Delamination Size Detection using Time of Flight of Anti-symmetric (Ao) and Mode Converted Ao mode of Guided Lamb Waves

2010 ◽  
Vol 21 (8) ◽  
pp. 817-825 ◽  
Author(s):  
C. Ramadas ◽  
M. Janardhan Padiyar ◽  
Krishnan Balasubramaniam ◽  
Makarand Joshi ◽  
C.V. Krishnamurthy
Keyword(s):  
Lamb Waves ◽  
Time Of Flight ◽  
Ao Mode

Lamb Wave Inspection of Concrete Beams

1999 ◽  
Author(s):  
Y. C. Jung ◽  
T. Kundu ◽  
M. Ehsani
Keyword(s):  
Lamb Wave ◽  
Concrete Beams ◽  
Lamb Waves ◽  
Time Of Flight ◽  
Signal Amplitude ◽  
Internal Defects ◽  
Longitudinal Waves ◽  
Ultrasonic Methods ◽  
Wave Technique ◽  
Flight Measurements

Abstract The feasibility of detecting defects in concrete beams using Lamb waves is investigated in this paper. The traditional ultrasonic methods for inspecting defects in concrete use the reflection and scattering of longitudinal waves by internal defects. Signal amplitude and time of flight measurements provide information about the internal defects in concrete. However, these methods are time consuming and often fail to detect honeycombs, closed cracks and small defects. In this paper the potential of the Lamb wave technique to detect those defects in large concrete beams is investigated. The Lamb wave technique is found to be reliable for detecting such defects in concrete beams.

scholarly journals Interdigital Piezopolymer Transducers for Time of Flight Measurements with Ultrasonic Lamb Waves on Carbon-Epoxy Composites under Pure Bending Stress

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Andrea Bulletti ◽  
Lorenzo Capineri
Keyword(s):  
Lamb Waves ◽  
Fiber Composite ◽  
Time Of Flight ◽  
Bending Moment ◽  
Wave Mode ◽  
Guided Wave ◽  
Pure Bending ◽  
Carbon Fiber Composite ◽  
Central Wavelength ◽  
Bending Stresses

Interdigital transducers fabricated with piezopolymer film have been realized to excite ultrasonic Lamb waves in a composite laminate subjected to pure bending stresses. Lamb waves were generated and detected in a cross-ply [0°/90°] 4 mm thick carbon-fiber composite, by using two interdigital transducers in pitch-catch configuration. We demonstrate that the choice of the piezopolymer transducer technology is suitable for this type of investigation and the advantages of the proposed transducer assembly and bonding are described. A full set-up is described to determine the relationship between the time of flight of the recorded signals and the applied bending moment. Interdigital transducers were designed according to simulations of the dispersion curves, in order to operate at a central frequency of 450 kHz. This frequency corresponds to a central wavelength of 16 mm and to a group velocity of about 6000 m/s for the first symmetric guided wave mode. The variations in the time of flight of ultrasonic recorded signals were measured as a function of the variations in the bending moment. The static and dynamic load tests were in good agreement with strain gage measurements performed in the micro deformation range (0–1400 µm/m).

Sizing of Interface Delamination in a Composite T-Joint Using Time-of-Flight of Lamb Waves

2011 ◽  
Vol 22 (8) ◽  
pp. 757-768 ◽  
Author(s):  
C. Ramadas ◽  
Krishnan Balasubramaniam ◽  
Makarand Joshi ◽  
C.V. Krishnamurthy
Keyword(s):  
Lamb Waves ◽  
Time Of Flight ◽  
Interface Delamination

Applications of Time-OF-Flight Secondary Ion Mass Spectrometry (TOF-SIMS)

1990 ◽  
Vol 48 (2) ◽  
pp. 308-309
Author(s):  
Bruno Schueler ◽  
Robert W. Odom
Keyword(s):  
Mass Spectrometry ◽  
Secondary Ion Mass Spectrometry ◽  
Structural Information ◽  
Time Of Flight ◽  
Biological Tissues ◽  
Polymer Surfaces ◽  
Tof Sims ◽  
Secondary Ions ◽  
Ion Mass Spectrometry ◽  
Secondary Ion

