Viscoelastic modeling of the magnetic losses in punch-degraded non-oriented electrical steel

This study examines the effect of punching on magnetic losses in non-oriented electrical steel using a viscoelastic model based on fractional-derivative operators. Specimens with identical material volume and increasing edge-affected area were characterized under alternating magnetization with controlled sinusoidal flux density. The frequency dependence of losses is described by a fractional order n and a coefficient ρ, related to viscoelastic mechanisms and material properties, respectively. The results show an almost monotonic increase of n with edge-affected area, providing a compact indicator of cutting-induced degradation, while ρ remains close to analytically predicted values. A scaling analysis links the experimental configurations to 1 kW transformers and motors. Loss predictions at elevated frequencies highlight the significant contribution of punching-induced degradation under practical operating conditions.