Measuring Magnetostriction in Electric Motor Stator Cores Considering Manufacturing Factors and Material Anisotropy

Magnetostriction in non‐oriented electrical steel constitutes the primary excitation mechanism for vibration in motor stator cores. While magnetostrictive anisotropy stems from a combination of intrinsic material characteristics and extrinsic factors—including grain size heterogeneity, residual stresses, and crystallographic texture—the manufacturing processes of stator cores introduce significant additional residual stresses. These process‐induced stresses further degrade magnetostrictive performance. Prevailing research, predominantly conducted on unprocessed silicon steel laminations under idealized conditions, has substantially underestimated magnetostrictive behavior in operational cores. To address this limitation, this study implemented a magnetostriction measurement system utilizing resistance strain gauges. Comprehensive characterization was performed on stator cores manufactured from 25SW1300‐grade steel, with particular emphasis placed on quantifying the anisotropy mechanisms and the specific influence of manufacturing processes. Obtained results found that the stator core loss exceeded that of single‐piece silicon steel sheets by more than 8%. Critically, localized magnetostrictive strain was found to be amplified by welded operations by 3 μm/m, representing a twofold increase relative to non‐welded regions. © 2026 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.