scholarly journals Embedded Active Sensors for In-Situ Structural Health Monitoring of Thin-Wall Structures

2002 ◽  
Vol 124 (3) ◽  
pp. 293-302 ◽  
Author(s):  
Victor Giurgiutiu ◽  
Andrei Zagrai ◽  
JingJing Bao
Keyword(s):  
Damage Detection ◽  
Health Monitoring ◽  
Near Field ◽  
Far Field ◽  
Thin Wall ◽  
Active Sensors ◽  
Aging Aircraft ◽  
Wall Structures ◽  
Aircraft Panels

The use of embedded piezoelectric-wafer active-sensors for in-situ structural health monitoring of thin-wall structures is presented. Experiments performed on aircraft-grade metallic specimens of various complexities exemplified the detection procedures for near-field and far-field damage. For near-field damage detection, the electro-mechanical (E/M) impedance method was used. Systematic experiments conducted on statistical samples of incrementally damaged specimens were followed by illustrative experiments on realistic aging aircraft panels. For far-field damage detection, guided ultrasonic Lamb waves were utilized in conjunction with the pulse-echo technique. Systematic experiments conducted on aircraft-grade metallic plates were used to develop the method, while experiments performed on realistic aging-aircraft panels exemplified the crack detection procedure.

Damage Detection in Simulated Aging-Aircraft Panels Using the Electro-Mechanical Impedance Technique

2000 ◽  
Author(s):  
Victor Giurgiutiu ◽  
Andrei Zagrai
Keyword(s):  
Damage Detection ◽  
Health Monitoring ◽  
Statistical Tests ◽  
Sensor Arrays ◽  
Impedance Method ◽  
Fem Modeling ◽  
Aircraft Structures ◽  
Aging Aircraft ◽  
Sensor Fabrication ◽  
Aircraft Panels

Abstract The aging of aerospace structures is a major current concern of civilian and military aircraft operators. PZT active sensors offer special opportunities for developing sensor arrays for in-situ health monitoring of aging aircraft structures. In this paper, we examine the structural health monitoring of aging aircraft structures with the electro-mechanical (E/M) impedance method. Local impedance methodology as well as damage detection strategy were developed. The detection of damage due to corrosion, structural cracks, and active sensor self-diagnostics with electro-mechanical (E/M) impedance method are discussed. The paper emphasis is sensor fabrication and installation procedures. Consistency and repeatability of sensor fabrication and installation were perfected and confirmed by statistical tests on a number of nominally identical specimens. Experiments on simple metallic beams were then performed and the results were compared with readily available theoretical predictions. Experiments on square plates manufactured from aircraft grade thin-gage stock followed. Statistical analysis of plate data confirmed that consistent and repeatability results could be achieved with our methodology. Finally, experiments on realistic aircraft panels with simulated crack and corrosion damage were performed. An array of four sensors were installed along a line emanating at a right angle from the crack, and E/M impedance readings were collected from all sensors. Consistency of sensor readings was verified. Also, the tendency of frequency to shift in the vicinity of the crack was noticed. However, further data processing, and detailed FEM modeling are still needed before full understanding of the correlation between crack presence and sensors readings is achieved.

scholarly journals Embedded Ultrasonics With Piezoelectric Wafer Active Sensors for Structural Health Monitoring of Thin-Wall Structures

Aerospace ◽  
2003 ◽  
Author(s):  
Victor Giurgiutiu
Keyword(s):  
Structural Health Monitoring ◽  
Health Monitoring ◽  
Crack Detection ◽  
Thin Wall ◽  
Large Area ◽  
Active Sensors ◽  
Structural Health ◽  
Piezoelectric Wafer Active Sensors ◽  
Wall Structures ◽  
Pulse Echo

The capability of embedded piezoelectric water active sensors (PWAS) to perform in-situ ultrasonic nondestructive evaluation (NDE) is explored. Laboratory tests are used to prove that PWAS can satisfactorily perform Lamb wave transmission and reception. Subsequently, pulse-echo method for crack detection in an aircraft panel is illustrated. For large area scanning, a PWAS phased array is used to create the embedded ultrasonics structural radar (EUSR). In conclusion, opportunities for implementation into structural health monitoring applications and further research needs are discussed.

Corrigendum to “Health Monitoring of Storage Tanks Subject to Near-Field and Far-Field Earthquakes” [Engineering Science & Technology, Volume 2 Issue 2 (2021) 116-130]

2021 ◽  
pp. 131
Author(s):  
Hossein Mirzaaghabeik ◽  
Rafael Holdorf Lopez ◽  
Marcos Souza Lenzi ◽  
Hamidreza Vosoughifar
Keyword(s):  
Health Monitoring ◽  
Near Field ◽  
Engineering Science ◽  
Far Field ◽  
Storage Tanks ◽  
Science Technology

Corrigendum to “Health Monitoring of Storage Tanks Subject to Near-Field and Far-Field Earthquakes” [Engineering Science & Technology, Volume 2 Issue 2 (2021) 116-130] https://doi.org/10.37256/est.222021640 Published online May 7, 2021.   The authors regret they missed to one of the authors, Hamidreza Vosoughifar, whose contribution to this paper that could not be ignored. The correct authorship should be: Hossein Mirzaaghabeik, Rafael Holdorf Lopez, Marcos Souza Lenzi, Hamidreza Vosoughifar.   The authors would like to apologize for the inconvenience caused.

