Research on the Mechanical and Thermal Properties of Carbon-Fiber-Reinforced Rubber Based on a Finite Element Simulation.

The comprehensive performance of rubber products could be significantly improved by the addition of functional fillers. To improve research efficiency and decrease the experimental cost, the mechanical and thermal properties of carbon-fiber-reinforced rubber were investigated using finite element simulations and theoretical modeling. The simplified micromechanical model was constructed through the repeatable unit cell with periodic boundary conditions, and the corresponding theoretical models were built based on the rule of mixture (ROM), which can be treated as the mutual verification.

An Investigation of Modular Composable Acoustic Metamaterials with Multiple Nonunique Chambers.

To make the sound absorber easy to fabricate and convenient for practical application, a modular composable acoustic metamaterial with multiple nonunique chambers (MCAM-MNCs) was proposed and investigated, which was divided into a front panel with the same perforated apertures and a rear chamber with a nonunique grouped cavity. Through the acoustic finite element simulation, the parametric studies of the diameter of aperture d, depth of chamber T0, and thickness of panel t0 were conducted, which could tune the sound absorption performances of MCAM-MNCs-1 and MCAM-MNCs-2 for the expected noise reduction effect. The effective sound absorption band of MCAM-MNCs-1 was 556 Hz (773-1329 Hz), 456 Hz (646-1102 Hz), and 387 Hz (564-951 Hz) for T = 30 mm, T = 40 mm, and T = 50 mm, respectively, and the corresponding average sound absorption coefficient was 0.

Analysis of Influencing Factors for Stackable and Expandable Acoustic Metamaterial with Multiple Tortuous Channels.

To reduce the noise generated by large mechanical equipment, a stackable and expandable acoustic metamaterial with multiple tortuous channels (SEAM-MTCs) was developed in this study. The proposed SEAM-MTCs consisted of odd panels, even panels, chambers, and a final closing plate, and these component parts could be fabricated separately and then assembled. The influencing factors, including the number of layers , the thickness of panel , the size of square aperture , and the depth of chamber were investigated using acoustic finite element simulation.

Modeling and Verification of Rolling Resistance Torque of High-Speed Rubber Track Assembly Considering Hysteresis Loss.

Due to the viscoelasticity of rubber materials, hysteresis loss due to deformation is the main reason for the rolling resistance of high-speed rubber tracks. Since the structure and material of high-speed rubber track assemblies are different from traditional tires and metal tracks, the rolling resistance theory of traditional wheeled and tracked vehicles is not applicable. Therefore, in order to determine the rolling resistance scientifically and accurately, the mechanism research of the rolling resistance of high-speed rubber track assembly is the key to the design of high-speed rubber crawler vehicles.

Effects of Aperture Shape on Absorption Property of Acoustic Metamaterial of Parallel-Connection Helmholtz Resonator.

A Helmholtz resonator (HR) with an embedded aperture is an effective acoustic metamaterial for noise reduction in the low-frequency range. Its sound absorption property is significantly affected by the aperture shape. Sound absorption properties of HRs with the embedded aperture for various tangent sectional shapes were studied by a two-dimensional acoustic finite element simulation.

Research on the Sound Insulation Performance of Composite Rubber Reinforced with Hollow Glass Microsphere Based on Acoustic Finite Element Simulation.

The composite rubber reinforced with hollow glass microsphere (HGM) was a promising composite material for noise reduction, and its sound insulation mechanism was studied based on an acoustic finite element simulation to gain the appropriate parameter with certain constraint conditions. The built simulation model included the air domain, polymer domain and inorganic particles domain. The sound insulation mechanism of the composite material was investigated through distributions of the sound pressure and sound pressure level.

Adjustable Sound Absorber of Multiple Parallel-Connection Helmholtz Resonators with Tunable Apertures Prepared by Low-Force Stereolithography of Photopolymer Resin.

The variable noise spectrum for many actual application scenarios requires a sound absorber to adapt to this variation. An adjustable sound absorber of multiple parallel-connection Helmholtz resonators with tunable apertures (TA-MPCHRs) is prepared by the low-force stereolithography of photopolymer resin, which aims to improve the applicability of the proposed sound absorber for noise with various frequency ranges. The proposed TA-MPCHR metamaterial contains five metamaterial cells.

