Maximum principal stress theory for the failure of a material at elastic point, is known A. Guest’s or Trecas’ theory B. St. Venant’s theory C. Rankine’s theory D. Von Mises’ theory

The correct answer is: D. Von Mises’ theory

Von Mises’ theory is a failure theory that states that a material will fail when the equivalent stress reaches a critical value. The equivalent stress is a measure of the combined effects of all the stresses acting on a material.

Guest’s or Trecas’ theory is a failure theory that states that a material will fail when the maximum principal stress reaches a critical value. The maximum principal stress is the largest of the three principal stresses acting on a material.

St. Venant’s theory is a failure theory that states that a material will fail when the maximum shear stress reaches a critical value. The maximum shear stress is the largest of the two shear stresses acting on a material.

Rankine’s theory is a failure theory that states that a material will fail when the octahedral shear stress reaches a critical value. The octahedral shear stress is a measure of the combined effects of all the shear stresses acting on a material.

Von Mises’ theory is the most widely used failure theory because it is relatively simple to use and it gives good results for a wide range of materials.