Research On The Landing Dynamic Performance For A Certain Type Of Aircraft Landing Gear

The current using situation of a certain type of aircraft is universally accessing to the mid and late life of the design, so malfunctions began to increase, for example, a lot of structural wear and tear, fatigue, cracks and other situations. In my department, there were two plane Rocker arm cracks of a certain type of the main landing gear failure from 2006 to 2007.At present,our department only take the methods such as expanding the scolpe of inspection,working for long hours to resolve this situlation, it will not only increase the workload of maintenance for workers, but also not achieve better results. Therefore, through the plane's landing gear dynamic mechanical behavior studies, we can detect and eliminate hidden problems early, which is currently an important thesis for maintenance work.From the two cases of landing gear structural cracks, this subject we did the simulation analysis of the force of landing gear in the overall status of aircraft landing, by the use of dynamic simulation software ADAMS/Aircraft calculated the force changed over time of the main landing gear rocker arm, got the moment of the rocker arm's maximum force. Based on the time of the maximum force, by the application of D'Alembert principle transform the dynamics question into the static's problem, through carrying out static finite element analysis of the rocker arm to find the weak positions, in order to provide theoretical guidance to improve the quality of aircraft maintenance. So the thesis has very important applying values. This article briefly introduces the following chapters of the study:The chapter two mainly introduce and summary the layout of the form and the structural characteristics of the landing gear, and the buffer structure, classification, principles of buffer and buffer job-related formulas for calculating the component of force, in order to lay the foundation for the later of the thesis research.In the third chapter, first of all, this chapter introduces the landing gear's selected mechanical model of and the basic assumptions. In accordance with the basic assumptions of this paper, we did mechanical analysis for the post landing gear and the articulated landing gear, focusing on analysis of aircraft landing gear and the whole mechanical model aircraft landing, and system-wide set up equations of motion and deep analysis the methods of calculating the component of forces.Chapter four firstly introduces multi-rigid-body dynamics ADAMS theory and dynamic simulation software ADAMS / Aircraft. And according to ADAMS / Aircraft's work flow and modeling principles, we set up the whole plane landing simulation models, and did the simulation experiments to draw the curve of the gravity of the aircraft center, the force and acceleration curves of the rocker arm changes with time. Through the simulation results compared with the actual simulation, that ultimately conceives that the entire plane landing simulation results by using ADAMS/Aircraft simulation software is right.In the fifth chapter, there are the introductions the basis of finite element theory and ANSYS software. According to the actual rocker arm forces and the modeling principles of ANSYS software, simplified model of the rocker arm and set up the model into the grid, by the application of D'Alembert principle transform the dynamics question into the static's problem. And by the use of dynamic static method in the ANSYS carried out finite element static analysis we obtain the radial stress and strain changes in trends, and correspond to draw the improvement measures.Through simulation experiments and finite element analysis finally reached the following conclusions:1.The whole aircraft landing simulation results with actual experimental results are basically in the error range of 4%,so it proves that the use of ADAMS / Aircraft landing simulation for the whole machine is practicable. And it prove that this simulation method has obvious advantages , namely, set up the whole machine model in the short period of time, a reduction of the workload modeling process, an intuitive easy-to-understand simulation results.2.By obtaining the curves of the status parameters changed with time in the whole aircraft landing process and through the force curve of the rocker arm which may have the greatest force time, then via analysis and calculating, found the greatest force moment and obtained the force and acceleration in the finite element analysis. Because it is difficult to do physical experiments, it reflects the advantages of the use of ADAMS / Aircraft simulation.3.Through the static analysis of rocker arm in ANSYS We came to the conclusion that: (1) Rocker arm is safe and reliable in the process of plane crash landing. (2) At the same time we can get two parts of stress concentration, one part is the rocker arm at the junction with the buffer, this just happened in my department, so it illustrates the analysis of this paper is in line with the conclusions of the actual rocker arm we use; another bend is in the central arm of P(Picture 1). According to the conclusions based on finite element analysis, we proposed the improvement measures on the location of stress concentration of the rocker arm, such as appropriate to enhance the thickness of the rocker arm or increase the length of contact arm. We put some measures to improve inspection and maintenance of the rocker arm, so the scope of inspection should be expanded and the inspection means should be changed in the maintenance of normal work, such as nondestructive testing methods can be used for the analysis of stress concentration to carry out regular site inspections.