In various engineering fields related to mechanical design, the use of important equipment mostly has the requirements of both lightweight design of support structure and harmful vibration control. But it is often difficult to be considered together.

Phononic crystal (PnC), as an artificial periodic composite structure, has a unique bandgap characteristic, which can prohibit the propagation of elastic waves in a specific frequency range, provide a new idea for the combination of lightweight design of support structure and harmful vibration control.

In a study published in International Journal of Mechanical Sciences, a research group led by ZHAO Haojiang from the Changchun Institute of Optics, Fine Mechanics and Physics (CIOMP) of the Chinese Academy of Sciences (CAS), combining the bandgap optimization of PnCs with the lightweight design of the support structure, proposed an integrated structure design method for vibration isolation and support.

Based on the improved NSGA-Ⅱ algorithm and finite element method, researchers established a set of calculation flow to realize the search iteration of available substructures and the solution of the corresponding objective functions. Taking a simple two-dimensional cantilever beam as an example, the feasibility of topology optimization design of vibration isolation and support integrated structure were verified. In the case, considering the comprehensive performance of vibration isolation and support, two optimization objective functions were proposed to reflect the overall support stiffness and relative bandgap width of the cantilever beam.

The innovation of this work is mainly concentrated in two points. The first and most important innovation is to integrate the macro mechanical performance design of the finite period support structure into the band gap topology design of its microstructure. Secondly, in order to realize the topology design of PnCs considering the requirements of macro structural stiffness and continuity, maze path-finding and other measures are integrated into the conventional NSGA-Ⅱ algorithm.

This research is expected to promote the practical progress of PnC vibration isolation and combine vibration isolators with lightweight support structures.