Article
Multidisciplinary Sciences
Haning Xiu, Ian Frankel, Harry Liu, Kai Qian, Siddhartha Sarkar, Brianna MacNider, Zi Chen, Nicholas Boechler, Xiaoming Mao
Summary: In this study, a two-dimensional topological Maxwell lattice is investigated through geometric numerical simulations and experiments, revealing spatial nonlinear wave-like phenomena and an equivalence between the deformation fields of two-dimensional topological Maxwell lattices and nonlinear dynamical phenomena in one-dimensional active systems. This research opens up new possibilities for topological mechanical metamaterials and expands their application potential in areas such as adaptive and smart materials and mechanical logic, enabling the creation of intricate, tailored spatial deformation and stress fields using concepts from nonlinear dynamics.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2023)
Article
Physics, Applied
Fangfang Ju, Xiao Zou, Sheng-You Qian, Xiaojun Liu
Summary: Our proposed non-Hermitian metasurface mirror, made of two-layers acoustic labyrinthine metamaterials, achieves full phase control and asymmetric acoustic retroflection for positive and negative incidence angles. The design shows potential applications in acoustic sensing, acoustic antennas, and noise control.
APPLIED PHYSICS EXPRESS
(2021)
Review
Physics, Applied
J. W. Rao, Y. T. Zhao, Y. S. Gui, X. L. Fan, D. S. Xue, C-M Hu
Summary: Dissipative coupling in a metamaterial structure leads to level attraction by cooperative radiation of resonators, supporting the coexistence of bound states in the continuum (BIC) and an antiresonance. By aligning BIC and antiresonance frequencies, control over the amplitude and phase of microwave transmission is achieved, resulting in a steep transition from complete extinction to nearly perfect transmission, accompanied by a phase jump indicative of slow light. Repurposing dissipation as a coupling mechanism opens up avenues for microwave sensing, switching, and realization of slow microwave.
PHYSICAL REVIEW APPLIED
(2021)
Article
Physics, Applied
Zhongming Gu, Tuo Liu, He Gao, Shanjun Liang, Shuowei An, Jie Zhu
Summary: A simple scheme to achieve acoustic CPA and laser modes by embedding a non-Hermitian dopant in a zero index metamaterial is proposed in this work. The effectiveness of these modes is ensured through theoretical derivation and numerical simulation, and their sensitivity can be controlled by adjusting structure parameters or the relative phase.
JOURNAL OF APPLIED PHYSICS
(2021)
Article
Materials Science, Multidisciplinary
Haiyan Fan, He Gao, Tuo Liu, Shuowei An, Xianghong Kong, Guoqiang Xu, Jie Zhu, Cheng-Wei Qiu, Zhongqing Su
Summary: Non-Hermiticity in acoustic crystals leads to exotic topological phenomena and allows for manipulation of topological modes. Our work demonstrates an acoustic quadrupole topological insulator, offering a reconfigurable and versatile approach to manipulating topological phenomena.
Article
Materials Science, Multidisciplinary
Zheng Zhang, Lin Bai, Liang Xu, Wei Xiang Jiang, Tie Jun Cui
Summary: This research introduces and demonstrates an acoustic prism using controllable meta-atoms that can be rotated to control the transmission direction of acoustic waves in real time, blocking waves from the opposite direction and operating in a wide frequency range.
PHYSICA STATUS SOLIDI-RAPID RESEARCH LETTERS
(2021)
Article
Physics, Applied
S. Puri, J. Ferdous, A. Shakeri, A. Basiri, M. Dubois, H. Ramezani
Summary: Researchers have proposed and tested a non-Hermitian acoustic superlattice that functions as a tunable precise filter, where the second sublattice's properties can be adjusted to absorb or reflect multiple frequencies with high accuracy.
PHYSICAL REVIEW APPLIED
(2021)
Article
Instruments & Instrumentation
Guangxin Liao, Zhenwei Wang, Congcong Luan, Jiapeng Liu, Xinhua Yao, Jianzhong Fu
Summary: This study demonstrates the fabrication of broadband acoustic focusing lens and asymmetric acoustic focusing lens using additive manufacturing technology, achieving focusing of acoustic waves in a wider frequency range. Experimental results show excellent performance of the designed focusing lens and asymmetric focusing lens, with good consistency between measured and simulated results.
