Application of low field magnetic resonance for defect detection in multi-layered cylindrical composite structures

ABSTRACT

Polymer-based Glass composite cylindrical structures consisting of multi-layered configuration for special applications were tested with low magnetic field nuclear magnetic resonance (NMR) technique. Relaxation times of chemical species at the interface of adhesive bond were investigated. Studies indicated that the single-sided NMR inspection of such composite structures is a feasible non-destructive evaluation technique to study the adhesive bond interface properties. Results of single-sided inspection over cylindrical surface using low field NMR having magnetic field strength of 0.3 T (12.88 MHz RF frequency) indicated distinct signal intensity values for different constituent materials. Interfacial defects such as de-bond and voids were detectable through the multi-layers of the structure. Overlapping defects at multiple interfaces have no bearing on the signal as well as relaxation times of constituent materials.

KEYWORDS:

• Composite
• multi-layer structure
• de-bond
• NMR
• NDE

Acknowledgements

Authors are thankful to The Technology Director, R&QA and The Director, ASL for the motivation, support and encouragement during the course of the work. Authors are highly obliged to recognize the timely testing support by NDED/DRDL, Hyderabad.

Disclosure statement

No potential conflict of interest was reported by the author(s).