Microwave NDE Research Articles

Fast VGG: An Advanced Pre-Trained Deep Learning Framework for Multi-Layered Composite NDE via Multifrequency Near-Field Microwave Imaging

ABSTRACT Microwave nondestructive testing (NDT) techniques show promise for composite inspection due to microwave signals’ ability to penetrate and interact with internal structures. However, current microwave imaging approaches have poor spatial resolution, struggling to distinguish defects from defect-free regions. This limits reliable subsurface analysis and widespread adoption. This paper introduces a novel multi-frequency microwave imaging fusion method using an open-ended waveguide and deep learning to enhance defect detection accuracy in carbon fiber-reinforced polymer (CFRP) composites. The proposed technique employs an optimized feature extraction strategy to improve differentiation between defective and sound areas for superior subsurface visualization. The method leverages VGG-19 for efficient feature extraction and parallel processing to merge information from multi-frequency images. Our method significantly improved detection accuracy and F1 score, surpassing non-deep learning image fusion techniques by at least 50%. The optimized fusion strategy enables clear visualization of various defect types across multiple subsurface layers. Our approach also reduces computation time versus standard VGG implementation by 3–4×, showing scalability. The results demonstrate the proposed method’s potential to overcome existing constraints and provide rapid, accurate subsurface analysis of complex CFRP structures through an optimized deep learning framework, holding significance for expanding microwave NDE applications.

A Hybrid Microwave NDE System for Rapid Inspection of GFRP Composites

A Hybrid Microwave NDE System for Rapid Inspection of GFRP Composites

Inspection of Gfrp Composites by Microwave NDE

Inspection of Gfrp Composites by Microwave NDE

Inspection of Profiled Frp Composite Structures by Microwave NDE

Inspection of Profiled Frp Composite Structures by Microwave NDE

Bond Quality Inspection of Bonded Surfaces using Microwave NDE

Bond Quality Inspection of Bonded Surfaces using Microwave NDE

Application of Microwave for Remote NDT and Distinction of Biofouling and Wall Thinning Defects Inside a Metal Pipe

Wall-thinning and biofouling/biofilm defects inside metal pipes are frequently reported, and each occurrence will cause a discontinuity along the metal pipe, which can be taken as a circular waveguide of microwave. If their existence and detailed distribution are unknown in advance, evaluated results may become confusing due to their possible coexistence and then complicate the correct interpretation of signals. To solve this problem, both S11 and S21 parameters are measured using a vector network analyzer and two newly designed probes. This experimental approach is based on the fact that similar reflections of different kinds of defects would have different wavelength changes and/or energy attenuation. Characteristic signals of these two kinds of defects are comparatively studied to distinguish them and generalize the remote microwave NDE application.

Microwave NDT of cement-based materials using far-field reflection coefficients

Periodic assessment of ageing civil structures is important for structural integrity and public safety. Numerous destructive and non-destructive techniques employing different energy sources have been proposed for structural health monitoring. Amongst the non-destructive evaluation techniques proposed for monitoring material strength and contents of concrete structures, techniques employing microwaves offer distinct advantages in that they are non-radioactive and provide good penetration, excellent contrast between steel reinforcement bar and concrete, and insensitivity to ambient temperature. In this paper, the feasibility of a far-field microwave NDE technique for concrete imaging is investigated via numerical simulations and experiments on cement based samples using far-field microwave reflection coefficients.

Overview of Microwave NDE Applied to Thick Composites

Overview of Microwave NDE Applied to Thick Composites

Introduction to the special issue onRecent developments on microwave NDE research

Introduction to the special issue onRecent developments on microwave NDE research

Introduction to the Special Issue on Recent Developments on Microwave NDE Research

Introduction to the Special Issue on Recent Developments on Microwave NDE Research

Introduction to the Special Issue onRecent Developments on Microwave NDE Research

Introduction to the Special Issue on<i>Recent Developments on Microwave NDE Research</i>

Numerical modeling of microwave NDE for plastics and composites

Numerical modeling of microwave NDE for plastics and composites

Microwave Diagnosis of Carbon Black Rubber Compounds and Porosity Estimation in Composites

ABSTRACTThe results of an in depth study of the dielectric properties of various rubber compounds at different microwave frequencies are discussed. Subsequently, the influence of carbon black volume percentage on the dielectric properties of rubber is studied in a wide frequency range (5 -24 GHz). The results show that the real and imaginary parts of rubber dielectric constant increase as a function of increasing carbon black percentage. Frequencies around 5 GHz show more sensitivity to small changes in the carbon volume content. The presence of curatives in uncured rubber samples is detected, which is an indication of the sensitivity of microwaves to the chemical reaction triggered by these curatives. Similar approach is used to measure the air content in specially prepared model material (plastic microbaloon-filled epoxy) samples with varying degrees of uniformly distributed air inclusion. The results of these measurements for a wide range of frequencies is also reported. Measurement analysis resulted in detecting variation in the air volume fraction of around 1.5%. The results confirm the utility of microwave NDE techniques for local porosity detection and evaluation in dielectric composites.