An impact imaging method for composite structures based on virtual time reversal

2015 ◽  
pp. 127-132
Keyword(s):  
Time Reversal ◽  
Composite Structures ◽  
Imaging Method ◽  
Virtual Time

A Time Reversal Imaging Method without Relying on Transfer Function for Impact and Damage Monitoring of Composite Structures

2013 ◽  
Vol 330 ◽  
pp. 542-548
Author(s):  
Lei Qiu ◽  
Shen Fang Yuan ◽  
Tian Xiang Huang
Keyword(s):  
Transfer Function ◽  
Time Reversal ◽  
Lamb Wave ◽  
Composite Structures ◽  
Structural Damage ◽  
Composite Panel ◽  
Synthesis Process ◽  
Propagation Mechanism ◽  
Imaging Method ◽  
Phase Synthesis

Composite structures adopted in aerospace structures have attracted much interest to structural health monitoring (SHM) for localization of impact and damage positions due to their poor impact resistance properties. Propagation mechanism and frequency dispersion characteristics of Lamb wave signals on composite structures are more complicated than that on simple aluminum plates. Recently, much attention has been paid to the research of time reversal focusing method because this method shows a promising advantage to give a focusing image of the structural damage, improve the signal-to-noise ratio and compensate the dispersion of Lamb wave signals. In this paper, aiming at developing a practical method for on-line localization of impact and damage on aircraft composite structures which can take advantage of time reversal focusing and does not rely on the transfer function, a new phase synthesis based time reversal focusing method is proposed. Impact and damage images are given out directly through time reversal focusing based on phase synthesis process of the signals. A SHM demonstration system is built on a composite panel of an aircraft wing box with many bolt holes and stiffeners using the phase synthesis based time reversal focusing method. The demonstration results show that this method can estimate the positions of impact and damage efficiently with a low sensitivity of velocity errors.

On research of a phase synthesis time reversal focusing method for damage imaging of complex composite structures

2012 ◽  
Vol 24 (2) ◽  
pp. 209-225 ◽  
Author(s):  
Zixue Qiu ◽  
Lei Qiu ◽  
Jiang Yuan ◽  
Guan Lu
Keyword(s):  
Structural Health Monitoring ◽  
Health Monitoring ◽  
Time Reversal ◽  
Composite Structures ◽  
Composite Panel ◽  
Imaging Method ◽  
Synthesis Time ◽  
Phase Synthesis ◽  
Structural Health ◽  
Damage Imaging

Time reversal focusing method has been proved to be an effective method for active Lamb wave–based structural health monitoring. In this article, aiming at developing a practical method for online localization of damage on aircraft composite structures that can take advantage of time reversal focusing and do not rely on the transfer function, a phase synthesis–based time reversal focusing method was proposed. In this method, damage images are given out directly through time reversal focusing, and the other imaging processes such as the delay-and-sum imaging method adopted in many researches of time reversal focusing are not needed. Based on the damage imaging method, a structural health monitoring demonstration system was built on a composite panel of an aircraft wing box with many bolt holes and stiffeners. The demonstrated results show that this method can estimate the positions of damages efficiently with a low sensitivity of group velocity errors and a high antijamming capability.

scholarly journals M-ary nonlinear sine chirp spread spectrum for underwater acoustic communication based on virtual time-reversal mirror method

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Songzuo Liu ◽  
Habib Hussain Zuberi ◽  
Yi Lou ◽  
Muhmmad Bilal Farooq ◽  
Shahabuddin Shaikh ◽  
...  
Keyword(s):  
Acoustic Communication ◽  
Time Reversal ◽  
Spread Spectrum ◽  
Underwater Acoustic Communication ◽  
Half Cycle ◽  
Spreading Factor ◽  
Underwater Acoustic ◽  
Virtual Time ◽  
Chirp Spread Spectrum ◽  
Time Reversal Mirror

AbstractLinear chirp spread spectrum technique is widely used in underwater acoustic communication because of their resilience to high multipath and Doppler shift. Linear frequency modulated signal requires a high spreading factor to nearly reach orthogonality between two pairs of signals. On the other hand, nonlinear chirp spread spectrum signals can provide orthogonality at a low spreading factor. As a result, it improves spectral efficiency and is more insensitive to Doppler spread than the linear counterpart. To achieve a higher data rate, we propose two variants (half cycle sine and full cycle sine) of the M-ary nonlinear sine chirp spread spectrum technique based on virtual time-reversal mirror (VTRM). The proposed scheme uses different frequency bands to transmit chirp, and VTRM is used to improve the bit error rate due to high multipath. Its superior Doppler sensitivity makes it suitable for underwater acoustic communication. Furthermore, the proposed method uses a simple, low-power bank of matched filters; thus, it reduces the overall system complexity. Simulations are performed in different underwater acoustic channels to verify the robustness of the proposed scheme.

An imaging method for the covered damage region of strand wire based on dual time reversal using piezoceramic transducers

2017 ◽  
Vol 26 (10) ◽  
pp. 104005 ◽  
Author(s):  
Hong Xiaobin ◽  
Zhou Jianxi ◽  
Lin Peisong ◽  
Huang Guojian
Keyword(s):  
Time Reversal ◽  
Imaging Method

An Enhanced Time-Reversal Method for Impact Damage Monitoring on Plate-Like Structures

2012 ◽  
Vol 525-526 ◽  
pp. 365-368
Author(s):  
Chun Lin Chen ◽  
Yu Long Li ◽  
Fuh Gwo Yuan
Keyword(s):  
Time Reversal ◽  
Composite Structures ◽  
Impact Damage ◽  
High Energy ◽  
Low Velocity ◽  
Energy Impact ◽  
Location Detection ◽  
Focusing Property ◽  
The Impact ◽  
Impact Events

Based on the self-focusing property of time-reversal (T-R) concept, a time focusing parameter was suggested to improve the impact source identification method developed in authors previous work. This paper presents a further study on monitoring relatively high energy impact events which caused induced damage on structures. Numerical verifications for a finite isotropic plate and a composite plate under low velocity impacts are performed to demonstrate the versatility of T-R method for impact location detection with induced plastic deformation and delamination damage on metallic and composite structures respectively. The focusing property of T-R concept was adequately utilized to detect impact/damage location. The results show that impact events with various features can be localized using T-R method by introducing the time focusing parameter. It is suited to monitor serious impact events on plate like structures in practice in future.

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