Study of Experimental and Assembly Uncertainties on Modal Parameter Estimates of Axial Piston Pumps

Finite Element Model Updating (FEMU) plays a pivotal role in enhancing the accuracy and reliability of structural dynamics models. Nonetheless, uncertainties related to experimental vibration testing and natural manufacturing variability introduce unavoidable variability in the results of Modal Parameter Extraction (MPE), which is the basis for updating. In this regard, this study delves into the inherent variability of estimates from MPE following from experimental vibration testing Axial Piston Pumps (APPs). Accordingly, we investigate the effect of material properties, boundary conditions and measurement noise, through several experimental vibration tests involving assembly-disassembly and exchange of components. These variations account for inherent manufacturing variability and tolerances both at the component and material level. The obtained vibration data is processed using non-parametric FRF estimates and the Stochastic Subspace Identification (SSI) algorithm, resulting in a collection of FRFs and modal parameter estimates (natural frequencies, damping ratios and mode shapes). We use multivariate analysis techniques to quantify the uncertainty of these estimates and to assess the individual effect of assembly and population uncertainties. These results serve as a basis for further investigation towards the updating of a FE model of the APP, and the quantification of modal parameter uncertainties within the material and substructure connectivity properties.