scholarly journals Analysis of an open-ended coaxial probe with lift-off for nondestructive testing

1994 ◽  
Vol 43 (5) ◽  
pp. 711-718 ◽  
Author(s):  
J. Baker-Jarvis ◽  
M.D. Janezic ◽  
P.D. Domich ◽  
R.G. Geyer
Keyword(s):  
Nondestructive Testing ◽  
Lift Off ◽  
Coaxial Probe

Open-Ended Coaxial Probes for Nondestructive Testing of Substrates and Circuit Boards

1994 ◽  
Vol 347 ◽  
Author(s):  
James Baker-Jarvis ◽  
Michael D. Janezic
Keyword(s):  
Nondestructive Testing ◽  
Coaxial Line ◽  
Wave Model ◽  
Circuit Boards ◽  
Low Frequencies ◽  
Full Wave ◽  
Coaxial Probes ◽  
Lift Off ◽  
Coaxial Probe ◽  
Probe Measurements

ABSTRACTThe results of the full-wave model theory for the open-ended coaxial probe with lift-off are presented and are applied to measurements of thin materials. The model allows the study of the open-ended coaxial probe as a nondestructive testing tool. The equations presented are valid for both dielectric and magnetic materials. The analysis yields insight into the effects of air gaps on probe measurements. Numerical results indicate that the probe is very sensitive to lift-off at low frequencies. This sensitivity decreases somewhat as frequency increases. In order for the field to penetrate the air gap, larger size coaxial line or higher frequencies need to be used. An application of the theory is performed by numerically solving the inverse problem using measured reflection coefficient.

scholarly journals Precision Permittivity Measurement for Low-Loss Thin Planar Materials Using Large Coaxial Probe from 1 to 400 MHz

2018 ◽  
Vol 2 (4) ◽  
pp. 81
Author(s):  
Kok Yeow You ◽  
Man Seng Sim
Keyword(s):  
Dielectric Constant ◽  
Dielectric Measurement ◽  
Tangent Loss ◽  
Outer Diameter ◽  
Low Loss ◽  
Probe Calibration ◽  
Lift Off ◽  
Tan Δ ◽  
Planar Materials ◽  
Coaxial Probe

This paper focuses on the non-destructive dielectric measurement for low-loss planar materials with a thickness of less than 3 mm using a large coaxial probe with an outer diameter of 48 mm. The aperture probe calibration procedure required only to make a measurement of the half-space air and three offset shorts. The reflection coefficient for the thin material is measured using a Keysight E5071C network analyzer from 0.3 MHz to 650 MHz and then converted to a relative dielectric constant, εr and tangent loss, tan δ via closed form capacitance model and lift-off calibration process. Average measurement error of dielectric constant, Δεr is less than 6% from 1 MHz to 400 MHz and the resolution of loss tangent, tan δ measurement is capable of achieving 10−3.

A Novel Technique for Eliminating Probe Lift-Off in Eddy Current Nondestructive Testing

2013 ◽  
Vol 291-294 ◽  
pp. 2474-2478
Author(s):  
Bo Ye ◽  
Ming Li ◽  
Fang Zeng
Keyword(s):  
Nondestructive Testing ◽  
Eddy Current ◽  
Measurement Accuracy ◽  
Excitation Frequency ◽  
Eddy Current Testing ◽  
Basic Principles ◽  
Current Testing ◽  
Novel Technique ◽  
Simulation Results ◽  
Lift Off

The lift-off problem is a very important problem in eddy current testing, which will influence the measurement accuracy. This paper proposes a novel technique for eliminating the probe lift-off in eddy current nondestructive testing. Firstly, the basic principles and characteristics of eddy current testing were introduced. Secondly, this paper analyzed and studied the coil impedance responses caused by the variations of the probe lift-off. Based on simulation results, this paper presents that choosing proper probe excitation frequency can eliminate the disturbance of coil impedance caused by the lift-off, and obtains better results.

scholarly journals Vector-Based Eddy-Current Testing Method

2018 ◽  
Vol 8 (11) ◽  
pp. 2289
Author(s):  
Cheng Li ◽  
Runcong Liu ◽  
Shangjun Dai ◽  
Nianmei Zhang ◽  
Xiaodong Wang
Keyword(s):  
Nondestructive Testing ◽  
Numerical Simulations ◽  
Lorentz Force ◽  
Eddy Current ◽  
Eddy Current Testing ◽  
Current Testing ◽  
Testing Method ◽  
Quantitative Results ◽  
Lift Off ◽  
Measuring Force

We present a type of eddy-current testing (ECT) method based on measuring the reaction of the Lorentz force by using a small permanent magnet (PM) as the probe. The means of measuring impedance is superseded by measuring force. By analyzing the variations in different components of the reaction of Lorentz force, the defects characteristics within the measured conductor can be revealed. The results indicate that the vector-based eddy-current testing method obtains good quantitative results and precisely evaluates the lift-off effect during measurement along two orthogonal directions. Numerical simulations are performed to provide supports for the experimental results. The method described in this paper may have great potential for use in industrial nondestructive testing applications.

