scholarly journals A Convolutional Neural Network for Impact Detection and Characterization of Complex Composite Structures

Sensors ◽  
2019 ◽  
Vol 19 (22) ◽  
pp. 4933 ◽  
Author(s):  
Iuliana Tabian ◽  
Hailing Fu ◽  
Zahra Sharif Khodaei
Keyword(s):  
Composite Structures ◽  
Energy Levels ◽  
Real Life ◽  
Ultrasonic Waves ◽  
Stiffened Panel ◽  
Network Architectures ◽  
Impact Detection ◽  
Passive Sensing ◽  
External Impact

This paper reports on a novel metamodel for impact detection, localization and characterization of complex composite structures based on Convolutional Neural Networks (CNN) and passive sensing. Methods to generate appropriate input datasets and network architectures for impact localization and characterization were proposed, investigated and optimized. The ultrasonic waves generated by external impact events and recorded by piezoelectric sensors are transferred to 2D images which are used for impact detection and characterization. The accuracy of the detection was tested on a composite fuselage panel which was shown to be over 94%. In addition, the scalability of this metamodelling technique has been investigated by training the CNN metamodels with the data from part of the stiffened panel and testing the performance on other sections with similar geometry. Impacts were detected with an accuracy of over 95%. Impact energy levels were also successfully categorized while trained at coupon level and applied to sub-components with greater complexity. These results validated the applicability of the proposed CNN-based metamodel to real-life application such as composite aircraft parts.

SKIN/STRINGER INTERFACE DAMAGE CHARACTERIZATION OF STIFFENED COMPOSITE STRUCTURES

2021 ◽  
Author(s):  
WARUNA SENEVIRATNE ◽  
VISHNU SASEENDRAN ◽  
MOHAMED SHAFIE ◽  
JOHN TOMBLIN
Keyword(s):  
Composite Structures ◽  
Structural Integrity ◽  
Cohesive Zone Model ◽  
Standardized Test ◽  
Stiffened Panel ◽  
Zone Model ◽  
Damage Initiation ◽  
Test Methodology ◽  
Damage Characterization

With stiffened composite panels being widely used in aerostructures, critical failure mechanics of the skin/stringer interface need to be thoroughly understood. The interface is design critical and must demonstrate the ability to sustain design limit load throughout the service life. Buckling and out-of-plane deformations, localized in a stiffened panel can initiate separation at the interface. In addition, presence of inherent manufacturing flaws or operational impact events can lead to premature separation and result in failure. Hence, to ensure structural integrity, thorough damage characterization of skin/stringer interface must be performed. The general building block certification approach used for analysis and test validation does not contain standardized test methods beyond the coupon level. In this study, a Seven-Point Bend (7PB) based test methodology is employed to induce localized buckling-based skin separation. The 7PB methodology is utilized to evaluate panels fabricated using both co-bonding and secondary-bonding methods. The experimental work is complimented by a cohesive zone model (CZM) where the disbond initiation and progressive damage growth at the skin/stringer interface is simulated. Delamination is observed at the interface, originating centrally and progressing asymmetrically along the length of the stringer until failure occurred. The zero-thickness cohesive elements based model implemented within this work was able to capture damage initiation and predicted the final damage map. The 7PB test methodology is demonstrated to be robust and can be introduced as a standard test practice to evaluate sub-elements.

