Monday  |  Salon 14  |  05:20 PM–05:40 PM

#18212–Base Excited Nonlinear Reduced Order Models using Hurty/Craig-Bampton Theory

Base excitation is a common shock and vibration test configuration used to qualify components for their expected lifetime of mechanical environments. The input is applied by kinematically enforcing acceleration boundary conditions via active control during experiments. The environments are intended to replicate the dynamics the component experiences within the system plus additional margin to capture uncertainty. This work develops a base excitation simulation framework in the form of an acceleration boundary condition applied to a nonlinear Hurty/Craig-Bampton (HCB) superelement. The nonlinear superelement consists of linear, fixed-interface modal degrees-of-freedom (DOF), physical boundary DOF with nonlinear element connections, and input boundary DOF. A secondary HCB transformation is applied to the nonlinear superelement model, without any additional reduction, such that only the input boundary DOF remain physical while the remaining DOF are transformed into fixed-interface modal DOF. With this change of coordinates, the acceleration boundary conditions are directly applied to the model while maintaining accuracy of the nonlinear internal forces. The approach is demonstrated on a flexible, nonlinear ratcheting mechanism and compared to an alternative approach based on the inclusion of a large, seismic mass connected to the input boundary DOF.

Robert Kuether   Sandia National Laboratories
David Najera-Flores   ATA Engineering, Inc.