Ultrasonic classification of thin layers within multi-layered materials

Tao

et al. 2020

Purpose Although a laser profile sensor (LPS) can be used to measure dimensions, the “shadow region” generally degrades the accuracy and precision of width measurements. The accuracy and precision of such measurements should be improved. Design/methodology/approach In this paper, the authors propose herein a technique that combines high dynamic range (HDR) imaging with logistic fitting. First, a HDR image is composed of several images acquired with different exposure times, which augments the grayscale of the object profile and significantly reduces overexposure. Next, the profile is fit to a logistic function, which provides accurate and precise edge coordinates. Finally, given the edge coordinates, the object width is calculated. Findings To verify the stability of this logistic algorithm, the authors simulate different noise conditions and different degrees of incomplete edge data. In addition, the progressiveness of the algorithm is demonstrated by comparing the results with those of other algorithms and with the height measurement. Furthermore, the suitability of the system is verified experimentally. Research limitations/implications Because of the limitation of the condition of laboratory, in the experimental section, this paper cannot represent perfectly the industrial situation. It makes this section limited in demonstration. Originality/value In this paper, the results show that the measurement accuracy and precision of the width is improved and exceeds that of the height measurement. The proposed HDR imaging method with logistic fitting may be applied to LPS width measurements, which should significantly aid the development of LPSs.

Section: Edge Localization With Logistic Fittingmentioning

confidence: 99%

High-precision width measurement method of laser profile sensor

Tao

et al. 2020

Proceedings of the Institution of Mechanical Engineers, Part C:

“…Several studies have been done to evaluate the different parameters of sandwich structures. Hagguld et al 7 studied the ultrasonic classification of thin films in multilayer materials by several methods (nominal logistic regression and discriminant analysis). Another interesting study is that of Le´vesque et al 8 where they carried out a quantitative and nondestructive characterization of the interfacial adhesion zone of a multilayer structure composed of metal-composite-metal.…”

Section: Introductionmentioning

confidence: 99%

“…Hagguld et al. 7 studied the ultrasonic classification of thin films in multilayer materials by several methods (nominal logistic regression and discriminant analysis). Another interesting study is that of Lévesque et al.…”

Section: Introductionmentioning

confidence: 99%

Influence of concrete age on the behavior of ultrasonic waves in interfaces (concrete–steel–concrete)

Raach

Derouiche

Messelmi

2020

This paper presents the influence of the composite age on the variation of the transmission and reflection coefficients. The composite is the concrete in our case. The studied structure is a multilayer structure composed of two elastic and isotropic layers where each one is characterized by its own physical properties. The problem is simplified in two-dimensional plane waves, and the influence of the attack angle on the acoustic impedances is also examined. Moreover, an experimental study is realized in the formulation of concrete and the measurement of waves propagation velocity. In this work, during the concrete formulation, three different types of concrete were developed: sand concrete, ordinary concrete, and high-performance concrete. The results of simulation and experiments demonstrate that the age of concrete and the internal concrete structure have a direct influence on the evolution of the acoustic parameters as well as the angle of incidence, which has considerably changed the behavior of the transmission and reflection coefficients. This internal structure is directly related to the age of the concrete where its maturity is not reached until after a certain age, which influences the behavior of the waves through the layers of the multilayer structure.

Inverse Problems in Science and Engineering

“…Some layered materials are the products of synthetic chemistry and represent a large class of compounds formed by metals, ceramics, polymers or fibre-reinforced polymers. Methods for non-destructive inspection of layered materials based on ultrasonic tests are becoming more and more popular for a wide range of industrial applications as a way of assuring product integrity and quality, and also as a mean to achieve its mechanical characterization [1][2][3].…”

Section: Introductionmentioning

confidence: 99%

“…Circuit simulation programmes are suitable and very efficient to assess the equivalence between the models; thus, we carried out the simulation of the forward problem by means of LTspice software. 1 Nevertheless, a computer program for the numerical calculation should be developed to implement the methodology to solve the inverse problem. Since the solution of the forward problem is essential for the later solution of the inverse problem, we dedicate the following two sections to the description and simulation of the direct problem.…”

Section: Introductionmentioning

confidence: 99%

Equivalent ultrasonic impedance in multilayer media. A parameter estimation problem

Messineo

Frontini

Eliçabe

et al. 2013

This article deals with ultrasonic transmission through multilayer systems. The equivalent ultrasonic impedance of such systems is based on the transmission line built as a convenient model to reduce the computational time for numerical evaluation. Also, the one dimensional wave equation is considered as the full model for the propagation of a plane wave inside the material. From numerical simulations, we obtained signals useful to assess the equivalent model. Results clearly depict coherence between the models since there are full agreements in the computed velocity and stress at each interface. The identification of the parameters involved in the model, characteristic acoustic impedance and time of flight, related to the layer densities and propagation velocities, is posed as a non-linear parameter estimation problem. An ultrasonic transmission is set up and the complete waveform is recorded after travelling through the layers. The minimization of a least squares objective function defined to measure the misfit between the real and predicted waveforms, in frequency, was successfully performed and the estimated parameters give useful information for the mechanical characterization of the sample.