Waveguide sensing for structural health monitoring at elevated temperatures: simulating corrosion damage reconstruction
27 Mar 2019-Vol. 10970, pp 1097009
TL;DR: In this article, a waveguide based method combined with synthetic focusing image reconstruction has been proposed for Structural Health Monitoring (SHM) of the components operating in hostile environments and is sometimes too complex and inaccessible for manual inspection.
Abstract: Ultrasonic transducers typically used for inspection such as wall thickness measurement are not suitable for high temperature applications and the inspections are more of a periodic and manual in nature instead of continuous. A waveguide based method combined with synthetic focusing image reconstruction has been proposed for Structural Health Monitoring (SHM) of the components operating in hostile environments and is sometimes too complex and inaccessible for manual inspection. This work follows to develop a waveguide based sensing method to implement a robust and accurate monitoring of surface back wall damage with moderate coverage range. Finite Element (FE) Analysis has been carried out to study the multi-modal behavior in waveguides of rectangular cross sectional geometry and to choose optimal mode(s) and geometry which are best suited for the application. Simulations based on 3D Elastodynamic and 2D Acoustic FE models has been taken to study and implement the reconstruction for different cases representing various levels of wall loss. The waveguide is being used for transmitting the ultrasonic guided waves into the structure under investigation and the received signals from the structure has been processed using Synthetic focusing technique for the surface back wall reconstruction to access damage caused by corrosion like phenomenon.
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01 Nov 2021
TL;DR: In this article, the authors study the propagation of shear horizontal (SH) guided wave in a strip waveguide and its interaction with the notch in the waveguide through simulation studies.
Abstract:
Surface temperature mapping is crucial for the monitoring and control of an object of interest, such as furnace, reactor pipes carrying hot fluids, or a component under a temperature-dependent process. While the use of waveguides for temperature measurement is well documented in literature, the attachment of the waveguide to a metallic component poses challenges. These include the relationship between the local waveguide temperature and that of the metal component, and wave leakage into the component. In this paper, the authors study the propagation of shear horizontal (SH) guided wave in a strip waveguide and its interaction with the notch embodiments in the waveguide. The effects of the type of notch and its depth on the SH mode characteristics are investigated through simulation studies. The mode of attachment of the waveguide to the metal component is by means a slot made in the component. The area of contact between the waveguide and metal component is optimized such that there is minimum wave leakage into the bulk material. Based on the simulation results, a waveguide strip is fabricated and used to monitor the local surface temperature of a test metal component. The waveguide is calibrated by correlating the time of flight (ToF) shift in the waveforms against reference temperature values. Thereafter, the instantaneous temperature of the metal component is determined from the calibration equations. A set of experimental trials are performed to check for repeatability. The experiments are conducted in near steady-state conditions for better accuracy in the measurements.
3 citations
18 May 2012
TL;DR: In this paper, a semi-analytical mesh-free model is presented which can simulate scattering of acoustic waves in two-dimensions while accounting for the effects of shadowing and multiple reflections at the surface.
Abstract: In ultrasonic thickness monitoring using permanently installed sensors, random signal variations due to coupling changes and manual operation are largely reduced. However, effects on the signal due to roughness introduced by corrosion and erosion processes cannot be removed. Ultrasonic scattering by rough surfaces is an extensive topic within the literature; however, many models rely heavily on approximations limiting their applications. In this paper, a semi-analytical mesh-free model is presented which can simulate scattering of acoustic waves in two-dimensions while accounting for the effects of shadowing and multiple reflections at the surface. The absence of mode conversion at oblique angles of incidence make this approach valid for SH wave scattering from 2.5D surfaces. The mathematical framework is based on the Distributed Point Source Method (DPSM) which has been adapted for use in two dimensions. Comparisons are made with the Finite Element Method (FEM) showing very good agreement while incurring...
2 citations
References
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TL;DR: The use of ultrasonic arrays for non-destructive evaluation has been extensively studied in the literature as mentioned in this paper, where the main advantages of arrays are their increased flexibility over traditional single element transducers, and their ability to produce immediate images of the test structure.
