Design and Additive Manufacturing of 3D Phononic Band Gap Structures Based on Gradient Based Optimization

Area of Science:

• Acoustics
• Materials Science
• Computational Mechanics

Background:

• Phononic band gaps are crucial for controlling wave propagation.
• Designing structures with maximized band gaps is an ongoing challenge.
• Topology optimization offers a powerful tool for material design.

Purpose of the Study:

• To develop a novel gradient-based approach for maximizing phononic band gaps.
• To design and fabricate cellular structures with significant band gaps.
• To explore applications in noise isolation.

Main Methods:

• A geometry projection method combining parametric shape and density-based topology optimization.
• Numerical simulations to determine band gap properties.
• Fabrication of 3D cellular metal structures using selective electron beam melting.
• Experimental verification of phononic band gaps through frequency response diagrams.

Main Results:

• Achieved relative and normalized band gaps exceeding 8 and 1.6 in 2D.
• Identified minimal strut size as a key controlling parameter for band gaps and stiffness.
• Successfully fabricated 3D structures with experimentally verified band gaps.
• Demonstrated band gaps extending into the audible frequency range.

Conclusions:

• The proposed gradient-based method is effective for maximizing phononic band gaps.
• The designed cellular structures show promise for noise isolation applications.
• Experimental validation confirms the numerical predictions, highlighting the practical applicability of the approach.