Time-dependent magnetization losses critically affect the performance of permanent magnets during their service lifetime. Quantifying these losses remains challenging, as existing analytical models and simulation tools lack suitable functions for accurate prediction. This work introduces a practical method to quantify these losses using the magnetic viscosity parameter and to predict future behavior via the time-dependent fluctuation field. Measurements on several magnet grades demonstrate that long-term stability can be reliably estimated with this approach, supporting both analytical evaluation and direct implementation in numerical simulations. Validation against long-term experiments confirms the accuracy of the method and its suitability for predicting magnetization evolution, enabling more targeted material selection.
Lanz et al. (Fri,) studied this question.