Sensor Networks for In-Situ Failure Identification in Woven Composites Throughout Impact

2007 ◽  
Author(s):  
Ryan Garrett ◽  
Kara Peters ◽  
Mohammed A. Zikry
Keyword(s):  
Sensor Networks ◽  
Optical Fibers ◽  
Matrix Material ◽  
Contact Forces ◽  
Low Velocity Impact ◽  
Woven Composites ◽  
Low Velocity ◽  
Cross Sectional ◽  
Fbg Sensors ◽  
The Impact

In this study, the development of embedded fiber Bragg grating (FBG) sensor networks within composite materials is investigated. Various densities of optical fibers were embedded within two-dimensional woven composite laminates, and low-velocity impact damage responses were evaluated to determine the effects on the mechanical behavior of the laminates. The woven composites were subjected to multiple strikes at 2 m/s until perforation occurred, and the impactor position and acceleration were monitored throughout each event. From these measurements, we obtained dissipated energies and contact forces for specimens with and without embedded optical fibers. Cross sectional optical micrographs of the specimens were also used to determine the local effects of the embedded fibers on neighboring fibers and the surrounding matrix material, both before and after impact events. Multiple FBG sensors were serially multiplexed together to create a single fiber sensing network capable of monitoring damage for each impact event. Residual strain information was gathered through strain distributions along the FBG sensors to map out the near-field and far-field regions with respect to the impact location. The resulting data will be used to better monitor and predict damage in the composite system when combined with global response data from the laminate itself.

scholarly journals Robust Identification of Strain Waves due to Low-Velocity Impact with Different Impactor Stiffness

Sensors ◽  
2019 ◽  
Vol 19 (6) ◽  
pp. 1283 ◽  
Author(s):  
Alessio Beligni ◽  
Claudio Sbarufatti ◽  
Andrea Gilioli ◽  
Francesco Cadini ◽  
Marco Giglio
Keyword(s):  
Sensor Networks ◽  
Low Velocity Impact ◽  
Time Of Arrival ◽  
Low Velocity ◽  
Metallic Structures ◽  
Robust Identification ◽  
Impact Monitoring ◽  
Multiple Impact ◽  
Processing Techniques ◽  
The Impact

Low-velocity impacts represent a major concern for aeronautical structures, sometimes producing barely detectable damage that could severely hamper the aircraft safety, even with regards to metallic structures. For this reason, the development of an automated impact monitoring system is desired. From a passive monitoring perspective, any impact generates a strain wave that can be acquired using sensor networks; signal processing techniques allow for extracting features useful for impact identification, possibly in an automatic way. However, impact wave characteristics are related to the impactor stiffness; this presents a problem for the evaluation of an impact-related feature and for the development of an automatic approach to impact identification. This work discusses the problem of reducing the influence of the impactor stiffness on one of the features typically characterizing the impact event, i.e., the time of arrival (TOA). Two passive sensor networks composed of accelerometers and piezoelectric sensors are installed on two metallic specimens, consisting of an aluminum skin and a sandwich panel, with aluminum skins and NOMEXTM honeycomb core. The effect of different impactor stiffnesses is investigated by resorting to an impact hammer, equipped with different tips. Subsequently, a method for data processing is defined to obtain a feature insensitive to the impactor stiffness, and this method is applied to multiple impact signals for feature uncertainty evaluation.

scholarly journals Improved impact response of hygrothermally conditioned carbon/epoxy woven composites

2016 ◽  
Vol 23 (6) ◽  
pp. 699-710 ◽  
Author(s):  
Yucheng Zhong ◽  
Sunil Chandrakant Joshi
Keyword(s):  
Carbon Fiber ◽  
Impact Resistance ◽  
Impact Testing ◽  
Low Velocity Impact ◽  
Elastic Response ◽  
Woven Composites ◽  
Low Velocity ◽  
Hygrothermal Conditioning ◽  
The Impact ◽  
Carbon Fiber Epoxy

AbstractThe effects of hygrothermal conditioning and moisture on the impact resistance of carbon fiber/epoxy composite laminates were investigated. Specimens were fabricated from carbon fiber/epoxy woven prepreg materials. The fabricated specimens were either immersed in water at 80°C or subjected to hot/wet (at 80°C in water for 12 h) to cold/dry (at -30°C in a freezer for 12 h) cyclic hygrothermal conditions, which resulted in different moisture contents inside the laminates. It was found that the absorbed moisture did not migrate out from composite materials at -30°C. Neither of the hygrothermal conditions in this study had detrimental effects on the microstructure of the laminates. Low-velocity impact testing was subsequently conducted on the conditioned specimens. When attacked by the same level of impact energy, laminates with different moisture levels experienced different levels of impact damage. Moisture significantly alleviated the extent of damage in carbon fiber/epoxy woven laminates. The elastic response of the laminate under impact was improved after hygrothermal conditioning. The mechanism behind the improved impact resistance after absorbing moisture was proposed and deliberated.

