SHM of pipes using torsional waves generated by in situ magnetostrictive tapes
TL;DR: In this article, an improved magnetostrictive sensors (MsSs) were used for structural health monitoring (SHM) of hard-to-inspect pipes using polymeric magnetic tape material that is suitable for use in a variety of industries.
Abstract: Long-range, torsional guided waves generated in pipes using magnetostrictive sensors (MsSs) have great potential for applications to the structural health monitoring (SHM) of hard-to-inspect pipes. This paper reports an improved MsS technique (when compared to related techniques currently used for the NDT of pipes) that uses polymeric magnetic tape material that is suitable for use in a variety of industries as an SHM tool for pipes. Improvements include increased efficiency, reduced cost and increased long-term survivability of the sensor system. Transduction efficiency was increased by reducing the sensor eddy current losses and by using a field concentrator strip. For long-term monitoring, a low-cost magnetic oxide based MsS material (video recording tape) having the required magnetic properties was used. The MsS strips were oriented to generate non-dispersive torsional guided ultrasonic waves that propagate long distances with minimal mode conversion. Further, considering both safety and long-term survivability of the sensor, low-power ultrasonic instrumentation was developed and tested. Measurements reported here demonstrate the sensitivity of this sensor to both radial notches (saw cuts) and drilled holes. Results also show that magnetic anisotropy of the strip plays a role in generating torsional waves. It is envisioned that results obtained from the present study will significantly enhance the ability to monitor the long-term structural health of piping systems.
Citations
More filters
TL;DR: Two modified SH0 wave PFP transducer designs are proposed: the rounded corner design and the dual design that has a very strong directivity that is useful for several guided-wave-based SHM applications.
Abstract: A piezoelectric fiber patch (PFP) is a transducer type that is suitable for guided-wave-based structural health monitoring (SHM) due to its light, thin, and flexible characteristics. In our previous work, a PFP-based transducer design for selective excitation of the zero-order shear horizontal wave mode (SH0) was introduced (shear horizontal PFP (SHPFP)). In this work, two modified SH0 wave PFP transducer designs are proposed: the rounded corner design and the dual design. The degree of improvement is determined by a numerical simulation and the dual design—the design with the most promise—is experimentally realized. Laser Vibrometry measured the generated wave field, confirming the results from the simulation. The new designs can generate an almost pure SH0 wave. The dual design has a very strong directivity that is useful for several guided-wave-based SHM applications. The conclusions on the design’s properties as a transmitter are also valid for its properties as a sensor due to the reciprocity of piezoelectric transducers.
12 citations
TL;DR: In this paper, a finite element analysis of the wave radiation pattern of a magnetostrictive patch transducer installed on a plate is presented. And the validity of the analysis is checked by comparing the simulated wave radiation patterns from the present analysis with experimental results.
Abstract: Transducers made of thin magnetostrictive patches and magnetic circuits have been recently developed as an effective means for non-destructive guided wave inspection of elastic structures. However, important characteristics of transducers, such as their wave radiation patterns, have been tested only by experiments or a first-order theoretical analysis. There have been some finite element analyses related to magnetostrictive actuators, but no numerical analysis has been performed to predict the wave radiation patterns of various magnetostrictive patch transducers. In this paper, we formulate a finite element procedure and implement it to predict the wave radiation pattern of a magnetostrictive patch transducer installed on a plate. In particular, a linearized model determining coupling matrix appearing in the magnetostrictive constitutive equation of a magnetostrictive patch in a transducer is developed. The developed model is then used to deal with the arbitrarily polarized static magnetic field induced in the transducers. For numerical efficiency, time-harmonic analysis is carried out and a technique to extract data corresponding to target guided wave modes is used. The validity of the developed finite element analysis is checked by comparing the simulated wave radiation patterns from the present analysis with experimental results. The reasons why certain radiation patterns are obtained for selected magnetic circuits are explained by physical reasoning and simulation results.
12 citations
TL;DR: In this article, a numerical model mimics the generation and detection of guided ultrasonic waves from the transducers of two annular arrays located inside a pipe, and the fastest mode of the detected signals is processed using the continuous wavelet transform and the Hilbert transform to extract two damage-sensitive features.
Abstract: This paper presents a numerical study where guided ultrasonic waves (GUWs) are processed using a new imaging algorithm for the health monitoring of pipes. The numerical model mimics the generation and detection of guided waves from the transducers of two annular arrays located inside a pipe. The fastest mode of the detected signals is processed using the continuous wavelet transform and the Hilbert transform to extract two damage-sensitive features. The estimation of the features for the healthy condition is formulated in terms of an optimization problem solved with a competitive optimization algorithm. Finally, a probabilistic approach is used to create an image of the pipe to reveal the presence of possible structural anomalies. With respect to most GUW-based imaging methods, the proposed approach is baseline-free which means that data from pristine pipes are not necessary. A commercial finite element code is utilized to mimic the operation of the two arrays each made of four ultrasonic transducers in contact with the interior wall of a pipe. While one of the transducers acts as transmitter, the other seven act as sensors, and this is repeated for all the elements of the rings. The time waveforms associated with all the possible actuator–sensor pairs are processed using the algorithm proposed here. To demonstrate the advantages of the proposed approach, the findings are compared to the results obtained using a conventional pitch-catch approach. The results are promising and future studies should focus on the experimental validation of the methodology.
12 citations
TL;DR: In this article, the magnetic shape anisotropy effect on sensing performance and directional sensitivity in a directional magnetostrictive patch transducer using a uniaxial comb-shaped nickel patch, for the use of ultrasonic guided Lamb wave technology in metallic planar structure.
