针对某型航空弹性薄壁机匣的模态共振问题,考虑航空机架弹性支承刚度,采用有限元法进行典型工况下约束模态分析,研究了薄壁机匣结构参数对约束模态固有频率的影响规律。结果表明优化支承位置是大幅度改变固有频率最有效的方式；当固有频率处在共振区间边缘时,可通过优化壁厚、筋板的方法小幅度调整。当两个支承位置位于机匣平面对称轴线时,固有频率最小且随着支承距离的减小而减小。随着薄壁厚度的增大,1、3、5、6阶模态频率减小,2、4阶增大。1、3阶模态频率基本不受筋板参数的影响；2、4阶模态频率随着筋板宽度、高度的增大和宽高比的减小而增大且4阶频率随着筋板角度的增大而增大；5、6阶模态频率随着筋板角度的增大、筋板宽度的减小而增大。在此基础上,对弹性薄壁机匣的结构参数进行优化使固有频率避开共振区间,提高了机匣的抗振能力。

In order to solve the resonance problem of an aviation elastic thin-walled casing, the finite element method was used to analyze the constrained modal under typical working conditions based on the elastic support stiffness of the aircraft frame. In this paper, the influence of structural parameters of aviation elastic thin-walled casing on the natural frequencies of constrained modal was studied. The results show that optimizing the position of constraint is the most effective way to change the natural frequencies greatly. When the natural frequency is at the edge of the resonance intervals, it can be adjusted slightly by optimizing the wall thickness and stiffener parameters. When the two constraint positions are located on the symmetry axis of the casing plane, the natural frequencies are minimum and decrease obviously with the decreasing of the constraint distance. With the increase of the thin-wall thickness, the 1st, 3rd, 5th and 6th modal frequencies decrease and the 2nd and 4th modal frequencies increase. The 1st and 3rd modal frequencies are almost not affected by the stiffener parameters. The 2nd, 4th modal frequencies increase with the increasing width and height of stiffener and decreasing stiffener aspect ratio. In addition, the 4th modal frequency increases with the increasing angle of stiffener. The 5th and 6th modal frequencies increase with increasing stiffener angle and decreasing stiffener width. On this basis, the structural parameters of the aviation elastic thin-walled casing were optimized to make the natural frequencies avoid the resonance intervals, thus improving the vibration resistance of the casing.

TH113.1

重庆市杰出青年科学基金项目(CSTB2022NSCQ-JQX0026)