Predicting Bearing Fatigue with Eddy current (NDT) - Remaining service life, detecting stress due to operation

Prof. Dr.-Ing. Stephan Sommer

Summary

The early detection of residual stresses in rolling bearings is crucial for predicting remaining service life and preventing unplanned failures. In this study, an innovative approach for the non-destructive detection of residual stresses using Eddy Current Testing (ECT) was developed and experimentally validated. The investigations were based on the use of the automated eddy current test bench VP250W (donated by Schaeffler) and supplemented by the portable device PL600.

Targeted tests on bearing samples – including specimens with defined surface and subsurface modifications – demonstrated that residual stresses can be detected not only in the direct deformation zone but also in adjacent areas. The measurement principle relies on the influence of elastic and plastic stress states on the material's electrical conductivity, which leads to measurable changes in the eddy current signal.

The experimental results highlight the method's high potential for in-service condition monitoring. In particular, the ability to localize load- and manufacturing-induced stress effects within the component opens new perspectives for predictive maintenance and service life estimation. The long-term objective is to integrate residual stress monitoring into fully automated systems such as the VP250W, enabling continuous and contactless industrial-scale monitoring.

This approach combines the advantages of advanced precision mechatronics with practical non-destructive testing, providing a novel contribution to rolling bearing diagnostics.