We develop a fully data-driven model of anisotropic finite viscoelasticity using neural ordinary differential equations as building blocks. We replace the Helmholtz free energy function and the dissipation potential with data-driven functions that a priori satisfy physics-based constraints such as objectivity and the second law of thermodynamics. Our approach enables modeling viscoelastic behavior of materials under arbitrary loads in three-dimensions even with large deformations and large deviations from the thermodynamic equilibrium. The data-driven nature of the governing potentials endows the model with much needed flexibility in modeling the viscoelastic behavior of a wide class of materials. We train the model using stress-strain data from biological and synthetic materials including humain brain tissue, blood clots, natural rubber and human myocardium and show that the data-driven method outperforms traditional, closed-form models of viscoelasticity.
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http://dx.doi.org/10.1016/j.cma.2023.116046 | DOI Listing |
Sci Rep
December 2024
Department of Electronics, Carleton University, Ottawa, ON, K1S 5B6, Canada.
In this paper, we propose a novel structure of anisotropic graphene-based hyperbolic metamaterial (AGHMM) sandwiched as a defect between two one-dimensional photonic crystals (PCs) in the terahertz (THz) region. The proposed structure is numerically simulated and analyzed using the transfer matrix method, effective medium theory and three-dimensional finite-difference time-domain. The defect layer of AGHMM consists of graphene sheets separated by subwavelength dielectric spacers.
View Article and Find Full Text PDFNanotechnology
December 2024
Department of Physics, King Faisal University, King Faisal University P.O. 380 Ahsaa 31982, Al Ahsa, 31982, SAUDI ARABIA.
An anisotropic plasmonic trimer is proposed as an effective spectroscopic amplifier for the maximum signal enhancement of the Hyper-Raman Scattering (HRS) process. The three-particle system is composed of asymmetric Au nanorings arranged collinearly in a J-aggregate configuration and illuminated by a longitudinally polarized light. The optical properties of the considered trimer have been numerically simulated by the Finite-Difference Time-Domain (FDTD) method.
View Article and Find Full Text PDFJ Vis Exp
December 2024
School of Biological Science and Medical Engineering, Southeast University; Mathematical Sciences Department, Worcester Polytechnic Institute.
Quantifying the mechanical properties of coronary arterial walls could provide meaningful information for the diagnosis, management, and treatment of coronary artery diseases. Since patient-specific coronary samples are not available for patients requiring continuous monitoring, direct experimental testing of vessel material properties becomes impossible. Current coronary models typically use material parameters from available literature, leading to significant mechanical stress/strain calculation errors.
View Article and Find Full Text PDFAnal Chem
December 2024
College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi 712100, China.
Integrating specific immune recognition, a desirable extinction coefficient, and conspicuous photothermal conversion ability into a single-immune probe to enhance the analysis performance represents an appealing yet significantly challenging task. Herein, by delicately manipulating the geometry of plasmonic nanoparticles from spherical to spiky, precise engineering approach-based spiky Au nanocubes (S-AuNCs) are employed to address this challenge, which fully exploits the plasmon resonance absorption-induced photothermal effect. The finite difference time domain (FDTD) method was employed to computationally simulate the electromagnetic and thermal fields while assessing the feasibility of regulating plasmon resonance for enhanced photothermal absorption.
View Article and Find Full Text PDFJ Phys Chem C Nanomater Interfaces
December 2024
Department of Chemistry, College of Staten Island, Staten Island, New York 10314, United States.
Density functional theory calculations and a finite deformation method are used to calculate second- and, most notably, third-order elastic constants of amorphous silicon and amorphous silicon dioxide, as represented by model structures generated via melt-quench force-field molecular dynamics simulations. Linear and nonlinear elastic constants are used to deduce macroscopic elastic moduli, such as the bulk and shear moduli, their pressure derivatives, and the elastic Grüneisen parameter. Our calculations show that the elastic properties of amorphous silicon reach the isotropic elastic limit within the nanometer length scale, attaining characteristics, both linear and nonlinear, comparable to those of crystalline silicon.
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