Molecular Dynamics Studies of the Mechanical Behaviors and Thermal Conductivity of Polyisoprene with Different Degrees of Polymerization.

Polyisoprene, with a high degree of polymerization, is the main component of natural rubber. In the industrial production process, it is necessary to adjust the length of the macromolecule of polyisoprene to improve its plasticity. It is thus of vital importance to explore the effect of the degree of polymerization of polyisoprene on its properties, e.

Polydopamine and Mercapto Functionalized 3D Carbon Nano-Material Hybrids Synergistically Modifying Aramid Fibers for Adhesion Improvement.

In order to solve the problem of poor interfacial adhesion between aramid fibers and a rubber matrix, an efficient and mild modification method was proposed via polydopamine and mercapto functionalized graphene oxide (GO) and carbon nanotube (CNTs) hybrids synergistically modifying aramid fibers. GO and CNTs were firstly stacked and assembled into unique 3D GO-CNTs hybrids through π-π conjugation. Then, the mercapto functionalization of the assembled 3D GO-CNTs hybrids was realized via the dehydration condensation reaction between the hydroxyls of GO and the silanol groups of coupling agent.

Investigation and Optimization of the Impact of Printing Orientation on Mechanical Properties of Resin Sample in the Low-Force Stereolithography Additive Manufacturing.

The mechanical properties of resin samples in low-force stereolithography additive manufacturing were affected by the printing orientation, and were investigated and optimized to achieve excellent single or comprehensive tensile strength, compressive strength, and flexural modulus. The resin samples were fabricated using a Form3 3D printer based on light curing technology according to the corresponding national standards, and they were detected using a universal testing machine to test their mechanical properties. The influence of the printing orientation was represented by the rotation angle of the resin samples relative to the -axis, -axis and -axis, and the parameters was selected in the range 0°-90° with an interval of 30°.

Optimal Design of Acoustic Metamaterial of Multiple Parallel Hexagonal Helmholtz Resonators by Combination of Finite Element Simulation and Cuckoo Search Algorithm.

To achieve the broadband sound absorption at low frequencies within a limited space, an optimal design of joint simulation method incorporating the finite element simulation and cuckoo search algorithm was proposed. An acoustic metamaterial of multiple parallel hexagonal Helmholtz resonators with sub-wavelength dimensions was designed and optimized in this research. First, the initial geometric parameters of the investigated acoustic metamaterials were confirmed according to the actual noise reduction requirements to reduce the optimization burden and improve the optimization efficiency.

Development of Adjustable Parallel Helmholtz Acoustic Metamaterial for Broad Low-Frequency Sound Absorption Band.

For the common difficulties of noise control in a low frequency region, an adjustable parallel Helmholtz acoustic metamaterial (APH-AM) was developed to gain broad sound absorption band by introducing multiple resonant chambers to enlarge the absorption bandwidth and tuning length of rear cavity for each chamber. Based on the coupling analysis of double resonators, the generation mechanism of broad sound absorption by adjusting the structural parameters was analyzed, which provided a foundation for the development of APH-AM with tunable chambers. Different from other optimization designs by theoretical modeling or finite element simulation, the adjustment of sound absorption performance for the proposed APH-AM could be directly conducted in transfer function tube measurement by changing the length of rear cavity for each chamber.

Study on Increasing the Binding Amount of Rubber and Reinforcing Filler by Adding Aromatic Solvent Oil.

The binding amount of rubber and reinforcing filler directly affects the quality of rubber products. The effect of aromatic solvent oil (S-150) on the binding amount of rubber and reinforcing filler was studied. In order to determine the suitability of rubber after adding S-150, the curing characteristics, physical performance and tensile properties of rubber samples were tested and analyzed.

Acoustic Metamaterials for Low-Frequency Noise Reduction Based on Parallel Connection of Multiple Spiral Chambers.

