Estimating Spall Severity in Rolling Element Bearings: A Supervised Learning Approach With Naturally Progressing Spalls

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Published Jul 3, 2026
Stephan Baggerohr Cees Taal Konstantinos Gryllias

Abstract

Estimating the severity of localized defects in rolling element bearings is critical for accurate Remaining Useful Life (RUL) estimation, yet it remains challenging under non-stationary operating conditions with fluctuating speeds. Existing data-driven methods struggle to generalise due to the lack of high-fidelity, damage-progression data, and susceptibility to machine-specific structural transfer functions. A Siamese Transformer based neural network is utilized to predict continuous spall size directly from concurrent vibration measurements across three selected operating speeds, reducing the need for long-term trending. Using the amplitudes at the ball-pass frequency and its harmonics from spectra, and a data augmentation strategy, the proposed approach aims to decouple the fault signature from the system transfer function. Trained on a single run-to-failure dataset of one N209 ECP bearing with automated ground truth sizing for labels, the network acts on a regression target to learn the mapping between spectral features and the defect size. Preliminary results suggest that this proof-of-concept framework shows promise for generalization to unseen speed combinations and synthetic transfer function profiles within the scope of the studied experiment.

How to Cite

Baggerohr, S., Taal, C., & Gryllias, K. . (2026). Estimating Spall Severity in Rolling Element Bearings: A Supervised Learning Approach With Naturally Progressing Spalls. PHM Society European Conference, 9(1), 1–11. https://doi.org/10.36001/phme.2026.v9i1.5030
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Keywords

Rolling element bearing diagnostics, Spall severity estimation, Siamese neural network, Transfer function augmentation

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Technical Papers