The market for electric and hybrid vehicles is expanding rapidly, and customer demands are tightening manufacturing tolerances. The cores of electric motors consist of stator and rotor lamination stacks that critically determine final performance, therefore quality assurance is essential. In practice, certain critical quality attributes are still verified by destructive tests, which are slow and costly in series production. This study examines whether Experimental Modal Analysis can contribute, as a non-destructive approach, to assessing the quality of inter-lamination joints in stator stacks. Specimens were excited with a known force and their responses measured, from these data we computed frequency response functions and identified natural frequencies using the PolyMAX method, then compared the results across measurement parameters and quality classes. The findings show that, under the present conditions, no single, universally valid criterion can be established. The choice of excitation strongly influences the number and quality of identified natural frequencies, additionaly any changes in sheet material produce significant shifts. We therefore conclude that any quality criterion must be dynamic and material-dependent, supported by reference calibration. Despite these challenges, experimental modal analysis shows potential within a quality-assurance workflow.
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