Enhancement Techniques for Ultrasonic Nondestructive Evaluation of Composite Materials

1990 ◽  
Vol 112 (2) ◽  
pp. 175-182 ◽  
Author(s):  
S. C. Wooh ◽  
I. M. Daniel
Keyword(s):  
Composite Materials ◽  
Impact Damage ◽  
Histogram Equalization ◽  
Matrix Cracking ◽  
Computer Data ◽  
Thermally Induced ◽  
Extraneous Noise ◽  
Suitable Combination ◽  
Contrast Stretching ◽  
Boundary Characteristics

Conventional ultrasonic C-scanning sometimes produces distorted and degraded images due to a variety of reasons, including surface roughness, beam dispersion, extraneous noise and imperfect fidelity of the total acquisition system. Enhancement techniques, using computer data acquisition and processing, can be used to enhance and restore the image. Enhancement techniques described include contrast stretching and median filtering, histogram equalization, thresholding, dynamic thresholding, thresholding depending on boundary characteristics, one-dimensional segmentation and intensity scans with hidden line removal. These enhancement techniques were applied and illustrated for five different types of damage in graphite/epoxy composite materials: (1) Embedded film patch in quasi-isotropic laminate; (2) impact damage in quasi-isotropic laminate; (3) matrix cracking due to static loading of crossply laminate; (4) fatigue damage in crossply laminate; and (5) thermally induced cracks in a thick crossply laminate. There is no single technique that is optimum in all cases. A suitable combination of techniques must be selected for optimum image quality.

Investigation of the mechanical and forming behaviour of 3D warp interlock carbon woven fabrics for complex shape of composite material

2021 ◽  
pp. 152808372098410
Author(s):  
Mehmet Korkmaz ◽  
Ayşe Okur ◽  
Ahmad Rashed Labanieh ◽  
François Boussu
Keyword(s):  
Composite Materials ◽  
Complex Shape ◽  
Impact Damage ◽  
Woven Fabrics ◽  
Forming Process ◽  
Warp Yarn ◽  
Delamination Resistance ◽  
Fabric Architecture ◽  
Weave Pattern ◽  
Carbon Fabrics

Composite materials which are reinforced with 3D warp interlock fabrics have outstanding mechanical properties such as higher delamination resistance, ballistic damage resistance and impact damage tolerance by means of their improved structural properties. Textile reinforcements are exposed to large deformations in the production stage of composite materials which have complex shape. Although good formability properties of 3D warp interlock fabrics in forming process were already proven by recent studies, further information is needed to elucidate forming behaviours of multi-layer fabrics which is produced with high stiffness yarns like carbon. In this study, 3D warp interlock carbon fabrics were produced on a prototype weaving loom and the same carbon yarn was used in two fabric directions with equal number of yarn densities. Fabrics were differentiated with regard to the presence of stuffer warp yarn, weave pattern and parameters of binding warp yarn which are angle and depth. Therefore, the effect of fabric architecture on the mechanical and formability properties of 3D warp interlock carbon fabrics could be clarified. Three different breaking behaviours of fabrics were detected and they were correlated with crimp percentages of yarn groups. In addition, the bending and shear deformations were analysed in view of parameters of fabric architectures. Two distinct forming behaviours of fabrics were determined according to the distribution of deformation areas on fabrics. Moreover, the optimal structure was identified for forming process considering the fabric architecture.

Multi-continuum analysis of thermally induced matrix cracking

2005 ◽  
Vol 72 (12) ◽  
pp. 1993-2008 ◽  
Author(s):  
Seth Nickerson ◽  
J. Steven Mayes ◽  
Jeffry S. Welsh
Keyword(s):  
Matrix Cracking ◽  
Thermally Induced ◽  
Continuum Analysis

Aspects of Strain Rate Effects on Some Composite Materials

2000 ◽  
Author(s):  
Emmanuel O. Ayorinde
Keyword(s):  
Acoustic Emission ◽  
Composite Materials ◽  
Strain Rate ◽  
Matrix Cracking ◽  
Epoxy Composites ◽  
Fiber Architecture ◽  
Strain Rate Effects ◽  
Rate Effects ◽  
General Strain ◽  
Ultrasonic Images

