scholarly journals Analysis of electromagnetic non-destructive evaluation modelling using Stratton-Chu formulation-based fast algorithm

2020 ◽  
Vol 378 (2182) ◽  
pp. 20190583
Author(s):  
Yang Bao ◽  
Jiming Song
Keyword(s):  
Fast Algorithm ◽  
Normal Component ◽  
Solution Process ◽  
Low Frequency ◽  
Iterative Solution ◽  
Basis Functions ◽  
Linear System Of Equations ◽  
Non Destructive Evaluation ◽  
Multi Stage ◽  
Non Destructive

The eddy current non-destructive evaluation (NDE) modelling using Stratton-Chu formulation-based fast algorithm is analysed. Stratton-Chu formulations, which have no low frequency breakdown issue, are selected for modelling electromagnetic NDE problems with low frequency and high conductivity approximations. As the main contribution of this article, the robustness and efficiency of the approximations, which result in big savings in both memory and CPU time, are validated and analysed using examples from practical EC testing. The boundary element method (BEM) is used to discretize the integral equations into a linear system of equations: the first order Rao-Wilton-Glisson (RWG) vector basis functions with the flat triangle meshes of the object and pulse basis functions are selected to expand the equivalent surface currents and the normal component of magnetic fields, respectively. Then the multilevel adaptive cross approximation (MLACA) algorithm is applied to accelerate the iterative solution process. The performance and efficiency of adaptively applying a multi-stage (level) algorithm based on the criteria concluded for the operators are shown. This article is part of the theme issue ‘Advanced electromagnetic non-destructive evaluation and smart monitoring’.

Non-Destructive Evaluation of a Delamination in Laminates by Lamb Wave Propagation

2007 ◽  
Vol 353-358 ◽  
pp. 2345-2348
Author(s):  
Zheng Hua Qian ◽  
Feng Jin ◽  
Zi Kun Wang ◽  
Kikuo Kishimoto
Keyword(s):  
Lamb Waves ◽  
Low Frequency ◽  
Relative Location ◽  
Laminated Plate ◽  
Non Destructive Evaluation ◽  
Symmetric Plane ◽  
Expansion Coefficients ◽  
Relative Errors ◽  
Lamb Wave Propagation ◽  
Non Destructive

The diffraction of Lamb waves by a finite delamination situated on a random plane parallel to the symmetric plane of a laminated plate is taken into account. Two imaginary planes are introduced to solve the problem by adopting the method of mode matching. By taking an appropriate finite number of terms of the infinite expansion series and some selected points on the two imaginary planes through convergence and precision tests, a matrix equation is obtained to evaluate the expansion coefficients numerically. Reflection coefficients versus the normalized length a/h and the relative location h1/h of the delamination are calculated in the low-frequency domain, the relative errors are found to be less than 1%. Results obtained indicate that the theory developed in this paper is meaningful for the detection of both the size and the location of a delamination in a laminated plate by cooperating with experimental techniques for the non-destructive evaluation (NDE) technology.

Wavelet Domain Solution of CSRBF SLAE for Image Interpolation Using Iterative Methods

2004 ◽  
Author(s):  
Luis A. Diago ◽  
Masaki Kitago ◽  
Ichiro Hagiwara
Keyword(s):  
Radial Basis Functions ◽  
Low Frequency ◽  
Direct Methods ◽  
Image Interpolation ◽  
Iterative Solution ◽  
Basis Functions ◽  
Wavelet Domain ◽  
Algebraic Equations ◽  
Linear Algebraic Equations ◽  
Radial Basis

Radial Basis Functions (RBF) are popular for interpolating scattered data. In this context, the solution of the system of linear algebraic equations (SLAE) is the most time-consuming operation. Techniques fail with large point sets consisting of more than several thousands of points when direct methods and global support are used. In this paper we demostrate that the solution of the SLAE in the wavelet domain is suitable for the problem of image interpolation by means of Compactly-Supported Radial Basis Functions (CSRBF). The iterative solution of SLAE with highly irregular matrices cannot be accelerated by wavelet transformation and subsequent sparcification if the transformed matrix is still highly irregular. To solve the SLAE in the wavelet domain, the ordering of the samples defines the spacial relationship and the energy of the coefficients in the low frequency domain. Two sorting algorithms for the wavelet domain solution are tested and compared with the spacial solution of the SLAE. Examples of image interpolation by means of CSRBF demostrate the superiority of the solution in the wavelet domain using GMRES iterative method.

