Efficient Unbalance Variation in Condensed FE Bodies

Abstract For multi-body simulations involving high-speed rotating components common in electric motors and turbochargers studying unbalance effects is of particular importance, in particular for the assessment of their NVH (noise vibration, harshness) characteristics. Detailed finite element (FE) models of components are condensed to representations with less degrees of freedom to allow viable simulation times for realistic assemblies. Performing parameter studies over variations in the unbalance properties of a body would therefore require the creation of variations of the finite element model and subsequent reduction for each component with variable unbalance properties. Such a procedure is computationally expensive, with the condensation of each component variant potentially taking multiple hours on modern desktop hardware. Additionally it typically requires manually performing steps across multiple software packages. The resulting workflows are too unattractive for routine usage. In this study we discuss an alternative approach, where small unbalance variations can be added directly to condensed FE models without needing access to the full FE model. This newly derived formalism hence allows efficient execution of unbalance parameter studies.