The vehicle industry being in the middle of transformation, the development of electric drives has come into engineers’ focus. The parameter evaluation of dynamic systems can be cumbersome when having nonlinearity in the structure, for example nonlinear stiffness characteristics. In such case, the standard linear approach, including EMA (Experimental Modal Analysis), modal superposition, FRF measurement (Frequency Response Function) and modal synthesis can not be applied. However, one of the main challenges in addressing nonlinearities is the lack of general tools to approach them. In this paper, a general framework to study nonlinearities in a structural dynamic context is presented. The method relies on standard random and sine sweep testing approaches to detect and localize nonlinearities, and on dedicated processing techniques to analyze the data and extract information on the nature of the analyzed nonlinearity. This approach is then used to study the behavior of an assembly of a lamella package of PMSM (Permanent Magnetic Synchronous Machines), where permanent magnets are embedded in the laminations. The magnets are surrounded by resin that holds them in place in their grooves. Characterizing the dynamic properties of such a structure is a relevant task in engineering development, for verifying numerical predictions. In this case, the relative motion of lamellas as well as the heavy influence of the polymer resin’s properties may result in nonlinear behavior.
