scholarly journals An Aircraft Pallet Damage Monitoring Method Based on Damage Subarea Identification and Probability-Based Diagnostic Imaging

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Bin Liu ◽  
Tingzhang Liu ◽  
Yue Lin ◽  
Jianfei Zhao
Keyword(s):  
Diagnostic Imaging ◽  
Lamb Wave ◽  
Damage Index ◽  
Imaging Method ◽  
Monitoring Method ◽  
Study Results ◽  
Damage Monitoring ◽  
Weighted Algorithm ◽  
Damage Simulation ◽  
Monitoring Area

To improve the safety and economy of aircraft pallet use, an aircraft pallet damage monitoring method based on damage subarea identification and probability-based diagnostic imaging is proposed. In the proposed method, first, the large aircraft pallet monitoring area is divided into rectangular subareas, and a piezoelectric transducer sensor is pasted on each vertex of the rectangular subarea that is used to excitation and sensing the Lamb wave. Second, the damage subarea is identified according to the diagonal damage indexes. Third, the damage position in the damage subarea is calculated using the probability-based diagnostic imaging method and coordinate probability weighted algorithm. Finally, the aircraft pallet damage can be localized based on the damage subarea position. Frequency selection and damage simulation study results show that the Lamb wave is sensitive to aircraft pallet damage whose centre frequency ranges from 50 kHz to 150 kHz, and the damage index of a steel ball is less than that of all real aircraft pallet damage from 95 kHz to 125 kHz. The verification results show that the proposed method can locate aircraft pallet damage with an error of less than 2 cm.

A Method of 3D Braided Composites Damage Monitoring

2015 ◽  
Vol 743 ◽  
pp. 861-865 ◽  
Author(s):  
Hua Zhang ◽  
Y.C. Xiao ◽  
Ming Li ◽  
G.Q. Liu ◽  
Jie Zhang
Keyword(s):  
Lamb Wave ◽  
Damage Index ◽  
Piezoelectric Sensors ◽  
Energy Change ◽  
Fatigue Load ◽  
Braided Composites ◽  
Index Method ◽  
Signal Energy ◽  
3D Braided Composites ◽  
Damage Monitoring

L shaped braided composites under fatigue load was researched, using piezoelectric sensors and active Lamb wave monitoring technology. HHT transform based signal envelope obtaining method and the damage index method based on signal energy change were used to monitor the damage extending of the braided composites.

scholarly journals Plate-like structure damage location identification based on Lamb wave baseline-free probability imaging method

2017 ◽  
Vol 9 (1) ◽  
pp. 168781401668570 ◽  
Author(s):  
Dongsheng Li ◽  
Zihao Jing ◽  
Mengdao Jin
Keyword(s):  
Lamb Wave ◽  
Time Window ◽  
Free Probability ◽  
Structural Response ◽  
Guided Wave ◽  
Time Of Arrival ◽  
Imaging Method ◽  
Detection Techniques ◽  
Damage Location ◽  
Ultrasonic Guided Wave

Damage-scattering signal extraction using conventional ultrasonic guided wave–based damage detection techniques requires the measurement of baseline data under pristine condition. This study proposes a baseline-free ultrasonic guided wave damage localization and imaging method based on Lamb wave baseline-free probability imaging method. Although traditional Lamb wave probability imaging can monitor damage location in plate-like structures, the absolute time of arrival and magnitude of the signal are affected by several factors and are therefore difficult to obtain. This study also proposes a probability-based hyperbola diagnostic imaging method that is based on different times of arrival and has no magnitude information. A distributed active sensor network conforming to a pulse-echo configuration and time window functions is developed to separate damage-scattering signals from structural response signals. Continuous wavelet transform is used to calculate the time of flight of damage signal waves. The numerical simulation and experiments validate the effectiveness of the proposed method in identifying damage.

scholarly journals Quantitative Monitoring of Tattoo Contrast Variations after 755-nm Laser Treatments in In Vivo Tattoo Models

Sensors ◽  
2020 ◽  
Vol 20 (1) ◽  
pp. 285
Author(s):  
Myeongjin Kim ◽  
Suhyun Park ◽  
Hyun Uk Lee ◽  
Hyun Wook Kang
Keyword(s):  
Laser Treatment ◽  
Quantitative Imaging ◽  
Imaging Method ◽  
Sprague Dawley ◽  
Scoring Method ◽  
Monitoring Method ◽  
Tattoo Removal ◽  
Quantitative Monitoring ◽  
Laser Treatments

