Spectrotemporal analysis of guided-wave pulse-echo signals: Part 1. Dispersive systems

2001 ◽  
Vol 41 (4) ◽  
pp. 324-331 ◽  
Author(s):  
S. -C. Wooh ◽  
K. Veroy
Keyword(s):  
Guided Wave ◽  
Wave Pulse ◽  
Dispersive Systems ◽  
Pulse Echo

scholarly journals Absolute stress measurement of structural steel members with ultrasonic shear-wave spectral analysis method

2017 ◽  
Vol 18 (1) ◽  
pp. 216-231 ◽  
Author(s):  
Zuohua Li ◽  
Jingbo He ◽  
Jun Teng ◽  
Qin Huang ◽  
Ying Wang
Keyword(s):  
Spectral Analysis ◽  
Structural Steel ◽  
Shear Wave ◽  
Wave Amplitude ◽  
Stress Measurement ◽  
Amplitude Spectrum ◽  
Uniaxial Stress ◽  
Wave Pulse ◽  
Steel Members ◽  
Pulse Echo

Absolute stress in structural steel members is an important parameter for the design, construction, and servicing of steel structures. However, it is difficult to measure via traditional approaches to structural health monitoring. The ultrasonic time-of-flight method has been widely studied for monitoring absolute stress by measuring the change in ultrasonic propagation time induced by stress. The time-of-flight of the two separated shear-wave modes induced by birefringence, which is particular to shear waves, is also affected by stress to different degrees. Their synthesis signal amplitude spectrum exhibits a minimum that varies with stress, which makes it a potential approach to evaluating uniaxial stress using the shear-wave amplitude spectrum. In this study, the effect of steel-member stress on the shear-wave amplitude spectrum from the interference of two shear waves produced by birefringence is investigated, and a method of uniaxial absolute stress measurement using shear-wave spectral analysis is proposed. Specifically, a theoretical expression is derived for the shear-wave pulse-echo amplitude spectrum, leading to a formula for evaluating uniaxial absolute stress. Three steel-member specimens are employed to investigate the influence of uniaxial stress on the shear-wave pulse-echo amplitude spectrum. The testing results indicate that the amplitude spectrum changes with stress and that the inverse of the first characteristic frequency in the amplitude spectrum and its corresponding stress exhibit a near-perfect linear relationship. On this basis, the uniaxial absolute stress of steel members loaded by a test machine is measured by the proposed method. Parametric studies are further performed on three groups of steel members made of 65# steel and Q235 steel to investigate the factors that influence the testing results. The results show that the proposed method can measure and monitor steel-members uniaxial absolute stress on the laboratory scale and has potential to be used in practical engineering with specific calibration.

scholarly journals 10 MHz Thin-Film PZT-Based Flexible PMUT Array: Finite Element Design and Characterization

Sensors ◽  
2020 ◽  
Vol 20 (15) ◽  
pp. 4335
Author(s):  
Jeong Nyeon Kim ◽  
Tianning Liu ◽  
Thomas N. Jackson ◽  
Kyusun Choi ◽  
Susan Trolier-McKinstry ◽  
...  
Keyword(s):  
Finite Element ◽  
Lead Zirconate Titanate ◽  
Focal Length ◽  
Spectral Response ◽  
Guided Wave ◽  
Center Frequency ◽  
Depth Of Field ◽  
High Frequency Ultrasound ◽  
Pulse Echo ◽  
2D Array

Piezoelectric micromachined ultrasound transducers (PMUT) incorporating lead zirconate titanate PbZr0.52Ti0.48O3 (PZT) thin films were investigated for miniaturized high-frequency ultrasound systems. A recently developed process to remove a PMUT from an underlying silicon (Si) substrate has enabled curved arrays to be readily formed. This research aimed to improve the design of flexible PMUT arrays using PZFlex, a finite element method software package. A 10 MHz PMUT 2D array working in 3-1 mode was designed. A circular unit-cell was structured from the top, with concentric layers of platinum (Pt)/PZT/Pt/titanium (Ti) on a polyimide (PI) substrate. Pulse-echo and spectral response analyses predicted a center frequency of 10 MHz and bandwidth of 87% under water load and air backing. A 2D array, consisting of the 256 (16 × 16) unit-cells, was created and characterized in terms of pulse-echo and spectral responses, surface displacement profiles, crosstalk, and beam profiles. The 2D array showed: decreased bandwidth due to protracted oscillation decay and guided wave effects; mechanical focal length at 2.9 mm; 3.7 mm depth of field for -6 dB; and -55.6 dB crosstalk. Finite element-based virtual prototyping identified figures of merit—center frequency, bandwidth, depth of field, and crosstalk—that could be optimized to design robust, flexible PMUT arrays.

