Effect of Thermal Residual Stress on FBG Sensors Embedded in Composite T-Stiffened Panels

2012 ◽  
Vol 152-154 ◽  
pp. 1550-1554
Author(s):  
Yu Jing Zhou ◽  
Gang Liu ◽  
Xue Qin Li ◽  
Xiao Su Yi
Keyword(s):  
Residual Stress ◽  
Reflection Spectrum ◽  
Thermal Residual Stress ◽  
Low Velocity Impact ◽  
Low Velocity ◽  
Stiffened Panels ◽  
Stiffened Composite Panels ◽  
Fbg Sensors ◽  
Comparison Of The Results ◽  
Strain Responses

The reflection spectrum from the Fiber Bragg Grating (FBG) sensors embedded in the composite was disturbed because of the thermal residual stress. In this study, two types of the FBG sensors, uncoated and UV-cured resin coated FBG sensors, were embedded in the triangle area of the T-stiffened composite panels. The strains during the curing process were measured by these two kinds of FBG sensors. Through the comparison of the results, it was found that the effect of thermal residual stress on the reflection spectrum could be attenuated when the FBG sensor was coated with UV-cured resin. Furthermore, the strain responses during the low-velocity impact test were observed by both two FBG sensors. The maximum-strain measured by the coated FBG sensors was more accurately than that measured by the uncoated one.

Effect of thermal residual stress on the reflection spectrum from FBG sensors embedded in CFRP composites

2002 ◽  
Author(s):  
Yoji Okabe ◽  
Shigeki Yashiro ◽  
Ryohei Tsuji ◽  
Tadahito Mizutani ◽  
Nobuo Takeda
Keyword(s):  
Residual Stress ◽  
Reflection Spectrum ◽  
Thermal Residual Stress ◽  
Cfrp Composites ◽  
Fbg Sensors

Strain Monitoring of T-Stiffened Panels Subjected to Low-Velocity Impact Using Embedded FBG Sensors

2012 ◽  
Vol 182-183 ◽  
pp. 1479-1483
Author(s):  
Yu Jing Zhou ◽  
Gang Liu ◽  
Xue Qin Li ◽  
Xiao Su Yi
Keyword(s):  
Impact Energy ◽  
Composite Structures ◽  
Online Monitoring ◽  
Low Velocity Impact ◽  
Low Velocity ◽  
Stiffened Panels ◽  
Velocity Impact ◽  
Strain Monitoring ◽  
Monitoring Technique ◽  
Fbg Sensors

The strain at the low-velocity impact proceeding was monitored by the fiber Bragg grating (FBG) sensors embedded in the triangle area of the T-stiffened panels. The results show that the strain in whole impact process can be monitored by FBG sensors. Furthermore, the max-strain measured by FBG sensors changed sensitively depending on the different impact energy. It can be hoped that the FBG sensors can be used as online-monitoring technique to improving the safety of the composite structures.

Compression after Impact Performance of Composite Stiffened Panels

2011 ◽  
Vol 415-417 ◽  
pp. 2231-2235 ◽  
Author(s):  
Zhe Sun ◽  
Fei Xu ◽  
Wei Xie ◽  
Bo Wang
Keyword(s):  
Structural Damage ◽  
Initial Imperfection ◽  
Maximum Load ◽  
Experimental Results ◽  
Low Velocity Impact ◽  
Thickness Direction ◽  
Low Velocity ◽  
Stiffened Panels ◽  
Velocity Impact ◽  
Compression After Impact

Composite stiffened panels are widely used in the modern aircraft structure with the advantages of light weight, structural efficiency and good crack performance. But the stiffened panels have poor performance at thickness direction, especially for low-velocity impact. First of all, compressive tests were investigated and analyzed for two types of composite stiffened panels, which are integrated specimens and post-impact specimens. And the effect of low-velocity impact to the supporting capacity of composite stiffened panels was researched. Secondly，the finite element model was established to simulate the CAI (Compression After Impact)strength with the equivalent hole method. It is found that the analyze results match the experimental results well. According to the experimental results, structural damage and the maximum load caused by impact energy are scattering. Then the imperfect factors were introduced to reflect the initial imperfection, namely the initial deflection at thickness direction. The effect of different imperfect factors to the maximum load was discussed.

scholarly journals Prediction of the Compresion-After-Impact Strength of Thin-Skin Stiffened Composite Panels

2000 ◽  
Vol 9 (4) ◽  
pp. 096369350000900 ◽  
Author(s):  
Y. Zhuk ◽  
C. Soutis ◽  
I. Guz
Keyword(s):  
Impact Damage ◽  
Low Velocity Impact ◽  
Composite Panels ◽  
Low Velocity ◽  
Damage Initiation ◽  
Mechanics Model ◽  
Stiffened Composite Panels ◽  
Open Hole ◽  
Thin Skin ◽  
The Impact

The compressive response of thin-skin stiffened composite panels with low velocity impact damage is examined. The finite element method together with the Soutis-Fleck fracture mechanics model is used to predict damage initiation in the form of fibre microbuckling in the 0° plies, propagation and final failure; in the model the impact damage is replaced with an equivalent circular or elliptical open hole. Theoretical results are compared to experimental data and found in good agreement.

scholarly journals Analytical Solutions to Predict Impact Behaviour of Stringer Stiffened Composite Aircraft Panels

2021 ◽  
Author(s):  
A. Chao Correas ◽  
A. Casares Crespo ◽  
H. Ghasemnejad ◽  
G. Roshan
Keyword(s):  
Impact Loading ◽  
Variable Stiffness ◽  
Impact Response ◽  
Low Velocity Impact ◽  
Analytical Models ◽  
Transverse Impact ◽  
Low Velocity ◽  
Mass System ◽  
Stiffened Panels ◽  
Velocity Impact

