scholarly journals An Experimental Study of Damage Detection on Typical Joints of Jackets Platform Based on Electro-Mechanical Impedance Technique

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7168
Author(s):  
Liaqat Ali ◽  
Sikandar Khan ◽  
Naveed Iqbal ◽  
Salem Bashmal ◽  
Hamad Hameed ◽  
...  
Keyword(s):  
Mechanical Impedance ◽  
Offshore Structures ◽  
Theoretical Background ◽  
Welded Steel ◽  
Electromechanical Impedance ◽  
Impedance Technique ◽  
Jacket Structures ◽  
Average Variance ◽  
Steel Joints ◽  
Non Destructive

Many methods have been used in the past two decades to detect crack damage in steel joints of the offshore structures, but the electromechanical impedance (EMI) method is a comparatively recent non-destructive method that can be used for quality monitoring of the weld in structural steel joints. The EMI method ensures the direct assessment, analysis and particularly the recognition of structural dynamics by acquiring its EM admittance signatures. This research paper first briefly introduces the theoretical background of the EMI method, followed by carrying out the experimental work in which damage in the form of a crack is simulated by using an impedance analyser at different distances. The EMI technique is used to identify the existence of damage in the welded steel joints of offshore steel jacket structures, and Q345B steel was chosen as the material for test in the present study. Sub-millimetre cracks were found in four typical welded steel joints on the jacket platform under circulating loads, and root average variance was used to assess the extent of the crack damage.

Non Destructive Evaluation Based on Impedance Method Using Embedded PZT Sensor

2009 ◽  
Vol 79-82 ◽  
pp. 35-38 ◽  
Author(s):  
Dong Yu Xu ◽  
Xin Cheng ◽  
Shi Feng Huang ◽  
Min Hua Jiang
Keyword(s):  
Structural Damage ◽  
Crack Depth ◽  
Impedance Method ◽  
Impedance Spectra ◽  
Electromechanical Impedance ◽  
Non Destructive Evaluation ◽  
Increasing Trend ◽  
Impedance Technique ◽  
Impedance Curve ◽  
Non Destructive

The structural damage of mortar caused by simulated crack was evaluated using embedded PZT sensor combining with dynamic electromechanical impedance technique. The influence of embedded PZT sensors layout on detecting structural damage induced by the simulated cracks was also investigated. The results indicate that with increasing the simulated crack depth, the impedance real part of PZT sensors shift leftwards accompanying with the appearance of new peaks in the spectra. When more simulated cracks occur, the shift of the impedance curve becomes more obvious, and the amounts of new peaks in the impedance spectra also increase. RMSD indices of the structures with PZT sensors embedded in them with different layout can show the structural incipient damage clearly. With increasing more simulated cracks in the mortar structures, RMSD values of the structures with different PZT sensors layout become larger, under the same depth, RMSD indices of the structures with PZT sensor embedded transversely and horizontally in them show the increasing trend.

The detection and measurement of overlapping fatigue cracks at welded joints by thin-skin electromagnetic fields

1988 ◽  
Vol 419 (1856) ◽  
pp. 69-89 ◽  
Keyword(s):  
Measurement Method ◽  
Fatigue Cracks ◽  
Current Field ◽  
Welded Steel ◽  
Non Destructive Evaluation ◽  
Thin Skin ◽  
Response Profiles ◽  
Steel Joints ◽  
Non Destructive ◽  
Probe Response

Fatigue cracks occur at different locations at the toes of welded steel joints. With continued load cycling it is often found that the cracks grow towards each other and overlap in adjacent parallel planes. It is useful to be able to detect and measure overlapping cracks and in this paper the characteristic responses to be expected from these features are calculated for the alternating-current field-measurement method of non-destructive evaluation by thin-skin theory. Typical signal profiles are calculated for probe traverses across the cracks and parallel to the edges. These are compared with experimental data obtained by using three pairs of overlapping notches with different proportions, cut in a steel block. The notches were interrogated by a thin-skin field at a frequency of 6 kHz. The calculations show that overlapping cracks give rise to asymmetric cross-crack signal profiles, which do not occur for single cracks, and to characteristic changes in curvature in the probe response profiles. These features are well confirmed by the experiments. The results also show that traverses along the crack edges can be used to find the positions of the crack ends.

