Study on Stealthy Characteristics of Electromagnetic Metamaterials

2012 ◽  
Vol 531-532 ◽  
pp. 276-279
Author(s):  
Ye Liu ◽  
Zhu Ying Li ◽  
Wang Zhou Zhang
Keyword(s):  
Electromagnetic Wave ◽  
Composite Materials ◽  
Physical Properties ◽  
Composite Structures ◽  
Electromagnetic Property ◽  
Transmission Characteristics ◽  
Physical Size ◽  
Natural Laws ◽  
Forming Condition ◽  
Electromagnetic Metamaterials

Metamaterials are artificial composite structures or composite materials, which possess supernormal physical properties that natural materials don’t have. Through orderly designing the structures in the critical physical size of materials, we can render the materials to break through some restriction in some certain apparent natural laws. Electromagnetic metamaterials, which have the unusual electromagnetic property of controlling the transmission of electromagnetic wave, are discussed in this paper. Also, forming condition of the metamaterials is testified in theory. In metamaterials, electromagnetic wave could come up to be bending around certain boundary, but its transmission characteristics have no change. According to the superiority of the metamaterials, the metamaterials have the unique military value in the aspect of stealth. And if metamaterials are realized in militarily, it’s no doubt that the possessors will have predominance.

Transmission electron microscopy of composite materials

1988 ◽  
Vol 46 ◽  
pp. 1012-1015
Author(s):  
K.P.D. Lagerlof
Keyword(s):  
Composite Materials ◽  
Physical Properties ◽  
Structural Defects ◽  
Structural Composites ◽  
Multiphase Materials ◽  
Structural Reinforcement ◽  
Transmission Electron ◽  
Reinforced Fiber ◽  
Particulate Reinforced Composites ◽  
Definition Of

Although most materials contain more than one phase, and thus are multiphase materials, the definition of composite materials is commonly used to describe those materials containing more than one phase deliberately added to obtain certain desired physical properties. Composite materials are often classified according to their application, i.e. structural composites and electronic composites, but may also be classified according to the type of compounds making up the composite, i.e. metal/ceramic, ceramic/ceramie and metal/semiconductor composites. For structural composites it is also common to refer to the type of structural reinforcement; whisker-reinforced, fiber-reinforced, or particulate reinforced composites [1-4].For all types of composite materials, it is of fundamental importance to understand the relationship between the microstructure and the observed physical properties, and it is therefore vital to properly characterize the microstructure. The interfaces separating the different phases comprising the composite are of particular interest to understand. In structural composites the interface is often the weakest part, where fracture will nucleate, and in electronic composites structural defects at or near the interface will affect the critical electronic properties.

Microstructure and Physical Properties of Clay-Polymer Composites

2000 ◽  
Vol 628 ◽  
Author(s):  
T.N. Blanton ◽  
D. Majumdar ◽  
S.M. Melpolder
Keyword(s):  
Composite Materials ◽  
Physical Properties ◽  
Polymer Composites ◽  
Basal Plane ◽  
X Ray Diffraction ◽  
X Ray ◽  
Layered Clay

ABSTRACTClay-polymer nanoparticulate composite materials are evaluated by the X-ray diffraction technique. The basal plane spacing provided information about the degree of intercalation and exfoliation of the 2: 1 layered clay structure. Both intercalation and exfoliation are controlled by the identity of the polymer and the clay:polymer ratio.

How the Explanations of Natural Laws Make Some Reducible Physical Properties Natural and Explanatorily Powerful

2018 ◽  
Author(s):  
Marc Lange
Keyword(s):  
Physical Properties ◽  
Scientific Practice ◽  
Center Of Mass ◽  
Natural Laws ◽  
Fundamental Properties

Some philosophers regard no reducible physical properties as perfectly natural. However, in scientific practice, some but not other reducible physical properties (such as the property of having a given center of mass) denote genuine, explanatorily potent respects in which various systems are alike. What distinguishes these natural reducible physical properties from arbitrary algebraic combinations of more fundamental properties? Some philosophers treat naturalness as a metaphysical primitive. However, this chapter I suggests that it is not—at least, not as far as the naturalness of reducible physical properties is concerned. Roughly speaking, it is argued here that a reducible physical property’s naturalness is grounded in its role in the explanation of laws.

