Problem 6.3 (dimensioning of a shaft under torsion and bending): consider a cylindrical, solid transmission shaft working in torsion coupled with bending. the most loaded cross-section is subjected to a couple m having components mt , 0, mb along principal axes with mt denoting the torque component and mb the bending component; the magnitude of the couple is m = 10 kn · m. the allowable stress is σa = 50 mpa and an equivalent (von mises) stress is defined as σeq = √ σ2 + 4τ 2 where σ and τ respectively refer to the normal stress and shear stress acting on the cross-section. dimension the radius r of the shaft.