Corrections for Membrane Strength in the Triaxial Test
Equations based on elastic thin cylindrical shell compression theory are developed for correcting stresses for membrane strength in a triaxial test. The corrections are expressed in terms of the unstretched dimensions, the diameter and thickness of the membrane, the axial and volumetric strain of the cylindrical membrane cavity referenced to its unstretched dimensions, together with E and v of the membrane rubber. The development specifically considers changes in membrane thickness as they occur during the straining process, and in particular its influence on the specification of E of the membrane. Direct experimental verification of the derived stress correction is provided in support of their validity.