Investigation of the relationship between the structural and material composition and band gap characteristics of periodic metal composite beams

Abstract

Vibration reduction strategies based on wave propagation phenomena, such as generating band gaps in periodic structures, are attracting attention in the field of mechanical engineering. This paper investigates how the structural and material compositions influence band gap characteristics (band gap frequencies and width) of composite beams of metallic materials with flat surfaces. The composite beams in this study are composed of the periodic structure of the "unit cell," and a unit cell consists of two different parts (called cells a and b). Numerical analysis to obtain a dispersion curve by applying the wave finite element method (WFEM) was first carried out to check band gap generation in the metallic composite beams. The relationship between structural characteristics (bending rigidity ratio, mass ratio, or length of the two parts of the unit cell) and the band gap characteristics was investigated numerically using the WFEM. Some composite beams with a band gap lower than 1 kHz with a broad frequency band were designed. Then, their frequency response characteristics were calculated using a commercial FEM software Ansys to confirm the vibration reduction (or suppression) effect in the specified frequency band. Actual metallic composite beams were created using a metal 3D printer, and excitation tests were conducted to verify the numerical results. As a result, band gap generation was demonstrated experimentally. Numerical investigations were also carried out to design composite beams of two different metals to have a wider band gap.

Keywords

• vibration of periodic structure
• vibration suppression
• band gap
• dispersion analysis
• frequency response analysis
• metal 3d printer