Analysis on the Dynamic Wave Attenuation Properties of Metaconcrete Considering a Quasi-Random Arrangement of Inclusions

Deborah Briccola,Anna Pandolfi

doi:10.3389/fmats.2020.615189

Abstract

The mitigation properties of metaconcrete cast with two types of resonant inclusions are assessed through wave transmission tests. Three cylindric metaconcrete specimens of regular size (20 cm height, 10 cm diameter), containing an equal number of different type of inclusions disposed in a semi-regular lattice, are tested in the longitudinal direction within the sonic range of frequencies. Inclusions, bi-material spheres consisting of a heavy core coated with a soft material, are characterized by a resonant behavior, evaluated numerically with a finite element modal analysis of a unit metaconcrete cell. Each metaconcrete specimen contains six layers consisting of six engineered aggregates of different type. Inclusions are disposed by rotating each layer with respect to the adjacent ones, as so as to create a pseudo-random arrangement. Specimens are excited by a sinusoidal signal of linearly growing frequency, sweeping a range centered at the translational eigenfrequency of the resonant inclusion. A standard plain concrete specimen is used as reference to define a transmissibility coefficient, that facilitates the quantification of the attenuation properties. With respect to plain concrete, all metaconcrete specimens show a marked (up to 80–90%) attenuation of the transmitted signal in proximity of the numerically estimated eigenfrequency of the inclusion. The intensity of the attenuation is weakly dependent on the type of the inclusion, while the frequency where the attenuation is observed depends markedly on the inclusion type. As a very positive quality in the view of practical applications, experimental results confirm that the attenuation effectiveness of metaconcrete is not related to the ordered microstructural arrangement.

Highlights

Metaconcrete is a relatively new type of concrete showing an enhanced dynamic behavior due to bimaterial spherical inclusions, made of a heavy metal core coated with a compliant polymeric layer
Metaconcrete in a Quasi-Random Arrangement shown in dynamic conditions, metaconcrete is regarded as a mechanical metamaterial, i.e., a locally resonant phononic crystal which exhibits different wave attenuation mechanisms depending on the frequency of the incoming wave
This study reports the findings of an experimental campaign carried out to assess the performance of metaconcrete and to highlight potential advantages deriving from the mixing of nonhomogenous engineered aggregates

Summary

Introduction

Metaconcrete is a relatively new type of concrete showing an enhanced dynamic behavior due to bimaterial spherical inclusions, made of a heavy metal core coated with a compliant polymeric layer. Metaconcrete in a Quasi-Random Arrangement shown in dynamic conditions, metaconcrete is regarded as a mechanical metamaterial, i.e., a locally resonant phononic crystal which exhibits different wave attenuation mechanisms depending on the frequency of the incoming wave. Phononic crystals often make use of Bragg-type band gaps Goffaux and Sánchez-Dehesa (2003); Hirsekorn (2004); Wang et al (2004c), where the periodicity of the structure induces vibration reduction within the material. In order to induce Bragg gaps in the low frequency range, the internal structure must be arranged in a spatial period of similar size to the wavelength of the incoming wave

Methods

Results

Conclusion