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.
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Dissertation•
01 Jan 2013
TL;DR: In this article, the degree of Doctor of Engineering (DBE) was awarded by Brunel University, London, UK, for a thesis entitled "Structural and Structural Engineering".
Abstract: This thesis was submitted for the degree of Doctor of Engineering and awarded by Brunel University
1 citations
Cites background from "SHM of pipes using torsional waves ..."
...In particular materials developed for use in magnetic recording, such as Nickel and Iron Oxide based films (video tape), have been found to work well (largely due to their flexibility allowing them to be conformable) and they are very cheaply available [Kannan et al., 2007]....
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TL;DR: In this paper, a face-shear d24 PZT wafer is proposed to excite and receive SH0 wave mode, where the d24 wafer was in-plane poled and its working electric field was applied along another orthogonal inplane direction.
Abstract: The non-dispersive fundamental shear horizontal (SH0) and torsional [T(0,1)] waves are extremely useful in guidedwave-based inspection techniques. However, excitation of SH0 and T(0,1) waves using piezoelectrics is always a challenge. In this work, firstly, a newly defined face-shear d24 PZT wafer is proposed to excite and receive SH0 wave mode. The d24 wafer is in-plane poled and its working electric field is applied along another orthogonal in-plane direction. Both finite element simulations and experiments show that single SH0 mode can be excited by using the d24 wafer along two orthogonal directions (0° and 90°). Then an omnidirectional SH0 wave piezoelectric transducer (OSHPT) is developed which consists of a circular array of twelve face-shear d24 trapezoidal PZT elements. Results show that the proposed OSH-PT exhibits good omnidirectional properties, no matter it is used as a SH0 wave transmitter or receiver. Finally, the development of a T(0,1) wave transducer for pipes based on a ring array of d24 PZT elements is described. Both finite element simulations and experiments show that the d24 elements ring can excite single T(0,1) mode and suppress all the unwanted non-axisymmetric modes. This work may greatly promote the applications of SH0 and T(0,1) waves in nondestructive testing (NDT) and structural health monitoring (SHM).
1 citations
TL;DR: In this article, a damage visualization technique using a fully noncontact laser ultrasonic measurement system and a synchronized scanning strategy is presented, where the laser beams for ultrasonic wave generation and detection are shot on the target structure with a constant and tiny distance, and these two laser beams are synchronously moved over the scanning area.
Abstract: This paper presents a damage visualization technique using a fully noncontact laser ultrasonic measurement system and a synchronized scanning strategy. The noncontact laser ultrasonic measurement system is composed of a Q-switched Nd:YAG laser for ultrasonic wave generation and a laser Doppler vibrometer (LDV) for ultrasonic wave detection. The laser beams for ultrasonic wave generation and detection are shot on the target structure with a constant and tiny distance, and these two laser beams are synchronously moved over the scanning area. Compared with conventional laser scanning strategies, the ultrasonic responses detected through the synchronized scanning strategy owns a much higher and more stable signal to noise ratio and the scanning time can be significantly reduced with less time averaging. By spatial comparison in the scanning area, damage can be detected and visualized without relying on baseline data obtained from the pristine condition of the target structure. In this paper, the developed technique is validated by visualization hidden corrosion in a steel straight pipe and a steel elbow pipe.
1 citations
TL;DR: In this article, the external loading effects on an ultrasonic guided wave (GW) magnetostrictive sensor using a nickel disk patch permanently attached to a thin metallic waveguide plate were investigated.
Abstract: This paper presents the external loading effects on an ultrasonic guided wave (GW) magnetostrictive sensor using a nickel disk patch permanently attached to a thin metallic waveguide plate. The circular magnetostrictive patch transducer (CMPT) consists of the surface-bonded nickel patch and a detachable magnetic circuit device enclosing a ring-shaped sensing coil and cylindrical biasing magnets. Various compressive and tensile stresses were applied to the nickel patch on account of the buckling response of the plate structure. Strain gauges attached to the nickel patch, a Hall effect sensing device, and a laser displacement sensor were utilized to verify the in-plane deformation and the corresponding magnetic flux density change of the nickel patch and the plate’s central deflection, respectively, under various external loading conditions of the plate. Several PZT wafers also mounted to the plate were individually used to generate a 30 kHz toneburst GW, which is less sensitive to local stiffness changes of the plate due to the buckling mode. The external loading effects on the CMPT were determined by evaluating the peak-to-peak amplitude variation of the direct arrival waveform of the GW signals acquired by the PZT and CMPT sensor networks. The experimental results demonstrate that the external load applied to the waveguide structure induces compressive and tensile stresses in the nickel patch, leading to distorted GW sensing performance and the directional pattern of the CMPT. Although the presented CMPT has an omnidirectional sensing profile due to its design configuration, the planar-stressed CMPT exhibits a specific directional sensing performance as a result of the stress-induced anisotropic magnetostriction of the nickel disk patch.
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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