scholarly journals Damage detection with the fundamental mode of edge waves

2020 ◽  
pp. 147592172092031
Author(s):  
James M Hughes ◽  
Munawwar Mohabuth ◽  
Aditya Khanna ◽  
James Vidler ◽  
Andrei Kotousov ◽  
...  
Keyword(s):  
Damage Detection ◽  
Fundamental Mode ◽  
Rayleigh Waves ◽  
Guided Waves ◽  
Mechanical Damage ◽  
Corrosion Damage ◽  
Propagation Distance ◽  
Wave Mode ◽  
Edge Waves ◽  
Phase And Group Velocities

Detection of mechanical damage using Lamb or Rayleigh waves is limited to relatively simple geometries, yet real structures often incorporate features such as free or clamped edges, welds, rivets, ribs and holes. All these features are potential sources of wave reflections and scattering, which make the application of these types of guided waves for damage detection difficult. However, these features can themselves generate so-called ‘feature-guided’ waves. This article details the first application of the fundamental mode of transient edge waves for detection of mechanical damage. The fundamental edge wave mode (ES0) – a natural analogue to Rayleigh waves – is weakly dispersive and may decay with propagation distance. The phase and group velocities of the ES0 wave mode are close to the fundamental shear horizontal (SH0) and symmetric Lamb (S0) wave modes, at low and high frequencies, respectively. It is therefore quite challenging to excite a single ES0 mode and avoid wave coupling. However, it was found experimentally that at medium range frequencies the ES0 mode can be decoupled from SH0 and S0 modes, and its decay is small, allowing for distant detection of defects and damage along free edges of slender structural components. This article provides a brief theory of edge waves, excitation methodology and successful examples of distant detection of crack-like and corrosion damage in I-beam sections, which are widely applied in engineering and construction.

scholarly journals Numerical Simulation on Micro-damage Detection In CFRP Composites Based on Nonlinear Ultrasonic Guided Waves

2021 ◽  
Keyword(s):  
Damage Detection ◽  
Composite Structures ◽  
Guided Waves ◽  
Second Harmonic ◽  
Wave Mode ◽  
Guided Wave ◽  
Reinforced Plastics ◽  
Matrix Cracks ◽  
Nonlinear Ultrasonic ◽  
Contact Acoustic Nonlinearity

Abstract. Micro-damages such as pores, closed delamination/debonding and fiber/matrix cracks in carbon fiber reinforced plastics (CFRP) are vital factors towards the performance of composite structures, which could collapse if defects are not detected in advance. Nonlinear ultrasonic technologies, especially ones involving guided waves, have drawn increasing attention for their better sensitivity to early damages than linear acoustic ones. The combination of nonlinear acoustics and guided waves technique can promisingly provide considerable accuracy and efficiency for damage assessment and materials characterization. Herein, numerical simulations in terms of finite element method are conducted to investigate the feasibility of micro-damage detection in multi-layered CFRP plates using the second harmonic generation (SHG) of asymmetric Lamb guided wave mode. Contact acoustic nonlinearity (CAN) is introduced into the constitutive model of micro-damages in composites, which leads to the distinct SHG compared with material nonlinearity. The results suggest that the generated second order harmonics due to CAN could be received and adopted for early damage evaluation without matching the phase of the primary waves.

scholarly journals The Detection of Impact Damage to the Edges of CFRP Plates Using Extensional Ultrasonic Edge Waves

2021 ◽  
Vol 40 (4) ◽  
Author(s):  
Jun Yu Harry Chu ◽  
Charles R. P. Courtney
Keyword(s):  
Damage Detection ◽  
Impact Damage ◽  
Damage Model ◽  
Composite Plates ◽  
Propagation Distance ◽  
Time Of Arrival ◽  
Edge Waves ◽  
Plate Edge ◽  
Carbon Fibre Reinforced Polymer ◽  
Pulse Echo

