Influence Of Layer Number Research Articles

Dynamic response of square sandwich panels with stagger-layered honeycomb cores under intensive near-field air blast loading

Metallic honeycomb sandwich panels have been widely used in energy dissipation due to large plastic deformation under impact/blast loading. In this paper, the dynamic response of a honeycomb sandwich panel with stagger-layered core under intensive near-field air blast loading is investigated. Comparative experiments are conducted for stagger-layered and typical honeycomb sandwich panels with the same geometrical size and mass. Numerical simulation has been undertaken based on the experiments. Numerical results coincide well with experimental results on the deformation/failure modes and center-point deflection of back face sheet. The influence of layer number as well as the geometrical parameters on the energy absorption ability of sandwich panels is clarified. Results show that stagger-layer arrangement of honeycomb core greatly improves energy dissipation capability of sandwich panels compared to typical one with the same mass. The increase of layer number and cell size benefits this effect. These findings indicates that core stagger-layer arrangement is a well choice to improve energy dissipation ability of sandwich panels under air blast loading, especially for highly intensive near-field blast loading.

Influence of Layer Number and Thickness of CrAlYN/CrAlYO Coatings on Phase Composition, Structure and Properties

Influence of Layer Number and Thickness of CrAlYN/CrAlYO Coatings on Phase Composition, Structure and Properties

Influence of layer number and sintering temperature on microstructural, tribological, and corrosion behavior of Al2O3–TiO2 multilayer coatings

The effects of layer number (2, 4, and 6-layer) and sintering temperature (800, 900, 1000, and 1100 °C) on the microstructure, wear, and corrosion properties of Al2O3–TiO2 multilayer coatings deposited on 316L stainless steel plates using the sol-gel dip coating technique were investigated. The wear characteristics were measured through ball-on-disc type dry sliding tests using an Al2O3 ball under a 1 N load, whereas the corrosion features were determined by potentiodynamic polarization tests conducted in a 3.5 wt% NaCl solution. Anatase, rutile, α-Al2O3, and γ-Al2O3 phases were obtained in the hybrid coatings, depending on the sintering temperatures. However, at 1100 °C, the coating did not adhere well to the substrate due to passive oxide film formation on the 316L plate, leading to spalling. Besides, the surface homogeneity deteriorated in the 6-layer coated sample due to higher organic removal and residual stresses. The corrosion rate decreased with the increasing number of layers, but the sensitivity to corrosion varied due to changes in surface properties. The 4-layer coated sample sintered at 1000 °C achieved the highest wear strength (improved by up to 71.1%) and corrosion resistance (increased by up to 90.4%) due to its decreased porosity and homogeneously distributed finer particles.

Analyzing the Electromagnetic Properties of CFRP by Using the Anisotropic FDTD Method

Carbon-fiber-reinforced-polymer (CFRP) materials have been widely used in military and civilian fields to replace metals as load-bearing structural components. Nevertheless, due to the complex and anisotropic internal structures, its electromagnetic (EM) protection capability is different from metal materials. Aiming at studying the EM properties of CFRP materials, an efficient analysis method based on the anisotropic finite-difference time-domain (FDTD) algorithm was proposed. First, the equivalent EM parameter tensors of a single-layer CFRP lamina were calculated by using the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$S$</tex-math></inline-formula> -parameter retrieval method. Then, a multilayer equivalent EM parameter model was established, and the execution equations of the anisotropic FDTD algorithm were derived. Finally, the influence of layer number, fiber orientation pattern, carbon fiber conductivity, and doping ratio on EM properties were studied by using the obtained method. The numerical analysis results indicated that the proposed method could improve the computational efficiency significantly while keeping the accuracy. The conclusions can provide certain engineering guidance for the electrical application of CFRP materials.

