Combined `heat flow and strength' optimization of geometry: mechanical structures most resistant to thermal attack

This paper outlines a new direction for fundamental heat transfer: a multidisciplinary approach (combined heat transfer and strength of materials) in the conceptual design of structures that have two functions, mechanical strength and resistance (survival) in the presence of sudden thermal attack. The two functions are considered simultaneously, from the start of conceptual design. This is unlike traditional approaches, where structures are optimized for mechanical strength alone, or for thermal resistance alone. In the first part of the paper, the profile of a beam loaded in bending is optimized by maximizing the lifetime in the presence of sudden heating. The propagation of the heat wave through the beam causes softening, because of the gradual transition from elastic behavior to thermoplastic behavior. In the second part of the paper, the subject is a beam of concrete reinforced with steel bars. It is shown that the clash between the mechanical and thermal objectives of the beam generates the shape of the beam cross-section, and the position of the steel bars in the beam cross-section. The generation of optimal architecture for maximal global performance under global constraints in freely morphing systems is constructal design. On the background of the constructal architectures that have been developed so far, the present paper outlines the first steps toward the constructal design of multiobjective (multidisciplinary) architectures.