| XIE Song-lin,AI Yan-ting,ZHAO Dan,TIAN Jing,LIU Yu,GUAN Peng,LIU Jun-nan.Contact Stiffness of Three-dimensional Rough Surface Based on Stochastic Process[J],51(9):326-334 |
| Contact Stiffness of Three-dimensional Rough Surface Based on Stochastic Process |
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| DOI：10.16490/j.cnki.issn.1001-3660.2022.09.034 |
| KeyWord:Gauss stochastic distribution theory three-dimensional rough surface finite element modeling response surface method normal contact stiffness critical autocorrelation coefficient |
| Author | Institution |
| XIE Song-lin |
Shenyang Aerospace University, Shenyang , China |
| AI Yan-ting |
Shenyang Aerospace University, Shenyang , China |
| ZHAO Dan |
AECC Sichuan Gas Turbine Establishment, Chengdu , China |
| TIAN Jing |
Shenyang Aerospace University, Shenyang , China |
| LIU Yu |
Shenyang Aerospace University, Shenyang , China |
| GUAN Peng |
Shenyang Aerospace University, Shenyang , China |
| LIU Jun-nan |
Shenyang Aerospace University, Shenyang , China |
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| Abstract: |
| Aircraft engines are the jewel in the crown of modern industry The aero-engine is a complex mechanical assembly containing many mechanical joint surfaces, and the casing flange is a typical mechanical joint surface. The mechanical joint surfaces is not smooth but consists of many micro-convex bodies in contact with each other, and the sum of the stiffness of the micro-convex bodies is called contact stiffness. Accurate calculation of contact stiffness is essential to the stability and dynamic characteristics analysis of the whole aircraft engine The work aims to establish a three-dimensional finite element model of normal contact stiffness for rough surfaces, and to study the sensitivity of normal contact stiffness to roughness, autocorrelation coefficient, elastic modulus, yield limit and other parameters. Firstly, based on stochastic process theory, two-dimensional digital filtering technology was used to generate rough surfaces satisfying Gauss distribution and exponential autocorrelation function, and a three-dimensional finite element model of rough surface contact was established. Then the static stiffness expression was derived according to the relationship between the static displacement of the joint surface and the force on the joint surface, and the normal contact stiffness of the two rough surfaces was obtained. The second-order response surface model was established according to the sample points selected by the central composite design method and the results of finite element calculation. Finally, the critical autocorrelation coefficient is defined and the relationship between the critical autocorrelation coefficient and other parameters is studied. The results of normal contact stiffness calculated by finite element method are reasonable, and the maximum error is less than 12.34% compared with the experimental results. The elastic deformation, plastic deformation and real contact area increase with the increase of load. Normal contact stiffness has a negative correlation with roughness. When the roughness is constant, normal contact stiffness increases first and then decreases with the autocorrelation coefficient. Normal contact stiffness has a negative correlation with the elastic modulus, and normal contact stiffness has a positive correlation with the yield strength. The change of roughness has the greatest influence on normal contact stiffness. When the pressure is 200 MPa, the roughness, autocorrelation coefficient, elastic modulus and yield limit are 0.8 μm, 18.91, 240 GPa and 355 MPa respectively, and the maximum normal contact stiffness reaches 121.53 MPa/mm. After optimization, the normal contact stiffness of the contact surface is increased by 247%. The change in the autocorrelation coefficient only affects the normal contact stiffness. The critical autocorrelation coefficient with roughness, modulus of elasticity and yield limit for optimal normal contact stiffness is obtained by response surface design. The formula for selecting the critical autocorrelation coefficient is given. The conclusion of this paper is that the established model is correct and accurate. A simple method is provided for the finite element modeling and calculation of rough surface normal contact stiffness. This paper can provide a guiding reference for the optimal design of the mounting edge contact stiffness of aero-engine, and provides theoretical guidance for the design of mounting edge parameters. At the same time, it also enriches and develops the aero-engine mounting side connection design system. |
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