Application of the extinction pulse technique to non-destructive control of dielectric materials

2002 ◽  
Author(s):  
D. Batrakov ◽  
S. Shulga ◽  
N. Zhuck
Keyword(s):  
Dielectric Materials ◽  
Pulse Technique ◽  
Non Destructive

Non-Destructive Testing of Thermoplastic Carbon Composite Structures

2020 ◽  
Vol 2020 (1) ◽  
pp. 34-52
Author(s):  
Rafał Szymański
Keyword(s):  
Composite Structures ◽  
Ultrasonic Method ◽  
Composite Panel ◽  
Aviation Industry ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Pulse Technique ◽  
Thermoplastic Matrix ◽  
The Subject ◽  
Non Destructive

AbstractThe article is in line with the contemporary interests of companies from the aviation industry. It describes thermoplastic material and inspection techniques used in leading aviation companies. The subject matter of non-destructive testing currently used in aircraft inspections of composite structures is approximated and each of the methods used is briefly described. The characteristics of carbon preimpregnates in thermoplastic matrix are also presented, as well as types of thermoplastic materials and examples of their application in surface ship construction. The advantages, disadvantages and limitations for these materials are listed. The focus was put on the explanation of the ultrasonic method, which is the most commonly used method during the inspection of composite structures at the production and exploitation stage. Describing the ultrasonic method, the focus was put on echo pulse technique and the use of modern Phased Array heads. Incompatibilities most frequently occurring and detected in composite materials with thermosetting and thermoplastic matrix were listed and described. A thermoplastic flat composite panel made of carbon pre-impregnate in a high-temperature matrix (over 300°C), which was the subject of the study, was described. The results of non-destructive testing (ultrasonic method) of thermoplastic panel were presented and conclusions were drawn.

The Prs2O3 /Si(001) Interface: a Mixed Si-Pr Oxide

2003 ◽  
Vol 765 ◽  
Author(s):  
Dieter Schmeißer ◽  
Jarek Dabrowski ◽  
Hans-Joachim Müssig
Keyword(s):  
Depth Profiling ◽  
Dielectric Materials ◽  
Interface Properties ◽  
Silicide Formation ◽  
Silicate System ◽  
No Formation ◽  
Interface Characteristics ◽  
Reactive Interface ◽  
Non Destructive ◽  
Natural Way

AbstractWe studied the Pr2O3/Si(001) interface by a non-destructive depth profiling using synchrotron radiation and photo-electron spectroscopy (SR-PES) at the undulator beam line U49/2-PGM2 and ab initio calculations. Our results provide evidence that a chemical reactive interface exists consisting of a mixed Si-Pr oxide such as (Pr2O3)(SiO)x(SiO2)y. There is no formation of neither an interfacial SiO2 nor interfacial silicide: all Si-Pr bonds are oxidized and all SiO4 units dissolve in the Pr oxide. Under ultrahigh vacuum conditions, silicide formation is observed only when the film is heated above 800°C in vacuum. Interfacial silicates like (Pr2O3)(SiO)x(SiO2)y are promising high-k dielectric materials, e.g., because they represent incremental modification of SiO2 films by Pr ions, so that the interface characteristics can be similar to Si-SiO2 interface properties. The Pr silicate system formed in a natural way at the interface between Si(001) and Pr2O3 offers an increased flexibility towards integration of Pr2O3 into future CMOS technologies.

Nondestructive Extraction of Parameters of Multilayered Media Using Terahertz Pulse Technique

Frequenz ◽  
2019 ◽  
Vol 73 (1-2) ◽  
pp. 63-70
Author(s):  
Surya Prakash Singh ◽  
Nilesh K. Tiwari ◽  
M. Jaleel Akhtar
Keyword(s):  
Refractive Index ◽  
Complex Refractive Index ◽  
Multilayered Structure ◽  
Terahertz Pulse ◽  
Destructive Testing ◽  
Multilayered Media ◽  
Pulse Technique ◽  
Non Invasive ◽  
Full Wave ◽  
Non Destructive

Abstract In this work, an efficient non-invasive terahertz pulse technique is proposed and investigated to determine the thickness and refractive index of each layer in an optically thick stratified media. A closed form formulations are derived for simultaneous extraction of the thickness and complex refractive index of each layer with the help of primary reflected signals from the multilayered structure. The proposed technique is numerically tested using a full wave electromagnetic simulator and is experimental verified in the millimeter wave frequency range by utilizing the power peaks corresponding to the primary reflected signals. The numerical and measured results of multilayered samples under test are in good agreement with the reference data. The proposed terahertz pulse technique can be used for non-destructive testing of the multilayered system existing in various industries.

