某起落架收放试验故障分析及间隙影响分析
Failure Analysis and Gap Impact Analysis of a Landing Gear's Extension-retraction Test

为了分析某型飞机前起落架在收放试验中出现试验件变形、机构卡滞的问题，结合试验现象，对整个机构进行载荷分析，得出机构故障机理，即关键传力部件之间存在间隙。在理论分析的基础上进行ADAMS多刚体动力学分析，对主要受力构件进行有限元分析，随后从制造误差和装配误差两个方面分析运动副间隙可能的取值范围，进而进行运动副含间隙情况下起落架机构卡滞位置的载荷分析，分析结果表明：装配误差导致的运动副间隙使得关键传力部件后拉杆出现8.31 mm变形，最大应力达到1 220 MPa，已超过材料的屈服极限，使得结构变形、机构传力路径改变进而导致机构卡滞。
The nose landing gear of a certain aircraft had some problems of deformation and clamping stagnation during extension-retraction tests. This study was carried out to analyze these problems. First, the load of the entire mechanism was analyzed combining the experimenting phenomenon. It was concluded that the gaps between key load transmission components lead to these mechanism faults. On the basis of theoretical analysis, the multi-rigid body dynamic analysis using ADAMS and the finite element analysis of the main members bearing load were carried out. The possible range of gap value was analyzed according to errors in manufacturing and assembly. And then, the load analysis of the landing gear mechanism was done in the case that the kinematic pair had gaps and the landing gear was stuck. From the analysis, the following results are concluded. The kinematic pair gaps caused by assembly errors render 8.31 mm long deformation on the primary load-transfer component, the rear bar. The maximum stress is up to 1 220 MPa, which has exceeded the yield limit and causes the mechanism deformation and the change of the load transmission route. It's the reason why the mechanism is stuck