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Gulzari, Muhammad
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Gulzari, Muhammad
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Now showing 1 - 7 of 7
- PublicationInverse design of a topological phononic beam with interface modesInspired by the idea of topological mechanics and geometric phase, the topological phononic beam governed by topological invariants has seen growing research interest due to generation of a topologically protected interface state that can be characterized by geometric Zak phase. The interface mode has maximum amount of wave energy concentration at the interface of topologically variant beams with minimal losses and decaying wave energy fields away from it. The present study has developed a deep learning based autoencoder (AE) to inversely design topological phononic beam with invariants. By applying the transfer matrix method, a rigorous analytical model is developed to solve the wave dispersion relation for longitudinal and bending elastic waves. By determining the phase of the reflected wave, the geometric Zak phase is determined. The developed analytical models are used for input data generation to train the AE. Upon successful training, the network prediction is validated by finite element numerical simulations and experimental test on the manufactured prototype. The developed AE successfully predicts the interface modes for the combination of topologically variant phononic beams. The study findings may provide a new perspective for the inverse design of metamaterial beam and plate structures in solid and computational mechanics. The work is a step towards deep learning networks suitable for the inverse design of phononic crystals and metamaterials enabling design optimization and performance enhancements.
13Scopus© Citations 10 - PublicationValley edge states with opposite chirality in temperature dependent acoustic media(IOP Publishing, 2024-05-31)
; ; ; ; The valley degree of freedom in phononic crystals and metamaterials holds immense promise for manipulating acoustic and elastic waves. However, the impact of acoustic medium properties on valley edge state frequencies and their robustness to one-way propagation in valley topological phononic crystals remains unexplored. While significant attention has been devoted to scatterer design embedded in honeycomb lattices within acoustic and elastic media to achieve valley edge states and topologically protected nontrivial bandgaps, the influence of variations in acoustic medium properties, such as wave velocity and density affected by environmental temperature, has been overlooked. In this study, we investigate the effect of valley edge states and topological phases exhibited by topological phononic lattices in a temperature-dependent acoustic medium. We observe that a decrease in wave velocity and density, influenced by changing environmental temperature, shifts the topological valley edge states to lower frequencies. Therefore, alongside phononic lattice design, it is crucial to consider the impact of acoustic medium properties on the practical application of acoustic topological insulators. This issue becomes particularly significant when a topological phononic crystal is placed in a wave medium that transitions from incompressible to compressible, where wave velocity and density are no longer constant. Our findings offer a novel perspective on investigating topological insulators in variable acoustic media affected by changing thermodynamic and fluid properties.13Scopus© Citations 1 - PublicationDesign and fabrication of 3D-printed composite metastructure with subwavelength and ultrawide bandgapsArchitected composite metastructures can exhibit a subwavelength ultrawide bandgap (BG) with prominent emerging applications in the structural vibration and noise control and, elastic wave manipulation. The present study implemented both forward and inverse design methods based on numerical simulations and machine learning (ML) methods, respectively to design and fabricate an architected composite metastructure exhibiting subwavelength and ultrawide BGs. The multilayer perceptron and radial basis function neural networks are developed for the inverse design of the composite metastructure and their accuracy and computation time are compared. The band structure revealed the presence of subwavelength and ultrawide BGs generated through local resonance and structural modes of the periodic composite lattice. Both in-plane and out-of-plane local resonant modes of the periodic lattice structure were responsible for inducing the BGs. The findings are confirmed by calculating numerical wave transmission curves and experiment tests on the fabricated supercell structures, utilizing 3D-printing technology. Both numerical and experimental results validate the ML prediction and the presence of subwavelength and ultrawide BG was observed. The design approach, research methodology and proposed composite metastructure will have a wide range of application in the structural vibration control and shock absorption.
13Scopus© Citations 2 - PublicationVibration Resonance and Dynamic Characteristics of Pillared Phononic Crystals and Acoustic MetamaterialsEngineered resonance phenomenon on surfaces have created an unprecedented world of surface science and technology. Branching resonant substructure as pillared phononic crystals and metamaterials emerge as a new class of synthetic structures with peculiar wave dispersion and dynamic properties that cannot be observed in natural materials. A fundamental property of interest includes dual behavior of pillared system that means exhibition of both Bragg and hybridization bandgaps. The rich resonance properties by this simple structure frontier a whole new research field in phononic crystals and metamaterials. The purpose of this article is to reproduce and combine different surface resonance phenomena reported in the literature on pillared structures with an insight on historical context, recent developments and future research prospects. The collection of findings reported here may provide a comprehensive insight on pillared resonances and help resolve the current challenges in the field to foster research spin-offs.