scholarly journals Quality control of substances by electromagnetic sensing in a waveguide

2020 ◽  
Keyword(s):  
Dielectric Constant ◽  
Electromagnetic Wave ◽  
Standing Wave ◽  
Dielectric Materials ◽  
Complex Dielectric Constant ◽  
Microwave Range ◽  
Dielectric Sample ◽  
Layered Dielectric ◽  
Dielectric Structures ◽  
Non Destructive

Relevance. The problems of remote non-destructive determination and control of quality indicators of a wide variety of material environments, in particular, household and food products, are relevant practically for all areas of the national economy, science and technology. The relevance of scientific research in the field of dielectrometry in the microwave range is also due to the needs for the development of high technologies in medicine and health care, the national economy in real time. The aim of this work is to develop the method of microwave waveguide dielectrometry based on the application of the theory of multilayer plane-layered dielectric structures to the determination of the complex dielectric constant of a substance from the values ​​of the standing wave ratio of the samples under study in a waveguide at two close frequencies. Materials and methods. The research is based on well-studied phenomena of interference of electromagnetic waves on multilayer plane-layered dielectric structures. By using a mathematical model of the phenomenon of interference of a plane electromagnetic wave on a three-layer dielectric structure, the ambiguity of determining the complex dielectric constant of a substance by the classical method of waveguide dielectrometry in the microwave range by measuring the standing wave ratio of a dielectric sample placed in the waveguide and the phase angle of the reflection coefficient is overcome. Results. A method is proposed for ensuring the unambiguity of determining the complex dielectric constant of a substance in waveguide dielectrometry on the basis of the theory of multilayer plane-layered dielectric structures. The method leads to an explicit expression for the complex reflection coefficient of an electromagnetic wave from the investigated dielectric sample placed in a rectangular waveguide. The complex dielectric constant of a substance is determined from the values ​​of the standing wave ratio at two close frequencies in the microwave range. By the found value of the dielectric constant and the tangent of the dielectric loss angle, the quality parameter of the substance is determined by comparing and optimizing two objective functions, including the arrays of reference values ​​of the complex dielectric constant obtained in the course of measurements and compiled in advance, and by comparing and optimizing the third objective function, previous functions. As an example of an indicator of the quality of a substance, the specific heat of combustion of coal was determined. Conclusions. The proposed method for determining the complex dielectric constant and quality indicators of dielectric materials in the microwave frequency range has been tested in the case of various types of coals, its efficiency has been proven and the reliability of the results has been proven. The method and the devices and software implemented on its basis are promising for non-destructive express control of dielectric materials and media.

Automatic defect recognition for pulsed terahertz inspection of basalt fiber reinforced composites

2016 ◽  
Vol 35 (4) ◽  
pp. 1346-1359 ◽  
Author(s):  
Przemyslaw Lopato
Keyword(s):  
Electromagnetic Waves ◽  
Dielectric Material ◽  
Conductive Polymer ◽  
Basalt Fiber ◽  
Principal Component ◽  
Dielectric Materials ◽  
Fiber Reinforced ◽  
Content Type ◽  
Non Destructive Evaluation ◽  
Non Destructive

Purpose – The purpose of this paper is to present a system for automatic recognition of defects detected in non-conductive polymer composites using pulsed terahertz imaging. Design/methodology/approach – On the beginning, non-destructive evaluation of composites using electromagnetic waves in terahertz frequency is shortly introduced. Next automatic defects recognition (ADR) algorithm is proposed, focussing on new features calculation. Dimensionality of features space is reduced by using principal component analysis. Finally, results of basalt fiber reinforced composite materials inspection and identification using artificial neural networks is presented and discussed. Findings – It is possible to develop ADR system for non-destructive evaluation of dielectric materials using pulsed terahertz technique. New set of features in time and frequency domains is proposed and verified. Originality/value – ADR in non-destructive testing is utilized in case of digital radiography and ultrasonic testing. Terahertz inspection with pulsed excitation is reported as a source of many useful information about the internal structure of the dielectric material. Up to now ADR based on terahertz non-destructive evaluation systems was not utilized.

scholarly journals Ultrasonic pulse technique for evaluation of mechanical damage in processed coffee beans

