The Effect of Ply Orientation and Damage Detection in Composite Stiffened Panel Using Lamb Waves

2019 ◽  
Vol 298 ◽  
pp. 161-166
Author(s):  
Ouadia Mouhat ◽  
Abdelmajid Bybi ◽  
Ahmed El Bouhmidi ◽  
Hasnae Boubel ◽  
Omaima Elmrabet ◽  
...  
Keyword(s):  
Acoustic Waves ◽  
Composite Structures ◽  
Laminate Composite ◽  
Lamb Waves ◽  
Stiffened Panel ◽  
Signal Acquisition ◽  
Frequency Increase ◽  
Stiffened Panels ◽  
Composite Stiffened Panel ◽  
Ply Orientation

The present work proposes a vibration study with different surface and layers orientations at 0°, 15°, 30°, 45°, 60°, 75° and 90°using the Abaqus finite element code, the frequencies Stratified laminate composite panels were studied and the comparison between damaged structures and perfect structures we used stiffened panels based on T-shaped reinforced fibers. Lamb waves (LW) were widely proposed for the long-range inspection of Structural Structural Health Monitoring (SHM) oriented composite structures, the obtained results show the angle effects on the natural frequency increase at a peak then decrease in the form of a sinusoidal half-curve and the numerical results found in this work can be compared to those of other authors in the same area of ​​research, A piezoelectric actuator is used to design acoustic waves and a sensor is used for signal acquisition.

scholarly journals Effects of plies orientations and initial geometric imperfections on buckling strength of a composite stiffened panel

2018 ◽  
Vol 191 ◽  
pp. 00008
Author(s):  
Ikram Feddal ◽  
Abdellatif Khamlichi ◽  
Koutaiba Ameziane
Keyword(s):  
Stiffened Panel ◽  
Buckling Mode ◽  
Element Analysis ◽  
Geometric Imperfections ◽  
Stiffened Panels ◽  
Specific Strength ◽  
Euler Buckling ◽  
Buckling Behavior ◽  
Composite Stiffened Panel ◽  
Strength And Stiffness

The use of composite stiffened panels is common in several activities such as aerospace, marine and civil engineering. The biggest advantage of the composite materials is their high specific strength and stiffness ratios, coupled with weight reduction compared to conventional materials. However, any structural system may reach its limit and buckle under extreme circumstances by a progressive local failure of components. Moreover, stiffened panels are usually assembled from elementary parts. This affects the geometric as well as the material properties resulting in a considerable sensitivity to buckling phenomenon. In this work, the buckling behavior of a composite stiffened panel made from carbon Epoxy Prepregs is studied by using the finite element analysis under Abaqus software package. Different plies orientations sets were considered. The initial distributed geometric imperfections were modeled by means of the first Euler buckling mode. The nonlinear Riks method of analysis provided by Abaqus was applied. This method enables to predict more consistently unstable geometrically nonlinear induced collapse of a structure by detecting potential limit points during the loading history. It was found that plies orientations of the composite and the presence of geometric imperfections have huge influence on the strength resistance.

Experimental and Numerical Study on Six- Point Bending Test of a Composite Stiffened Panel

2011 ◽  
Vol 328-330 ◽  
pp. 1309-1312
Author(s):  
Qiang Ye ◽  
San San Xiao ◽  
Pu Hui Chen
Keyword(s):  
Cohesive Zone Model ◽  
Numerical Study ◽  
Bending Test ◽  
Stiffened Panel ◽  
Zone Model ◽  
Buckling Mode ◽  
Stiffened Panels ◽  
Shell Elements ◽  
Composite Stiffened Panel ◽  
Post Buckling

A six-point bending test was presented to simulate skin/stiffener debonding under anti-symmetrical loading conditions. A novel rig was design via which the anti-symmetrical bending deformations can be forced on to the specimens. Experimental study on six-point bending test of composite stiffened panels of T700/QY8911 was done by using this rig. The tests are numerically analyzed using the finite element code ABAQUS, modeling the entire stiffened panel by shell elements, and investigating the progressive delamination by means of the cohesive zone model. The results of numerical analyses are compared to the experimental ones in terms of load-displacement curves and debonding positions between skin and stringer. The experimental and numerical resulits show that the anti-symmetrical bending deformation is the main factor which results in the asymmetrical propagation of the debonding between the skin and the stiffener. The failure mechanisms of the test are similar to the ones which induces skin/stiffener debonding during post-buckling in the anti-symmetrical buckling mode.

