Substructuring of a Nonlinear Beam Using a Modal Iwan Framework, Part II: Nonlinear Modal Substructuring

Abstract

In a companion paper (Roettgen, D.R., et al.: Substructuring of a nonlinear beam using modal Iwan framework, Part 1: nonlinear modal model identification. Presented at the international modal analysis conference XXXV, Garden Grove, 2017), "Substructuring of a nonlinear beam using modal Iwan framework, Part I: Nonlinear Modal Model Identification", nonlinear modal models are constructed for an experimental substructure that represent the dynamics using a set of uncoupled weakly nonlinear modes. This assumes that the linear modes of the structure remain uncoupled so that the nonlinearity can be described in a mode by mode fashion. These nonlinear modal models can be used to simulate the response of the experimental system. This paper demonstrates the use of these models to represent a substructure in an experimental-analytical substructuring prediction. The authors utilize the transmission simulator method on the experimentally derived models to generate predictions of a modified Brake-Reuss Beam system. The substructuring predictions are then compared to a truth test data set to validate the method. To further understand the limitations of the method and its sensitivity to measurement noise, the modal substructuring approach is also simulated on a finite element model of the beam that contains three discrete nonlinear elements to represent the joint.

Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.