The Structural Nonlinear Damage Detection Based on Linear Time Series Algorithm

2015 ◽  
Vol 744-746 ◽  
pp. 345-350 ◽  
Author(s):  
Liu Jie Chen ◽  
Ling Yu ◽  
Tan Xiao
Keyword(s):  
Damage Detection ◽  
Health Monitoring ◽  
Linear Time ◽  
Moving Average ◽  
Autoregressive Moving Average ◽  
Building Structure ◽  
Computational Costs ◽  
Story Building ◽  
New Algorithms

Two new algorithms for nonlinear damage detection are proposed based on linear model with autoregressive moving average (ARMA) in this paper. Firstly, a novel DSF is defined and the DSFs are identified and classified followed by cluster analysis or Bayesian discrimination. Secondly, the performances of the presented algorithms are evaluated and verified by the experimental data of a three-story building structure. Finally, the illustrated results show the algorithms are efficient tools for nonlinear damage detection. They grant a higher accuracy and improve the reliability of nonlinear damage detection whilst reducing computational costs. It can thus be inferred that the proposed algorithms are applicable for Structural Health Monitoring (SHM) in situ.

Study of Microscale Three-Dimensional Printing Using Near-Field Melt Electrospinning

2017 ◽  
Author(s):  
Xiangyu You ◽  
Chengcong Ye ◽  
Ping Guo
Keyword(s):  
High Resolution ◽  
3D Printing ◽  
Low Cost ◽  
Near Field ◽  
Three Dimensional ◽  
Thin Wall ◽  
Direct Writing ◽  
Melt Electrospinning ◽  
Wall Structures ◽  
Jet Trajectory

Three-dimensional (3D) printing of microscale structures with high resolution (sub-micron) and low cost is still a challenging work for the existing 3D printing techniques. Here we report a direct writing process via near-field melt electrospinning to achieve microscale printing of single filament wall structures. The process allows continuous direct writing due to the linear and stable jet trajectory in the electric near-field. The layer-by-later stacking of fibers, or self-assembly effect, is attributed to the attraction force from the molten deposited fibers and accumulated negative charges. We demonstrated successful printing of various 3D thin wall structures (freestanding single walls, double walls, annular walls, star-shaped structures, and curved wall structures) with a minimal wall thickness less than 5 μm. By optimizing the process parameters of near-field melt electrospinning (electric field strength, collector moving speed, and needle-to-collector distance), ultrafine poly (ε-caprolactone) (PCL) fibers have been stably generated and precisely stacked and fused into 3D thin-wall structures with an aspect ratio of more than 60. It is envisioned that the near-field melt electrospinning can be transformed into a viable high-resolution and low-cost microscale 3D printing technology.

scholarly journals Label-Free Imaging of Single Nanoparticles Using Total Internal Reflection-Based Leakage Radiation Microscopy

Nanomaterials ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 615
Author(s):  
Liwen Jiang ◽  
Xuqing Sun ◽  
Hongyao Liu ◽  
Ruxue Wei ◽  
Xue Wang ◽  
...  
Keyword(s):  
Total Internal Reflection ◽  
Near Field ◽  
Internal Reflection ◽  
In Situ Monitoring ◽  
Far Field ◽  
Label Free ◽  
Polystyrene Nanospheres ◽  
Leakage Radiation Microscopy ◽  
Leakage Radiation

Label-free, fast, and single nanoparticle detection is demanded for the in situ monitoring of nano-pollutants in the environment, which have potential toxic effects on human health. We present the label-free imaging of single nanoparticles by using total internal reflection (TIR)-based leakage radiation microscopy. We illustrate the imaging of both single polystyrene (PS) and Au nanospheres with diameters as low as 100 and 30 nm, respectively. As both far-field imaging and simulated near-field electric field intensity distribution at the interface showed the same characteristics, i.e., the localized enhancement and interference of TIR evanescent waves, we confirmed the leakage radiation, transforming the near-field distribution to far-field for fast imaging. The localized enhancement of single PS and Au nanospheres were compared. We also illustrate the TIR-based leakage radiation imaging of single polystyrene nanospheres with different incident polarizations. The TIR-based leakage radiation microscopy method is a competitive alternative for the fast, in situ, label-free imaging of nano-pollutants.

scholarly journals Measurement uncertainty caused by distance errors during in situ tests of wind turbines

2019 ◽  
Vol 17 ◽  
pp. 19-25
Author(s):  
Cornelia Reschka ◽  
Sebastian Koj ◽  
Sven Fisahn ◽  
Heyno Garbe
Keyword(s):  
Electromagnetic Field ◽  
Measurement Uncertainty ◽  
Field Distribution ◽  
Wind Turbines ◽  
Near Field ◽  
Observation Point ◽  
Far Field ◽  
In Situ Tests ◽  
Electromagnetic Emissions

Abstract. During the assessment of the electromagnetic emissions of wind turbines (WTs), the aspects of measurement uncertainty must be taken into account. Therefore, this work focuses on the measurement uncertainty which arises through distance errors of the measuring positions around a WT. The measurement distance given by the corresponding standard is 30 m with respect to the WT tower. However, this determined distance will always differ e.g. due to unevenness of the surrounding ground, leading to measurement uncertainties. These uncertainties can be estimated with the knowledge of the electromagnetic field distribution. It is assumed in standard measurements, that the electromagnetic field present is a pure transversal electromagnetic field (far field). Simulations of a simplified WT model with a hub height of 100 m shows that this assumption is not effective for the whole frequency range from 150 kHz to 1 GHz. For frequencies below 3 MHz the field distribution is monotonically decreasing with the distance from the WT since it behaves like an electrical small radiator. Whereas for frequencies above 3 MHz, where the investigated model forms an electrical large radiator, the field distribution becomes more complex and the measurement uncertainty of the field strength at the observation point increases. Therefore, this work focuses on investigations where the near field becomes a far field. Based on the simulation results, a method for minimizing the uncertainty contribution caused by distance errors is presented. Therefore, advanced measurement uncertainty during in situ test of WTs can be reduced.

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