AbstractExtensional edge waves propagate along the edges of plates, with low attenuation in the propagation direction and amplitude decreasing rapidly (within one or two wavelengths) in the direction perpendicular to the plate edge. This makes them an ideal candidate for inspecting the edges of plate-like structures. Here, finite-element models and experiments are used to investigate the propagation and scattering of extensional edge waves in composite plates and application to damage detection is demonstrated. Piezoceramic transducers attached to the edge of a 4-mm-thick carbon-fibre-reinforced polymer (CFRP) plate were used to excite 140-kHz edge waves and damage detection demonstrated using two experimental configurations: pitch-catch and two-transducer pulse-echo. Damage due to edge-on impacts of 5 J and 10 J were detected in both configurations. A mass-addition damage model was used to investigate the effect of damage location. Detection was specific to damage within 33 mm (1.5 wavelengths) of the plate edge with propagation unaffected by features beyond that distance. The time of arrival of reflected signals in pulse-echo mode was accurately predicted using the edge-wave group velocity indicating that this configuration can be used for locating damage on edges. The localisation of edge waves means that they can specifically detect damage at the edges of structures, and attenuation measurements indicate that their useful propagation distance is large (5.5 m).

scholarly journals High-resolution thickness maps of corrosion using SH1 guided wave tomography

2021 ◽  
Vol 477 (2245) ◽  
pp. 20200380
Author(s):  
Andreas A. E. Zimmermann ◽  
Peter Huthwaite ◽  
Brian Pavlakovic
Keyword(s):  
Petrochemical Industry ◽  
Guided Waves ◽  
Corrosion Damage ◽  
Wave Mode ◽  
Guided Wave ◽  
Resolution Limit ◽  
First Order ◽  
Wave Tomography ◽  
Plane Direction ◽  
Shear Horizontal

Quantifying corrosion damage is vital for the petrochemical industry, and guided wave tomography can provide thickness maps of such regions by transmitting guided waves through these areas and capturing the scattering information using arrays. The dispersive nature of the guided waves enables a reconstruction of wave velocity to be converted into thickness. However, existing approaches have been shown to be limited in in-plane resolution, significantly short of that required to accurately image a defect target of three times the wall thickness (i.e. 3 T) in each in-plane direction. This is largely due to the long wavelengths of the fundamental modes commonly used, being around 4 T for both A0 and S0 at the typical operation points. In this work, the suitability of the first-order shear-horizontal guided wave mode, SH1, has been investigated to improve the resolution limit. The wavelength at the desired operating point is significantly shorter, enabling an improvement in resolution of around 2.4 times. This is first verified by realistic finite-element simulations and then validated by experimental results, confirming the improved resolution limit can now allow defects of maximum extent 3T-by-3T to be reliably detected and sized, i.e. a long-pursued goal of guided wave tomography has been achieved.

Guided Wave Damage Detection in Power-Plant-Tubes by Using Magnetostrictive Transducer Arrays

2015 ◽  
Author(s):  
Peng Guo ◽  
Hongyuan Li ◽  
Zhenhua Tian ◽  
Hong Xu
Keyword(s):  
Power Plant ◽  
Damage Detection ◽  
Guided Waves ◽  
Small Diameter ◽  
Wave Mode ◽  
Guided Wave ◽  
Detection Technique ◽  
Thick Wall ◽  
Transducer Arrays ◽  
Magnetostrictive Transducer

This paper presents an efficient damage detection technique for power-plant-tubes by using guided waves and magnetostrictive transducer arrays. Particularly, our detection technique focuses on the small diameter and thick wall power-plant-tubes, such as superheater tubes, reheater tubes and water wall tubes. Firstly, the damage effects on guided waves in small diameter and thick wall tubes were studied by using three-dimensional finite element method. The wave reflections and mode conversions induced by damage were investigated. Secondly, based on T (0, 1)-F (n, 2) modes, magnetostrictive transducers were designed for guided wave generation and sensing in small diameter and thick wall tubes. The designed magnetostrictive transducers can effectively generate and measure guided waves, especially the non-dispersive torsional T (0, 1) wave mode. Finally, a magnetostrictive transducer array was developed for damage detection in small diameter and thick wall tubes. Through a virtual focusing array imaging algorithm, intensity images were constructed, which can show both the location and size of damage.

