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ISRO 2015 Mechanical Engineering Questions, Answers and Explanation

ISRO 2015 Mechanical Engineering Questions, Answers and Explanation

11. Which of the following is applied to brittle materials?
a) maximum principal stress theory
b) maximum principal strain theory
c) maximum strain energy theory
d) maximum shear stress theory

Answer
a) maximum principal stress theory

Explanation [Strength of Materials]
Ductile Materials - Planes of maximum shear exist in the material at 45o and the material begins to slide along these planes. Maximum shear stress theory/ Total strain energy theory can be used.
Brittle Materials - When the normal stress in the material reaches the ultimate stress the material fails suddenly by fracture. Maximum principal stress theory can be used.

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