Three dimensional controlled-source electromagnetic forward modeling by edge-based finite element with a divergence correction

Geophysics ◽  
2021 ◽  
pp. 1-71
Author(s):  
Wenwu Tang ◽  
Yaoguo Li ◽  
Jianxin Liu ◽  
Juzhi Deng
Keyword(s):  
Finite Element ◽  
Electric Field ◽  
Normal Component ◽  
Solution Process ◽  
Iterative Solution ◽  
Controlled Source ◽  
Correction Technique ◽  
Speed Up ◽  
Edge Based ◽  
Minimal Residual

We present an edge-based finite element modeling algorithm with a divergence correction for calculating controlled-source electromagnetic (CSEM) responses of a 3D conductivity earth model. We solve a curl-curl equation to directly calculate the secondary electric field in order to eliminate the source singularity. The choice of the edge-based finite element method enables us to properly handle the discontinuity of the normal component of electric fields across conductivity boundaries. Although we can solve the resulting complex-symmetric linear system of equations efficiently by a quasi-minimal residual method preconditioned with an incomplete Cholesky decomposition for the high frequency band, the iterative solution process encounters a common problem in the field formulation and does not converge within a practically feasible number of iterations for low frequencies. To overcome this difficulty and to accelerate the iterative solution process in general, we combine a divergence correction technique with the secondary field solution using the quasi-minimal residual solver. We have found that applying the divergence correction intermittently during the iterative solution process ensures the calculation of sufficiently accurate electric and magnetic fields and can significantly speed up the solution process by more than an order of magnitude. We have tested the efficiency and accuracy of the proposed algorithm with 1D and 3D models, and have found that the divergence correction technique is able to guide the electric field to satisfy the boundary conditions across conductivity interfaces. Although there is a computational overhead required for applying the divergence correction, that cost is significantly offset by the substantial gains in the solution accuracy and speed-up. The work makes the field-based curl-curl formulation using edge elements an efficient and practical method for CSEM simulations.

scholarly journals NDE Detection and Characterization of Damage in Honeycomb Sandwich Composites

2019 ◽  
Vol 264 ◽  
pp. 01007
Author(s):  
Kwang-Hee Im ◽  
Sun-Kyu Kim ◽  
Young-Tae Cho ◽  
Yong-Deuck Woo ◽  
Jong-An Jung ◽  
...  
Keyword(s):  
Low Frequency ◽  
Sandwich Composite ◽  
Displacement Curve ◽  
Composite Panels ◽  
Evaluation Technique ◽  
Terahertz Waves ◽  
Damage Level ◽  
Non Destructive Evaluation ◽  
Honeycomb Sandwich ◽  
Non Destructive

This study deals with a non-destructive evaluation technique for detecting defects in composite panels. In this non-destructive evaluation technique, various low-frequency techniques are applied such as a tapping technology. Another terahertz wave application will be utilized. In particular, the tapping technique is utilized in order to evaluate the characteristics of the honeycomb member based on the hysteresis effect analysis. Here, the area surrounded by the hysteresis loop in the force-displacement curve is related to the increased internal friction loss that is the cause of the energy absorption absorbed by the composite member after the load is applied. The loop area where the composite member was damaged was well agreed with the damage level. Artificial defects were manufactured on the surface of honeycomb sandwich composite panels. An NDE technique was proposed in order to detect defects by using terahertz waves and was discussed for tuning the practical use.

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