Time-of-flight secondary ion mass spectrometry (TOF-SIMS) provides unique capabilities for elemental and molecular compositional analysis of a wide variety of surfaces. This relatively new technique is finding increasing applications in analyses concerned with determining the chemical composition of various polymer surfaces, identifying the composition of organic and inorganic residues on surfaces and the localization of molecular or structurally significant secondary ions signals from biological tissues. TOF-SIMS analyses are typically performed under low primary ion dose (static SIMS) conditions and hence the secondary ions formed often contain significant structural information.This paper will present an overview of current TOF-SIMS instrumentation with particular emphasis on the stigmatic imaging ion microscope developed in the authors’ laboratory. This discussion will be followed by a presentation of several useful applications of the technique for the characterization of polymer surfaces and biological tissues specimens. Particular attention in these applications will focus on how the analytical problem impacts the performance requirements of the mass spectrometer and vice-versa.

Assessment of extracranial-intracranial bypass in Moyamoya disease using 3T time-of-flight MR angiography: Comparison with CT angiography

VASA ◽  
2014 ◽  
Vol 43 (4) ◽  
pp. 278-283 ◽  
Author(s):  
Qian Chen ◽  
Rongfeng Qi ◽  
Xiaoqing Cheng ◽  
Changsheng Zhou ◽  
Song Luo ◽  
...  
Keyword(s):  
Image Quality ◽  
Moyamoya Disease ◽  
Mr Angiography ◽  
Time Of Flight ◽  
Consecutive Series ◽  
Tof Mra ◽  
Bypass Patency ◽  
Significant Difference ◽  
Contrast Technique ◽  
Vessel Integrity

Background: To evaluate the value of time-of-flight MR angiography (TOF MRA) for the assessment of extracranial-intracranial (EC-IC) bypass in Moyamoya disease in comparison with computed tomography angiography (CTA). Patients and methods: A consecutive series of 23 patients with Moyamoya disease were analyzed retrospectively. Twenty three patients underwent 25 procedures of extracranial-intracranial bypass. Cranial CTA was performed within one week after the surgery to assess bypass patency. Then TOF MRA was scanned within 24 h after CTA on a 3T MRI system. Using 5-point scales (0 = poor to 4 = excellent), two radiologists rated the image quality and vessel integrity of bypass for three segments (extracranial, trepanation, intracranial). Results: Image quality was high in both CTA and TOF MRA (mean quality score 3.84 ± 0.37 and 3.8 ± 0.41), without statistical difference (p = 0.66). Mean scores of TOF MRA with respect to bypass visualization were higher than CTA in the intracranial segment (p = 0.026). No significant difference of bypass visualization regarding the extracranial and trepanation segments was found between TOF MRA and CTA (p = 0.66 and p = 0.34, respectively). For the trepanation segment, TOF MRA showed pseudo lesions in 2 of all 25 cases. Conclusions: 3T TOF MRA, a non-contrast technique not exposing the patients to radiation, proved to be at least equal to CTA for the assessment of EC-IC bypass, and even superior to CTA with respect to the intracranial segment. In addition, readers should be aware of a potential overestimation showing focal pseudo lesions of the bypass at the trepanation segment in TOF MRA.

A TIME-OF-FLIGHT MASS SPECTROMETER FOR SIMS AND FIELD IONISED NEUTRAL ANALYSIS USING A PULSED LMIS

1987 ◽  
Vol 48 (C6) ◽  
pp. C6-577-C6-582 ◽  
Author(s):  
A. R. Waugh ◽  
D. R. Kingham ◽  
C. H. Richardson ◽  
M. Goff
Keyword(s):  
Mass Spectrometer ◽  
Time Of Flight ◽  
Flight Mass Spectrometer
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