scholarly journals Nondestructive Testing for Corrosion Evaluation of Metal under Coating

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Ruikun Wu ◽  
Hong Zhang ◽  
Ruizhen Yang ◽  
Wenhui Chen ◽  
Guotai Chen
Keyword(s):  
Nondestructive Testing ◽  
Complex Structures ◽  
Testing Methods ◽  
Corrosion Detection ◽  
The Past ◽  
Corrosion Evaluation ◽  
Nondestructive Testing Methods ◽  
Novel Approaches ◽  
Lift Off

The use of steel has grown rapidly over the past decades. However, corrosion under coating detection still presents challenges for nondestructive testing (NDT) techniques. One of such challenges is the lift-off introduced by complex structures. Inaccessibility due to structure leads corrosion to be undetected, which can lead to catastrophic failure. Furthermore, lift-off effects reduce the sensitivities. The limitations of existing NDT techniques heighten the need for novel approaches to the characterization of corrosion. This paper begins with a discussion of the challenges associated with corrosion detection of metal under coating. Secondly, reviews are given of the most NDT methods used for the detection of corrosion under coating. The different techniques based on nondestructive testing methods such as ultrasonic, acoustic, electromagnetic, radiographic, and thermographic have been detailed out. This review presents the significance and advantages provided by the emerging NDT techniques. In the end, the trends and identified problems are summarized.

Finite Element Modeling of Remote-Field Eddy Current Problems for the Nondestructive Testing of Metal Tube

1989 ◽  
Vol 111 (2) ◽  
pp. 101-108 ◽  
Author(s):  
R. Palanisamy
Keyword(s):  
Finite Element ◽  
Nondestructive Testing ◽  
Wall Thickness ◽  
Eddy Current ◽  
Early Recognition ◽  
Detection Sensitivity ◽  
Oil Well ◽  
Phase Lag ◽  
Apparent Contradiction ◽  
Lift Off

The remote-field eddy current effect refers to a low frequency eddy current nondestructive testing (NDT) phenomenon in tubular conductors (magnetic or nonmagnetic) in which the behavior of both amplitude and phase of induced magnetic field are in apparent contradiction to the conventional eddy current theory. Equal detection sensitivity across the wall thickness, linear relationship between the output signal phase-lag and the wall thickness, and absence of the lift-off problem are some of the attractive and contradicting features of this technique. Despite its early recognition and useful application in down-hole inspection of oil-well casing, no development of adequate scientific base that could explain this phenomenon has been reported. This paper describes modeling of this phenomenon using the finite element numerical analysis technique. Amplitude and phase of the sensor coil output have been predicted using this model for different axisymmetric test geometries, material properties, and excitation frequencies.

Electromagnetic nondestructive testing at high lift-off using a magnetic image conduit

2013 ◽  
Vol 27 (5) ◽  
pp. 1287-1293 ◽  
Author(s):  
Jinyi Lee ◽  
Jongwoo Jun ◽  
Jungmin Kim ◽  
Minhhuy Le
Keyword(s):  
Nondestructive Testing ◽  
Magnetic Image ◽  
High Lift ◽  
Lift Off

scholarly journals Precision Permittivity Measurement for Low-Loss Thin Planar Materials Using Large Coaxial Probe from 1 to 400 MHz

2018 ◽  
Author(s):  
Kok Yeow You ◽  
Man Seng Sim
Keyword(s):  
Dielectric Constant ◽  
Relative Dielectric Constant ◽  
Dielectric Measurement ◽  
Tangent Loss ◽  
Outer Diameter ◽  
Low Loss ◽  
Probe Calibration ◽  
Lift Off ◽  
Planar Materials ◽  
Coaxial Probe

This paper focuses on the non-destructive dielectric measurement for low-loss planar materials with a thickness of less than 3 mm using a large coaxial probe with an outer diameter of 48 mm. The aperture probe calibration procedure required only to make a measurement of the half-space air and three offset shorts. The reflection coefficient for the thin material is measured using a Keysight E5071C network analyzer from 0.3 MHz to 650 MHz and then converted to a relative dielectric constant and tangent loss via closed form capacitance model and lift-off calibration process. Measurement error of dielectric constant, Δεr is less than 2.5 % from 1 MHz to 400 MHz and the resolution of loss tangent, tan δ  measurement is capable of achieving 3×10-3.

Dual solar satellites ready for lift-off

Nature ◽  
2006 ◽  
Author(s):  
Geoff Brumfiel
Keyword(s):  
Lift Off
Sign in / Sign up

Export Citation Format

Share Document