Microstructure and physical properties of composite nonwovens produced by incorporating cotton fibers in elastic spunbond and meltblown webs for medical textiles

2021 ◽  
pp. 152808372110042
Author(s):  
Partha Sikdar ◽  
Gajanan S Bhat ◽  
Doug Hinchliff ◽  
Shafiqul Islam ◽  
Brian Condon
Keyword(s):  
Tensile Strength ◽  
Physical Properties ◽  
Composite Structures ◽  
High Surface ◽  
High Surface Area ◽  
Barrier Properties ◽  
Cotton Fibers ◽  
Adult Care ◽  
Medical Textiles ◽  
Improved Performance

The objective of this research was to produce elastomeric nonwovens containing cotton by the combination of appropriate process. Such nonwovens are in demand for use in several healthcare, baby care, and adult care products that require stretchability, comfort, and barrier properties. Meltblown fabrics have very high surface area due to microfibers and have good absorbency, permeability, and barrier properties. Spunbonding is the most economical process to produce nonwovens with good strength and physical properties with relatively larger diameter fibers. Incorporating cotton fibers into elastomeric nonwovens can enhance the performance of products, such as absorbency and comfort. There has not been any study yet to use such novel approaches to produce elastomeric cotton fiber nonwovens. A hydroentangling process was used to integrate cotton fibers into produced elastomeric spunbond and meltblown nonwovens. The laminated web structures produced by various combinations were evaluated for their physical properties such as weight, thickness, air permeability, pore size, tensile strength, and especially the stretch recovery. Incorporating cotton into elastic webs resulted in composite structures with improved moisture absorbency (250%-800%) as well as good breathability and elastic properties. The results also show that incorporating cotton can significantly increase tensile strength with improved spontaneous recovery from stretch even after the 5th cycle. Results from the experiments demonstrate that such composite webs with improved performance properties can be produced by commercially used processes.

scholarly journals Defects and uncertainties of adhesively bonded composite joints

2021 ◽  
Vol 3 (9) ◽  
Author(s):  
Sadik Omairey ◽  
Nithin Jayasree ◽  
Mihalis Kazilas
Keyword(s):  
Composite Materials ◽  
Composite Structures ◽  
Production Efficiency ◽  
Adhesive Bonding ◽  
Detection Methods ◽  
Bonded Joints ◽  
Adhesively Bonded ◽  
Adhesively Bonded Joints ◽  
Wide Range ◽  
Bonded Composite

AbstractThe increasing use of fibre reinforced polymer composite materials in a wide range of applications increases the use of similar and dissimilar joints. Traditional joining methods such as welding, mechanical fastening and riveting are challenging in composites due to their material properties, heterogeneous nature, and layup configuration. Adhesive bonding allows flexibility in materials selection and offers improved production efficiency from product design and manufacture to final assembly, enabling cost reduction. However, the performance of adhesively bonded composite structures cannot be fully verified by inspection and testing due to the unforeseen nature of defects and manufacturing uncertainties presented in this joining method. These uncertainties can manifest as kissing bonds, porosity and voids in the adhesive. As a result, the use of adhesively bonded joints is often constrained by conservative certification requirements, limiting the potential of composite materials in weight reduction, cost-saving, and performance. There is a need to identify these uncertainties and understand their effect when designing these adhesively bonded joints. This article aims to report and categorise these uncertainties, offering the reader a reliable and inclusive source to conduct further research, such as the development of probabilistic reliability-based design optimisation, sensitivity analysis, defect detection methods and process development.

scholarly journals Introduction to Macroscopic Optimal Design in the Mechanics of Composite Materials and Structures

2021 ◽  
Vol 5 (2) ◽  
pp. 36
Author(s):  
Aleksander Muc
Keyword(s):  
Composite Materials ◽  
Composite Structures ◽  
Constitutive Relations ◽  
A Priori ◽  
Chemical Properties ◽  
Composite Plates ◽  
Failure Criteria ◽  
Lagrange Equations ◽  
Homogenization Methods ◽  
Mechanics Of Composite Materials

The main goal of building composite materials and structures is to provide appropriate a priori controlled physico-chemical properties. For this purpose, a strengthening is introduced that can bear loads higher than those borne by isotropic materials, improve creep resistance, etc. Composite materials can be designed in a different fashion to meet specific properties requirements.Nevertheless, it is necessary to be careful about the orientation, placement and sizes of different types of reinforcement. These issues should be solved by optimization, which, however, requires the construction of appropriate models. In the present paper we intend to discuss formulations of kinematic and constitutive relations and the possible application of homogenization methods. Then, 2D relations for multilayered composite plates and cylindrical shells are derived with the use of the Euler–Lagrange equations, through the application of the symbolic package Mathematica. The introduced form of the First-Ply-Failure criteria demonstrates the non-uniqueness in solutions and complications in searching for the global macroscopic optimal solutions. The information presented to readers is enriched by adding selected review papers, surveys and monographs in the area of composite structures.

