Discussion on symmetry of optimum topology design

Recent study by Rozvany discussed an important topic in structural topology optimization: non-uniqueness and symmetry. This paper demonstrates that for the frame topology optimization with frequency objective or frequency constraints, the topology optimum is not symmetric even when the geometry, material distribution and ground structure are symmetric. Two benchmark examples with fundamental frequency constraints support our view. Nonlinear and non-convex constraints are contributors to non-symmetric optimum solution for the class of topology optimization problems considered here.