Research On Wear Mechanism Of Contact Interface Of Heavy-load Incremental Launching Equipment

Incremental launching equipment is an efficient and safe bridge construction equipment,which is widely used in bridge construction using incremental launching technology.During the incremental launching process,the preset operation is mainly realized by the surface-to-surface contact of the sliding contact surface in the equipment.The bearing capacity and the friction and wear characteristics between the contact surfaces directly determine the working state of the whole equipment,and affect the working efficiency and service life of the device.Based on contact mechanics and fractal theory,the characterization and simulation of contact surfaces is improved as a basic tool.The contact characteristics,the friction behavior and the wear mechanism of sliding contact surface are studied.The evolution law of different influencing factors on contact,friction and wear properties is explored to guide engineering practice,which has engineering practical value.The main contents are as follows:A method to characterize the contact surface morphology of incremental launching equipment is proposed.Starting from the relevant parameters used to characterize the surface topography,the corresponding parameter calculation method is given and the conversion method between traditional parameters and fractal parameters is provided.The two-dimensional profile and three-dimensional topography of rough surface are simulated based on fractal theory.According to the calculation and analysis of the surface roughness characteristic parameters of the contact surface of incremental launching device,the fractal parameters are acquired,and the multi-scale threedimensional surface morphology characteristics of the actual contact surface are simulated.Based on fractal theory and Hertz theory,a new multi-scale three-dimensional elastoplastic contact model for rough surfaces considering friction factors is established.The critical contact area and critical deformation conditions of the asperity at different scales are derived.The microcontact fractal model of the multi-scale asperity is established.The total contact load and the total real contact area of friction surface are obtained by modifying the area distribution function of different scales.The influence of fractal parameters and scale level on the real contact area and the normal load of the surface is studied.In order to verify the validity of the model in this paper,a comparative analysis with other models and experimental data is carried out.A fractal model of friction and wear of the contact interface of equipment is established.The fractal model of maximum static friction force and static friction coefficient is established by introducing fractal theory and multi-scale calculation concept combined with Tresca yield condition.Based on the theory of molecular mechanical friction,the kinematics and contact mechanics of a single asperity on the sliding contact surface are analyzed.Considering that the micro-contact area of the asperity has scale correlation,the fractal model of the sliding friction coefficient is established.On the basis of traditional adhesion theory,combined with fractal theory and multi-scale concept,a fractal wear model of sliding contact interface is established,and the variation of wear rate with surface fractal parameters,sliding speed and normal load are predicted.The friction and wear behavior of the sliding contact surface of incremental launching deviced is studied.According to the actual working principle of sliding contact surface of equipment,a friction and wear test-bed is designed to carry out the friction and wear performance test of the sliding pair.The friction coefficient,wear rate and the evolution process of macroscopic and microscopic morphology of the sliding pair under different load conditions without lubrication are studied.The wear behavior of sliding pair is described and the wear mechanism is revealed.The friction and wear behavior of the rolling contact interface of equipment is studied.The self-developed rolling friction and wear test-bed is used to conduct the friction and wear performance of the rolling pair.The variation trend of friction coefficient and the surface morphology and cross-sectional microstructure of rolling pair under different loads without lubrication is analyzed.The damage law and wear mechanism of the rolling pair are revealed.In contrast with the friction and wear behavior of sliding surface,it provides a basis for engineering practice of incremental launching equipment.This paper combines theoretical analysis with modeling,simulation research and experimental analysis.Results obtained from this paper develop the related theories of sliding contact surface characterization and simulation,contact characteristics and friction and wear mechanism,which provides design basis and technical support for the development and application of heavy-load incremental launching equipment.