Development of a Reliable Failure Assessment Diagram by Persian Curve

A conventional tool for assessing the integrity of structures containing flaws is, the Failure Assessment Diagram (FAD). The (FAD) is a combination of the limiting conditions for load, the flaw size and fracture toughness or yielding stress. The abscissa is the load ratio and the ordinate is the toughness ratio. The toughness ratio is defined as a function of the load ratio. Three options are available for this function. The (FAD) drive is based on parameters of fracture mechanics. Classical fracture mechanics contains epistemic uncertainty and is unreliable. As a result, the state of the art for the (FAD) is also unreliable. The present authors' team, conducted an extensive investigation in the past two decades, which led to the birth of the change of state philosophy that is digested in the Persian Curve. In the present paper the Persian Curve is used for development of a reliable (FAD). The validity of the work is verified via concise mathematical logics and comparison of the results with those of the others.