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.

scholarly journals Impact Response and Damage Characteristics of Carbon Fiber Reinforced Aluminum Laminates Under Low Velocity Impact Loading

2020 ◽  
Vol 9 (4) ◽  
pp. 1831-1837
Keyword(s):  
Impact Energy ◽  
Impact Load ◽  
Three Dimensional ◽  
Low Velocity Impact ◽  
Fe Model ◽  
Low Velocity ◽  
Fiber Layer ◽  
Cross Sectional ◽  
Velocity Impact ◽  
The Impact

CARALL hybrid material has been extensively used in the aircraft structure due to their competitive impact strength. Low velocity impact test is utilized to evaluate the impact and damage properties for such material. It is also employed to observe complex damage mechanisms. A numerical modelling is an alternative way for impact assessment. This paper investigates the impact and damage properties under low velocity impact using numerical modeling and experimental work. A three-dimensional (3D) finite element (FE) model was devolved and validated with two studies from the literature. This model was meshed with solid elements. It was subjected to 2.4 m/s impact velocity and to 10 J impact energy. Absorbed energy, penetration, impact load and damage morphology were obtained. The impact energy was efficiently absorbed by the material. Both aluminum alloy layers underwent plastic deformation whereas the fiber layer failed. A macroscopic cross-sectional morphology was presented using the FE model. An agreement between the numerical and the experiment results were achieved and discussed.

Impact response of nanoparticle reinforced 3D woven spacer/epoxy composites at cryogenic temperatures

2021 ◽  
pp. 002199832110370
Author(s):  
Ferhat Yıldırım ◽  
Ahmet Caner Tatar ◽  
Volkan Eskizeybek ◽  
Ahmet Avcı ◽  
Mustafa Aydın
Keyword(s):  
Composite Structures ◽  
Impact Resistance ◽  
Low Velocity Impact ◽  
Woven Composites ◽  
Cryogenic Temperatures ◽  
Low Velocity ◽  
Impact Performance ◽  
Fiber Reinforced Polymer Composites ◽  
3D Woven Composites ◽  
The Impact

Fiber-reinforced polymer composites serving in harsh conditions must maintain their performance during their entire service. The cryogenic impact is one of the most unpredictable loading types, leading to catastrophic failures of composite structures. This study aims to examine the low-velocity impact (LVI) performance of 3D woven spacer glass-epoxy composite experimentally under cryogenic temperatures. LVI tests were conducted under various temperatures ranging from room temperature (RT) to −196°C. Experimental results reveal that the 3D composites gradually absorbed higher impact energies with decreasing temperature. Besides, the effect of multi-walled carbon nanotube and SiO2 nanofiller reinforcements of the matrix on the impact performance and the damage characteristics were further assessed. Nanofiller modification enhanced the impact resistance up to 30%, especially at RT. However, the nanofiller efficiency declined with decreasing temperature. The apparent damages were visually examined by scanning electron microscopy to address the damage formation. Significant outcomes have been achieved with the nanofiller modification regarding the new usage areas of 3D woven composites.

Influence of Structure Unit and the Distribution on the Low-Velocity Impact Property of the 3D Woven Composites

2012 ◽  
Vol 502 ◽  
pp. 169-173
Author(s):  
Yan Qing Li ◽  
Jia Ying Sun ◽  
Wei Tian ◽  
Cheng Yan Zhu
Keyword(s):  
Impact Resistance ◽  
Impact Property ◽  
Low Velocity Impact ◽  
Woven Composites ◽  
Material Structure ◽  
Absorbed Energy ◽  
Low Velocity ◽  
Velocity Impact ◽  
3D Woven Composites ◽  
The Impact

In this paper, the low-velocity impact properties of the 3D woven composites were tested. Through the study on the relationship of absorbed energy and material structure, the impact resistance of the composites has been discussed. The research results show that the low-velocity impact resistance of quasi-orthogonal composites is the best, the low-velocity impact resistance of orthogonal composites is the worst and angle tangled of interlayer joint composites stand somewhere between the two. Adding quasi-orthogonal unit into the structure, the low-velocity impact property of the composites can be enhanced efficiently. On the other hand, if the unit distribution of the enforced fabric is changed, the break time and break point will be changed. But the effect on the total absorbed energy is not obvious.

