飞机起落架舱门收放联动机构气密性分析

Air Tightness Analysis of Landing Gear Door Linkage Retraction Mechanism

对于起落架联动的舱门机构,由于结构传动刚度的影响,所承载的气动载荷会引起舱门的开度进而存在气密性问题。为了分析该问题,首先建立了起落架舱门联动机构的力学模型,明确了舱门密封件的受力情况;基于非线性不可压缩Mooney-Rivlin本构理论,建立了P形密封圈有限元模型,得出了其在工作状态下的静压曲线;最后建立了起落架舱门联动机构刚柔耦合模型,采用增加舱门预紧力形式以抵消舱门开度的影响,并分析了不同风载工况下的舱门气密性情况。结果表明:气动载荷引起的舱门开度使得密封圈接触应力变小,有可能导致密封失效;当直角挡件间距为15.3mm时,压缩率31%,平均接触应力0.228N,密封性能良好。通过在前拉杆、后舱门拉杆分别施加10500N、1200N的轴向预紧力,可满足舱门的气密性要求。

For the landing gear door linkage mechanism,since the impact of structural rigidity of transmission,aerodynamic loads will cause the open size of the door and then air-tightness problems.ln order to analyze the problems,mechanical equations of the extending-retracting mechanism were set up,which identified the forces of door seals.Based on the theory of nonlinearity and incompressible Mooney-Rivlin constitutive equation,a finite element model of P-ring seals was established, which conduced to get the hydrostatic curves of the seals at working process. A rigid-flexible coupling prototype of landing gear mechanism was established to figure out the air tightness under different aerodynamic load conditions ,by increasing preload to offset the impact of the opening of the door.The results show that elastic deformation of relevant members caused by aerodynamic loads, is an important cause of seal failure,which leads to P-ring seals without contact or small contact stress. When the shortest distance of the rectangular baffles reaches to 15.3mm,the compression rate to 31 percent,the average contact stress to 0.228N, it indicates a good sealing performance.Axial preloads about 10500N and 1200N are separately applied to the rod of front door and the rod of rear door to improve air tightness.