– The purpose of this paper is to present a system for automatic recognition of defects detected in non-conductive polymer composites using pulsed terahertz imaging.
Abstract
Purpose
The purpose of this paper is to present a system for automatic recognition of defects detected in non-conductive polymer composites using pulsed terahertz imaging.
Design/methodology/approach
On the beginning, non-destructive evaluation of composites using electromagnetic waves in terahertz frequency is shortly introduced. Next automatic defects recognition (ADR) algorithm is proposed, focussing on new features calculation. Dimensionality of features space is reduced by using principal component analysis. Finally, results of basalt fiber reinforced composite materials inspection and identification using artificial neural networks is presented and discussed.
Findings
It is possible to develop ADR system for non-destructive evaluation of dielectric materials using pulsed terahertz technique. New set of features in time and frequency domains is proposed and verified.
Originality/value
ADR in non-destructive testing is utilized in case of digital radiography and ultrasonic testing. Terahertz inspection with pulsed excitation is reported as a source of many useful information about the internal structure of the dielectric material. Up to now ADR based on terahertz non-destructive evaluation systems was not utilized.
Details
Keywords
Przemyslaw Lopato, Tomasz Chady, Ryszard Sikora, Stanislaw Gratkowski and Marcin Ziolkowski
The purpose of this paper is to describe the full‐wave modelling of pulsed terahertz systems utilized in non‐destructive testing.
Abstract
Purpose
The purpose of this paper is to describe the full‐wave modelling of pulsed terahertz systems utilized in non‐destructive testing.
Design/methodology/approach
At the outset, some basic information on the terahertz NDT are outlined and then, general remarks on its numerical modelling are presented. Frequency domain FEM and time domain FDTD analysis is carried out. Finally comparison of computed and measured signals is shown in order to prove numerical analysis correctness.
Findings
It is possible to model in a relatively simple way a terahertz system for nondestructive evaluation of dielectric materials. In contrast to other published work, the entire measuring setup is modelled, including photoconductive antenna with hemispherical lens, focusing lens and evaluated material with exemplary defect.
Originality/value
This paper gives a description of the terahertz non‐destructive testing system with comparison of simulated and measured results.