The effect of nanoparticle additive on surface milling in glass fiber reinforced composite structures

2021 ◽  
pp. 096739112110141
Author(s):  
Ferhat Ceritbinmez ◽  
Ahmet Yapici ◽  
Erdoğan Kanca
Keyword(s):  
Composite Materials ◽  
Glass Fiber ◽  
Composite Structures ◽  
Fiber Composite ◽  
Cutting Speed ◽  
Fiber Reinforced ◽  
Fiber Reinforced Composite ◽  
Reinforced Composite ◽  
Glass Fiber Reinforced ◽  
Composite Layers

In this study, the effect of adding nanosize additive to glass fiber reinforced composite plates on mechanical properties and surface milling was investigated. In the light of the investigations, with the addition of MWCNTs additive in the composite production, the strength of the material has been changed and the more durable composite materials have been obtained. Slots were opened with different cutting speed and feed rate parameters to the composite layers. Surface roughness of the composite layers and slot size were examined and also abrasions of cutting tools used in cutting process were determined. It was observed that the addition of nanoparticles to the laminated glass fiber composite materials played an effective role in the strength of the material and caused cutting tool wear.

scholarly journals ВИДИ МЕТРОЛОГІЧНИХ ХАРАКТЕРИСТИК І СКЛАДУ РОБІТ З ЇХ ВИЗНАЧЕННЯ НА ОСНОВНИХ СТАДІЯХ ІСНУВАННЯ КОМПОЗИТНИХ КОНСТРУКЦІЙ АГРЕГАТІВ ПОВІТРЯНИХ СУДЕН ТРАНСПОРТНОЇ КАТЕГОРІЇ

2021 ◽  
pp. 146-157
Author(s):  
М. Н. Журибеда
Keyword(s):  
Composite Materials ◽  
Polymer Composite ◽  
Metrological Support ◽  
Composite Structures ◽  
Metrological Characteristics ◽  
Polymer Composite Materials ◽  
Production Operation ◽  
Complex Criterion ◽  
Design Production ◽  
Technical Products

It is shown that the development of the concept of metrological support for the creation of composite structures of aircraft aggregates of the transport category and their support at all stages of the existence of an aircraft should be based on the formation of a complex criterion for the effectiveness of the use of polymer composite materials. It is noted that the effectiveness of a structure made of polymer composite materials is provided by various methods, methods and technical means of metrology. The structure of a complex of studies aimed at developing the concept of metrological support is discussed, the first point of which is to analyze the types of metrological characteristics and the scope of work to determine them at the main stages of the existence of composite structures of aircraft aggregates of the transport category. Based on the analysis of numerous publications on the problem of metrological support of the main stages of creating technical products, the main types of measurements of the metrological characteristics of composite structures of aircraft aggregates of the transport category have been established, and the composition of the nomenclature of works on metrological support of the main stages of the existence of these structures has been determined. 12 main types of measurements of parameters have been identified, on which the whole variety of production physical quantities and the description of the properties and characteristics of structures of aircraft aggregates made of polymer composite materials are based. The composition of the main works on the metrological support of the four stages of the existence of the aircraft is revealed: design, production, operation and disposal of composite structures formed into systems of sequential blocks for performing these works. It is shown that the tasks of metrological support at the facility manufacturers should be solved during the technological preparation of serial production and testing of the installation series of products, and also take into account the peculiarities of aircraft operation and disposal of composite structural elements in terms of work safety and economic efficiency of their results. An enlarged sequence has been established for organizing work on metrological support for measuring the properties of composite structures of aircraft aggregates at aviation enterprises. The results presented in the first approximation provide a solution to practically important aspects of the problem under discussion.

scholarly journals The development of an advanced composite structure using evolutionary design methods

2009 ◽  
Author(s):  
◽  
David Van Wyk
Keyword(s):  
Composite Materials ◽  
Composite Structure ◽  
Composite Structures ◽  
Empirical Method ◽  
Optimum Shape ◽  
Evolutionary Design ◽  
Structural Optimisation ◽  
Design For Manufacture ◽  
Advanced Composite ◽  
Evolutionary Optimisation

The development of an evolutionary optimisation method and its application to the design of an advanced composite structure is discussed in this study. Composite materials are increasingly being used in various fields, and so optimisation of such structures would be advantageous. From among the various methods available, one particular method, known as Evolutionary Structural Optimisation (ESO), is shown here. ESO is an empirical method, based on the concept of removing and adding material from a structure, in order to create an optimum shape. The objective of the research is to create an ESO method, utilising MSC.Patran/Nastran, to optimise composite structures. The creation of the ESO algorithm is shown, and the results of the development of the ESO algorithm are presented. A tailfin of an aircraft was used as an application example. The aim was to reduce weight and create an optimised design for manufacture. The criterion for the analyses undertaken was stress based. Two models of the tailfin are used to demonstrate the effectiveness of the developed ESO algorithm. The results of this research are presented in the study.

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