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35 results on '"Heo, Hyeonu"'

1. Coupled resonator acoustic waveguides-based acoustic interferometers designed within two-dimensional phononic crystals: experiment and theory

Author

Martínez-Esquivel, David, Méndez-Sánchez, Rafael Alberto, Heo, Hyeonu, Martínez-Argüello, Angel Marbel, Mayorga-Rojas, Miguel, Neogi, Arup, and Reyes-Contreras, Delfino

Subjects
Physics - Applied Physics
Abstract

The acoustic response of defect-based acoustic interferometer-like designs, known as Coupled Resonator Acoustic Waveguides (CRAWs), in two-dimensional phononic crystals (PnCs) is reported. The PnC is composed of steel cylinders arranged in a square lattice within a water matrix with defects induced by selectively removing cylinders to create Mach-Zehnder-like (MZ) defect-based interferometers. Two defect-based acoustic interferometers of MZ-type are fabricated, one with arms oriented horizontally and another one with arms oriented diagonally, and their transmission features are experimentally characterized using ultrasonic spectroscopy. The experimental data are compared with finite element method (FEM) simulations and with tight-binding (TB) calculations in which each defect is treated as a resonator coupled to its neighboring ones. Significantly, the results exhibit excellent agreement indicating the reliability of the proposed approach. This comprehensive match is of paramount importance for accurately predicting and optimizing resonant modes supported by defect arrays, thus enabling the tailoring of phononic structures and defect-based waveguides to meet specific requirements. This successful implementation of FEM and TB calculations in investigating CRAWs systems within phononic crystals paves the way for designing advanced acoustic devices with desired functionalities for various practical applications, demonstrating the application of solid-state electronics principles to underwater acoustic devices description.

Published
2023

2. Multifunctional acoustic device based on phononic crystal with independently controlled asymmetric rotating rods

Author

Heo, Hyeonu, Krokhin, Arkadii, Neogi, Arup, Cui, Zhiming, Yuan, Zhihao, Hua, Yihe, Ju, Jaehyung, and Walker, Ezekiel

Subjects
Physics - Applied Physics
Abstract

A reconfigurable phononic crystal (PnC) is proposed where elastic properties can be modulated by rotation of asymmetric solid scatterers immersed in water. The scatterers are metallic rods with cross-section of 120{\deg} circular sector. Orientation of each rod is independently controlled by an external electric motor that allows continuous variation of the local scattering parameters and dispersion of sound in the entire crystal. Due to asymmetry of the scatterers, the crystal band structure possesses highly anisotropic bandgaps. Synchronous rotation of all the scatterers by a definite angle changes regime of reflection to regime of transmission and vice versa. The same mechanically tunable structure functions as a gradient index medium by incremental, angular reorientation of rods along both row and column, and, subsequently, can serve as a tunable acoustic lens, an acoustic beam splitter, and finally an acoustic beam steerer.

Published
2023

3. Enhanced Instantaneous Elastography in Tissues and Hard Materials Using Bulk Modulus and Density Determined without Externally Applied Material Deformation

Author

Jin, Yuqi, Walker, Ezekiel, Krokhin, Arkadii, Heo, Hyeonu, Choi, Tae-Youl, and Neogi, Arup

Subjects
Physics - Medical Physics, Condensed Matter - Other Condensed Matter
Abstract

Ultrasound is a continually developing technology that is broadly used for fast, non-destructive mechanical property detection of hard and soft materials in applications ranging from manufacturing to biomedical. In this study, a novel monostatic longitudinal ultrasonic pulsing elastography imaging method is introduced. Existing elastography methods require an acoustic radiational or dynamic compressive externally applied force to determine the effective bulk modulus or density. This new, passive M-mode imaging technique does not require an external stress, and can be effectively utilized for both soft and hard materials. Strain map imaging and shear wave elastography are two current categories of M-mode imaging that show both relative and absolute elasticity information. The new technique is applied to hard materials and soft material tissue phantoms for demonstrating effective bulk modulus and effective density mapping. As compared to standard techniques, the effective parameters fall within 10% of standard characterization methods for both hard and soft materials. As neither the standard A-mode imaging technique nor the presented technique require an external applied force, the techniques are applied to composite heterostructures and the findings presented for comparison. The presented passive M-mode technique is found to have enhanced resolution over standard A-mode modalities.

Published
2019

13. On the elastodynamic properties of octet truss-based architected metamaterials.

Author

Oudich, Mourad, Huang, Edward, Heo, Hyeonu, Xu, Zhenpeng, Cui, Huachen, Gerard, Nikhil JRK, Zheng, Xiaoyu, and Jing, Yun

Subjects
MECHANICAL behavior of materials, ELASTIC waves, MATERIALS science, METAMATERIALS
Abstract

Architected metamaterials have emerged as a central topic in materials science and mechanics, thanks to the rapid development of additive manufacturing techniques, which have enabled artificial materials with outstanding mechanical properties. This Letter seeks to investigate the elastodynamic behavior of octet truss lattices as an important type of architected metamaterials for high effective strength and vibration shielding. We design, fabricate, and experimentally characterize three types of octet truss structures, including two homogenous structures with either thin or thick struts and one hybrid structure with alternating strut thickness. High elastic wave transmission rate is observed for the lattice with thick struts, while strong vibration mitigation is captured from the homogenous octet truss structure with thin struts as well as the hybrid octet truss lattice, though the underlying mechanisms for attenuation are fundamentally different (viscoelasticity induced dampening vs bandgaps). Compressional tests are also conducted to evaluate the effective stiffness of the three lattices. This study could open an avenue toward multifunctional architected metamaterials for vibration shielding with high mechanical strength. [ABSTRACT FROM AUTHOR]

Published
2023
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29. Thermoviscoelastic modeling of a nonpneumatic tire with a lattice spoke.