Laser lights have been used by dermatologists for tattoo removal through photothermal interactions. However, most clinical studies used a visual scoring method to evaluate the tattoo removal process less objectively, leading to unnecessary treatments. This study aimed to develop a simple and quantitative imaging method to monitor the degree of tattoo removal in in vivo skin models. Sprague Dawley rat models were tattooed with four different concentrations of black inks. Laser treatment was performed weekly on the tattoos using a wavelength of 755 nm over six weeks. Images of non-treated and treated samples were captured using the same method after each treatment. The intensities of the tattoos were measured to estimate the contrast for quantitative comparison. The results demonstrated that the proposed monitoring method quantified the variations in tattoo contrast after the laser treatment. Histological analysis validated the significant removal of tattoo inks, no thermal injury to adjacent tissue, and uniform remodeling of epidermal and dermal layers after multiple treatments. This study demonstrated the potential of the quantitative monitoring technique in assessing the degree of clearance level objectively during laser treatments in clinics.

Numerical and experimental investigation of damage severity estimation using Lamb wave–based imaging methods

2018 ◽  
Vol 30 (4) ◽  
pp. 618-635 ◽  
Author(s):  
Asaad Migot ◽  
Yeasin Bhuiyan ◽  
Victor Giurgiutiu
Keyword(s):  
Lamb Wave ◽  
Lamb Waves ◽  
Wave Interaction ◽  
Crack Size ◽  
Imaging Method ◽  
Size Estimation ◽  
Local Approach ◽  
Imaging Methods ◽  
Imaging Results ◽  
Scattering Wave

In this article, estimation of crack size, shape, and orientation was investigated numerically and experimentally using Lamb waves. A hybrid global–local approach was used in conjunction with the imaging methods for the numerical simulation. The hybrid global–local approach allowed fast and efficient prediction of scattering wave signals for Lamb wave interaction with crack from various incident directions. The simulation results showed the directionality effect of the scattering wave signals and suggested an optimum transmitter–sensor configuration. Two imaging methods were used: one involves the synthetic time reversal concept and the other involves Gaussian distribution function. Both imaging methods show very good agreement during simulations. Experiments were designed and conducted based on the simulated results. A network of eight piezoelectric wafer active sensors was used to capture the scattering waves from the crack. Both the pitch-catch and pulse-echo experimental modes were used. The directionality effect of incident Lamb waves on the imaging results was studied. The effect of summation, multiplication, and combined algorithms for each imaging method was studied. It was found that both methods can successfully predict the crack size and orientation. An attempt was made to use these imaging methods for detecting and sizing smaller sized damage (1- to 3-mm-diameter hole). It was found that these methods can successfully localize the hole, but size estimation was a bit challenging because of the smaller dimensions. The scattering waves for various hole sizes were studied.

scholarly journals Piezoceramic-Based Damage Monitoring of Concrete Structure for Underwater Blasting

Sensors ◽  
2020 ◽  
Vol 20 (6) ◽  
pp. 1672 ◽  
Author(s):  
Jianfeng Si ◽  
Dongwang Zhong ◽  
Wei Xiong
Keyword(s):  
Damage Detection ◽  
Piezoelectric Transducer ◽  
Impact Load ◽  
Wavelet Packet ◽  
Blast Hole ◽  
Damage Index ◽  
Underwater Explosion ◽  
Damage Monitoring ◽  
Concrete Materials ◽  
The Impact

This paper developed a piezoelectric-transducer-based damage detection of concrete materials after blasting. Two specimens (with or without an energy-relieving structure) were subjected to a 40 m deep-underwater blasting load in an underwater-explosion vessel, and their damage was detected by a multifunctional piezoelectric-signal-monitoring and -analysis system before and after the explosion. Statistical-data analysis of the piezoelectric signals revealed four zones: crushing, fracture, damage, and safe zones. The signal energy was analyzed and calculated by wavelet-packet analysis, and the blasting-damage index was obtained after the concrete specimen was subjected to the impact load of the underwater explosion. The damage of the two specimens gradually decreased from the blast hole to the bottom of the specimen. The damage index of the specimen with the energy-relieving structure differed for the fracture area and the damage area, and the damage protection of the energy-relieving structure was prominent at the bottom of the specimen. The piezoelectric-transducer-based damage monitoring of concrete materials is sensitive to underwater blasting, and with wavelet-packet-energy analysis, it can be used for postblasting damage detection and the evaluation of concrete materials.

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.

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