[Paper Review] Seismic auxetic metamaterials as novel earthquake protections

Bogdan Ungureanu, Younes Achaoui+3 more|arXiv (Cornell University)|Oct 29, 2015

Cellular and Composite Structures45 references3 citations

TL;DR

This paper proposes a novel class of seismic auxetic metamaterials that create artificial band gaps in soil to block seismic waves. By engineering negative elastic parameters like Poisson’s ratio and shear modulus, these meter-scale metamaterials suppress wave propagation at seismic frequencies, offering a new mechanism for earthquake protection through spectral band gap engineering.

ABSTRACT

We propose that wave propagation through a class of elastodynamic metamaterials opens unprecedented avenues in seismic wave protection based on spectral properties of auxetic metamaterials. The elastic parameters of these metamaterials, like the Poisson ratio { u}, bulk modulus B, shear modulus G, or the mass density {ho}0, are known to exhibit negative values in elastic stop bands. We show here that the propagation of seismic waves with different frequencies can be influenced by a meter scale version of auxetic metamaterials buried in the soil. More precisely, we numerically examine and illustrate the markedly different behaviors between the propagation of seismic waves through a continuum isotropic elastic medium (concrete) and our seismic auxetic metamaterials utilized here like a foundation of the building one would like to protect. This novel class of seismic metamaterials opens band gaps at frequencies compatible with seismic waves when they are designed appropriately, what makes them interesting candidates for seismic isolation structures.

Motivation & Objective

• To explore the potential of auxetic metamaterials in mitigating seismic wave propagation through soil.
• To address the challenge of protecting structures from destructive seismic waves by designing materials with tailored elastic properties.
• To demonstrate that engineered band gaps in auxetic metamaterials can effectively isolate buildings from seismic frequencies.
• To compare wave behavior in conventional concrete with that in auxetic metamaterials to highlight performance advantages.

Proposed method

• Numerical simulation of wave propagation through a continuum isotropic elastic medium (concrete) as a baseline for comparison.
• Design of a meter-scale auxetic metamaterial with tunable elastic parameters, including negative Poisson’s ratio and shear modulus.
• Use of spectral analysis to identify elastic stop bands where wave propagation is suppressed.
• Modeling of bulk modulus and mass density to achieve negative effective parameters in specific frequency ranges.
• Implementation of band gap engineering principles to create frequency-specific wave attenuation in soil.
• Comparison of wave transmission and reflection characteristics between conventional concrete and auxetic metamaterials.

Experimental results

Research questions

• RQ1 Can auxetic metamaterials with engineered elastic parameters create band gaps that suppress seismic wave propagation?
• RQ2 How do the spectral properties of auxetic metamaterials influence wave transmission in soil compared to conventional materials?
• RQ3 What role do negative elastic parameters—such as Poisson’s ratio and shear modulus—play in forming effective seismic band gaps?
• RQ4 To what extent can a meter-scale auxetic metamaterial embedded in soil provide seismic isolation for structures?
• RQ5 How do the wave behaviors in auxetic metamaterials differ from those in standard concrete under seismic excitation?

Key findings

• Auxetic metamaterials exhibit negative elastic parameters such as Poisson’s ratio and shear modulus within specific frequency bands, enabling wave suppression.
• The metamaterials create artificial band gaps at frequencies compatible with seismic waves, effectively blocking wave transmission.
• Numerical results show significantly reduced wave propagation through the auxetic metamaterial compared to conventional concrete.
• The band gap formation is directly linked to the engineered spectral properties of the metamaterial, particularly negative effective moduli.
• The proposed design enables seismic wave isolation at the scale of building foundations using a meter-scale metamaterial embedded in soil.
• The metamaterial’s performance is attributed to its unique combination of negative elastic parameters and tailored mass density.