Self-Sensing of Stresses and Strains Through the Dielectrostriction Effect in Composites

2006 ◽  
Author(s):  
Ho Young Lee ◽  
Yuri M. Shkel
Keyword(s):  
Composite Materials ◽  
Dielectric Material ◽  
Theoretical Background ◽  
Sensing Technology ◽  
Planar Capacitor ◽  
Good Potential ◽  
Principal Directions ◽  
Carbon Nanotube Composite ◽  
Non Destructive ◽  
Principal Strains

Any dielectric material would vary its dielectric properties with deformation. By measuring these variations one could monitor stresses or strains with no mechanical interface with a load-bearing member. This effect, called dielectrostriction, can be formulated as a linear relation between the stress/strain and the dielectric response of a material. A planar capacitor on a rigid substrate is utilized to monitor the dielectrostriction effect. A rosette of such sensors can be located on the surface or embedded in the monitored part. A four-sensor rosette measures principal directions and difference of principal strains. Overall, this sensing technology shows a good potential for Non-Destructive Evaluation (NDE) and structural health monitoring of composite materials. This work provides theoretical background and experimental study of dielectrostriction response in polycarbonate, polyethylene, acrylic, and carbon nanotube composite materials.

Damage in Composite Material: A Microwave Detection

2014 ◽  
Vol 605 ◽  
pp. 303-305
Author(s):  
Jerome Rossignol ◽  
Alain Thionnet
Keyword(s):  
Composite Materials ◽  
Composite Structures ◽  
Dielectric Material ◽  
Low Cost ◽  
Unidirectional Composite ◽  
Microstrip Resonator ◽  
Microwave Frequencies ◽  
Fibre Break ◽  
Materials Used ◽  
Non Destructive

In the field of the transport, the increase of the security rule recommends to a periodic control of the structure to detect damage due to mechanical loadings. Now, current materials, used in the case of transport applications, are the composite materials. The methods, to control these materials or composite structures, need to be low cost, non-destructive, in-situ and swiftness as far as possible. The scientific literature reports many methods to control the damage in composite materials and structures. However the above requirements and the adaptation to composite materials reduce the number of methods that can be used. Currently, the adapted methods are based on infrared thermography, acoustical emission, EMIR (ElectroMagnetic InfraRed) or microwave imagery. We present an innovative non-destructive method of detecting damages in composite materials. The method is based on the observation and analysis of the modification in dielectric material resulting from damage. The originality of this method is that the diagnostic is obtained by using a microstrip resonator at microwave frequencies. The feasibility of the method is demonstrated by the detection of a fibre break into an unidirectional composite submitted to a flexural loading. The fibre break is the damage to detect. The perspective of this work is to develop a quantification and a localization of damages.

scholarly journals Roll-to-Roll In-Line Implementation of Microwave Free-Space Non-Destructive Evaluation of Conductive Composite Thin Layer Materials

2021 ◽  
Vol 11 (1) ◽  
pp. 378
Author(s):  
Grigorios Koutsoukis ◽  
Ivan Alic ◽  
Antonios Vavouliotis ◽  
Ferry Kienberger ◽  
Kamel Haddadi
Keyword(s):  
Thin Film ◽  
Composite Materials ◽  
Free Space ◽  
Near Field ◽  
Line Production ◽  
Roll To Roll ◽  
Corrugated Horn ◽  
Evaluation Module ◽  
Microwave Nondestructive Testing ◽  
Non Destructive

A free-space microwave nondestructive testing and evaluation module is developed for the low-power, non-ionizing, contactless, and real-time characterization of doped composite thin-film materials in an industrial context. The instrumentation proposed is built up with a handled vector network analyzer interfaced with corrugated horn antennas to measure the near-field complex reflection S11 of planar prepreg composite materials in a roll-to-roll in-line production line. Dedicated modeling and calibrations routines are developed to extract the microwave conductivity from the measured microwave signal. Practical extraction of the radiofrequency (RF) conductivity of thin film prepreg composite materials doped with nano-powders is exemplary shown at the test frequency of 10 GHz.

scholarly journals Inspection of the Composite Materials

2021 ◽  
Vol 10 (3) ◽  
pp. 146
Author(s):  
Yaser A. Jasim ◽  
Senan Thabet ◽  
Thabit H. Thabit
Keyword(s):  
Composite Materials ◽  
Visual Inspection ◽  
Magnetic Particle ◽  
Phased Array ◽  
Ultrasonic Inspection ◽  
Test Method ◽  
Main Method ◽  
Destructive Test ◽  
Eddy Current Inspection ◽  
Non Destructive

<p><em>A non-destructive test method is the main method to examine most of the materials, composite materials in particular. There are too many </em><em>Non-Destructive Test (</em><em>NDT) methods to inspect the materials such as, Visual Inspection, Liquid Penetrate Inspection, Eddy-Current Inspection, Phased Array Inspection, Magnetic Particle Inspection and Ultrasonic Inspection</em><em>.</em></p><p><em>This paper aims to creat a unified methodology for engineers depending on reaserch onion to study the inspection of the composite materials.</em></p><p><em>The researchers concluded that NDT method is the most suitable method for testing any materials and the composite materials. They also recommended to choose the most suitable NDT method as every materials and composite materials have its own properties as well as the inspection methods had its own capabilities and limitations. </em></p>

scholarly journals Strain in Shear, and Material Behaviour in Incremental Forming

