Spectrotemporal analysis of guided-wave pulse-echo signals: Part 2. Numerical and experimental investigations

2001 ◽  
Vol 41 (4) ◽  
pp. 332-342 ◽  
Author(s):  
S. -C. Wooh ◽  
K. Veroy
Keyword(s):  
Guided Wave ◽  
Experimental Investigations ◽  
Wave Pulse ◽  
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 Detection of debonding in adhesive joints using Lamb wave propagation

2019 ◽  
Vol 262 ◽  
pp. 10012
Author(s):  
Magdalena Rucka ◽  
Erwin Wojtczak ◽  
Jacek Lachowicz
Keyword(s):  
Wave Propagation ◽  
Lamb Waves ◽  
Visual Assessment ◽  
Guided Wave ◽  
Steel Plates ◽  
Experimental Investigations ◽  
Mechanical Degradation ◽  
Adhesively Bonded ◽  
Destructive Testing ◽  
Out Of Plane

Adhesively bonded joints are widely used in many branches of industry. Mechanical degradation of this type of connections does not have significant symptoms that can be noticed during visual assessment, so non-destructive testing becomes a very important issue. The paper deals with experimental investigations of adhesively bonded steel plates with different defects. Five samples (an intact one and four with damages in the form of partial debonding) were prepared. The inspection was conducted with the use of guided wave propagation method. Lamb waves were excited at one point of the sample, whereas the out-of-plane velocity signals were recorded in a number of points spread over the area of overlap. The processing of signals consisted of calculations of weighted root mean square (WRMS). The results of the analysis showed that the WRMS maps allow for identification and determination of size and shape of debonding areas.

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.

An improved design of shear horizontal guided wave electromagnetic acoustic transducer

2020 ◽  
Vol 62 (8) ◽  
pp. 494-497
Author(s):  
Xu Zhang ◽  
Sheng Feng ◽  
Jun Tu ◽  
Xiaochun Song
Keyword(s):  
Guided Waves ◽  
Cost Effective ◽  
Guided Wave ◽  
Experimental Investigations ◽  
Electromagnetic Acoustic Transducer ◽  
Rectangular Array ◽  
Acoustic Transducers ◽  
Acoustic Transducer ◽  
Improved Design ◽  
Shear Horizontal

This work proposes the use of a Halbach magnet structure to enhance the generation efficiency of shear horizontal (SH) guided waves on a plate. SH waves are normally generated using periodic permanent magnet (PPM) electromagnetic acoustic transducers (EMATs). Two PPM configurations are designed using a Halbach magnet array and the enhancements of the static magnetic fields of the two magnet arrays are validated by the finite element method, indicating that these configurations can increase the peak flux density compared with the conventional configuration. Numerical analysis and experimental investigations indicate that a racetrack coil combined with either a rectangular or triangular Halbach magnet array can enhance the amplitude of the SH guided wave by factors of ∼1.2 and ∼1.1, respectively, and that the rectangular array performs better and is more cost effective.

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
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