Random uncertainty of aeroelastic system

An effective numerical simulation method for reliability, line sampling technique, is proposed to analyze the probability and sensitivity characteristics of flutter with structural random parameters. By computing the eigenvalues of the state equations of aeroelastic system, the flutter characteristics can be analyzed. The safety margin of flutter is founded by using of flutter critical velocity. The partial derivatives of the failure probability with respect to the random parameters are derived in detail, which can describe the effect of random parameters on the failure probability quantificationally, so it can guide the structural optimization design. And then considering a two-dimensional three-degrees of freedom airplane wing with aileron as the calculation model of flutter, importance sampling (IS) method and line sampling technique (LST) are used to analyze the randomness uncertainty of flutter. The results show that the random variables of frequency have more significant effects on the flutter reliability than the structural size and mass ratio. Then the reliability of the wing flutter is analyzed with the randomness of frequency. Considering the results of importance sampling as the approximately exact ones, the results of LST are agreed with the exact ones. The computational efficiency of LST is improved greatly than that of IS method.