One-dimensional Composite Structure Research Articles

Tunable nonreciprocal transmission based on non-Hermitian optical system with magnetic optical materials in a one-dimensional multilayer structure

In this study, a one-dimensional composite structure composed of a PT-symmetric system and magnetic optical (MO) materials is designed. The nonreciprocal propagation of a one-dimensional multilayer structure is investigated both theoretically and numerically based on the transfer matrix theory. Different from the single nonreciprocal frequency in the parity-time (PT) system, two adjacent band gaps are changed into a pair of nonreciprocal bands under the effect of MO materials and a PT system above the PT exceptional point, and extraordinary transmissions are inspired in some nonreciprocal frequencies. At the same time, the nonreciprocal propagation bands can be tuned based on the different choices of external magnetic field directions. Furthermore, with an increase in the gain/loss factor, the two nonreciprocal band gaps both disappear and form two bands with an extraordinary transmission at certain frequencies. Such peculiar properties in the composite structure may have broad potential applications in communication and integration devices.

Flexible Sb/Sb2O3-C nanofibers as binder-free anodes for high-performance and stable sodium-ion batteries

Antimony-based electrode materials with conventional slurry-casting process still face great challenges such as tedious preparation process and unsatisfying cycling stability for sodium ion batteries (SIBs). Therefore, the design and fabrication of integrated electrodes with binder-free and even current collector-free are highly significant. Herein, we fabricated flexible Sb/Sb2O3-C nanofibers (NFs) films utilizing a facile combination of electrospinning technique and carbonization. Sb/Sb2O3 nanoparticles are well embedded in carbon NFs with a fiber diameter of ca. 340 nm. The fabricated NFs films can be directly used as binder and current collector-free anodes for SIBs and exhibited high-capacity and long-lifetime cycles (385.6 mAh g−1 over 500 cycles). Ex situ SEM and TEM observations re-appear their intact fibrous network morphology and stable one-dimensional composite structures after hundreds of discharging-charging cycles, demonstrating that Sb/Sb2O3-C NFs film is a promising binder-free electrode for SIBs.

Thermal rectification mechanism of one-dimensional composite structure with interface thermal contact resistance

Thermal rectification refers to the phenomenon that heat fluxes or equivalent thermal conductivities are different under the same temperature difference when temperature gradient directions are different. The nature of the thermal rectification is that the structure has different effective thermal conductivities in different directions. Most of previous studies focused on thermal rectification of temperature-dependent thermal conductivity materials or variable cross section area structure, and the effect of thermal contact resistance at the interface was investigated very rarely. In the present paper we present the analytical and finite element numerical solution of temperature field and thermal rectification ratios of a composite structure with variable cross section area and thermal conductivity under different interface thermal contact resistances. The prescribed temperature boundary condition is introduced by penalty method, and the temperature jump condition at the interface is implemented by the definition of thermal contact resistance directly. The nonlinear heat conduction problem caused by temperature-dependent thermal conductivity and interface thermal contact resistance is then solved with a direct iteration scheme. Comparisons between experimental results and the present theoretical and numerical results show the feasibility of the proposed model. Then parameter investigations are also conducted to reveal the effect of some key geometric and material parameters. Numerical results show that thermal contact resistance plays an important role in the temperature field and thermal rectification ratio of the two-segment thermal rectifier. With the increase of the length ratio, thermal ratification ratio increases first and decreases then, and the optimal length ratio varies with both thermal contact resistance and cross-section radius change rate of the two segments. In general, the existence of thermal contact resistance can increase the total thermal resistance of the rectifier and magnify the distinction of the heat flux in forward and reverse cases. However, if the thermal contact resistance is too large, this distinction will decrease and correspondingly the thermal rectification ratio becomes low. With the increase of the boundary temperature difference, thermal rectification ratio increases due to the effect of temperature-dependent thermal conductivity. In the present study, we propose a theoretical and numerical approach to designing and optimizing the length ratio, cross-section radius change rate, thermal conductivity, boundary temperature difference and interface thermal contact resistance to obtain the maximal thermal rectification ratio of a bi-segment thermal rectifier, as well as the manipulation of thermal flux in engineering applications.

Band gap behaviour of optimal one-dimensional composite structures with an additive manufactured stiffener

In this work, the banded behaviour of composite one-dimensional structures with an additive manufactured stiffener is examined. A finite element method is used to calculate the stiffness, mass and damping matrices, and periodic structure theory is used to obtain the wave propagation of one-dimensional structures. A multi-disciplinary design optimisation scheme is developed to achieve optimal banded behaviour and structural characteristics of the structures under investigation. Having acquired the optimal solution of the case study, a representative specimen is manufactured using a carbon fibre cured plate and additive manufactured nylon-based material structure. Experimental measurements of the dynamic performance of the hybrid composite structure are conducted using a laser vibrometer and electrodynamic shaker setup to validate the finite element model.

The Wavelet Spectral Finite Element-based user-defined element in Abaqus for wave propagation in one-dimensional composite structures

A Wavelet Spectral Finite Element (WSFE)-based user-defined element (UEL) is formulated and implemented in Abaqus (commercial finite element software) for wave propagation analysis in one-dimensional composite structures. The WSFE method is based on the first-order shear deformation theory to yield accurate and computationally efficient results for high-frequency wave motion. The frequency domain formulation of the WSFE leads to complex-valued parameters, which are decoupled into real and imaginary parts and presented to Abaqus as real values. The final solution is obtained by forming a complex value using the real number solutions given by Abaqus. Four numerical examples are presented in this article, namely an undamaged beam, a beam with impact damage, a beam with a delamination, and a truss structure. A multi-point constraint subroutine, defining the connectivity between nodes, is developed for modeling the delamination in a beam. Wave motions predicted by the UEL correlate very well with Abaqus simulations. The developed UEL largely retains the computational efficiency of the WSFE method and extends its ability to model complex features.

Versatile hydrothermal synthesis of one-dimensional composite structures

In this paper we report on a versatile hydrothermal approach developed to fabricate one-dimensional (1D) composite structures. Sulfur and selenium formed liquid and adsorbed onto microrods as droplets and subsequently reacted with metallic ion in solution to produce nanoparticles-decorated composite microrods. 1D composites including ZnO/CdS, ZnO/MnS, ZnO/CuS, ZnO/CdSe, and FeOOH/CdS were successfully made using this hydrothermal strategy and the growth mechanism was also discussed. This hydrothermal strategy is simple and green, and can be extended to the synthesis of various 1D composite structures. Moreover, the interaction between the shell nanoparticles and the one-dimensional nanomaterials were confirmed by photoluminescence investigation of ZnO/CdS.