Cement-based mechanical metamaterials with spiral resonators for vibration control
Koichi Imagawa, Motohiro Ohno, Yoichiro Koga, Tetsuya Ishida
Abstract
ABSTRACT This paper presents a single-phase cement-based mechanical metamaterial for vibration control. The unit cell consists of a cement-based matrix with tailored spiral slits, functioning as an embedded spring-mass system. The local resonance of the spiral resonators generates a band gap within a specific frequency range, in which input vibration energy is effectively absorbed. Both experimental and analytical investigations were conducted to demonstrate the feasibility of this cement-based metamaterial. First, the frequency response under sinusoidal excitation was evaluated using finite element analysis. The simulation results indicated that a metamaterial plate consisting of three unit cells exhibits a distinct band gap ranging from 46 Hz to 62 Hz. To validate this unique behavior, specimens were prepared using fiber reinforced cement mortar, and their transmissibility was measured by sine sweep testing. The experimental results confirmed a band gap ranging from 21 Hz to 50 Hz. Furthermore, significant anti-resonant vibration in the spiral resonators was observed during testing. Following this feasibility study, strategies for adjusting the band gap range by tailoring the internal structure were explored. Analytical modeling and numerical simulations suggest that tailoring the unit cell design alone involves a trade-off between achieving a low-frequency band gap and widening the band gap width. However, by employing different unit cell designs and optimizing their arrangement within the structure, it is possible to widen the band gap while maintaining its position. Such non-periodic metamaterial designs offer greater flexibility for tuning band gaps, enabling more versatile applications.