Abstract Effects of moderate straining speed on the material and damage characteristics of beam samples of graphite/epoxy and E-glass/epoxy composites were investigated. The basic fiber architecture utilized was unidirectional, axial layup, but data was also obtained for the 45-degree orientation. Ultrasonic and acoustic emission (AE) inspections were utilized. The acoustic emission records show matrix cracking. The ultrasonic images revealed the regions of failure. The results show that in general, strain rate notably affects material and damage properties.

scholarly journals Anfis to Detect Brain Tumor Using MRI

2018 ◽  
Vol 7 (3.27) ◽  
pp. 209
Author(s):  
Susmita Mishra ◽  
M Prakash ◽  
A Hafsa ◽  
G Anchana
Keyword(s):  
Fuzzy Logic ◽  
Brain Tumor ◽  
Graphical Representation ◽  
Fuzzy Inference ◽  
Early Stage ◽  
Histogram Equalization ◽  
Input Image ◽  
Inference System ◽  
Magnetic Resonance Imaging Mri ◽  
Contrast Stretching

Processing of Magnetic Resonance Imaging(MRI) is one of the widely known best techniques to diagnose brain tumor since it gives better results than ultrasound or X-Ray images. The main objective is to diagnose the presence and extraction of brain tumor using MRI images. Image preprocessing includes contrast stretching, noise filtering and Adaptive Histogram Equalization(AHE). AHE gives a graphical representation of digital image without enhancing above the desired level. The next stage involves transferring the redundant information in input image to reduced set of features is called feature selection and is done by color, shape or texture of an image. Image is segmented using incorporation of Artificial Neural Networks(ANN) and Fuzzy logic called Adaptive Neuro-Fuzzy Inference System(ANFIS) wherein we get the desired output to differentiate tumor affected and normal image with its severity level. Since we deal with uncertainty much more, fuzzy logic serves as a vibrant tool in representing human knowledge as IF-THEN rules. MATLAB has been implemented in detection and extraction of tumor at an early stage. 

scholarly journals Peningkatan Kualitas Citra pada Citra Digital Gelap

2020 ◽  
Vol 4 (2) ◽  
pp. 136-144
Author(s):  
Faisal Dharma Adhinata ◽  
Ariq Cahya Wardhana ◽  
Diovianto Putra Rakhmadani ◽  
Akhmad Jayadi
Keyword(s):  
Histogram Equalization ◽  
Log Transformation ◽  
Bit Plane ◽  
Contrast Stretching

Salah satu tahap utama dalam pemrosesan citra digital adalah peningkatan kualitas citra. Citra yang berwarna gelap tidak terlihat detail informasi yang terkandung pada citra. Bahkan objek yang tampak pada citra bisa tidak terlihat karena pengambilan citra dilakukan pada pencahayaan kurang. Citra gelap perlu dilakukan peningkatan kualitas citra supaya detail informasi citra dapat terlihat secara visual. Beberapa algoritma peningkatan kualitas citra digital diantaranya negative transformation, log transformation, contrast stretching, bit plane slice, dan histogram equalization. Pada penelitian ini akan dikaji beberapa algoritma peningkatan kualitas citra untuk melihat hasil terbaik dari kasus citra gelap. Berdasarkan hasil percobaan, diperoleh hasil terbaik menggunakan algoritma histogram equalization. Algoritma histogram equalization menghasilkan histogram citra yang tersebar rata sehingga detail informasi citra dapat dilihat secara visual.

scholarly journals Damage detection in laminar thermoplastic composite materials by means of embedded optical fibers

