A Dynamic Modeling Method And Its Application In Structures With Nonlinearity And Uncertainty

Structural nonlinearity and uncertainty are common phenomenon encounterted in practicalengineering structures. With the revolution of computer technology and improving of design level,structural nonlinearity and uncertainty are attracting more researchers in the dynamic design processof critical equipments such as the aero-engine.The influence of nonlinearity and uncertainty onstructural dynamic analysis and the methods of dynamic modeling and model validation for structureswith nonlinearitis and uncertainties are hot topics gradually in recent years.Based on the study of Validation Challenge of Structural Dynamics Problem developed by SandiaNational Laboratories (2006), a simple3DOF mathematic model with nonlinear stiffness and dampingbehaviour, together with the parameter variation, is constructed. The influence of nonlinearities anduncertainties on structural dynamic analysis is discussed and a solution which separates nonlinearitiesfrom uncertainties through vibration tests is developed to establish the most accurate model possibly.This solution is verified by numerical simulation of the3DOF model.Subsequently, a framed structure with bolted joints is designed and manufactured. Dynamicproperties analysis and response prediction of the structure are performed through finite elementsimulation, modal testing and model updating.At last, a simple Jeffcott rotor model with nonlinear stiffness is constructed. The influence ofunbalance on the nonlinear rotor is discussed and a method of identifying and quantifying thenonlinear stiffness terms in the rotor is developed.