Physical Ultrasonics of Composites

2011 ◽  
Author(s):  
Dale Chimenti ◽  
Stanislav Rokhlin ◽  
Peter Nagy
Keyword(s):  
Composite Laminates ◽  
Stiffness Matrix ◽  
Composite Plates ◽  
Anisotropic Media ◽  
Anisotropic Materials ◽  
Ultrasonic Waves ◽  
Laminated Plates ◽  
Structure Characteristic ◽  
Major Advance

Physical Ultrasonics of Composites is a rigorous introduction to the characterization of composite materials by means of ultrasonic waves. Composites are treated here not simply as uniform media, but as inhomogeneous layered anisotropic media with internal structure characteristic of composite laminates. The objective here is to concentrate on exposing the singular behavior of ultrasonic waves as they interact with layered, anisotropic materials, materials which incorporate those structural elements typical of composite laminates. This book provides a synergistic description of both modeling and experimental methods in addressing wave propagation phenomena and composite property measurements. After a brief review of basic composite mechanics, a thorough treatment of ultrasonics in anisotropic media is presented, along with composite characterization methods. The interaction of ultrasonic waves at interfaces of anisotropic materials is discussed, as are guided waves in composite plates and rods. Waves in layered media are developed from the standpoint of the "Stiffness Matrix", a major advance over the conventional, potentially unstable Transfer Matrix approach. Laminated plates are treated both with the stiffness matrix and using Floquet analysis. The important influence on the received electronic signals in ultrasonic materials characterization from transducer geometry and placement are carefully exposed in a dedicated chapter. Ultrasonic wave interactions are especially susceptible to such influences because ultrasonic transducers are seldom more than a dozen or so wavelengths in diameter. The book ends with a chapter devoted to the emerging field of air-coupled ultrasonics. This new technology has come of age with the development of purpose-built transducers and electronics and is finding ever wider applications, particularly in the characterization of composite laminates.

scholarly journals A New Piano-Stool Ruthenium(II) P-Cymene-Based Complex: Crystallographic, Hirshfeld Surface, DFT, and Luminescent Studies

Crystals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 13
Author(s):  
Mohd. Muddassir ◽  
Abdullah Alarifi ◽  
Mohd. Afzal
Keyword(s):  
Density Functional ◽  
Weak Interactions ◽  
Energy Levels ◽  
Hirshfeld Surface ◽  
Binding Energies ◽  
Orbital Energy ◽  
Aminosalicylic Acid ◽  
Full Characterization

A new complex (Ru(η6-p-cymene)(5-ASA)Cl2) (1) where 5-ASA is 5-aminosalicylic acid has been prepared by reacting the ruthenium arene precursors ((η6-arene)Ru(μ-Cl)Cl)2, with the 5-ASA ligands in a 1:1 ratio. Full characterization of complex 1 was accomplished by elemental analysis, IR, and TGA following the structure obtained from a single-crystal X-ray pattern. The structural analysis revealed that complex 1 shows a “piano-stool” geometry with Ru-C (2.160(5)- 2.208(5)Å), Ru-N (2.159(4) Å) distances, which is similar to equivalents sister complex. Density functional theory (DFT) was used to calculate the significant molecular orbital energy levels, binding energies, bond angles, bond lengths, and spectral data (FTIR, NMR, and UV–VIS) of complex 1, consistent with the experimental results. The IR and UV–VIS spectra of complex 1 were computed using all of the methods and choose the most appropriate way to discuss. Hirshfeld surface analysis was also executed to understand the role of weak interactions such as H⋯H, C⋯H, C-H⋯π, and vdW interactions, which play a significant role in the crystal environment’s stability. Moreover, the luminescence results at room temperature show that complex 1 gives a more intense emission band positioned at 465 nm upon excitation at 330 nm makes it a suitable candidate for the building of photoluminescent material.

Characterization of heat transfer and friction loss of water turbulent flow in a narrow rectangular duct under 25–40 kHz ultrasonic waves

Ultrasonics ◽  
2021 ◽  
Vol 114 ◽  
pp. 106366
Author(s):  
Korpong Viriyananon ◽  
Jirachai Mingbunjerdsuk ◽  
Teerapat Thungthong ◽  
Weerachai Chaiworapuek
Keyword(s):  
Heat Transfer ◽  
Turbulent Flow ◽  
Ultrasonic Waves ◽  
Friction Loss ◽  
Rectangular Duct

