Aeroelastic random gust response analysis of aircraft structures in time domain using simulations

摘要

This paper presents a time domain method for determining the dynamic aeroelastic response of aircraft lifting surfaces under random gust loads. The random response analysis is carried out using a combination of Newmarkx2019;s technique and Monte Carlo Simulations (MCS). Newmarkx2019;s direct integration method has been employed for solving the differential equations of motion in time domain. The proposed method is based on aerodynamic strip theory. The unsteady aerodynamic forces on the wing are calculated from the theory of two-dimensional thin airfoils in non-uniform motion. The theory takes proper account of x2018;unsteadinessx2019; by using the Kussnerx2019;s and Wagnerx2019;s unsteady lift functions while calculating the aerodynamic forces. The random gust load is modelled as a stationary random process13; and specified as an ensemble of velocity time histories generated using MCS. The proposed method is demonstrated by considering the case of an aircraft, which is free in vertical translation with wing being elastic in bending and restrained against twisting. The studies reported in this paper demonstrate the advantage of combining Newmarkx2019;s technique with MCS in the realistic estimation of random dynamic response of aircraft structures subjected to random gust loads. The results of such studies will be useful13; to carryout reliability analysis and safety assessment of aircraft structures.