The Compressive Strength of Short Circular Tubes

DOUGLAS and Carmichael (REF. 1) have suggested formulae relating the compressive strength at failure of short circular tubes with their ultimate tensile strength and thickness radius ratio. Robertson (REF. 2) has tested Southwell's theoretical formula for thin-walled circular tubes. Further tests on medium and thick tubes by the author have indicated that the new data and that of Douglas and Carmichael can best be correlated by the inclusion of yet another property of the tube material. The representation, within the specified limits, is extremely good and taken in conjunction with existing data on thin tubes, the strength of tubes under this loading condition can be predicted over a wide range of material properties and geometrical dimensions. Also included in the author's data are extensometer tests over the elastic and early plastic regions of compression. A comparison of the resultant proof stresses with those of control tensile tests verifies their equality except under certain interesting conditions.