AbstractThis paper aims to develop an analytical method to predict the low-velocity impact response of simply supported stringer stiffened panels. Since the combination of stringer and panel provides aircraft structure with variable thicknesses, significant mathematical modelling is required to predict the transverse impact response of this type of designs. Within this analysis, the effect of variable stiffness distribution due to the stringer presence has been included. The performance of various layups is investigated to find the most suitable combination for panel-stringer laminate under impact loading. Analytical models were developed based on a spring-mass system to predict the dynamic behaviour of the striker-plate domain and, finally, determine the contact force history, which shows the main novelty of this research. Compared with Finite Element results, the model developed proved to successfully predict stringer stiffened composite panels' response with a range of layups and geometry designs under low-velocity impact loading conditions. The analytical results agree with the available data in the literature, and the error is less than 5%.

Low Velocity Impact Localization on CFRP Based on FBG Sensors and ELM Algorithm

2015 ◽  
Vol 15 (8) ◽  
pp. 4451-4456 ◽  
Author(s):  
Mingshun Jiang ◽  
Shizeng Lu ◽  
Qingmei Sui ◽  
Huijun Dong ◽  
Yaozhang Sai ◽  
...  
Keyword(s):  
Low Velocity Impact ◽  
Low Velocity ◽  
Velocity Impact ◽  
Fbg Sensors ◽  
Impact Localization

scholarly journals Low Velocity Impact Localization of Variable Thickness Composite Laminates

Sensors ◽  
2021 ◽  
Vol 21 (18) ◽  
pp. 6103
Author(s):  
Guan Lu ◽  
Yuchen Zhou ◽  
Yiming Xu
Keyword(s):  
Variable Thickness ◽  
Composite Laminates ◽  
Composite Structures ◽  
Low Velocity Impact ◽  
Low Velocity ◽  
Localization Performance ◽  
Fbg Sensors ◽  
The Impact ◽  
Impact Localization ◽  
Thickness Correction

Variable thickness composite laminates (VTCL) are susceptible to impact during use and may result in irreparable internal damage. In order to locate the internal impact damage of complex composite structures and monitor the impact signals of VTCL at the same time, a low velocity impact (LVI) monitoring system based on an optical fiber sensing network was constructed. Fiber Bragg grating (FBG) sensors are suitable for monitoring strain characteristics. By arranging FBG sensors on the laminate, we studied the spectrum analysis and localization of the impact signal collected by a FBG demodulator at constant temperature. The prior knowledge of variable thickness composite structures is difficult to obtain, and the multi-sensor dynamic monitoring is complex and difficult to realize. In order to locate the LVI of composite structures without prior knowledge, based on empirical mode decomposition (EMD), we proposed an impact localization method with zero-mean normalized cross-correlation (ZNCC) and thickness correction. The experimental results of LVI localization verification show that the ZNCC algorithm can effectively remove the temperature cross-sensitivity and impact energy influencing factors, and the thickness correction can reduce the interference of variable thickness characteristics on localization performance . The maximum localization error is 24.41 mm and the average error is 15.67 mm, which meets engineering application requirements. The method of variable-thickness normalization significantly improves impact localization performance for VTCL.

Damage Localization in a Stiffened Composite Panel Using a Lamb Wave Based Tomography Approach

2011 ◽  
Author(s):  
Anthony J. Vizzini ◽  
Yingtao Liu ◽  
Aditi Chattopadhyay
Keyword(s):  
Composite Structures ◽  
Impact Damage ◽  
Matching Pursuit ◽  
Low Velocity Impact ◽  
Composite Panel ◽  
Low Velocity ◽  
Stiffened Panels ◽  
Time Frequency ◽  
Matching Pursuit Decomposition ◽  
High Level

In structural health monitoring (SHM) of aerospace components, such as stiffened panels, detection and localization of damage is an important issue. This paper presents a methodology for determining the existence and location of low velocity impact damage in a stiffened composite panel. Using a matching pursuit decomposition algorithm, converted modes due to damage were extracted in the time-frequency domain. The energy of the converted mode was then used in conjunction with a probabilistic tomography approach that was able to localize the damage with a high level of accuracy. The results obtained confirm the ability of this approach to detect and localize damage in complex composite structures.

A strain amplitude-based algorithm for impact localization on composite laminates

2011 ◽  
Vol 22 (17) ◽  
pp. 2061-2067 ◽  
Author(s):  
Cristobal Hiche ◽  
Clyde K. Coelho ◽  
Aditi Chattopadhyay
Keyword(s):  
Strain Amplitude ◽  
Composite Laminates ◽  
Composite Structures ◽  
Composite Plates ◽  
Low Velocity Impact ◽  
Low Velocity ◽  
Sensor Orientation ◽  
Fbg Sensors ◽  
The Impact ◽  
Impact Localization

Automated detection of damage due to low energy impacts in composite structures is very important for aerospace structural health monitoring applications. Low-velocity impact creates subsurface damage that can significantly reduce the stiffness of a component, yet show barely visible damage. This article proposes a novel methodology for impact localization based on the maximum strain amplitude measured by fiber Bragg grating (FBG) sensors during an impact event. The approach correlates the strain amplitude of each sensor pair to find the location of highest strain corresponding to the impact location. This approach requires minimal knowledge of the structure and fewer number of sensors as opposed to current localization methods. Both simulation and experimental data are used as proof of concept. Since FBG sensors measure strain in only one direction, the effect of sensor orientation on the performance of the algorithm is also studied. The algorithm is tested on graphite/epoxy composite plates and shows good localization results in all impact cases considered.

Sign in / Sign up

Export Citation Format

Share Document