Abstract: This article presents the magnetic shape anisotropy effect on sensing performance and directional sensitivity in a directional magnetostrictive patch transducer using a uniaxial comb-shaped nickel patch, for the use of ultrasonic guided Lamb wave technology in metallic planar structure. The uniaxial comb patch was modified from a disc-shaped patch made of polycrystalline nickel, so that its comb fingers were aligned to a specific radial direction to promote the magnetic shape anisotropy in the nickel patch. Previously, it was found that a magnetostrictive patch transducer using a nickel disc patch appeared to have omnidirectional sensitivity for sensing guided Lamb waves in an aluminum plate due to the isotropic magnetostrictive nature of polycrystalline nickel. In this work, we initially investigated a theoretical approach to determine demagnetization factor change caused by the geometrical shape modification of a nickel patch, which strongly correlated with a specific magnetization characteristic of the...
12 citations
Cites background from "SHM of pipes using torsional waves ..."
...Kannan et al. (2007) reported torsional guided wave generation using oriented magnetostrictive strips (video recording tape) in metallic pipes....
[...]
TL;DR: In this article, the first-order torsional wave was used to detect axial cracks in cylindrical structures using torsion wave generated by piezoelectric macro-fiber composite.
Abstract: In cylindrical structures such as pipelines and pressure vessels, cracks are most likely to occur along the longitudinal (axial) direction, and they can be fatal to the serviceability of the structures. However, the conventional wave propagation–based crack detection techniques are not sensitive to this type of cracks. This article focuses on the identification of axial cracks in cylindrical structures using torsional wave generated by piezoelectric macro-fiber composite. The first-order torsional wave, which is a nondispersive pure shear wave propagating at a fixed wave speed, is utilized in this work because, intuitively, it is more sensitive to axial cracks than the longitudinal waves. The crack position is determined by the time of flight of the wave pack, while the crack propagation is monitored by measuring the variation in the crack-induced disturbances. Numerical simulations have been conducted to investigate the feasibility of the proposed method, and experimental tests on aluminum pipes have bee...
12 citations
Cites methods from "SHM of pipes using torsional waves ..."
...Kannan et al. (2007) used magnetostrictive tape transducer to generate guided waves which can cover large area for detecting radial saw cuts and drilled holes....
[...]
References
More filters
TL;DR: The concept of sensor networks which has been made viable by the convergence of micro-electro-mechanical systems technology, wireless communications and digital electronics is described.
17,936 citations
683 citations
01 Jan 1997
TL;DR: In this article, a general-purpose program that can create dispersion curves for a very wide range of systems and then effectively communicate the information contained within those curves is presented, using the global matrix method to handle multi-layered Cartesian and cylindrical systems.
Abstract: The application of guided waves in NDT can be hampered by the lack of readily available dispersion curves for complex structures. To overcome this hindrance, we have developed a general purpose program that can create dispersion curves for a very wide range of systems and then effectively communicate the information contained within those curves. The program uses the global matrix method to handle multi-layered Cartesian and cylindrical systems. The solution routines cover both leaky and non-leaky cases and remain robust for systems which are known to be difficult, such as large frequency-thicknesses and thin layers embedded in much thicker layers. Elastic and visco-elastic isotropic materials are fully supported; anisotropic materials are also covered, but are currently limited to the elastic, non-leaky, Cartesian case.
485 citations
TL;DR: Magnetic crystal anisotropy and magnetostriction have been measured in various single crystals of ferrites having compositions represented approximately by $M{\mathrm{Fe}}_{2}{\mathrm{\O}}_{4}$, where $M$ stands for Mn, Fe, Co, Ni, and Zn in various proportions.
Abstract: Magnetic crystal anisotropy and magnetostriction have been measured in various single crystals of ferrites having compositions represented approximately by $M{\mathrm{Fe}}_{2}{\mathrm{O}}_{4}$, where $M$ stands for Mn, Fe, Co, Ni, and Zn in various proportions. Special attention is given to heat-treatment in a magnetic field.The magnetic anisotropy of cobalt ferrite at room temperature is as high as 4\ifmmode\times\else\texttimes\fi{}${10}^{6}$ ergs/${\mathrm{cm}}^{2}$. Magnetostriction is as high as 800\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}6}$. Magnetic anneal is effective at temperatures as low as 150\ifmmode^\circ\else\textdegree\fi{}C, and causes the hysteresis loop to become square. In polycrystalline material the response to magnetic anneal is a maximum at compositions intermediate between Co${\mathrm{Fe}}_{2}$${\mathrm{O}}_{4}$ and ${\mathrm{Fe}}_{3}$${\mathrm{O}}_{4}$.The constants for the various specimens are tabulated. Values of the anisotropy constants of Mn${\mathrm{Fe}}_{2}$${\mathrm{O}}_{4}$ at 20\ifmmode^\circ\else\textdegree\fi{}C and -196\ifmmode^\circ\else\textdegree\fi{}C are the same as those determined from ferromagnetic resonance experiments. At -196\ifmmode^\circ\else\textdegree\fi{}C the constant for ${\mathrm{Ni}}_{0.75}$${\mathrm{Fe}}_{2.25}$${\mathrm{O}}_{4}$ differs markedly from that determined by ferromagnetic resonance; this is to be expected from the relaxation phenomena observed by Galt, Yager, and Merritt.
446 citations
Journal Article•
425 citations