PULSE-ECHO REFLECTIONOFTHE SH0 GUIDED WAVE MODE FROM A PART-THICKNESS ELLIPTICAL DEFECT IN A PLATE

2010 ◽  
Author(s):  
J. Ma ◽  
P. Cawley ◽  
M. Lowe ◽  
Donald O. Thompson ◽  
Dale E. Chimenti
Keyword(s):  
Wave Mode ◽  
Guided Wave ◽  
Pulse Echo ◽  
Part Thickness

Multimode dispersion compensated pulse-echo guided wave inspection

2015 ◽  
Author(s):  
R. A. Roberts ◽  
E. Peters ◽  
D. E. Chimenti
Keyword(s):  
Guided Wave ◽  
Pulse Echo

Guided wave-based detection of delamination and matrix cracking in composite laminates

2010 ◽  
Vol 225 (1) ◽  
pp. 123-131 ◽  
Author(s):  
T Wandowski ◽  
P Malinowski ◽  
P Kudela ◽  
W Ostachowicz
Keyword(s):  
Composite Laminates ◽  
Guided Waves ◽  
Guided Wave ◽  
Matrix Cracking ◽  
Detection Methods ◽  
Localization Algorithm ◽  
Reflected Waves ◽  
Signal Processing Algorithms ◽  
Pulse Echo ◽  
Pulse Echo Method

The aim of this article was a numerical and experimental study of the active damage detection methods based on piezoelectric elements attached to a composite laminate. In considered case, guided waves were excited and received in a structure using pulse-echo method. It means that after exciting a structure with a pulse, an array of sensors located on a structure was used to ‘listen' for reflected waves coming from discontinuities. The main part of structural health monitoring system is signal-processing algorithms, which allow to detect and localize damage. Algorithm applied in this research results in special maps that indicate damage location. In this article, a damage localization algorithm was described and experimentally tested. The proposed method was successfully tested on a carbon—epoxy part of a helicopter.

Ultrasonic Circumferential Guided Wave for Pitting-Type Corrosion Imaging at Inaccessible Pipe-Support Locations

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
K. Shivaraj ◽  
Krishnan Balasubramaniam ◽  
C. V. Krishnamurthy ◽  
R. Wadhwan
Keyword(s):  
Guided Waves ◽  
Pipe Wall ◽  
Element Model ◽  
Higher Order ◽  
Guided Wave ◽  
Structural Layout ◽  
Ultrasonic Guided Wave ◽  
Experimental Parameters ◽  
Data Acquisition Card ◽  
Pulse Echo

A higher order cylindrically guided ultrasonic wave was used for the detection and sizing of hidden pitting-type corrosion in the hidden crevice regions (between the pipe and the pipe supports) without lifting or disturbing the structural layout arrangement of the pipelines. The higher order circumferential guided waves were generated using a piezoelectric crystal based transducer, located at the accessible top region of the pipes, in a pulse-echo mode. By studying the experimental parameters such as dispersion, particle displacement, and wavelength of the ultrasonic guided wave modes, an appropriate higher order mode was selected for excitation using an appropriately designed acrylic angle wedge that conforms to the pipe’s outer curvature. A manual pipe crawler was designed with a provision for holding the wedge, and the essential hardware such as data acquisition card, encoder, etc., was integrated with the system so that the corrosion was mapped in real time during the scanning of the pipes. The system was validated on pipes ranging from 6in.to24in. outer diameters of wall thicknesses up to 12mm, by mapping defects as small as 1.5mm diameter and 25% penetration wall thickness. A 2D finite element model using ABAQUS® was used to understand the wave propagation in pipe wall and its interaction with pinhole-type defects.

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