A thin-walled cylindrical tube made of 7075-T6 aluminum has a wall thickness of 2.5 mm and a diameter at mid-thickness of 50 mm. An axial load of 60 kN torsion is applied along with a torque of 1.0 kN·m. What is the safety factor against yielding? E = 71 GPa 0.2% yield strength, σy = 469 MPa Ultimate strength, σ = 578 MPa Elongation 100εf = 11