Abstract: An ultrasonic array is a single transducer that contains a number of individually connected elements. Recent years have seen a dramatic increase in the use of ultrasonic arrays for non-destructive evaluation. Arrays offer great potential to increase inspection quality and reduce inspection time. Their main advantages are their increased flexibility over traditional single element transducer methods, meaning that one array can be used to perform a number of different inspections, and their ability to produce immediate images of the test structure. These advantages have led to the rapid uptake of arrays by the engineering industry. These industrial applications are underpinned by a wide range of published research which describes new piezoelectric materials, array geometries, modelling methods and inspection modalities. The aim of this paper is to bring together the most relevant published work on arrays for non-destructive evaluation applications, comment on the state-of the art and discuss future directions. There is also a significant body of published literature referring to use of arrays in the medical and sonar fields and the most relevant papers from these related areas are also reviewed. However, although there is much common ground, the use of arrays in non-destructive evaluation offers some distinctly different challenges to these other disciplines.
818 citations
TL;DR: This paper describes an alternative approach in which the full matrix of time domain signals from every transmitter–receiver pair is captured and post-processed and shown to offer significant performance advantages for NDE.
Abstract: Processing of ultrasonic array data is traditionally based on having parallel transmission circuits that enable staggered firing of transmitter elements to produce the desired wavefront. This paper describes an alternative approach in which the full matrix of time domain signals from every transmitter–receiver pair is captured and post-processed. Various post-processing approaches are modelled and assessed in terms of their ability to image a point-like reflector. Experimental results are then presented which show good quantitative agreement with the modelled results. An advanced processing algorithm is also implemented which allows the array to be focused at every point in the target region in both transmission and reception. This approach is shown to offer significant performance advantages for NDE.
747 citations
TL;DR: In this paper, the authors present a review of the studies of the propagation of the waves and their sensitivity to defects which have been conducted in order to provide a sound scientific basis for the method.
581 citations
TL;DR: The design of a high-temperature ultrasonic thickness gauge that bypasses problems of depolarization and differential thermal expansion of the different materials within a transducer causes them to fail is described.
Abstract: Conventional ultrasonic transducers cannot withstand high temperatures for two main reasons: the piezoelectric elements within them depolarize, and differential thermal expansion of the different materials within a transducer causes them to fail. In this paper, the design of a high-temperature ultrasonic thickness gauge that bypasses these problems is described. The system uses a waveguide to isolate the vulnerable transducer and piezoelectric elements from the high-temperature measurement zone. Use of thin and long waveguides of rectangular cross section allows large temperature gradients to be sustained over short distances without the need for additional cooling equipment. The main problems that had to be addressed were the transmission and reception of ultrasonic waves into and from the testpiece that the waveguides are coupled to, and optimization of the wave propagation along the waveguide itself. It was found that anti-plane shear loading performs best at transmitting and receiving from the surface of a component that is to be inspected. Therefore, a nondispersive guided wave mode in large-aspect-ratio rectangular strips was employed to transmit the anti-plane shear loading from the transducer to the measurement zone. Different joining methods to attach the waveguides to the component were investigated and experiments showed that clamping the waveguides to the component surface gave the best results. The thickness of different plate samples was consistently measured to within less than 0.1 mm. Performance at high temperatures was tested in a furnace at 730°C for 4 weeks without signal degradation. Thicknesses in the range of 3 to 25 mm could be monitored using Hanning windowed tonebursts with 2 MHz center frequency.
129 citations
TL;DR: In this article, the authors present an initial study of the feasibility of using measurements of the velocity and attenuation of the quasi-Scholte mode on a plate to obtain the longitudinal velocities and attenuations of an embedding medium.
Abstract: In the food industry and other industries, rheological measurements and determination of particle sizes in suspensions and emulsions is of great importance for process and quality control. Current test cell based ultrasonic methods exist but are often inconvenient. An attractive alternative could be to insert a simple measurement “dipstick” into the fluid; this paper presents an initial study of the feasibility of using measurements of the velocity and attenuation of the quasi-Scholte mode on a plate to obtain the longitudinal velocity and attenuation of an embedding medium. The attenuation of the quasi-Scholte mode is caused by two mechanisms: shear leakage and attenuation due to the bulk longitudinal attenuation of the embedding material. In a calibration test the bulk longitudinal velocity and viscosity of glycerol were determined experimentally. Measurements agreed well with results from conventional methods and literature data. Quantitative results and an independent validation for honey, a very visc...
77 citations