SMART MATERIALS AND STRUCTURES
(2021)
Article
Multidisciplinary Sciences
Tuo Liu, Shuowei An, Zhongming Gu, Shanjun Liang, He Gao, Guancong Ma, Jie Zhu
Summary: This study demonstrates the control of acoustic vortex generation by controlling the on-off states of two coherent monopolar sources, achieving switchable OAM without system reconfiguration. It offers new opportunities for chiral sound manipulation and tunable acoustic OAM devices.
Review
Physics, Multidisciplinary
Jie Luo, Yun Lai
Summary: Accidental degeneracy plays a vital role in the generation of novel band dispersions. Structures exhibiting accidental Dirac-like conical dispersion at the center of the Brillouin zone can have unique features, such as zero-index behavior and wave tunneling. Introduction of non-Hermiticity in the system can lead to appearance of exceptional points and various other unique dispersions. Similar phenomena are observed in phononic structures.
FRONTIERS IN PHYSICS
(2022)
Article
Multidisciplinary Sciences
Curtis Rasmussen, Andrea Alu
Summary: The efficiency and bandwidth of traditional passive acoustic radiators are severely limited, but these constraints can be overcome by loading a piezoelectric transducer with a non-Foster active circuit, resulting in significantly improved radiation bandwidth and efficiency. Experimental results demonstrate a threefold increase in bandwidth, paving the way for non-Foster acoustic radiation technologies.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2021)
Article
Multidisciplinary Sciences
Li Zhang, Yihao Yang, Yong Ge, Yi-Jun Guan, Qiaolu Chen, Qinghui Yan, Fujia Chen, Rui Xi, Yuanzhen Li, Ding Jia, Shou-Qi Yuan, Hong-Xiang Sun, Hongsheng Chen, Baile Zhang
Summary: The experimental realization of the non-Hermitian skin effect in a one-dimensional non-reciprocal acoustic crystal demonstrates unique features such as bipolar localization and Bloch point, revealing previously unnoticed characteristics of NHSE originating from complex non-Hermitian winding topology.
NATURE COMMUNICATIONS
(2021)
Article
Engineering, Mechanical
Xiangzhen Han, Li Li, Chaosheng Mei, Yujin Hu, Xuelin Wang
Summary: This study proposes an acoustic source localization method based on acoustic valley-Hall topological insulators (VHTIs), which uses a thin film to improve directional sound reception and decrease the half-power beamwidth.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2022)
Article
Multidisciplinary Sciences
Zhiling Zhou, Sibo Huang, Dongting Li, Jie Zhu, Yong Li
Summary: Utilizing nonlocality between subunits, ultrathin acoustic metamaterials achieve broadband sound absorption and desired impedance profiles. The over-damped recipe and the reduced excessive response recipe are employed for impedance matching and broadband near-perfect absorption.
NATIONAL SCIENCE REVIEW
(2022)
Article
Multidisciplinary Sciences
Kai Wang, Avik Dutt, Charles C. Wojcik, Shanhui Fan
Summary: The recent theoretical work discovered that the braid group characterizes the topology of non-Hermitian periodic systems, where the complex band energies can braid in momentum space. This study introduces a tight-binding lattice model that can achieve arbitrary elements in the braid group of two strands B-2 and experimentally demonstrates topological complex-energy braiding of non-Hermitian bands in a synthetic dimension. The results provide a direct demonstration of the braid-group characterization of non-Hermitian topology and open a pathway for designing and realizing topologically robust phases in open classical and quantum systems.
