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Quantitative Visualization of Buried Defects in GFRP via Microwave Reflectometry
Ruonan Wang1, Yang Fang1, Qianxiang Gao1
1State Key Laboratory for Strength and Vibration of Mechanical Structures, Shaanxi Engineering Research Centre of NDT and Structure Integrity Evaluation, School of Aerospace Engineering, Xi'an Jiaotong University, Xi'an 710049, China.
This study demonstrates that microwave NDT effectively detects subsurface defects in glass fiber-reinforced polymer (GFRP) structures. Optimal testing sensitivity and approximately 90% accuracy in defect area evaluation are achieved when microwave polarization aligns with GFRP fibers.
Area of Science:
- Materials Science
- Nondestructive Testing
- Microwave Engineering
Background:
- Glass fiber-reinforced polymer (GFRP) is crucial in aerospace, energy, and transportation.
- Internal defects in GFRP can compromise structural integrity and safety.
- Effective quantitative nondestructive testing (NDT) is essential for GFRP structures.
Purpose of the Study:
- To investigate quantitative screening of subsurface impact damage and air voids in GFRP using microwave reflectometry.
- To analyze the influence of microwave polarization on defect detection sensitivity.
- To develop and validate a microwave NDT system for imaging and quantitative evaluation of GFRP defects.
Main Methods:
- Theoretical analysis of equivalent relative permittivity to determine optimal microwave polarization.
- Development of a microwave NDT system for defect imaging.
- Implementation of a direct-wave suppression method using singular-value decomposition for enhanced image quality.
- Application of a defect-edge identification method for quantitative area assessment.
Main Results:
- Testing sensitivity is maximized when microwave electric-field polarization is parallel to GFRP fiber direction.
- The proposed microwave reflectometry method, combined with advanced processing, achieved an average accuracy of approximately 90% in evaluating the in-plane area of buried defects.
- High-quality defect images were obtained using the direct-wave suppression technique.
Conclusions:
- Microwave reflectometry is a promising NDT technique for detecting subsurface defects in GFRP.
- Optimizing microwave polarization significantly enhances detection sensitivity.
- The developed processing methods enable accurate quantitative evaluation of defect dimensions in GFRP structures.