2006 ◽  
Vol 60 (7-8) ◽  
pp. 176-179
Author(s):  
Aleksandar Kojovic ◽  
Irena Zivkovic ◽  
Ljiljana Brajovic ◽  
Dragan Mitrakovic ◽  
Radoslav Aleksic
Keyword(s):  
Composite Materials ◽  
Optical Fiber ◽  
Real Time ◽  
Optical Fibers ◽  
Impact Damage ◽  
Experimental Testing ◽  
Low Energy ◽  
Thermoplastic Composite ◽  
Woven Fabric ◽  
The Impact

This paper investigates the possibility of applying optical fibers as sensors for investigating low energy impact damage in laminar thermoplastic composite materials, in real time. Impact toughness testing by a Charpy impact pendulum with different loads was conducted in order to determine the method for comparative measurement of the resulting damage in the material. For that purpose intensity-based optical fibers were built in to specimens of composite materials with Kevlar 129 (the DuPont registered trade-mark for poly(p-phenylene terephthalamide)) woven fabric as reinforcement and thermoplastic PVB (poly(vinyl butyral)) as the matrix. In some specimens part of the layers of Kevlar was replaced with metal mesh (50% or 33% of the layers). Experimental testing was conducted in order to observe and analyze the response of the material under multiple low-energy impacts. Light from the light-emitting diode (LED) was launched to the embedded optical fiber and was propagated to the phototransistor-based photo detector. During each impact, the signal level, which is proportional to the light intensity in the optical fiber, drops and then slowly recovers. The obtained signals were analyzed to determine the appropriate method for real time damage monitoring. The major part of the damage occurs during impact. The damage reflects as a local, temporary release of strain in the optical fiber and an increase of the signal level. The obtained results show that intensity-based optical fibers could be used for measuring the damage in laminar thermoplastic composite materials. The acquired optical fiber signals depend on the type of material, but the same set of rules (relatively different, depending on the type of material) could be specified. Using real time measurement of the signal during impact and appropriate analysis enables quantitative evaluation of the impact damage in the material. Existing methods in most cases use just the intensity of the signal before and after the impact, as the measure of damage. This method could be used to monitor the damage in real time, giving warnings before fatal damage occurs.

scholarly journals Modeling the Effective Conductive Properties of Polymer Nanocomposites with a Random Arrangement of Graphene Oxide Particles

2021 ◽  
pp. 167-180
Author(s):  
M. A Tashkinov ◽  
A. D Dobrydneva ◽  
V. P Matveenko ◽  
V. V Silberschmidt
Keyword(s):  
Finite Element ◽  
Graphene Oxide ◽  
Composite Materials ◽  
Polymer Matrix ◽  
Matrix Cracking ◽  
Tunneling Effect ◽  
Representative Volume ◽  
Representative Volume Elements ◽  
Oxide Particles ◽  
Conductive Properties

Сomposite materials are widely used in various industrial sectors, for example, in the aviation, marine and automotive industries, civil engineering and others. Methods based on measuring the electrical conductivity of a composite material have been actively developed to detect internal damage in polymer composite materials, such as matrix cracking, delamination, and other types of defects, which make it possible to monitor a composite’s state during its entire service life. Polymers are often used as matrices in composite materials. However, almost always pure polymers are dielectrics. The addition of nanofillers, such as graphene and its derivatives, has been successfully used to create conductive composites based on insulating polymers. The final properties of nanomodified composites can be influenced by many factors, including the type and intrinsic properties of nanoscale objects, their dispersion in the polymer matrix, and interphase interactions. The work deals with modeling of effective electric conductive properties of the representative volume elements of nanoscale composites based on a polymer matrix with graphene oxide particles distributed in it. In particular, methods for evaluating effective, electrically conductive properties have been studied, finite element modelling of representative volumes of polymer matrices with graphene oxide particles have been performed, and the influence of the tunneling effect and the orientation of inclusions on the conductive properties of materials have been investigated. The possibility of using models of resistive strain gauges operating on the principle of the tunneling effect is studied. Based on the finite-element modeling and graph theory tools, we created approaches for estimating changes in the conductive properties of the representative volume elements of a nanomodified matrix subjected to mechanical loading.

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