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.

Active sensing of impact damage in composite sandwich panels by low frequency Lamb waves

2008 ◽  
Vol 112 (1131) ◽  
pp. 279-283 ◽  
Author(s):  
C. Soutis ◽  
K. Diamanti
Keyword(s):  
Lamb Waves ◽  
Impact Damage ◽  
Low Frequency ◽  
Practical Applications ◽  
Reinforced Plastics ◽  
Composite Sandwich ◽  
Composite Sandwich Structures ◽  
Inspection Strategy ◽  
Extent Of Damage ◽  
Non Destructive

Abstract The development of a robust non-destructive system to detect and monitor the extent of damage in carbon fibre reinforced plastics (CFRP) during service life is a key problem in many practical applications, especially in the aircraft industry. The lack of such technique has severely limited the potentially extensive use of composite materials. In this study a cost and time effective inspection strategy for in-service health monitoring of composites is demonstrated using the fundamental anti-symmetric A 0 Lamb mode at frequencies of 15-20kHz. In principle, this method involves analysis of the transmitted and/or reflected wave after interacting with the test-piece boundaries or discontinuities (defects). In the present work, the applicability of the technique to composite sandwich structures is explored and defects of critical size are successfully detected.

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’.

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