Prediction of Torsional Strength of Tubes

Abstract

A simplified analysis technique has been developed to predict torsional strength of tubes or shafts including plastic buckling limits and effects of plastic redistribution through the tube wall. Buckling predictions employ well-known formulas and concepts, but are combined in a unique procedure which provides improved accuracy over present known techniques. It was concluded that Batdorf’s equation, previously considered applicable only to relatively short tubes, is also applicable even to long slender tubes when wall stress redistribution effects are included. It was further concluded that Gerard’s recommendations for plasticity reduction factor were very accurate when obtained from compression stress-strain curves through application of the maximum shear stress theory in plasticity. Experimental verification of torsional strength prediction methods is needed for alloys other than aluminum, especially at elevated temperatures.