Understanding of water desalination in two-dimensional porous membrane via molecular dynamics

To explore energy-efficient two-dimensional porous materials for water desalination is an urgent demand for rational utilization of water and sustainable development. In addition, how the pore hydrophilicity influencing the desalination performance remains elusive. Basing on molecular dynamics (MD) simulations, we herein proposed ultrathin membranes of 2D covalent organic frameworks (COFs) with triazine units that are competent to reject ions efficiently while giving access to high water permeability. The ordered porous structure of these two COFs membranes (CTF-FUM and TPMA) enable nearly 100% salt rejection and show remarkable higher water permeation (∼57.2 and ∼ 48.1 L cm−2 day−1 MPa−1, respectively) over 3 magnitude compared to commercial TFC membranes (∼0.03 L cm−2 day−1 MPa−1). As a further step, the influence of layer number on membrane desalination performance was discussed to understand the underlying mechanisms. Compared to TPMA multilayer, it was found that CTF-FUM multilayer with hydrophobic pore shows less water permeability and higher transport resistance, and even has no obvious water transport through the 8-layer membrane. This MD simulation work gives a microscopic insight into 2D COF membranes on desalination and suggests that TPMA multilayer might be a promising membrane material for desalination applications.

Electrochemical Behavior of Glassy Carbon Electrode Modified by Layer-by-layer Self-assembly of Functional Graphene

In this paper, an electroactive polymer (PEI-Fc) was prepared by bonding ferrocene groups to the backbone of poly(ethyleneimine). On the other hand, sulfo-group modified graphene oxide (SGO) was also prepared. The multilayer film was constructed on glassy carbon electrode surface by the layer-by-layer adsorption method using PEI-Fc, SGO and PSS.The electorchemical activity of ferrocene in PEI-Fc/PSS or PEI-Fc/SGO film modified electrode was studied, especially the influence of layer number and pH. It is shown clearly that the graphene oxide(GO) has an inhibitory effect of electron transfer. Reduction of graphene oxide(RGO) increases the specific surface area of the glassy carbon electrode, and it is an ideal candidate for electrode modification. It is also found that ferrocene exhibited stronger electrochemical response in PEI-Fc/SGO film compared to the film without SGO. And the response of ferrocene increased with layer number and decrease of pH.

Influence of layer number and sintering on ferroelectric behaviour of barium titanate films prepared with sol-gel method

We have studied ferroelectric behaviour of barium titanate (BaTiO3) thin films prepared with sol-gel method. BaTiO3 solutions were deposited onto silicon substrates with different numbers of layers via spin coating method. The obtained samples were sintered at 700 °C and 800 °C. Structure and ferroelectric properties of the samples were investigated using X-ray diffraction (XRD) and Sawyer–Tower circuit. As observed from XRD patterns, number of layers affected the films structure. Results also showed that crystallographic system of BaTiO3 thin films was characterized by a tetragonal structure. Maximum polarization increased with an increase in layer number. Spontaneous polarization was also observed increasing with an increase in temperature.

Influence of layer number and air gap on the ballistic performance of multi-layered targets subjected to high velocity impact by copper EFP

Ballistic performance of monolithic and multi-layered steel targets penetrated by EFP is investigated both experimentally and numerically. Terminal effects of multi-layered targets are summarized to assess the pros and cons of composite structures from a macro perspective. Correspondingly, morphology features of fracture surfaces and microstructure evolution of the craters are analyzed to reveal failure mechanisms of sub-structures. The results show that the monolithic target presents less effective than in-contact or spacing multi-layered targets as the dominant response of multi-layered targets is global plastic deformation and bulging which involved bending and stretching behavior. When the number of layers grows, the local plastic deformation increases rapidly and may lead to the failure of multi-layered targets. Moreover, the air gap increases the ballistic resistance of multi-layered targets especially as the width of air gap is larger than half length of projectile.

Enhanced sound insulation and mechanical properties of LDPE/mica composites through multilayered distribution and orientation of the mica

In this work, the composites with multilayered distribution of the mica were fabricated by a multilayer coextrusion technique. The influence of layer number on sound insulation and mechanical properties of multilayered composites was investigated. The distribution, dispersion and orientation of mica particulates in composites were characterized by PLM and SEM. The sound insulation property of composites was measured by four microphone impedance tube. PLM and SEM images showed that the mica was distributed as the multilayered structure along the thickness direction of the composites. With the increase of layer number, more mica aggregates delaminated into thin flakes and aligned parallel to the flow direction. Compared to the conventional composites, the multilayered composites showed the enhanced sound insulation efficiency and mechanical properties. The discontinuity of sound impedance and the improved stiffness were considered to play a crucial role in the improvement of sound transmission loss.