Statistical Analysis of SHM Passive Sensing Systems

2015 ◽  
Vol 665 ◽  
pp. 241-244
Author(s):  
Marco Thiene ◽  
Zahra Sharif Khodaei ◽  
M.H. Aliabadi
Keyword(s):  
Statistical Analysis ◽  
Health Monitoring ◽  
Sensor Failure ◽  
Impact Detection ◽  
Sensing Systems ◽  
Detection And Identification ◽  
Passive Sensing ◽  
Service Load ◽  
Reliability And Robustness ◽  
Load Conditions

Structural Health Monitoring (SHM) techniques have gained an increased interest to be utilised alongside NDI techniques for aircraft maintenance. However, to take the SHM methodologies from the laboratory conditions to actual structures under real load conditions requires them to be assessed in terms of reliability and robustness. In this work, a statistical analysis is carried out for a passive SHM system capable of impact detection and identification. The sensitivity of the platform to parameters such as noise, sensor failure and in-service load conditions has been investigated and reported.

PREPARATION AND CHARACTERIZATION OF Zr-DOPED TiN NANOFILM

2007 ◽  
Vol 21 (18n19) ◽  
pp. 3455-3458
Author(s):  
ANPING LIU ◽  
YINFENG WANG ◽  
XUEHENG YANG
Keyword(s):  
Thin Film ◽  
Corrosion Resistance ◽  
Energy Level ◽  
Mixed Crystal ◽  
Energy Levels ◽  
Energy Band Structure ◽  
Reactive Magnetron ◽  
Tin Coating ◽  
New Energy

The Zr -doped TiN coating, a nanometer (Ti, Zr)N thin film, has been deposited by reactive magnetron sputtering on slides and Al substrates. The crystalline phase and energy band structure have been analyzed by XRD and STS. The results of XRD show that the (Ti, Zr)N film is poly crystalline and consisted of mixed crystal of TiN and ZrN phase. The STS spectra show that Zr -doping didn't change the position and band-gap of energy level, only two new energy levels appeared, Eg = 0.33eV and Eg = 0.42eV. According to the results of measurement, (Ti, Zr)N has higher hardness and better corrosion resistance than TiN by Zr -doping.

scholarly journals The Effect of High Glass Fiber Content and Reinforcement Combination on Pulse-Echo Ultrasonic Measurement of Composite Ship Structures

2021 ◽  
Vol 9 (4) ◽  
pp. 379
Author(s):  
Sang-Gyu Lee ◽  
Daekyun Oh ◽  
Jong Hun Woo
Keyword(s):  
Glass Fiber ◽  
Composite Laminates ◽  
Composite Structures ◽  
Ultrasonic Waves ◽  
Ship Structures ◽  
Glass Fiber Reinforced ◽  
Gfrp Composite ◽  
Chopped Strand Mat ◽  
Composite Ship ◽  
Pulse Echo

Ship structures made of glass fiber-reinforced polymer (GFRP) composite laminates are considerably thicker than aircraft and automobile structures and more likely to contain voids. The production characteristics of such composite laminates were investigated in this study by ultrasonic nondestructive evaluation (NDE). The laminate samples were produced from E-glass chopped strand mat (CSM) and woven roving (WR) fabrics with different glass fiber contents of 30–70%. Approximately 300 pulse-echo ultrasonic A-scans were performed on each sample. The laminate samples produced from only CSM tended to contain more voids compared with those produced from a combination of CSM and WR, resulting in the relative density of the former being lower than the design value, particularly for high glass fiber contents of ≥50%. The velocity of the ultrasonic waves through the CSM-only laminates was also lower for higher glass fiber contents, whereas it steadily increased for combined CSM–WR laminates. Burn-off tests of the laminates further revealed that the fabric configuration of the combined CSM–WR laminates was of higher quality, prevented the formation of voids, and improved inter-layer bonding. These findings indicate that combined CSM–WR laminates should be used to achieve more accurate ultrasonic NDE of GFRP composite structures.

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