A Comparison of Different Boundary Condition Correction Methods

摘要

Fixed base correction methods have been increasingly used to transform flexible or dynamically active boundary conditions into fixed boundaries in modal tests. This paper examines the extraction of fixed base modes from a demonstration test article utilizing different frequency response function (FRF) and mode shape based methods. First, fixed base FRFs are directly calculated utilizing the base acceleration measurements or constraint shapes as the references. Second, constraints shapes are applied to the nominal mode shapes. Finally, a hybrid method is investigated that calculates FRFs from baseline mode shapes and then calculates fixed base modes using the FRF-based methods.