling occurred earlier before extrusion, complete filling of this space delayed until the portion of the D‐ring near the extrusion gap extruded. It was further noted that an internal pressure of up to 5.89 MPa was required to initiate extrusion in the D‐ring with a ratio of H₁/H₂ = 3.0.     

Investigating the performance of square ring under uniform squeeze rate and internal pressure

Transportation and controlling fluid flow under high pressures in pumps, valves, boilers and heat exchangers is a common exercise in the industries. The main challenge, however that has confronted designers and manufacturers of pumps and valves along with those responsible for the maintenance and upkeep of such types of machinery is managing leakages at the positions where the seals are used. One fundamental feature of seal packing is the ability of the seal to ′flow′ into the groove spaces and effectively block fluid from passing through them. The square ring has shown good ‘flow’ behavior in addition to offering low contact stresses. This research seeks to investigate the performance of the square ring. The Hertz contact theory and photoelastic experimental hybrid method are used in the study of the performance of the square ring under a squeeze rate of 20 % and varying internal pressure. It was observed that while increasing the applied internal pressure, the deformation length and angle increased due to the high stresses produced by the applied pressure. Additionally, was initiated at an internal pressure of 0.98 MPa.     

Use of weight functions and photoelastic experimental hybrid method to study the contact problem

The contact problem involving flat punches has been the subject of many investigations mainly due to the crucial role it plays in many engineering applications. The contact problem has however, been widely approached from a theoretical point of view and there is a lack of experimental verifications due to the limited number of laboratory techniques capable of supplying detailed information about contact parameters. In order to gain an understanding of such problems, this study uses an experimental approach to investigate the stresses arising from photoelastic models when compressed against each other using Riemann‐Hilbert's weight functions and photoelastic experimental hybrid method. The study shows that this approach is effective in determining the magnitudes of contact stresses as well as interior stresses which up to date have been scarcely investigated. It is further shown that high stresses exist when a photoelastic model with a sharp corner is pressed against straight surface of the bottom half space and by introducing fillet radii at the sharp corners, significant stress reductions of up to 62.66% is observed.