Article
Nanoscience & Nanotechnology
Kristen A. Miller, Lawrence B. Alemany, Soumyabrata Roy, Qianqian Yan, Pedro Guerra Demingos, Chandra Veer Singh, Sampath Alahakoon, Eilaf Egap, Edwin L. Thomas, Pulickel M. Ajayan
Summary: This study presents a facile two-step synthesis method for producing high-quality 2D polymer films with benzoxazole linkages. The films exhibit promising mechanical properties and microporous structures, and can be exfoliated into nanosheets.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Multidisciplinary Sciences
Han Sol Kang, Chanho Park, Hongkyu Eoh, Chang Eun Lee, Du Yeol Ryu, Youngjong Kang, Xuenyan Feng, June Huh, Edwin L. Thomas, Cheolmin Park
Summary: This study visualizes and analyzes the structural defects that affect the rapid response of visible light in a block copolymer photonic crystal. It reveals the diffusional pathway of solvents through these defects.
Article
Polymer Science
Wenpeng Shan, Inbal Weisbord, Xueyan Feng, Jinho Hyon, Gkreti-Maria Manesi, Apostolos Avgeropoulos, Tamar Segal-Peretz, Edwin L. Thomas
Summary: Creating ultrathin films via ballistic impact-induced frictional material transfer is a new approach for additive manufacturing. The covalently bonded A and B block brushes in A/B lamellar diblock copolymers are robust mechanical units that can undergo extreme deformation. Impact of microspheres against a rigid substrate causes slip and thinning of the bottommost layers. For angled impacts, enhanced shear stress leads to brush slip and frictional transfer.
Article
Materials Science, Multidisciplinary
Claire Griesbach, Tyler Gerczak, Yongfeng Zhang, Ramathasan Thevamaran
Summary: TRISO nuclear fuel particles have a layered spherical shell designed to retain fission products, but failure often occurs in the porous pyrocarbon buffer layer. Detailed characterization of the buffer porosity and its heterogeneous distribution is necessary to understand the failure mechanisms. In this study, FIB-SEM tomography was used to reconstruct the buffer microstructure with high spatial resolution. The analysis revealed an overall porosity of around 14% and an increase in local porosity towards the inner pyrocarbon layer. This information provides insight into the process-structure-property-performance relations of TRISO fuel particles and can inform the prediction of particle failure under irradiation.
JOURNAL OF NUCLEAR MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Komal Chawla, Abhishek Gupta, Ramathasan Thevamaran
Summary: Creating lightweight architected foams as strong and stiff as their bulk constituent material has always been a challenge. However, through the use of hierarchical vertically aligned carbon nanotube foams, we have successfully achieved constant stiffness-to-density and energy dissipation-to-density ratios, enabling a linear scaling with density. This transformation not only improves the foams' structural stiffness at low densities, but also enhances their damping capacity and energy absorption efficiency, allowing access to the ultra-lightweight regime in the property space. Such synergistic scaling of material properties is highly desirable for protective applications in extreme environments.
Article
Materials Science, Multidisciplinary
Jizhe Cai, Claire Griesbach, Savannah G. Ahnen, Ramathasan Thevamaran
Summary: We investigate the strain-rate-dependent mechanical behavior of single-crystal aluminum with different crystal orientations using high-velocity micro-projectile impact testing and quasistatic nanoindentation. The dynamic hardness initially increases with impact velocity and reaches a plateau at a higher hardness than that of quasistatic indentations. Different plastic deformation mechanisms with a gradient dislocation density evolution govern the dynamic behavior. Beyond the deeply plastic regime, a stable plastic regime with unique microstructure evolution and dynamic hardness is discovered. This work demonstrates an effective approach to introduce strong spatial gradients in dislocation density in metals to enhance surface mechanical properties.
Correction
Multidisciplinary Sciences
Rodion Kononchuk, Jizhe Cai, Fred Ellis, Ramathasan Thevamaran, Tsampikos Kottos
Article
Materials Science, Multidisciplinary
Gregory M. Grason, Edwin L. Thomas
Summary: The article presents a framework for understanding the structure of supramolecular network crystals in soft matter using mesoatomic building blocks. These building blocks play a similar role to atomic or molecular subunits in hard matter crystals. By analyzing the shapes, internal structures, and local packing of these mesoatomic elements, the article proposes a set of rules for decomposing network crystals into unique mesoatomic building blocks. Additionally, the article suggests that mesoatoms are kinetically favored intermediate structures that guide the assembly of network crystals.
