Analysis Of Sealing Characteristics Of Ellipsoidal Head Taper Hole And Beam Pipe Joint

As an important connecting part widely used in aerospace field,pipe joints and hydraulic components such as pumps,cylinders and valves are connected together through pipelines to form an aviation hydraulic system.Because of the high temperature and pressure,the pipe joints are easy to damage and cause leakage when the aircraft works.Most aviation accidents are caused by pipe joints If leakage occurs,light leakage will affect liquid transportation,and waste of resources will affect normal work.If it is serious,aviation accidents will occur,which will cause great harm to people’s lives and property.So how to ensure that the pipe joint can work normally in high temperature and high pressure,that is,how to reduce the leakage rate becomes critical.But in the actual project,the domestic manufacturers have some deficiencies in the research of the sealing mechanism of the pipe joints,and the design of the pipe joints is mainly based on experience.Unreasonable joint design will directly cause serious sealing problems,which will affect the normal operation of aircraft and even endanger people’s lives.Therefore,it is very important to study the sealing characteristics of pipe joints.In this paper,two most common pipe joints in aviation system are studied: cone head-cone hole pipe joint and beam pipe joint.In order to reduce the calculation time,the paper uses Python language to model parametric model and MATLAB adjust ABAQUS to calculate automatically.The target parameters are the width and pressure of sealing surface,and contact theory is the base.Based on the above analysis,the paper studies the relationship between the sealing characteristics of the pipe joint and its internal factors,including assembly parameters and structural parameters,as well as external factors including roughness and ambient temperature.Based on the above analysis,the paper studies how the sealing joint leaks fundamentally,so as to obtain reliable design criteria and assembly requirements of the sealing joint to ensure its leakage rate In the scope of safety,the aviation system is ensured.The detailed contents of this paper are as follows:1)The sealing principle is expounded and the sealing conditions are obtained.First of all,how the contact surface deforms when sealing is explained from the micro level,and the conclusion is that the width and pressure of the sealing surface are the key points to make the structure sealed.According to the analysis results of predecessors on the sealing principle,the conditions that can make the structure seal and the basis of realizing the seal are obtained.Next,the contact theory of ABAQUS is elaborated,and it is explained in detail that the size of finite element mesh will directly affect the calculation accuracy.Finally,the classical Hertz contact problem is studied to verify the correctness of the finite element method,and the calculation results of the cone head-cone hole pipe joint by two finite element software are compared to verify that the finite element software can be used to calculate the contact problem,which provides the basis for the numerical analysis and calculation in the following chapters.2)In view of the fact that the ellipsoid contact surface is smoother than the cone contact surface,the maximum Mises stress and the maximum contact stress will be smaller wh en the ideal sealing state is achieved,which can improve the service life and cycle of the pipe joint,and save the cost,the cone part of the traditional cone cone cone hole pipe joint is changed to ellipsoid joint,and its sealing characteristics are studied.Firstly,it describes how to model and calculate the initial load,and then uses Python language to carry out parametric modeling and MATLAB to call ABAQUS to automatically calculate the structural parameters of the pipe joint,as well as the relationship between environmental parameters and sealing surface width,maximum Mises stress and contact area.Then,according to the requirements and environment of the pipe joint,the relationship between the sealing characteristics and the parameters is studied,so as to obtain the appropriate range of the parameters in the practical engineering problems when the pipe joint reaches the ideal sealing state.Finally,by comparing the results of previous analysis on the sealing characteristics of cone head-cone hole pipe joint,it is concluded that the maximum Mises stress and the maximum contact stress of ellipsoid headcone hole pipe joint are smaller than that of cone head-cone hole pipe joint when the ideal sealing state is achieved,which can improve the service life of the pipe joint.3)The sealing characteristics of beam pipe joint in complex environment are studied.First of all,how to model and determine the initial load is described.Next,parametric modeling is also carried out by using Python language and ABAQUS is called by MATLAB to automatically calculate the relationship diagram of roughness,ambient temperature and sealing surface width,maximum Mises stress and contact area of the pipe joint,.Then,according to the requirements of the pipe joint and the environment,the relationship between the sealing characteristics and the environmental parameters is studied,so as to obtain the appropriate range of the environmental parameters in the practical engineering problems when the pipe joint reaches the ideal sealing state.