Q. If a shaft made from ductile material is subjected to combined bending and twisting moment, calculations based on which one of the following failure theories will give the most conservative value?
✅ Correct Answer: (D)
Maximum distortion energy theory
Explanation: When a shaft made from ductile material is subjected to combined bending and twisting moments, the failure criteria need to account for both normal and shear stresses. Among the given options, the Maximum distortion energy theory, also known as the Von Mises stress theory or Tresca-Maxwell theory, provides the most conservative value for failure prediction.