scholarly journals Structural health monitoring ultrasonic thickness measurement accuracy and reliability of various time-of-flight calculation methods

2016 ◽  
Author(s):  
Thomas J. Eason ◽  
Leonard J. Bond ◽  
Mark G. Lozev
Keyword(s):  
Structural Health Monitoring ◽  
Health Monitoring ◽  
Measurement Accuracy ◽  
Time Of Flight ◽  
Thickness Measurement ◽  
Calculation Methods ◽  
Structural Health ◽  
Ultrasonic Thickness Measurement ◽  
Ultrasonic Thickness

Computation of Wave Propagation in Damped Specimen for Damage Detection

2014 ◽  
Vol 783-786 ◽  
pp. 2296-2301 ◽  
Author(s):  
Veena Jawali ◽  
Prakash Parasivamurthy ◽  
Ashwini Nagesh
Keyword(s):  
Structural Health Monitoring ◽  
Damage Detection ◽  
Monitoring System ◽  
Health Monitoring ◽  
Time Of Flight ◽  
Source Location ◽  
Wave Source ◽  
Health Monitoring System ◽  
Structural Health ◽  
Structural Health Monitoring System

Aim of a structural health monitoring system must be to collect sufficient information about the damage for appropriate remedial measures to be taken to ensure safety. The preliminary step in the process of damage assessment is locating the damage .One of the challenges faced by the structural health monitoring system is monitoring in-flight damages. Localization of in-flight damages or sudden impacts can be achieved by monitoring the acoustic emissions in real time mode. In this paper, an approach based on the employment of Piezo-electric transducer rosettes to locate the acoustic emission source in an aluminum plate is presented. Using the strain gage rosette concepts adapted for piezoelectric transducers, the wave strain principal angles are determined. When two rosettes are used, the intersection of the principal wave strain directions detected by the rosettes gives the wave source location. The method does not require the knowledge of wave velocity in the medium in contrast to the time of flight based location. Hence, this technique can be used in anisotropic or complex structures where the source localization using the conventional time of flight method is difficult. The principal strain angle using the voltage response of the transducers and the rosette principles are obtained and the co-ordinates of the wave source location are calculated using the co-ordinates of the centroids of the rosettes in MATLAB.According to the tests, the rosette piezo-transducer outperforms the single piezo elements to a degree justifying its complexity. The rosette piezo transducer provides more damage related information compared to single elements and hence the performance of the damage detection system can be significantly improved if rosettes are used.

scholarly journals Implementation and Evaluation of Vision-Based Sensor Image Compression for Close-Range Photogrammetry and Structural Health Monitoring

Sensors ◽  
2020 ◽  
Vol 20 (23) ◽  
pp. 6844
Author(s):  
Luna Ngeljaratan ◽  
Mohamed A. Moustafa
Keyword(s):  
Structural Health Monitoring ◽  
Image Compression ◽  
Health Monitoring ◽  
Measurement Accuracy ◽  
Small Scale ◽  
Response Measurement ◽  
Static Test ◽  
Structural Health ◽  
Close Range Photogrammetry ◽  
Close Range

Much research is still underway to achieve long-term and real-time monitoring using data from vision-based sensors. A major challenge is handling and processing enormous amount of data and images for either image storage, data transfer, or image analysis. To help address this challenge, this study explores and proposes image compression techniques using non-adaptive linear interpolation and wavelet transform algorithms. The effect and implication of image compression are investigated in the close-range photogrammetry as well as in realistic structural health monitoring applications. For this purpose, images and results from three different laboratory experiments and three different structures are utilized. The first experiment uses optical targets attached to a sliding bar that is displaced by a standard one-inch steel block. The effect of image compression in the photogrammetry is discussed and the monitoring accuracy is assessed by comparing the one-inch value with the measurement from the optical targets. The second application is a continuous static test of a small-scale rigid structure, and the last application is from a seismic shake table test of a full-scale 3-story building tested at E-Defense in Japan. These tests aimed at assessing the static and dynamic response measurement accuracy of vision-based sensors when images are highly compressed. The results show successful and promising application of image compression for photogrammetry and structural health monitoring. The study also identifies best methods and algorithms where effective compression ratios up to 20 times, with respect to original data size, can be applied and still maintain displacement measurement accuracy.

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