PHYSICAL REVIEW MATERIALS
(2023)
Article
Engineering, Mechanical
Abhishek Gupta, Arkady Kurnosov, Tsampikos Kottos, Ramathasan Thevamaran
Summary: Boosting signals with amplification mechanisms is common, but attenuating mechanisms are less desired due to their negative impacts on efficiency. However, a new viewpoint suggests that attenuation can be used as a design element to enhance actuation force while maintaining signal quality. This study demonstrates the concept by designing a non-Hermitian metamaterial and provides a proof-of-principle for the design of reconfigurable nano-indenters and robotic actuators.
EXTREME MECHANICS LETTERS
(2023)
Article
Physics, Applied
Ilaie Nadejde, Edwin L. Thomas, Pavel I. Galich
Summary: This study expands the complete omnidirectional bandgaps of high symmetry two-dimensional phononic crystal designs through simple geometric changes. The experimental validation demonstrates the feasibility of achieving extreme ultrasonic attenuation using non-symmetric designs for both P- and S-waves. Practical insights into improving acoustic properties of phononic crystals are discussed.
APPLIED PHYSICS LETTERS
(2023)
Article
Engineering, Mechanical
Claire Griesbach, Jizhe Cai, Seog-Jin Jeon, Ramathasan Thevamaran
Summary: We demonstrate the ability to enhance the strength and toughness in metals by tailoring the plasticity mechanisms through impact-induced nanostructures. The gradient nanostructures exhibit heterogeneous deformation, leading to improved strength and toughness. The activation of different plasticity mechanisms depends on the specific impact-induced nanostructures.
INTERNATIONAL JOURNAL OF PLASTICITY
(2023)
Article
Chemistry, Multidisciplinary
Seungyeol Lee, Jizhe Cai, Shiyun Jin, Hiromi Konishi, Dongzhou Zhang, Amanda S. Barnard, Ramathasan Thevamaran, Huifang Xu
Summary: The phase relationships of TiO2 polymorphs are important in the study of earth and planetary science. This study used the LIPIT technique to investigate the shock metamorphism of TiO2 polymorphs and utilized various characterization techniques to analyze the phase transformations. The results provide insights into shock metamorphism in minerals and rocks and help expand our understanding of the process on planetary bodies.
ACS EARTH AND SPACE CHEMISTRY
(2023)
Article
Materials Science, Multidisciplinary
Abhishek Gupta, Ramathasan Thevamaran
Summary: Recent progress in non-Hermitian physics and the notion of exceptional point (EP) degeneracies have led to the development of novel metamaterials for elastic wave control. This study reports strategies to achieve EPs in passive non-Hermitian elastodynamic systems using viscoelastic materials with differential loss. The authors demonstrate that certain viscoelastic elastomers follow a specific behavior that allows for the emergence of EPs, paving the way for hypersensitive metamaterials.
JOURNAL OF PHYSICS-MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
I-Ming Lin, Chih-Ying Yang, Yi-Ming Wang, Wei-En Wang, Yu-Chueh Hung, Edwin L. Thomas, Yeo-Wan Chiang
Summary: By using bicontinuous and nanoporous ordered nanonetworks, innovative materials with exceptional optical and mechanical properties can be created. These materials have a high surface-to-volume ratio and porosity, opening up new possibilities for material design.
Article
Chemistry, Physical
Komal Chawla, Jizhe Cai, Dakotah Thompson, Ramathasan Thevamaran
Summary: Thermal transport properties are crucial for lightweight foams used as shock-absorbing layers. This study demonstrates tailored thermal properties achieved by introducing a hexagonally close-packed cylindrical architecture in vertically aligned carbon nanotube (VACNT) foams. The architected VACNTs exhibit higher intrinsic thermal conductivity and lower intrinsic thermal resistance compared to non-architected VACNTs. These superior thermal transport properties enable the development of lightweight protective materials for extreme engineering applications.