구조적 비선형성에 의한 주파수비 변화가 2 자유도계 익형의 공탄성 반응에 미치는 영향

Abstract

Aeroelastic analysis of two degree of freedom airfoil system with structural nonlinearities is performed. The considered structural nonlinearities are freeplay, friction, hardening bilinear, and softening bilinear nonlinearities in pitch or plunge degree of freedom. And, the case containing freeplay and friction nonlinearities in both the pitch and plunge degree of freedom is considered. Subsonic DHM and supersonic DPM are used for the unsteady aerodynamic analysis. Frequency domain analysis is performed using describing function and V-g method. And time domain -analysis is also performed using rational function approximation. Response characteristics are investigated for the change of the frequency ratio(the ratio of plunging frequency to pitching frequency).