Mapping structural topology optimization problems to quantum annealing

Quantum computing (QC) is a rapidly growing technology in the field of computation that has garnered significant attention in recent years. This emerging technology has become particularly relevant due to the increasing complexity of optimization problems and their expanding search spaces. As a result, innovative solutions that can surpass the limitations of the current optimization paradigms executed on classic computers are becoming necessary. D-wave, a specialized quantum computer, presents a novel solution for addressing intricate optimization problems with remarkable speed advantages over traditional methods. However, a major hurdle in terms of utilizing the D-wave platform for topology optimization design is the conversion of an optimization problem into formulas that can be comprehended by a quantum annealing machine. This is because the D-wave platform is limited to solving quadratic unconstrained binary optimization problems or Ising model problems, making it necessary to find a way to adapt the task of interest to these specific types of optimization problems. This paper examines the current reality concerning the extremely limited availability of quantum computing resources. We focus on small-scale discrete structural topology optimization problems as a starting point and establish a mapping relationship between quantum bits and the cross-sectional area variables of truss elements. Utilizing this mapping, a quadratic unconstrained binary optimization model is developed with these variables. We propose a nested optimization process with dynamically adjusted cross-sectional areas, which enables the development of a quantum annealing approach for optimizing the topology of discrete variables. Our method is validated through numerical experiments, demonstrating its efficiency.