THEORY OF FAILURES - Introduction

THEORIES OF FAILURE 

     When a structural element has to be designed,then it is important to determine its strength and stability based on the elasticity,yielding and fracture.As a element alone , it is easy to determine its structural behavior in terms of simple stress and strain.But in reality, the structure cannot be analysed as a part since , load applied and its corresponding stress and strain behavior will be in complex form.Some of the theories were designed to predict failure pattern for simple loads were also declared to be feasible for complex loading also.But these theories used to predict failure pattern in complex loading , failed to provide proper results in practical conditions, hence they are termed as theories of failure.The following are the five theories of failure put forth by researchers.

1. Rankine's theory or Maximum Principal Stress theory.
2. Columb's theory or Maximum Shear stress theory.
3. St Venant's theory or Maximum Strain theory.
4. Beltrami and Haigh's theory or Maximum strain energy theory.
5. Von-Mises theory or Maximum Energy distortion theory.