Damage Index Comparison for a Composite Stiffened Panel Using Lamb Wave

2007 ◽  
Vol 26-28 ◽  
pp. 1265-1268 ◽  
Author(s):  
Chan Yik Park
Keyword(s):  
Lead Zirconate Titanate ◽  
Lamb Waves ◽  
Impact Damage ◽  
Damage Index ◽  
Lead Zirconate ◽  
Low Velocity Impact ◽  
Stiffened Panel ◽  
Low Velocity ◽  
Composite Stiffened Panel ◽  
Index Comparison

Various damage index (DI) algorithms of detecting changes such as a loosen bolt and a delamination development in a composite structure were examined using ultrasonic Lamb waves generated by embedded piezoelectric active sensors. The DI is a single value that is a function of response signal’s attenuation due to any damage or changes in a structure. Various DI algorithms such as active damage interrogation (ADI), time domain root men square (RMS), short time Fourier Transform (STFT) and time reversal (TR) were discussed. For experimental validation, a composite stiffened panel was used, and loosen bolt damage and low-velocity- impact damage were tested. In order to pitch and catch Lamb waves, surface mounted PZTs (lead zirconate titanate) were used. According to the DI algorithms, appropriate ultrasonic guided Lamb waves were selected for actuators. Each set of DI algorithm and drive signal showed different characteristics to detect the damage.

Lamb-Wave Based Technique for Impact Damage Detection in Composite Stiffened Panels

2011 ◽  
Vol 488-489 ◽  
pp. 5-8 ◽  
Author(s):  
Z. Sharif-Khodaei ◽  
Ramon Rojas-Diaz ◽  
M.H. Aliabadi
Keyword(s):  
Lamb Waves ◽  
Impact Damage ◽  
Three Dimensional ◽  
Element Model ◽  
Propagation Characteristic ◽  
Stiffened Panel ◽  
Stiffened Panels ◽  
Imaging Algorithm ◽  
Before And After ◽  
Three Dimensional Finite Element

The propagation characteristic of Lamb waves activated by Piezoelectric actuators and collected by sensors in a stiffened panel has been investigated. A network of actuators is used to scan the structure before and after the presence of damage. A diagnostic imaging algorithm has been developed based on the probability of damage at each point of the structure measured by the signal reading of sensors in the benchmark and damaged structure. A damage localization image is then reconstructed by superimposing the image obtained from each sensor-actuator path. Three-dimensional finite element model with a transducer network is modeled. Damage is introduced as a small softening area in the stiffened panel. Applying the imaging algorithm, the damage location was predicted with good accuracy. This method proves to be suitable for stiffened panels, where the complicated geometry and boundary reflections make the signal processing more complicated.

scholarly journals The Effects of Ply Orientation on Nonlinear Buckling of Aircraft composite Stiffened Panel

2019 ◽  
Vol 13 (50) ◽  
pp. 126-140
Author(s):  
Ouadia Mouhat ◽  
Abdelmajid Bybi ◽  
Ahmed El Bouhmidi ◽  
Mohamed Rougui
Keyword(s):  
Stiffened Panel ◽  
Nonlinear Buckling ◽  
Composite Stiffened Panel ◽  
Ply Orientation

A fast procedure for the design of composite stiffened panels

2015 ◽  
Vol 119 (1212) ◽  
pp. 185-201 ◽  
Author(s):  
C. Bisagni ◽  
R. Vescovini
Keyword(s):  
Minimum Weight ◽  
Buckling Load ◽  
Stiffened Panel ◽  
Preliminary Design ◽  
Stiffened Panels ◽  
Design Variables ◽  
Epoxy Material ◽  
Composite Stiffened Panel ◽  
Post Buckling ◽  
Fast Procedure

