Measuring the Frequency-Dependent Attenuation Coefficients of Solids Using a Pulse-Echo Ultrasonic Method

2021 ◽  
Author(s):  
Guangdong Zhang ◽  
Xiongbing Li ◽  
Shuzeng Zhang ◽  
Tribikram Kundu
Keyword(s):  
Ultrasonic Method ◽  
Attenuation Coefficients ◽  
Frequency Dependent ◽  
Pulse Echo

scholarly journals Correction of B-scan distortion for optimum ultrasonic imaging of backwalls with complex geometries

2020 ◽  
Vol 62 (4) ◽  
pp. 184-191
Author(s):  
S Davì ◽  
C Mineo ◽  
C MacLeod ◽  
S G Pierce ◽  
A Gachagan ◽  
...  
Keyword(s):  
Ultrasonic Method ◽  
Maximum Amplitude ◽  
Constant Thickness ◽  
Cross Sectional ◽  
Industrial Sectors ◽  
Aerospace Manufacturing ◽  
Lower Amplitude ◽  
Complex Shapes ◽  
Ultrasonic Phased Array ◽  
Pulse Echo

Ultrasound undergoes refraction and reflection at interfaces between media of different acoustic refractive indices. The most common ultrasonic method (pulse-echo) monitors the reflected energy to infer the presence of flaws, whereas the lower amplitude of refracted signals is ignored. When the reflector is orientated normally with respect to the ultrasonic beam, the received echo signal shows the maximum amplitude. The pulse-echo method also relies on monitoring the amplitude of the backwall echo to identify or confirm the presence of defects. This works well for parts with constant thickness and with planar backwalls. Unfortunately, parts with complex backwalls are common to many industrial sectors. For example, applications such as aerospace structures often require parts with complex shapes. Assessing such parts reliably is not trivial and can cause severe downtime in the aerospace manufacturing processes or during in-service inspections. This work aims to improve the ultrasonic inspectability of parts with complex backwalls, through sending ultrasonic beams from the frontwall side. Ultrasonic phased array probes and state-of-the-art instrumentation allow ultrasonic energy to be sent into a part at wide ranges of focusing depths and steering angles. This allows for tracking of the backwall profile, thus hitting it normally and maximising the amplitude of the reflected echo at any point. However, this work has shown that a cross-sectional scan resulting from multiple ultrasonic beams, which are sent at variable incidence angles, can present significant geometrical distortion and cannot be of much use for accurate defect visualisation and sizing. This paper introduces a generalised algorithm developed to remove geometric distortions and the effect that variable refraction coefficients have on the transmitted and received amplitudes. The algorithm was validated through CIVA simulations for two example parts with complex backwalls, considering isotropic materials.

Effect of Temperature and Frequency on the Acoustic Properties of Konjac Glucomannan-Agar Gels as Tissue Mimicking Materials

2020 ◽  
Vol 307 ◽  
pp. 351-356
Author(s):  
Anis Nazihah Mat Daud ◽  
Md Supar Rohani ◽  
Rosly Jaafar
Keyword(s):  
Soft Tissue ◽  
Konjac Glucomannan ◽  
Acoustic Properties ◽  
Effect Of Temperature ◽  
Attenuation Coefficients ◽  
Phase Velocities ◽  
Agar Gels ◽  
Immersion Technique ◽  
Pulse Echo

In this study, we determine the effect of temperature and frequency on the acoustic properties of konjac glucomannan (KGM)-agar gels to confirm their compatibilities as tissue mimicking materials (TMMs). The acoustic properties of four samples; A (KGM-0.10 g agar), B (KGM-0.20 g agar), C (KGM-0.30 g agar) and D (KGM-0.40 g agar) were measured using pulse echo immersion technique. Findings indicated that the longitudinal velocities of all samples were increased while their attenuation coefficients were decreased as the temperature increased from 27.0 to 37.0°C. It also showed that the phase velocities of all samples were independent to frequency but their attenuation coefficients were increased as the frequency increased from 4.0 to 6.0 MHz. KGM-agar gels are compatible as soft TMMs since their acoustic properties are comparable with the acoustic properties of soft tissue.

Detection of contact damage in ceramics by an ultrasonic method

1998 ◽  
Vol 13 (7) ◽  
pp. 1899-1904 ◽  
Author(s):  
Hyo Sok Ahn ◽  
Said Jahanmir ◽  
John A. Slotwinski ◽  
Gerald V. Blessing
Keyword(s):  
Silicon Nitride ◽  
Glass Ceramic ◽  
Ultrasonic Method ◽  
Circular Ring ◽  
Ultrasonic Technique ◽  
Surface Cracks ◽  
Compressional Waves ◽  
Different Depths ◽  
Pulse Echo ◽  
Hertzian Cone

A pulse-echo ultrasonic technique consisting of focused normal-incident compressional waves was used for the detection and evaluation of surface and subsurface damage in micaceous glass-ceramic and silicon nitride samples. The damage was produced by indentation with a tungsten carbide ball. The nature of the damage was found to be material-dependent and was classified into two types: Hertzian cone cracks in the silicon nitride, and distributed subsurface microcracks in the glass-ceramic. While the cone cracks were visible on the surface as circular ring cracks, the distributed subsurface microcracks were not associated with any visible surface cracks. Both the cone cracks and the distributed subsurface microcracks were easily detected by the ultrasonic technique. In addition, the ultrasonic beam was focused to different depths below the surface of the glass-ceramic sample to probe the subsurface region containing the microfracture damage.

Ultrasonic Attenuation Measurements of in Vivo Human Muscle

1982 ◽  
Vol 4 (3) ◽  
pp. 290-295 ◽  
Author(s):  
J. Ophir ◽  
N. F. Maklad ◽  
R. H. Bigelow
Keyword(s):  
Analysis Of Variance ◽  
Ultrasonic Attenuation ◽  
Human Muscle ◽  
Normal Range ◽  
Attenuation Coefficients ◽  
Quadriceps Femoris Muscle ◽  
Pulse Echo ◽  
Pulse Echo Method ◽  
Femoris Muscle

Attenuation measurements were performed on the quadriceps femoris muscle of 10 normal volunteers. The measurements were made using a statistical narrowband pulse echo method operating at 4.3 MHz. The results show a normal range of 4.71 ± 0.44 dB cm-1 (mean ± S.D.). A one-way analysis of variance was performed on the data which concluded that the populations of attenuation coefficients among the subjects were indeed distinct at the p < 0.0005 level.

Elastic constants of YCa4O(BO3)3 and NdCa4O(BO3)3 single crystals by the pulse-echo ultrasonic method

2012 ◽  
Author(s):  
A. Sotnikov ◽  
H. Schmidt ◽  
M. Weihnacht ◽  
S. J. Zhang ◽  
T. R. Shrout ◽  
...  
Keyword(s):  
Single Crystals ◽  
Elastic Constants ◽  
Ultrasonic Method ◽  
Pulse Echo
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