Influence of Layer Number on Mechanical Property of Steel Hollow Sphere Sheet Sandwich Construction

Two sheets of steel hollow sphere sheet (TEC SHEET) are laminated and its mechanical property is investigated by means of stab proof test. The construction is sandwiched by a pair of pure aluminum plates with two kinds of bonding methods. Three point bending test and compression test are conducted for the construction. As the results, stab proof strength is advanced more than that of a single layer sheet. In the bending test, bending load increases with increase of the layer in the sandwich construction. Bending mechanism is investigated and the influence of bonding method on breakage condition of the sandwiches. Compression test for the sandwich construction and foam metal filling construction is conducted and the difference of the energy consumption behavior is investigated.

Preparation of Er3+:Y3Al5O12/TiO2 composite film and influence of layer number and layer sequence on the visible-light photocatalytic activity

In this work, the Er3+:Y3Al5O12 as up-conversion luminescence agent was mixed with TiO2 and the corresponding Er3+:Y3Al5O12/TiO2 composite films were prepared on the one-sided surface of treated sheet glass through sol-gel dip-coating method. The prepared Er3+:Y3Al5O12/TiO2 composite films were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). Their photocatalytic activities were examined through the degradation of some organic dyes under visible-light irradiation. The degradation process of organic dyes was monitored by UV-Vis spectrophotometer. Furthermore, some main influence factors on the visible-light photocatalytic activity of Er3+:Y3Al5O12/TiO2 composite film such as heat-treatment temperature and heat-treatment time were studied. The results indicate that three layer Er3+:Y3Al5O12/TiO2 composite films with one Er3+:Y3Al5O12/TiO2 composite film (as first layer close to sheet glass) and two pure TiO2 film (as second and third layers) display a higher visible-light photocatalytic activity during photocatalytic degradation of Azo Fuchsine. In addition, the results showed that the visible-light photocatalytic activity of Er3+:Y3Al5O12/TiO2 composite film related to the layer number and layer sequence on the sheet glass. Perhaps, the research results may offer some meaningful references for developing solar energy continuous flow wastewater treatment reactor.

AFM characterisation of sol‐gel TiO2 films deposited on stainless steel

AbstractOne‐layer, two‐layer and three‐layer titania films on AISI 304 stainless steel were deposited by sol‐gel process and dip‐coating method. Two sols were prepared by using titanium isopropoxide as a precursor, propanol as a solvent, nitric acid as a catalyst and acetylacetone for peptization. Both of the prepared sols contained the same amount of mentioned components, the only difference was in the addition of polyethylene glycol (PEG) as templating reagent to one of the sols. After calcination at 550°C, deposited films on the stainless steel substrate were characterized by atomic force microscope (AFM). Influence of layer number as well as addition of polyethylene glycol on morphology of titania films was analysed and discussed. Generally, by increasing the number of layers and by addition of polyethylene glycol, roughness parameters increase by changing surface topography. The surface topography analysis is very important when choosing the adequate industrial application of prepared layers.

Catalytic Oxidation of NADH on Gold Electrode Modified by Layer-by- Layer Self-Assembly of Thermostable Diaphorase and Redox Polymer

A redox polymer, poly(ethylenimine)ferrocene (PEI-Fc) was synthesized by attaching ferrocene groups to the backbone of water soluble poly(ethylenimine), and multilayer film in nanoscale was assembled on gold electrode by alternate layer-by-layer adsorption (LBL) of the positively charged PEI-Fc and the negatively charged thermostable diaphorase (DI) from B.Stearothermophilus. The LBL process was monitored and analyzed by quartz crystal microbalance (QCM) technique, which confirmed the formation of the multilayer structure. The electrochemical oxidation of coenzyme (reduced nicotinamide adenine dinucleotide, NADH) was observed on the electrode fabricated with PEI-Fc/DI multilayer film, and the influence of layer number on current response was investigated. The modified electrode retained ca. 65% relative response after storage in buffer for two months and 50% relative response after incubation at 80 °C for 3 min, which inferred that the multilayer structure was unique stable. A NAD-dependent glucose-6-phosphate dehydrogenase (G6PDH) was also immobilized via the same LBL technique, and electrode modified with PEI-Fc/DI/G6PDH film exhibited current response to glucose-6- phosphate in the presence of free NAD+.