Abstract

This study investigates the effect of vibration-induced loose connections on signal reflection (S11) for loose connection identification in aerospace coaxial cables using distributed sensing approach, which is effective in filtering the noise and identifying minor discontinuities. In this approach, a sliding gated window is applied to S11 signal, a fast Fourier transform is performed over the gated windows, cross-correlation is computed between the baseline and vibration-affected signals, and the standard deviation is mapped along the cable length. Sinewave signals from 9 kHz to 5 GHz were swept through cables with vibrating connectors under three conditions: fully tightened, loosened by 180°, and 360°. Vibration tests were conducted at frequencies of 0–640 Hz and magnitudes of 0.5–4G. Results show that fully tightened cable connectors exhibit a rapid increase in response up to approximately 80 Hz, followed by a gradual rise until approximately 320 Hz and saturation beyond approximately 320 Hz. At 180° loosening, the response followed an exponential cosine trend with small fluctuations at low vibration frequencies. The 360° loosened connector showed contrasting behavior: distributed responses decreased significantly at higher vibration magnitudes (1–4G) due to resonance and combined effect of connector orientation, resonance, and gravitational effect which caused the loose connector to turn toward tightening, whereas at 0.5G, the response increased exponentially, with small fluctuations at lower frequencies up to 80 Hz, followed by a gradual exponential increase. These findings confirm that distributed vibration sensing effectively identifies connector loosening and can be used for predictive maintenance in any dynamic environment by identifying loose connection in advance of failure.

Department(s)

Mechanical and Aerospace Engineering

Second Department

Electrical and Computer Engineering

Publication Status

Open Access

Comments

Missouri University of Science and Technology, Grant None

Keywords and Phrases

aircraft data transmission line; coaxial cable; distributed sensing; non-destructive evaluation; predictive maintenance; signal reflection; Vibration-induced loose connection

International Standard Serial Number (ISSN)

1741-3168; 1475-9217

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2026 SAGE Publications, All rights reserved.

Creative Commons Licensing

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.

Publication Date

01 Jan 2026

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