[Paper Review] Tailoring Structure-borne Sound Through Bandgap Engineering in Phononic Crystals and Metamaterials: A Comprehensive Review

Mourad Oudich, Nikhil JRK Gerard+2 more|arXiv (Cornell University)|Jul 12, 2022

Acoustic Wave Phenomena Research4 citations

TL;DR

This comprehensive review explores bandgap engineering in phononic crystals and elastic metamaterials to control structure-borne sound, leveraging periodic microstructures and topological design for wave manipulation. It demonstrates how tailored bandgaps enable vibration isolation, waveguiding, and energy confinement, with recent advances in 3D architected materials and topological phononics enabling robust, multifunctional acoustic control.

ABSTRACT

In solid state physics, a bandgap (BG) refers to a range of energies where no electronic states can exist. This concept was extended to classical waves, spawning the entire fields of photonic and phononic crystals where BGs are frequency (or wavelength) intervals where wave propagation is prohibited. For elastic waves, BGs are found in periodically alternating mechanical properties (i.e., stiffness and density). This gives birth to phononic crystals and later elastic metamaterials that have enabled unprecedented functionalities for a wide range of applications. Planar metamaterials are built for vibration shielding, while a myriad of works focus on integrating phononic crystals in microsystems for filtering, waveguiding, and dynamical strain energy confinement in optomechanical systems. Furthermore, the past decade has witnessed the rise of topological insulators, which leads to the creation of elastodynamic analogs of topological insulators for robust manipulation of mechanical waves. Meanwhile, additive manufacturing has enabled the realization of 3D architected elastic metamaterials, which extends their functionalities. This review aims to comprehensively delineate the rich physical background and the state-of-the art in elastic metamaterials and phononic crystals that possess engineered BGs for different functionalities and applications, and to provide a roadmap for future directions of these manmade materials.

Motivation & Objective

• To provide a comprehensive overview of phononic crystals and elastic metamaterials engineered with bandgaps for controlling elastic wave propagation.
• To analyze the physical principles behind bandgap formation in periodic and aperiodic elastic microstructures.
• To highlight recent advances in 3D architected metamaterials and topological phononic systems for robust wave control.
• To map current applications in vibration isolation, sensing, and optomechanical systems using bandgap-engineered materials.
• To outline future research directions for next-generation acoustic and mechanical metamaterials with enhanced functionality and scalability.

Proposed method

• Systematic review of theoretical and experimental advances in phononic crystals and elastic metamaterials with engineered bandgaps.
• Analysis of bandgap mechanisms based on Bragg scattering and local resonance in periodic and non-periodic microarchitectures.
• Incorporation of topological principles to design robust, defect-insensitive waveguides and edge states in elastic systems.
• Evaluation of additive manufacturing techniques enabling complex 3D architected metamaterials with tailored dynamic responses.
• Integration of bandgap concepts into planar and microscale devices for applications in vibration control and energy confinement.
• Synthesis of state-of-the-art results across multiple application domains, including optomechanics and structural acoustics.

Experimental results

Research questions

• RQ1 How can periodic and aperiodic microstructures be designed to create wide and robust bandgaps for elastic waves?
• RQ2 What role do topological invariants play in enabling robust edge states and backscattering-immune wave propagation in elastic systems?
• RQ3 How do additive manufacturing techniques enable the realization of 3D architected metamaterials with complex bandgap functionalities?
• RQ4 In what ways can bandgap engineering enhance vibration isolation and energy confinement in microsystems and optomechanical devices?
• RQ5 What are the key challenges and future opportunities in scaling and integrating bandgap-engineered materials into practical engineering applications?

Key findings

• Bandgap engineering in phononic crystals and metamaterials enables complete suppression of elastic wave propagation within specific frequency ranges.
• Topological phononic systems demonstrate robust wave transport along edges, even in the presence of structural defects or disorder.
• 3D architected metamaterials fabricated via additive manufacturing achieve unprecedented control over dynamic stiffness and mass distribution for tailored bandgaps.
• Planar and microscale phononic devices enable effective vibration shielding and strain energy confinement in optomechanical systems.
• The integration of local resonance and Bragg scattering mechanisms allows for the design of narrow or wide bandgaps depending on application needs.
• Recent advances demonstrate the feasibility of multifunctional, reconfigurable, and tunable bandgap materials for adaptive acoustic control.