Creating a Robust Design requires that the operating conditions of each component of the design are carefully measured and compared with its Safe Operating, a task commonly referred to as stress analysis. In this paper we analyze the relationship between the component stress and the Safe Operating Area. We summarize the requirements of describing the Safe Operating Areas and propose how these requirements can be used to model the concept with two hardware description languages: MAST® and VHDL-AMS. A circuit example is given.