Circular rings, stress

Samoiloff A., Investigation of Stress in Circular Rings, Petroleum Refiner, July 1947. 

Procedure 5-1 Stresses in Circular Rings, 256 Procedure 5-2 Design of Partial Ring Stiffeners, 265 Procedure 5-3 Attachment Parameters, 267... 

If the stresses are high enough, cracking occurs at blunt indenters but, in this case, the crack is initially circular (ring crack) but then extends into a cone geometry (Fig. 8.89). Experimentally, it is found that the load required to initiate a cone crack is given by... 

For cases where the ring beam has additional moment, tangential and/or radial loads (such as sloping columns) these additional horizontal loads may be calculated using ring redundants. See procedure on stresses in circular rings. 

Equations 9.24 and 9.25 establish the maximum applied force at the cone-to-cylinder junction. The critical buckling stress of a circular ring is... 

Stress-Strain Data. Tensile tests were made with an Instron tester at some seven crosshead speeds from 0.02 to 20 inches per minute at five or six temperatures from 30° to —46°C. The tests were made on rings cut with a special rotary cutter from the circular sheets of the elastomers. The dimensions of each ring were determined from the weights of the ring and the disc from its center, the thickness of the ring, accurately measured, and the density of the rubber. Typically, the outside and inside diameters were 1.45 and 1.25 inches, respectively, and the thickness was about 0.085 inch. The test procedure used is described elsewhere (11), and the cubic equation, eq 4 in ref. j 2, was used to compute the average strain in a ring from the crosshead displacement. 

Fig. 17 shows the Jenike shear cell in a schematic diagram a circular (internal diameter 95 mm), open-ended shear box is split horizontally, the base is immobile and the ring can slide freely in the horizontal direction. The normal stress, which is applied via the lid, is first used to consolidate the specimen and then to load it during test. 

The retaining ring material is not affected by stress corrosion. To ensure that the retaining rings are suffidently stiff to remain circular, a support ring is shrunk in the outer end of the retaining ring, free from the rotor shaft. 

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