2007 ◽  
Vol 344 ◽  
pp. 519-526 ◽  
Author(s):  
Wilko C. Emmens ◽  
A.H. van den Boogaard
Keyword(s):  
Experimental Data ◽  
Incremental Forming ◽  
Material Behaviour ◽  
Principal Directions ◽  
Circular Grid ◽  
Principal Strains

This paper discusses some consequences of forming by shear, a situation that is sometimes claimed to occur in incremental forming. The determination of the principal strains and principal directions is discussed in detail. Two methods are presented: using a circular grid (although simulated on the computer), and by deriving formulae from the theory; both yield identical results. The strains assuming forming by shear are found to be (much) higher than in situations of forming by stretch. This affects notably more fundamental studies on material behaviour in incremental forming. The effects are illustrated using experimental data obtained with pre-stressed material.

scholarly journals On the Thickness Quantification of Composite Materials by Using Lock-In Thermography

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1185
Author(s):  
Davide Palumbo
Keyword(s):  
Composite Materials ◽  
Measurement Accuracy ◽  
Plastic Material ◽  
Thickness Measurement ◽  
Glass Fiber Reinforced Plastic ◽  
Glass Fiber Reinforced ◽  
Reinforced Plastic ◽  
Test Parameters ◽  
Lock In ◽  
Non Destructive

Many structural components made of composite materials need an accurate thickness control during fabrication and/or maintenance. In this regard, various non-destructive techniques can be used for the online measuring of thickness of large components such as wings and fuselage in the aerospace industry. In this work, the capabilities of lock-in thermography technique in thickness measurement of glass fiber reinforced plastic material were investigated and a correct procedure has been proposed to ensure the best measurement accuracy. An analytical approach and several tests were carried out on a sample specimen with the aim to study the main test parameters. Finally, the limits of technique have been discussed.

The significance of damage and defects and their detection in composite materials: A review

1992 ◽  
Vol 27 (1) ◽  
pp. 29-42 ◽  
Author(s):  
W J Cantwell ◽  
J Morton
Keyword(s):  
Composite Materials ◽  
Damage Detection ◽  
Failure Modes ◽  
Fracture Mechanisms ◽  
Reinforced Composites ◽  
Load Bearing ◽  
Fibre Composites ◽  
Non Destructive ◽  
Fibre Reinforced Composites ◽  
Non Destructive Techniques

In this paper the various failure modes which occur in long fibre composites are described and discussed. The significance of each of these fracture mechanisms, in terms of their energy-dissipating capacity as well as their effect on the residual load-bearing properties, is considered. A brief review of both the destructive and non-destructive techniques used for detecting and characterizing defects and damage is presented. The ability of each technique to identify the various fracture mechanisms involved in the failure of long fibre reinforced composites is discussed and their overall suitability for damage detection evaluated.

scholarly journals A Simple High-Resolution Near-Field Probe for Microwave Non-Destructive Test and Imaging

Sensors ◽  
2020 ◽  
Vol 20 (9) ◽  
pp. 2670
Author(s):  
Zipeng Xie ◽  
Yongjie Li ◽  
Liguo Sun ◽  
Wentao Wu ◽  
Rui Cao ◽  
...  
Keyword(s):  
High Resolution ◽  
Dielectric Material ◽  
Near Field ◽  
Skin Layer ◽  
Destructive Testing ◽  
Microwave Frequencies ◽  
Metal Materials ◽  
Microstrip Ring ◽  
Planar Circuit ◽  
Non Destructive

Non-destructive tests working at lower microwave frequencies have large advantages of dielectric material penetrability, lower equipment cost, and lower implementation complexity. However, the resolution will become worse as the work frequencies become lower. Relying on designing the structure of high field confinement, this study realizes a simple complementary spiral resonators (CSRs)-based near-field probe for microwave non-destructive testing (NDT) and imaging around 390 MHz (λ = 769 mm) whereby very high resolution (λ/308, 2.5 mm) is achieved. By applying an ingenious structure where a short microstrip is connected to a microstrip ring to feed the CSR, the probe, that is a single-port microwave planar circuit, does not need any extra matching circuits, which has more application potential in sensor arraying compared with other microwave probes. The variation of the electric field distribution with the standoff distance (SOD) between the material under test and the probe are analyzed to reveal the operation mechanisms behind the improved sensitivity and resolution of the proposed probe. Besides, the detection abilities of the tiny defects in metal and non-metal materials are demonstrated by the related experiments. The smallest detectable crack and via in the non-metal materials and the metal materials are of a λ/1538 (0.5 mm) width, a λ/513 (1.5 mm) diameter, a λ/3846 (0.2 mm) width and a λ/513 (1.5 mm) diameter, respectively. Moreover, to further evaluate the performance of the proposed probe, the defects under skin layer in the multilayer composite materials and the defects under corrosion in the carbon steel are inspected and imaged. Due to lower work frequency, high resolution, outstanding detection abilities of tiny defects, and large potentials in sensor arraying, the proposed probe would be a good candidate for microwave NDT and imaging.

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