When a shaft carries combined bending and torsional stresses, a factor 𝛼 is introduced in the stress calculation because ___________.  (a) a deviation exists between theoretical and experimental...

When a shaft carries combined bending and torsional stresses, a factor 𝛼 is introduced in the stress calculation because ___________.

 (a) a deviation exists between theoretical and experimental results

 (b) the torsional shear stress maybe not a completely reversed stress

 (c) the bending stress maybe not a completely reversed stress

 (d) the shaft has stress concentration