Nanostructural Synergism as Mn-N-C Channels in Manganese (IV) Oxide and Fluffy g-C3N4 Layered Composite with Exceptional Catalytic Capabilities

An engineering approach to estimation of the transverse shear stresses in layered composites is developed. The technique is based on the well-known D. I. Zhuravsky equation for shear stresses in an isotropic beam upon transverse bending. In general, application of this equation to a composite beam is incorrect due to the heterogeneity of the composite structure. According to the proposed method, at the first stage of its implementation, a transition to the equivalent model of a homogeneous beam is made, for which the Zhuravsky formula is valid. The transition is carried out by changing the shape of the cross section of the beam, provided that the bending stiffness and generalized elastic modulus remain the same. The calculated shear stresses in the equivalent beam are then converted to the stress values in the original composite beam from the equilibrium condition. The main equations and definitions of the method as well as the analytical equation for estimation of the transverse shear stress in a composite beam are presented. The method is verified by comparing the analytical solution and the results of the numerical solution of the problem by finite element method (FEM). It is shown that laminate stacking sequence has a significant impact both on the character and on the value of the transverse shear stress distribution. The limits of the applicability of the developed technique attributed to the conditions of the validity of the hypothesis of straight normal are considered. It is noted that under this hypothesis the shear stresses do not depend on the layer shear modulus, which explains the absence of this parameter in the obtained equation. The classical theory of laminate composites is based on the similar assumptions, which gives ground to use this equation for an approximate estimation of the transverse shear stresses in in a layered composite package.

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Singularities at the Tip of a Crack Normal to the Interface of an Anisotropic Layered Composite.

10.21236/ada131504 ◽

1983 ◽

Author(s):

T. C. T. Ting ◽

P. H. Hoang

Keyword(s):

Layered Composite

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Double-layered fiber for lightweight flexible clothing providing shielding from low-dose natural radiation

Scientific Reports ◽

10.1038/s41598-021-83272-3 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Seon-Chil Kim ◽

Jun Sik Son

Keyword(s):

Low Dose ◽

Layered Composite ◽

Radiation Shielding ◽

Flight Attendants ◽

Low Dose Radiation ◽

Natural Radiation ◽

Composite Yarn ◽

Materials Used ◽

Fiber Fabric ◽

Dose Radiation

AbstractNatural and medical radiation are the most frequent sources of daily low-dose radiation exposure for the general public, but these radiation levels are generally acceptable. Among various occupations, aviation crew members and medical workers are exposed to high levels of radiation from scattered rays. This study focused on developing clothing for shielding aviation crew members from natural radiation during air travel. Materials were selected considering their radiation-shielding properties. A tungsten double-layered composite yarn and a polyethylene terephthalate (PET) fiber fabric containing BaSO4 were manufactured. The characteristics and shielding performances of the products were analyzed. Prototypes of a protective scarf (for shielding the thyroid gland) and apron (for shielding the torso) for flight attendants were produced. A lightweight fabric was produced that neither restricts the movement of the wearer nor causes them skin discomfort. The shielding performances of the tungsten composite and PET fiber fabrics containing BaSO4 were 0.018 mmPb and 0.03 mmPb, respectively, demonstrating low-dose shielding that may be useful for protecting aviation crew members from scattered rays. The characteristics of the developed fibers are comparable to those of materials used in clothing production; therefore, low-dose radiation-shielding clothing could be manufactured for use in aviation, medical, and other industries.

