A Substructure Synthesis Method with Nonlinear ROM Including Geometric Nonlinearities

Chao An,Changchuan Xie,Chao Yang,Yang Meng

doi:10.3390/aerospace8110344

Abstract

Large flexible aircraft are often accompanied by large deformations during flight leading to obvious geometric nonlinearities in response. Geometric nonlinear dynamic response simulations based on full-order models often carry unbearable computing burden. Meanwhile, geometric nonlinearities are caused by large flexible wings in most cases and the deformation of fuselages is small. Analyzing the whole aircraft as a nonlinear structure will greatly increase the analysis complexity and cost. The analysis of complicated aircraft structures can be more efficient and simplified if subcomponents can be divided and treated. This paper aims to develop a hybrid interface substructure synthesis method by expanding the nonlinear reduced-order model (ROM) with the implicit condensation and expansion (ICE) approach, to estimate the dynamic transient response for aircraft structures including geometric nonlinearities. A small number of linear modes are used to construct a nonlinear ROM for substructures with large deformation, and linear substructures with small deformation can also be assembled comprehensively. The method proposed is compatible with finite element method (FEM), allowing for realistic engineering model analysis. Numerical examples with large flexible aircraft models are calculated to validate the accuracy and efficiency of this method contrasted with nonlinear FEM.

Highlights

Geometric nonlinearities must be considered in the design process of modern, highperformance aircraft, especially high-altitude long-endurance (HALE) aircrafts
Cooper and Cestino et al introduced the implicit condensation and expansion (ICE) method to aeroelastic analysis of large flexible wings coupled with the double lattice method (DLM) and the results presented the important influence of geometric nonlinearities in aircraft structures [16,17]
Nonlinear reduced-order model (ROM) based on ICE techniques is an efficient method for large flexible structure modeling

Summary

Introduction

Geometric nonlinearities must be considered in the design process of modern, highperformance aircraft, especially high-altitude long-endurance (HALE) aircrafts. Because of light-weight design and substantial flexibility, the wings of HALE aircraft always have high slenderness and produce large deformation during flight. Such large deformation leads to vital changes in structural stiffness characteristics and aerodynamic configuration, which obviously affect dynamic response, stability and flight performance of aircraft [1,2,3]. For complex aircraft structures, detailed FEM models of structures often tend to possess large numbers of DoFs in order to account for extremely detailed geometric features and material distributions

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Methods

Results

Conclusion