Quantifying the Effect of Component Inertial Properties on System Level Dynamics

Abstract

Structures are subject to many environments in the lifetime of an assembly, and mechanical environments such as vibration are particularly significant when considering structural integrity. In the early development cycle, mechanical environment test specifications are often derived from assemblies with simplified “mass mock” components. The assumptions for these simplified components generally mimic total mass and center of gravity, but do not always capture moments of inertia. Historically, environments for mass mock components are enveloped and used for future iterations of the true component’s qualification. This work aims to understand and characterize differences in dynamic response due to changes in inertial properties of a component. The FEM of a test structure for this work includes a system level model with true components that will be compared to a FEM with mass mock components. Both versions of the structure will be evaluated based on dynamic response at the component and system levels. The validity and limitations of using mass mock components with approximate inertial properties for deriving environmental specifications will be explored.