Maximum shear stress theory for the failure of a material at the elastic limit, is known A. Guest’s or Trecas’ theory B. St. Venant’s theory C. Rankine’s theory D. Haig’s theory

The correct answer is A. Guest’s or Trecas’ theory.

Guest’s or Trecas’ theory is a failure theory that states that a material will fail when the maximum shear stress reaches a critical value. This theory is based on the assumption that the material is isotropic and homogeneous.

St. Venant’s theory is a failure theory that states that a material will fail when the maximum principal stress reaches a critical value. This theory is based on the assumption that the material is isotropic and homogeneous.

Rankine’s theory is a failure theory that states that a material will fail when the maximum principal stress or the minimum principal stress reaches a critical value. This theory is based on the assumption that the material is isotropic and homogeneous.

Haig’s theory is a failure theory that states that a material will fail when the maximum shear stress or the maximum principal stress reaches a critical value. This theory is based on the assumption that the material is isotropic and homogeneous.

Guest’s or Trecas’ theory is the most conservative of the four theories, meaning that it predicts that the material will fail at the lowest stress level. St. Venant’s theory is the least conservative of the four theories, meaning that it predicts that the material will fail at the highest stress level. Rankine’s theory is intermediate between Guest’s or Trecas’ theory and St. Venant’s theory. Haig’s theory is similar to Guest’s or Trecas’ theory, but it also takes into account the effect of the intermediate principal stress.