2017 ◽  
Vol 38 (5) ◽  
pp. 3007
Author(s):  
Mariana De Oliveira e Silva ◽  
Francisco Carlos Gomes ◽  
Stella Dellyzete Veiga Franco da Rosa
Keyword(s):  
Elastic Modulus ◽  
Stress Wave ◽  
Storage Conditions ◽  
Ultrasonic Pulse ◽  
Coffee Bean ◽  
Pulse Technique ◽  
Indirect Measure ◽  
Coffee Beans ◽  
The Impact ◽  
Non Destructive

The knowledge of the physical characteristics of the coffee bean allows the transition from the conventional storage model in bags to the silo storage, and as an indirect measure of the improvement and conservation of the quality of the stored grain. The elastic modulus allows comparisons on the strength of material. The variations of this occur due to its chemical composition, microstructures and material defects, being able to be used as indicator of the physical integrity of the grain. The ultrasonic pulse technique is an alternative to obtain the elastic modulus in a simple and non-destructive way. In this context, it was proposed the development of a non-destructive methodology that will perform the quality evaluation by determining the elastic modulus of the coffee beans. For this purpose, a reference silo was constructed, reproducing the storage conditions, and the elastic modulus values were determined. The values obtained by the Stress Wave Timer apparatus are between 2.54 and 4.23 MPa, with a maximum load of 8.32 kN, and a calculated vertical pressure of 1,526 kPa. To evaluate the impact of the storage conditions and the loads applied during the non-destructive test, laboratory tests applied in seeds were performed, and the tetrazolium test was the only one able to differentiate the samples. It was concluded that Stress Wave Timer was able to determine the elastic modulus values for the coffee bean mass and could be used as an indicative of the quality.

Evaluation of a Novel Microwave Based NDT Inspection Method for Polyethylene Joints

2011 ◽  
Author(s):  
Ken Murphy ◽  
David Lowe
Keyword(s):  
Low Voltage ◽  
Cold Fusion ◽  
Dielectric Materials ◽  
Field Trials ◽  
Microwave Imaging ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Inspection Method ◽  
Butt Welds ◽  
Non Destructive

Exova is continuing in the long tradition of Pipeline Developments Limited (PDL) in the UK with research, development, testing, quality assurance (QA) and failure analysis of modern plastic pipe materials and joints. Along with this ongoing work Exova has assessed various non destructive testing (NDT) techniques in an attempt to further improve the reliability of Polyethylene (PE) joints in the field. In the past, reliable inspection of PE pipe joints using NDT has proven to be difficult, but this has generally been based upon the use of existing metallic inspection methods, including radiography and ultrasound. However neither radiography nor ultrasound can reliably detect key issues that are known to affect PE joint quality such as fine particulate contamination and cold fusion in butt welds and misalignment and contamination in electrofusion joints. Advances in technology have seen the development of a new non destructive testing (NDT) technique using low voltage microwave imaging. Microwave imaging has been developed in North America by Evisive Inc to inspect modern dielectric materials such as PE. Comprehensive laboratory testing indicated that this technique could be used reliably and repeatedly to detect issues related to poor PE joint fabrication in butt welds and electrofusion joints. Issues which have been identified include fine particle contamination, lack of fusion and misalignment. More recently field trials have been carried out on various PE joints, to establish a correlation between the microwave NDT results obtained and mechanical testing results.

Characterizing Dielectric Materials using Monostatic Transmission- and Reflection-Ellipsometry

Frequenz ◽  
2017 ◽  
Vol 71 (3-4) ◽  
Author(s):  
Jan Barowski ◽  
Ilona Rolfes
Keyword(s):  
Incident Angle ◽  
Dielectric Materials ◽  
Microwave Frequencies ◽  
Single Antenna ◽  
Accurate Knowledge ◽  
Non Destructive ◽  
Source Of Error ◽  
Transmission And Reflection

AbstractThe characterization of dielectric materials at microwave frequencies can be done by various measurement principles. Free space methods are a commonly used approach if the material under test (MUT) has to be characterized in-situ or in a non-destructive manner. Since the transmission and reflection parameters of a finite sized dielectric slab typically depend on its thickness, accurate knowledge about this parameter is of high importance. The ellipsometric approach presented in this paper eliminates the thickness dependence and thus allows to reduce a major source of error. This is achieved by performing four measurements. These measure the transmission and reflection factors of the MUT in both polarizations at an incident angle of 45°. The high stability of the measurement allows a simple monostatic setup utilizing a single antenna. The measurements in this paper are performed using Polytetrafluoroethylene (PTFE) and Polyvinylchloride (PVC) blocks in the frequency range from 22 GHz to 26 GHz.

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