AbstractThis paper describes the analysis and the minimum weight optimisation of a fuselage composite stiffened panel made from carbon/epoxy material and stiffened by five omega stringers. The panel investigated inside the European project MAAXIMUS is studied using a fast tool, which relies on a semi-analytical procedure for the analysis and on genetic algorithms for the optimisation. The semi-analytical approach is used to compute the buckling load and to study the post-buckling response. Different design variables are considered during the optimisation, such as the stacking sequences of the skin and the stiffener, the geometry and the cross-section of the stiffener. The comparison between finite element and fast tool results reveals the ability of the formulation to predict the buckling load and the post-buckling response of the panel. The reduced CPU time necessary for the analysis and the optimisation makes the procedure an attractive strategy to improve the effectiveness of the preliminary design phases.

scholarly journals Frequency-domain study of nonthermal gigahertz phonons reveals Fano coupling to charge carriers

2020 ◽  
Vol 6 (51) ◽  
pp. eabd4540
Author(s):  
Thomas Vasileiadis ◽  
Heng Zhang ◽  
Hai Wang ◽  
Mischa Bonn ◽  
George Fytas ◽  
...  
Keyword(s):  
Frequency Domain ◽  
Acoustic Waves ◽  
Lamb Waves ◽  
Charge Carriers ◽  
Acoustic Phonons ◽  
Phonon Spectra ◽  
Electron Hole Plasma ◽  
Nonequilibrium Conditions ◽  
Microelectronic Components ◽  
Anti Stokes

Telecommunication devices exploit hypersonic gigahertz acoustic phonons to mediate signal processing with microwave radiation, and charge carriers to operate various microelectronic components. Potential interactions of hypersound with charge carriers can be revealed through frequency- and momentum-resolved studies of acoustic phonons in photoexcited semiconductors. Here, we present an all-optical method for excitation and frequency-, momentum-, and space-resolved detection of gigahertz acoustic waves in a spatially confined model semiconductor. Lamb waves are excited in a bare silicon membrane using femtosecond optical pulses and detected with frequency-domain micro-Brillouin light spectroscopy. The population of photoexcited gigahertz phonons displays a hundredfold enhancement as compared with thermal equilibrium. The phonon spectra reveal Stokes–anti-Stokes asymmetry due to propagation, and strongly asymmetric Fano resonances due to coupling between the electron-hole plasma and the photoexcited phonons. This work lays the foundation for studying hypersonic signals in nonequilibrium conditions and, more generally, phonon-dependent phenomena in photoexcited nanostructures.

A General Ply Design for Aero Engine Composite Fan Blade

2017 ◽  
Author(s):  
Jiaguangyi Xiao ◽  
Yong Chen ◽  
Qichen Zhu ◽  
Jun Lee ◽  
Tingting Ma
Keyword(s):  
Composite Laminates ◽  
Composite Structures ◽  
Stacking Sequence ◽  
Composite Blade ◽  
Arduous Task ◽  
Aero Engine ◽  
Margin Of Safety ◽  
Fan Blade ◽  
The Impact ◽  
Ply Orientation

Composite fan blade ply lay-up design, which includes ply drop-off/shuffle design and stacking sequence design, makes fan blade structures different from traditional composite structures. It gives designers more freedom to construct high-quality fan blades. However, contemporary fan blade profiles are quite complex and twisted, and fan blade structures are quite different from regular composite structures such as composite laminates and composite wings. The ply drop-off design of a fan blade, especially for a fully 3D fan blade, is still an arduous task. To meet this challenge, this paper develops a ply lay-up way with the help of a software called Fibersim. The fully 3D fan blade is cut into ply pieces in Fibersim. As a result, an initial ply sequence is created and ply shuffle could revise it. Because of the complexity of ply shuffling, the ply shuffle table developed in this paper mainly refers to the design experience gained from simple plate-like laminate structures and some criterion. Besides, the impact of different ply orientation patterns on the reliability of composite fan blade is studied through static and modal numerical analysis. The results show that this ply lay-up idea is feasible for aero engine composite fan blade. Under the calculated rotating speeds, the ply stacking sequence 4 (i.e.[−45°/0°/+45°/0°] with the outer seven groups are [−45°/0°/−45°/0°]) shows the greatest margin of safety compared with other stacking sequences. Modal analysis shows that plies with different angles could have relatively big different impacts on blades vibration characteristics. The composite fan blade ply design route this paper presents has gain its initial success and the results in this paper might be used as basic references for composite blade initial structural design.

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