Yield and flow behavior of initially anisotropic aluminum tube under multiaxial stresses

The yield and flow characteristics of an initially orthotropic material under multiaxial stresses are investigated. Experiments are conducted wherein an aluminum tube is loaded axially using a hydraulic-type multiaxial stress testing machine. A load cell with strain gages fixed to its surface is used to measure the axial load and torque. Results reveal that flow stress rises to a maximum value under a proportionally combined loading of axial load,internal pressure and torsion.