Coupling the level set method and the topological gradient in structural optimization

A numerical coupling of two recent methods in shape and topology optimization of structures is proposed. On the one hand, the level set method, based on the shape derivative, is known to easily handle boundary propagation with topological changes. However, in practice it does not allow for the nucleation of new holes. On the other hand, the bubble or topological gradient method is precisely designed for introducing new holes in the optimization process. Therefore, the coupling of these two methods yields an efficient algorithm which can escape from local minima. It have a low CPU cost since it captures a shape on a fixed Eulerian mesh. The main advantage of our coupled algorithm is to make the resulting optimal design more independent of the initial guess.