Author

Yoo, Sairom, Uddin, Md Salah, Heo, Hyeonu, Ju, Jaehyung, and Choi, Seok-Ju

Abstract

Nonpneumatic tires made from materials with a low viscoelastic energy loss can be an option for developing tires with a low rolling resistance. For better fuel-efficient design of nonpneumatic tires, the rolling energy loss of the nonpneumatic tires may need to be analyzed at a component level. The objective of this study is to develop a numerical tool that can quantify the rolling energy loss and the corresponding internal heat generation of a nonpneumatic tire. We construct a thermomechanical model that covers the interaction between the deformation and the related heat generation in an elastomer material. We suggest, for various vehicle loads and various rolling speeds, a coupled thermoviscoelastic material model for a nonpneumatic tire with a hexagonal cellular spoke in order to investigate the temperature distribution of the nopneumatic tire generated by hysteresis and convection loss to the air. Using a hyperviscoelastic material model developed from uniaxial (tension and compression) tests and dynamic mechanical analysis, a thermomechanical model is constructed by combining a shear-deformation-induced hysteresis and a cooling procedure when exposed to the air. The model of the temperature rise of the nonpneumatic tire is validated using temperature measurement with a thermal imaging camera during rolling of the nonpneumatic tire. The developed tool combining the viscoelastic material model with the aerodynamic heat loss quantifies well the hysteretic energy loss and the temperature distribution at each component of the nonpneumatic tire. [ABSTRACT FROM AUTHOR]

Published
2017
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34. Manufacturing and Characterization of Hybrid Bulk Voxelated Biomaterials Printed by Digital Anatomy 3D Printing.

Author

Heo, Hyeonu, Jin, Yuqi, Yang, David, Wier, Christopher, Minard, Aaron, Dahotre, Narendra B., and Neogi, Arup

Subjects
*THREE-dimensional printing, *PRINT materials, *DIGITAL printing, *MANUFACTURING processes, *3-D printers, *BIOMATERIALS, *BULK modulus
Abstract

The advent of 3D digital printers has led to the evolution of realistic anatomical organ shaped structures that are being currently used as experimental models for rehearsing and preparing complex surgical procedures by clinicians. However, the actual material properties are still far from being ideal, which necessitates the need to develop new materials and processing techniques for the next generation of 3D printers optimized for clinical applications. Recently, the voxelated soft matter technique has been introduced to provide a much broader range of materials and a profile much more like the actual organ that can be designed and fabricated voxel by voxel with high precision. For the practical applications of 3D voxelated materials, it is crucial to develop the novel high precision material manufacturing and characterization technique to control the mechanical properties that can be difficult using the conventional methods due to the complexity and the size of the combination of materials. Here we propose the non-destructive ultrasound effective density and bulk modulus imaging to evaluate 3D voxelated materials printed by J750 Digital Anatomy 3D Printer of Stratasys. Our method provides the design map of voxelated materials and substantially broadens the applications of 3D digital printing in the clinical research area. [ABSTRACT FROM AUTHOR]

Published
2021
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35. Programmable Mechanical Metamaterials with Negative Poisson's Ratio and Negative Thermal Expansion

Author

Heo, Hyeonu

Subjects
metamaterial, negative thermal expansion, compliant porous structure, bi-materi, Engineering, Mechanical
Abstract

Programmable matter is a material whose properties can be programmed to achieve particular shapes or mechanical properties upon command. This is an essential technique that could one day lead to morphing aircraft and ground vehicles. Metamaterials are the rationally designed artificial materials whose properties are not observed in nature. Their properties are typically controlled by geometry rather than chemical compositions. Combining metamaterials with a programmable function will create a new area in the intelligent material design. The objective of this study is to design and demonstrate a tunable metamaterial and to investigate its thermo-mechanical behavior. An integrated approach to the metamaterial design was used with analytical modeling, numerical simulation, and experimental demonstration. The dynamic thermo-mechanical analysis was used to measure base materials' modulus and thermal expansion coefficient as a function of temperature. CPS, the unit cell of the metamaterial, is composed of circular holes and slits. By decomposing kinematic rotation of the arm and elastic deformation of a bi-material hinge, thermo-mechanical constitutive models of CPS were developed and it was extended to 3D polyhedral structures for securing isotropic properties. Finite element based numerical simulations of CPS and polyhedral models were conducted for comparison with the analytical model. 3D printing of multi-materials was used for sample fabrication followed by tests with uniaxial compressive mechanical tests and thermal tests at 50℃. From the analytical model of the metamaterial, the contour plots were obtained for the effective properties – Poisson's ratio, the effective coefficient of thermal expansion of the metamaterial as a function of geometry and materials. A controllable range of temperature and strain was identified associated with maximized thermal expansion mismatch and contact on the slit surface of CPS, respectively. This work will pave the road toward the design of programmable metamaterials with both mechanically- and thermally- tunable capability and provide unique thermo-mechanical properties with a programmable function.

Published
2016

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