The fundamental ultrasonic edge wave mode: Propagation characteristics and potential for distant damage detection

Ultrasonics ◽  
2021 ◽  
Vol 114 ◽  
pp. 106369
Author(s):  
James M. Hughes ◽  
Munawwar Mohabuth ◽  
Andrei Kotousov ◽  
Ching-Tai Ng
Keyword(s):  
Damage Detection ◽  
Wave Mode ◽  
Edge Wave ◽  
Mode Propagation ◽  
Propagation Characteristics

Compressional‐wave velocities in attenuating media: A laboratory physical model study

Geophysics ◽  
2000 ◽  
Vol 65 (4) ◽  
pp. 1162-1167 ◽  
Author(s):  
Joseph B. Molyneux ◽  
Douglas R. Schmitt
Keyword(s):  
Phase Velocity ◽  
Group Velocity ◽  
Wave Velocity ◽  
Propagation Distance ◽  
Compressional Wave ◽  
Arrival Times ◽  
Wave Velocities ◽  
Amplitude Maximum ◽  
Phase And Group Velocities ◽  
Group Velocities

Elastic‐wave velocities are often determined by picking the time of a certain feature of a propagating pulse, such as the first amplitude maximum. However, attenuation and dispersion conspire to change the shape of a propagating wave, making determination of a physically meaningful velocity problematic. As a consequence, the velocities so determined are not necessarily representative of the material’s intrinsic wave phase and group velocities. These phase and group velocities are found experimentally in a highly attenuating medium consisting of glycerol‐saturated, unconsolidated, random packs of glass beads and quartz sand. Our results show that the quality factor Q varies between 2 and 6 over the useful frequency band in these experiments from ∼200 to 600 kHz. The fundamental velocities are compared to more common and simple velocity estimates. In general, the simpler methods estimate the group velocity at the predominant frequency with a 3% discrepancy but are in poor agreement with the corresponding phase velocity. Wave velocities determined from the time at which the pulse is first detected (signal velocity) differ from the predominant group velocity by up to 12%. At best, the onset wave velocity arguably provides a lower bound for the high‐frequency limit of the phase velocity in a material where wave velocity increases with frequency. Each method of time picking, however, is self‐consistent, as indicated by the high quality of linear regressions of observed arrival times versus propagation distance.

Investigation of Sensor Placement in Lamb Wave-Based SHM Method

2012 ◽  
Vol 518 ◽  
pp. 174-183 ◽  
Author(s):  
Pawel Malinowski ◽  
Tomasz Wandowski ◽  
Wiesław M. Ostachowicz
Keyword(s):  
Wave Propagation ◽  
Damage Detection ◽  
Guided Waves ◽  
Sensor Placement ◽  
Detection Algorithm ◽  
Piezoelectric Sensors ◽  
Optimal Placement ◽  
Laser Vibrometer ◽  
Contact Method ◽  
Monitoring Method

In this paper the investigation of a structural health monitoring method for thin-walled parts of structures is presented. The concept is based on the guided elastic wave propagation phenomena. This type of waves can be used in order to obtain information about structure condition and possibly damaged areas. Guided elastic waves can travel in the medium with relatively low attenuation, therefore they enable monitoring of extensive parts of structures. In this way it is possible to detect small defects in their early stage of growth. It is essential because undetected damage can endanger integrity of a structure. In reported investigation piezoelectric transducer was used to excite guided waves in chosen specimens. Dispersion of guided waves results in changes of velocity with the wave frequency, therefore a narrowband signal was used. Measurement of the wave field was realized using laser scanning vibrometer that registered the velocity responses at points belonging to a defined mesh. An artificial discontinuity was introduced to the specimen. The goals of the investigation was to detect it and find optimal sensor placement for this task. Determination of the optimal placement of sensors is a very challenging mission. In conducted investigation laser vibrometer was used to facilitate the task. The chosen mesh of measuring points was the basis for the investigation. The purpose was to consider various configuration of piezoelectric sensors. Instead of using vast amount of piezoelectric sensors the earlier mentioned laser vibrometer was used to gather the necessary data from wave propagation. The signals gather by this non-contact method for the considered network were input to the damage detection algorithm. Damage detection algorithm was based on a procedure that seeks in the signals the damage-reflected waves. Knowing the wave velocity in considered material the damage position can be estimated.

scholarly journals Device Concept for the Generation of Guided Waves for Early Damage Detection

2012 ◽  
Vol 47 ◽  
pp. 1185-1188 ◽  
Author(s):  
E. Köppe ◽  
M. Bartholmai ◽  
J. Prager
Keyword(s):  
Damage Detection ◽  
Guided Waves ◽  
Early Damage
Sign in / Sign up

Export Citation Format

Share Document