Acoustic metamaterials based on Helmholtz resonance have perfect sound absorption characteristics with the subwavelength size, but the absorption bandwidth is narrow, which limits the practical applications for noise control with broadband. On the basis of the Fabry-Perot resonance principle, a novel sound absorber of the acoustic metamaterial by parallel connection of the multiple spiral chambers (abbreviated as MSC-AM) is proposed and investigated in this research. Through the theoretical modeling, finite element simulation, sample preparation and experimental validation, the effectiveness and practicability of the MSC-AM are verified.

Development and Optimization of Broadband Acoustic Metamaterial Absorber Based on Parallel-Connection Square Helmholtz Resonators.

An acoustic metamaterial absorber of parallel-connection square Helmholtz resonators is proposed in this study, and its sound absorption coefficients are optimized to reduce the noise for the given conditions in the factory. A two-dimensional equivalent simulation model is built to obtain the initial value of parameters and a three-dimensional finite element model is constructed to simulate the sound absorption performance of the metamaterial cell, which aims to improve the research efficiency. The optimal parameters of metamaterial cells are obtained through the particle swarm optimization algorithm, and its effectiveness and accuracy are validated through preparing the experimental sample using 3D printing and measuring the sound absorption coefficient by the standing wave tube detection.

Enhancing the Interfacial Adhesion with Rubber Matrix by Grafting Polydopamine-Carbon Nanotubes onto Poly(p-phenylene terephthalamide) Fibers.

To enhance the interfacial adhesion between poly(p-phenylene terephthalamide) (PPTA) fibers and a rubber matrix without damaging the fiber structures, aminated carbon nanotubes (NH-CNTs) were mildly deposited onto the fiber surface by combining the biomimetic modification of dopamine via the Michael addition reaction. Furthermore, differences between the "one-step" method and the "two-step" method were researched through adjusting the addition sequence of NH-CNTs. The surface morphologies and chemical structures of PPTA fibers before and after modification were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS).

Preparation and Characterization of Gradient Compressed Porous Metal for High-Efficiency and Thin-Thickness Acoustic Absorber.

Increasing absorption efficiency and decreasing total thickness of the acoustic absorber is favorable to promote its practical application. Four compressed porous metals with compression ratios of 0%, 30%, 60%, and 90% were prepared to assemble the four-layer gradient compressed porous metals, which aimed to develop the acoustic absorber with high-efficiency and thin thickness. Through deriving structural parameters of thickness, porosity, and static flow resistivity for the compressed porous metals, theoretical models of sound absorption coefficients of the gradient compressed porous metals were constructed through transfer matrix method according to the Johnson-Champoux-Allard model.

A Novel Method for Deposition of Multi-Walled Carbon Nanotubes onto Poly(p-Phenylene Terephthalamide) Fibers to Enhance Interfacial Adhesion with Rubber Matrix.

In order to enhance the interfacial adhesion of poly(p-phenylene terephthalamide) (PPTA) fibers to the rubber composites, a novel method to deposit multi-walled carbon nanotubes (MWCNTs) onto the surface of PPTA fibers has been proposed in this study. This chemical modification was performed through the introduction of epoxy groups by Friedel⁻Crafts alkylation on the PPTA fibers, the carboxylation of MWCNTs, and the ring-opening reaction between the epoxy groups and the carboxyl groups. The morphologies, chemical structures, and compositions of the surface of PPTA fibers were characterized by scanning electron microscope, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy.

Comparative analysis of oxidation methods of reaction-sintered silicon carbide for optimization of oxidation-assisted polishing.

Combination of the oxidation of reaction-sintered silicon carbide (RS-SiC) and the polishing of the oxide is an effective way of machining RS-SiC. In this study, anodic oxidation, thermal oxidation, and plasma oxidation were respectively conducted to obtain oxides on RS-SiC surfaces. By performing scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM-EDX) analysis and scanning white light interferometry (SWLI) measurement, the oxidation behavior of these oxidation methods was compared.

Ultrasmooth reaction-sintered silicon carbide surface resulting from combination of thermal oxidation and ceria slurry polishing.

An ultrasmooth reaction-sintered silicon carbide surface with an rms roughness of 0.424 nm is obtained after thermal oxidation for 30 min followed by ceria slurry polishing for 30 min. By SEM-EDX analysis, we investigated the thermal oxidation behavior of RS-SiC, in which the main components are Si and SiC.