Design of Functionally Graded Structures for Enhanced Thermal Behavior

Multi-material structures take advantage of beneficial properties of different materials to achieve an increased level of functionality. In an effort to reduce the weight of vehicle components such as brake disk rotors, which are generally made of cast iron, light materials such as aluminum alloys may be used. These materials, however, may lead to unacceptable temperature levels. Alternatively, functionally graded structures may offer a significant decrease in weight without altering thermal performance. The design of such structures is not trivial and is the focus of this paper. The optimization combines a transient heat transfer finite element code with a genetic algorithm. This approach offers the possibility of finding a global optimum in a discrete design space, although this advantage is balanced by high computational expenses due to many finite element analyses. The goal is to design a brake disk rotor for minimum weight and optimal thermal behavior using two different materials. Knowing that computational time can quickly become prohibitively high, strategies, such as finite element grouping to reduce the number of design variables and local mesh refinement, must be employed to efficiently solve the design problem. This paper discussed the strengths and weaknesses of the proposed design method.