Electromechanical Impedance Method for Damage Detection of Typical Joint on Jacket Platform

2018 ◽  
Author(s):  
Boying Zhang ◽  
Hamad Hameed ◽  
Yuxin Xu ◽  
Chonglin Zhang ◽  
Yong Bai
Keyword(s):  
Health Monitoring ◽  
Mechanical Impedance ◽  
Theoretical Background ◽  
Impedance Method ◽  
Laboratory Measurements ◽  
Direct Evaluation ◽  
Jacket Platform ◽  
Health Monitoring System ◽  
Electromechanical Impedance ◽  
Experimental Works

Health monitoring of welded structural joints is a very important factor of the engineering community. Electro-mechanical impedance (EMI) technique allows the direct evaluation of structural dynamics by evaluating its E/M impedance or admittance signatures. This paper first gives a brief introduction of the theoretical background on the described method. Then, the described EMI technique is applied to recognize the presence of damage by executing experimental works where the damage in the form of crack is simulated with an impedance analyzer at various distances. Four typical welded metallic joints on a jacket platform successfully produced submillimeter cracks under cyclic loading and root mean square deviation (RMSD) is used to evaluate the degree of crack damage. Finally, an outcome of laboratory measurements performed with developed structural health monitoring system based on the electromechanical impedance phenomenon is presented.

Research of EMI Structural Health Monitoring Based on BP Neural Networks

2012 ◽  
Vol 188 ◽  
pp. 231-235
Author(s):  
Fu Hou Xu ◽  
Dong Dong Wen ◽  
Yu Xiang Zhang ◽  
Hua Cheng Li
Keyword(s):  
Neural Networks ◽  
Structural Damage ◽  
Mechanical Impedance ◽  
Bp Neural Networks ◽  
Impedance Analyzer ◽  
Electromechanical Impedance ◽  
Impedance Response ◽  
Impedance Technique ◽  
Coupling Characteristic ◽  
Neural Network Input

Based on the coupling characteristic of piezoelectric ceramics (PZT) and electro-mechanical, impedance changes were measured by the impedance analyzer. Aluminum plate’s impedance response under different load conditions was analyzed with electromechanical impedance technique. BP neural networks were established to identify the structural damage status and the RMSDR was calculated as neural network input data, then the networks was trained and validated. Experiment results show that the trained network can successfully identify the structural load state.

A PZT-based electromechanical impedance method for monitoring the moisture content of wood

Sensor Review ◽  
2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Quan Zhai ◽  
Jicheng Zhang ◽  
Guofeng Du ◽  
Yulong Rao ◽  
Xiaoyu Liu
Keyword(s):  
Moisture Content ◽  
Mechanical Impedance ◽  
Impedance Method ◽  
Impedance Change ◽  
Monitoring Method ◽  
Content Type ◽  
Electromechanical Impedance ◽  
Wide Range ◽  
Impedance Technique ◽  
Piezoelectric Impedance

Purpose At present, piezoelectric impedance technology has been used in the study of wood damage monitoring. However, little effort has been made in the research on the application of piezoelectric impedance system to monitor the change of wood moisture content (MC). The monitoring method of wood MC is used by piezoelectric impedance technique in this study. Design/methodology/approach One piezoceramic transducer is bonded to the surface of wood specimens. The MC of the wood specimens increases gradually from 0% to 60% with 10% increments; the mechanical impedance of the wood specimen will change, and the change in the mechanical impedance of the structure is reflected by monitoring the change in the electrical impedance of lead zirconate titanate. Therefore, this paper investigates the relationship between wood MC change and piezoelectric impedance change to verify the feasibility of the piezoelectric impedance method for monitoring wood MC change. Findings The experiment verified that the real part of impedance of the wood increased with the increase of wood MC. Besides, the damage index root mean square deviation is introduced to quantify the damage degree of wood under different MC. At the same time, the feasibility and validity of this experiment were verified from the side by finite element simulation. Finally, MC monitoring by piezoelectric impedance technique is feasible. Originality/value To the best of the authors’ knowledge, this work is the first to apply piezoelectric ceramics to the monitoring of wood MC, which provides a theoretical basis for the follow-up study of a wide range of wood components and even wood structure MC changes.