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Buckling, post-buckling and geometrically nonlinear analysis of thin-walled beams using a hypothetical layered composite cross-sectional model

Acta Mechanica ◽

10.1007/s00707-021-02936-3 ◽

2021 ◽

Author(s):

N. Einafshar ◽

M. Lezgy-Nazargah ◽

S. B. Beheshti-Aval

Keyword(s):

Nonlinear Analysis ◽

Layered Composite ◽

Geometrically Nonlinear ◽

Cross Sectional ◽

Geometrically Nonlinear Analysis ◽

Post Buckling ◽

Thin Walled ◽

Sectional Model

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Dispersion and attenuation of shear wave in couple stress stratum due to point source

Journal of Vibration and Control ◽

10.1177/1077546321998880 ◽

2021 ◽

pp. 107754632199888

Author(s):

Richa Kumari ◽

Abhishek K Singh

Keyword(s):

Point Source ◽

Shear Wave ◽

Couple Stress ◽

Imperfect Interface ◽

Layered Composite ◽

Functionally Graded ◽

Function Technique ◽

Dispersive Wave ◽

Attenuation Profiles ◽

Dispersion And Attenuation

This study discusses the propagation of a horizontally polarised shear wave in a layered composite structure consisting of couple stress stratum over a functionally graded orthotropic viscoelastic substrate due to point source existing at an imperfect interface of the stratum and substrate. Because of the CS effect in the stratum, the existence of the second kind of dispersive (shear) wave is established along with conventional first kind of a shear wave. The closed-form dispersion equations and damping equations of the first and second kind of a dispersive wave are derived by adopting non-traditional boundary conditions and Green’s function technique. The effect of characteristic length of microstructure, imperfect bonding parameter and functional gradient parameters on velocity profiles and attenuation profiles of the first and second kind of dispersive wave has been computed numerically and delineated graphically. For validation, established results are matched with the classical one.

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Synthesis of ZIF-9(III)/Co LDH layered composite from ZIF-9(I) based on controllable phase transition for enhanced electrocatalytic oxygen evolution reaction

Chemical Engineering Journal ◽

10.1016/j.cej.2021.128784 ◽

2021 ◽

Vol 414 ◽

pp. 128784

Author(s):

Weibin Chen ◽

Changshui Wang ◽

Shibiao Su ◽

Hai Wang ◽

Dandan Cai

Keyword(s):

Phase Transition ◽

Oxygen Evolution ◽

Oxygen Evolution Reaction ◽

Layered Composite

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Preparation and Properties of Layered SiC-Graphene Composites for EDM

Materials ◽

10.3390/ma14112916 ◽

2021 ◽

Vol 14 (11) ◽

pp. 2916

Author(s):

Ondrej Hanzel ◽

Zoltán Lenčéš ◽

Peter Tatarko ◽

Richard Sedlák ◽

Ivo Dlouhý ◽

...

Keyword(s):

Electrical Conductivity ◽

Surface Layer ◽

Positive Influence ◽

Layered Composite ◽

Layered Composites ◽

Good Adhesion ◽

Electric Discharge Machining ◽

Layer Sequence ◽

The Individual ◽

Scratch Tests

Three and five-layered silicon carbide-based composites containing 0, 5, and 15 wt.% of graphene nanoplatelets (GNPs) were prepared with the aim to obtain a sufficiently high electrical conductivity in the surface layer suitable for electric discharge machining (EDM). The layer sequence in the asymmetric three-layered composites was SiC/SiC-5GNPs/SiC-15GNPs, while in the symmetric five-layered composite, the order of layers was SiC-15GNPs/SiC-5GNPs/SiC/SiC-5GNPs/SiC-15GNPs. The layered samples were prepared by rapid hot-pressing (RHP) applying various pressures, and it was shown that for the preparation of dense 3- or 5-layered SiC/GNPs composites, at least 30 MPa of the applied load was required during sintering. The electrical conductivity of 3-layered and 5-layered composites increased significantly with increasing sintering pressure when measured on the SiC surface layer containing 15 wt.% of GNPs. The increasing GNPs content had a positive influence on the electrical conductivity of individual layers, while their instrumented hardness and elastic modulus decreased. The scratch tests confirmed that the materials consisted of well-defined layers with straight interfaces without any delamination, which suggests good adhesion between the individual layers.

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