Research On Contact Model Of Rough Surface Based On Real Topography

Contact deformation generally exists in industrial production and will affect the use of processing and manufacturing equipment.A machine tool is composed of a large number of parts,two related parts will have contact.There is a yield limit in the materials of contact parts.Excessive load on the two contact parts will lead to irreversible deformation on the surface of the parts,and even change the macro shape of the parts,which will affect the life and normal use of the parts,and finally affect the operation and processing of the whole machine tool.The contact model is established for the contact surface between parts,the influencing factors of the contact process are analyzed,and the formula of deformation theory of the contact model is calculated,which provides a reference for the theoretical analysis of the contact field.The main research contents of this paper are as follows:(1)Establish a new contact model of friction micro-convex body.Based on the Hertz contact theory,the conclusion that the friction coefficient will affect the normal deformation of contact under the action of arbitrary tangential force is taken as the breakthrough,the four stages of contact deformation of micro-convex body are analyzed,and the functional formula of contact area and contact load is calculated.The probability density function of the micro-convex body is obtained by combining with the two-dimensional area probability density function,and all deformation stages of the rough surface are analyzed.The fractal dimension is fixed and the friction coefficient is divided into three ranges.(2)The data of contact surface morphology were reconstructed and the fractal dimension was obtained.The aluminum alloy samples were selected for surface processing,and the atomic force microscope was used to detect any region of the metal surface to obtain the interval coordinate points of the detection region,and the data points were simplified,removed and repaired to reconstruct the real morphology model.Based on the detection data,the fractal dimension of the surface was calculated by projection method,and the fractal dimension value was 2.82.(3)A numerical example of a new friction contact model is analyzed by using the fractal dimension.The fractal dimension values were substituted into the calculation examples,and eight friction coefficient values were selected to analyze the changes of contact area,contact load and deformation in all the contact deformation stages.When the friction coefficient is greater than 0.3,the change of the overall contact area and contact load with the deformation amount is consistent.When the friction coefficient is from 0 to 0.3,the contact area and the contact load increase with the deformation in the elastic-plastic stage.(4)The contact model of real morphology is analyzed by ANSYS simulation,and the results are compared with the calculation formula.Simulation analysis was carried out on the micro-convex body contact model and the real rough surface solid model,respectively.The maximum normal force was applied to the two contact simulations,the same duration was set and the same fixed tangential force was applied,and the simulation results of eight groups of friction coefficient values were obtained.The relationship between micro-convex body contact load and deformation amount and the relationship between overall rough surface contact load and deformation amount were compared with the simulation results under the same condition,and the comparison results were more similar.