Study On Contact Of Rough Surface And Leakage Characteristics Of Pipeline Seal

Pipeline seal is widely used in hydraulic systems which is operating in a variety of complex environments such as aerospace,navigation and so on.They are important components for ensuring efficient delivery of fluid media.Once the pipeline seal leaks,it will seriously damage the safety of the system.Therefore,the analysis of pipeline sealing performance is a key issue related to system reliability.The sealing interface presents a high degree of complexity due to the randomness of the surface roughness.The rough surface topography and applied load are the key parameters affecting the sealing performance.At present,there is a lack of analytical methods for evaluating the quantitative relationship between rough surface topography,applied load and sealing performance in metal contact seal design at home and abroad.In view of this,this paper establishes a set of quantitative analysis methods to predict the relationship between rough surface morphology,applied load and sealing performance,which can provide guidance for the design of pipeline seals.The main research work is as follows:Firstly,the three-dimensional geometric modeling of the sealing rough surface topography is carried out.The rough surface point cloud data is obtained by the autocorrelation function method,and the data is transformed into the geometric model by the automatic modeling program.The method realizes the automatic modeling process of three-dimensional random rough surface,and retains the microscopic details of surface roughness,and provides a parametric geometric model for the contact mechanics analysis of rough surfaces.Secondly,the finite element method is used to simulate the elastoplastic contact mechanics between the rough surface and the rigid plane,and the relationship between the contact area ratio and the surface topography parameters and applied load is obtained.The results show that the surface topography parameters and applied load significantly affect the contact area ratio;the smaller the root mean square roughness,the smaller the surface fluctuation,the larger the contact area ratio is.Thirdly,in order to solve the problem that the computation of large variable sample space traversal is difficult to achieve,a method of establishing the functional relationship between rough surface topography parameters and applied load and contact area ratio by orthogonal experiment is proposed.The test results show that the calculation result of the fitting function satisfies the accuracy requirement,and the orthogonal experiment method can replace the large-scale finite element contact mechanics calculation,and significantly improve the efficiency of the contact area ratio calculation.Finally,based on the percolation theory,the contact interface grid model is constructed,and the leakage probability is used as the index parameter to judge the sealing performance.The automatic path finding algorithm is used to calculate and analyzes the seal-leak transition characteristics.The results show that with the increase of contact area ratio,the probability of seal leakage decreases sharply;the smaller the surface roughness,the smaller the fluctuation,the larger the applied load,the larger the contact area and the better the sealing performance.Thereby,a method of directly predicting the sealing performance from a rough surface and applying a load is formed.