对我国以往常用前起落架载荷谱存在问题的探索

 通过对轰六前起落架主、辅减摆器使用载荷谱的实测、疲劳试验实施方法和试验结果的介绍与分析,初步探索了我国以往常用前起落架载荷谱中存在的问题以及疲劳试验结果与前起落架外场实际破坏不符的原因。并对今后编制前起落架载荷谱和确定前起落架疲劳试验加载方法提出了改进意见。

INDENTIFICATION OF NONLINEAR PROPERTIES OF AN AIRCRAFT LANDING GEAR SHOCK STRUT

A simple but realistic method for identifying nonlinear stiffness and damping of a widely used aircraft air-oil shock strut has been developed in this paper In the method a power series expansion is used to model the nonlinear dynamic properties of the strut,and after intro- ducing new variables,the nonlinear identification problem can be reduced to a linear one with unknown linear parameters.An unbiased, efficient and consistent estimator for the vector of the linear parameters is obtained-under conditions of minimizing the sum of squares residuals which are assumed to be stationary and uncorrelated with the observed data. The order and the most ef- fective independent variables in the model are determined by the criterion of residual series corre- lation information entropy and the procedure of the best subset regression respectively Experi- ment demonstrates that the results are quite satisfactory and the method developed is realistic,which can be used to study the dynamic properties of the strut in full detail.