Experimental and numerical behaviors of GFRP laminates under low velocity impact

2020 ◽  
Vol 54 (21) ◽  
pp. 2999-3007
Author(s):  
Hüseyin E Yalkın ◽  
Ramazan Karakuzu ◽  
Tuba Alpyıldız
Keyword(s):  
Contact Force ◽  
Impact Energy ◽  
Damage Mechanics ◽  
Matrix Material ◽  
Impact Testing ◽  
Low Velocity Impact ◽  
Low Velocity ◽  
Velocity Impact ◽  
Wide Range ◽  
The Impact

The aim of the study is to investigate the behavior of laminated composites under low velocity impact both experimentally and numerically. With this aim, the effects of wide range impact energy values between 10 J and 60 J were evaluated experimentally and numerically for the laminate of [±45/(0/90)2]S oriented unidirectional E-glass as reinforcing material and epoxy resin for matrix material. Different impactor velocities were used to maintain the impact energy values and experimental impact tests were generated with drop weight impact testing machine at room temperature. Numerical simulations were performed using LS-DYNA finite element analysis software with a continuum damage mechanics-based material model MAT058. Contact force between impactor and laminate, and transverse deflection at the center of laminate results were obtained as a function of time and used to plot contact force–time curves, contact force–deflection curves and absorbed energy-impact energy curves. Also, delamination area was examined. Finally, numerical results were compared with experimental results and a good correlation between them was observed.

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.

scholarly journals Optimisation of Through-Thickness Embedding Location of Fibre Bragg Grating Sensor in CFRP for Impact Damage Detection

Polymers ◽  
2021 ◽  
Vol 13 (18) ◽  
pp. 3078
Author(s):  
Helena Rocha ◽  
Ugo Lafont ◽  
João P. Nunes
Keyword(s):  
Impact Damage ◽  
Large Diameter ◽  
Real Life ◽  
Low Velocity Impact ◽  
Bragg Grating ◽  
Fibre Bragg Grating ◽  
Low Velocity ◽  
Residual Strains ◽  
Fbg Sensors ◽  
The Impact

Aerospace composites are susceptible to barely visible impact damage (BVID) produced by low-velocity-impact (LVI) events. Fibre Bragg grating (FBG) sensors can detect BVID, but often FBG sensors are embedded in the mid-plan, where residual strains produced by impact damage are lower, leading to an undervaluation of the damage severity. This study compares the residual strains produced by LVI events measured by FBG embedded at the mid-plan and other through-thickness locations of carbon fibre reinforced polymer (CFRP) composites. The instrumented laminates were subjected to multiple low-velocity impacts while the FBG signals were acquired. The FBG sensor measurements allowed not only for the residual strain after damage to be measured, but also for a strain peak at the time of impact to be detected, which is an important feature to identify the nature and presence of BVID in real-life applications. The results allowed an adequate optical fibre (OF) embedding location to be selected for BVID detection. The effect of small- and large-diameter OF on the impact resistance of the CFRP was compared.

Experimental Investigation on the Low-Velocity Impact Damage of 3D Angle-Interlock Woven Composites

2012 ◽  
Vol 487 ◽  
pp. 793-797 ◽  
Author(s):  
Li Juan Yu ◽  
Li Min Jin ◽  
Zhi Lin Niu ◽  
Bao Zhong Sun ◽  
Yi Zhu Zheng ◽  
...  
Keyword(s):  
Failure Modes ◽  
Shear Failure ◽  
Impact Damage ◽  
Low Velocity Impact ◽  
Impact Behavior ◽  
Woven Composites ◽  
Low Velocity ◽  
Plane Shear ◽  
Velocity Impact ◽  
The Impact

In this paper, the low-velocity impact behavior of the 3D angle-interlock woven glass-fiber/epoxy composites (3DAWCs) were tested and analyzed under several levels of impact energies. The energy-time curves, deflection-time curves and load-deflection curves were obtained to show the impact damage behavior. It was found that the damage magnitude increases with the impact energy, and the composite structure can effectively reduce the in-plane shear failure. In addition, the failure modes were also photographed to illustrate the damage mechanisms of the3DAWCs.

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