Scopus© Citations 1 27 - PublicationNegative Poisson’s ratio locally resonant seismic metamaterials vibration isolation barrier(Springer, 2024-05-07)
; ; ; ; In recent decades, the application of seismic metamaterials to protect civil infrastructures being free of the damage of earthquakes has been attracting extensive attention. Specifically, the proposed locally resonant seismic metamaterials provide the probability of isolating the low-frequency seismic wave using a small-size isolation barrier. However, in previous studies, the energy absorption properties of locally resonant seismic metamaterials remain one of the least understood aspects of isolation. Benefit from the fascinating energy absorption characteristic of negative Poisson ratio (NPR) metamaterial, we creatively design a new seismic metamaterial structure by assembling the locally resonant seismic metamaterial and NPR metamaterial, to isolate seismic waves. The sound cone technique combining the transmission spectrum is employed to identify the surface wave from the hybrid waves. The generation mechanism of frequency bandgap and the isolation effectiveness of the proposed seismic metamaterial are discussed in detail. The results indicate that the generation of ultra-low and ultra-wide frequency bandgap with the range of 0.65 Hz–18.9 Hz is attributed to the locally resonant and energy absorption of the proposed seismic metamaterial structure and the excellent isolation effect is achieved by transforming the surface wave into the bulk wave. The frequency bandgap narrows as the distance increases between each resonator. In addition, the mechanical properties of the NPR bearing, such as the Poisson ratio, mass density, and elastic modulus, have remarkable impact on the frequency bandgap, especially on the upper bound frequency. In practical engineering, the NPR bearing with a low Poisson ratio, small mass density, and high elastic modulus is suggested for the design of the NPR locally resonant seismic metamaterial structures. Time domain analysis for the practical seismic wave verifies that the proposed seismic metamaterial has a promising application in isolating ultra-low and ultra-wide seismic waves, with the isolation effectiveness larger than 70%. This work contributes a new locally resonance seismic metamaterial design idea for isolating and adjusting the low-frequency seismic wave.1 - PublicationMachine learning and deep learning in phononic crystals and metamaterials – A reviewMachine learning (ML), as a component of artificial intelligence, encourages structural design exploration which leads to new technological advancements. By developing and generating data-driven methodologies that supplement conventional physics and formula-based approaches, deep learning (DL), a subset of machine learning offers an efficient way to understand and harness artificial materials and structures. Recently, acoustic and mechanics communities have observed a surge of research interest in implementing machine learning and deep learning methods in the design and optimization of artificial materials. In this review we evaluate the recent developments and present a state-of-the-art literature survey in machine learning and deep learning based phononic crystals and metamaterial designs by giving historical context, discussing network architectures and working principles. We also explain the application of these network architectures adopted for design and optimization of artificial structures. Since this multidisciplinary research field is evolving, a summary of the future prospects is also covered. This review article serves to update the acoustics, mechanics, physics, material science and deep learning communities about the recent developments in this newly emerging research direction
2Scopus© Citations 52 - PublicationPhononic crystal based sensor to detect acoustic variations in methyl & ethyl nonafluorobutyl etherPhononic crystals and metamaterials have been widely studied for wave manipulation applications. In this study, we propose a conceptual framework for a new type of acoustic bio-chemical sensor that works based on the principle of phononic crystals and metamaterials to detect the temperature and pressure changes in active solvents like Methyl Nonafluorobutyl Ether (MNE) and Ethyl Nonafluorobutyl Ether (ENE). First, a wide low-frequency bandgap is obtained from the proposed composite unit cell structure with trampoline effect. Then a defect is introduced to adjust the localize cavity modes inside the reported bandgap. Later, the cavity is filled with MNE and ENE solvents that eventually resulted into fluid-solid coupling physics. The numerical wave dispersion curves and transmission profiles show presence of Fano-like interference/resonance effect evident from the observation of asymmetrical transmission profile. Such robust asymmetrical transmission peak is generated due to coupling of incident waves with scattered wave field emitted from the MNE and ENE solvents upon excitation. The variation in acoustic properties of MNE and ENE caused by temperature and pressure fields on newly born Fano-like asymmetrical transmission profile is studied. The proposed acoustic bio-chemical sensor governed by Fano-interference effect efficiently capture the variation in acoustic properties of MNE and ENE solvents at relatively low-frequency regime that makes this approach favorable for sensing applications. Such smart acoustic bio-chemical sensors can have useful applications in pharmaceutical production, petrochemicals and capturing ingredients of cosmetic and beauty products.
Scopus© Citations 5 14