scholarly journals Finite Element Simulation of Electro-Mechanical Impedance Technique

2015 ◽  
Vol 1115 ◽  
pp. 539-542
Author(s):  
Kamyar Tahmasebpour ◽  
Meftah Hrairi ◽  
Mohd Sultan I.S. Dawood
Keyword(s):  
Finite Element ◽  
Piezoelectric Materials ◽  
Piezoelectric Element ◽  
Mechanical Impedance ◽  
Signal Frequency ◽  
Impedance Method ◽  
Electromechanical Impedance ◽  
Finite Element Software ◽  
Sensor Position ◽  
Impedance Technique

Electro-mechanical impedance method is emerging as an important and powerful technique for structural health monitoring (SHM). Active elements of the technique are Piezoelectric Wafer Active Sensor (PWAS) bonded on the structure. Modeling and simulation of PWAS and host structure play an important role in the SHM applications with PWAS. For decades finite element method has been extensively applied in the analysis of piezoelectric materials and structures. In this paper, piezoelectric element and a host metallic structure were modeled using Ansys finite element software to find the Electromechanical Impedance (EMI) according to the signal frequency. After that, the EMI signature of the beam was found for different position of the PWAS patch. The study shows that sensor position may directly control the EMI signature.

Fatigue Behaviour of Friction Stir Welded Steel Joints

2014 ◽  
Vol 891-892 ◽  
pp. 1488-1493 ◽  
Author(s):  
José Azevedo ◽  
Virgínia Infante ◽  
Luisa Quintino ◽  
Jorge dos Santos
Keyword(s):  
Base Material ◽  
Welding Process ◽  
Steel Structures ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Welded Steel ◽  
Shipbuilding Industry ◽  
Friction Stir ◽  
Steel Joints

The development and application of friction stir welding (FSW) technology in steel structures in the shipbuilding industry provide an effective tool of achieving superior joint integrity especially where reliability and damage tolerance are of major concerns. Since the shipbuilding components are inevitably subjected to dynamic or cyclic stresses in services, the fatigue properties of the friction stir welded joints must be properly evaluated to ensure the safety and longevity. This research intends to fulfill a clear knowledge gap that exists nowadays and, as such, it is dedicated to the study of welded steel shipbuilding joints in GL-A36 steel, with 4 mm thick. The fatigue resistance of base material and four plates in as-welded condition (using several different parameters, tools and pre-welding conditions) were investigated. The joints culminate globally with defect-free welds, from which tensile, microhardness, and fatigue analyses were performed. The fatigue tests were carried out with a constant amplitude loading, a stress ratio of R=0.1 and frequency between 100 and 120 Hz. The experimental results show the quality of the welding process applied to steel GL-A36 which is reflected in the mechanical properties of joints tested.

Time-domain spectral element method for modelling of the electromechanical impedance of disbonded composites

2018 ◽  
Vol 29 (16) ◽  
pp. 3214-3221 ◽  
Author(s):  
Piotr Fiborek ◽  
Paweł H Malinowski ◽  
Paweł Kudela ◽  
Tomasz Wandowski ◽  
Wiesław M Ostachowicz
Keyword(s):  
Spectral Element Method ◽  
Spectral Element ◽  
Impedance Method ◽  
Adhesively Bonded ◽  
Destructive Testing ◽  
Electromechanical Impedance ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
Non Destructive ◽  
Element Method

The research focuses on the electromechanical impedance method. The electromechanical impedance method can be treated as non-destructive testing or structural health monitoring approach. It is important to have a reliable tool that allows verifying the integrity of the investigated objects. The electromechanical impedance method was applied here to assess the carbon fibre–reinforced polymer samples. The single and adhesively bonded samples were investigated. In the reported research, the electromechanical impedance spectra up to 5 MHz were considered. The investigation comprised of modelling using spectral element method and experimental measurements. Numerical and experimental spectra were analysed. Differences in spectra caused by differences in considered samples were observed.

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