Study on the Clear Boundary Determination from Results of the Phase Field Design Method

This study proposes a systematic process to clarify the boundary of optimum shapes obtained from the phase field design method. Topology optimization generally suffers from unclear boundary definition due to the gray scale area. The phase field design method, one of topology optimization design methods, has benefits not only to avoid the re-initialization process in traditional level set method-based structural design but also to define high-resolution boundary compared with other topological design schemes. However, the diffusion region generated near boundaries of the resultant structure from the phase field design method still causes gray scale area. To clarify boundaries of the resultant optimal shape, the appropriate value of the diffusion coefficient is determined, and successive application of the adaptive mesh refinement is performed. The proposed process was applied to two numerical examples for MBB beam design and three-dimensional nano-antenna design and the validity of the process to define the clear structural boundary is confirmed.