Finite Element Analysis Based On Elasto-Plastic Contact Of 3-D Real Rough Surface

Frictional wear is one of the primary reasons of energy consumed,and frictional wear mostly happens in contact area.The mutual contact surface of slippage friction is rough, furthermore,contact capability between the rough surfaces depend on microcosmic elastic plastic transformation and frictional heat among contact surfaces.Therefore,elastic plastic contact issue of real rough surface and the flash temperature of engineering rough surface and thermal mechanical stress analysis are need to be investigated systematically.It is proposed the new model of real rough surface based on 3D measured method and reverse engineering method,the main work is investigating the rule between the parameters in elastic stage and elastic-plastic stage with the same roughness or different and contact capability based on finite element analysis method.Reliability and life of use of mechanical equipment and friction of moving parts' surface or abrasion of friction pairs is closely related.Abrasion of friction is one of the main reasons of energy consumption,and that research shows that,abrasion of friction is occurred in contact area;therefore,the simulation of real contact area plays an important role for understanding tribology such as process of friction force,abrasion,fatigued contact,adhesive force and lubrication.At present calculation and description of real contact surface is still the most unsubstantial field in tribology,hence it is necessary to systematically study for issues of elastic-plastic contact of real rough surface and flash temperature and thermal-structure coupled stress of engineering roughness surface,from the perspective of numerical simulation,the rule between parameters of elastic stage and elastic-plastic stage and heat transfer law of friction moving interface is further analyzed.Considering that the study of real rough surfaces based on digital technology is relatively less,and limitations of use of analytical method when solving the complex problems,in this dissertation,finite element methods based on digital real rough surfaces is employed to research the issues of issues of elastic-plastic contact.First of all,shape and morphology with four different coarseness of turning surfaces is obtained by the instruments Wyko NT1100,secondly,least square methods is used to remove the Bad points and noise points and to do another preprocessing manipulation such data reduction, subsequently,3D solid models of real rough surface is captured by reverse modeling,and its finite elements contact model is established,which is prepare for the posterior finite element analysis.Eventually,from the perspective of numerical simulation,the rule between the parameters in elastic stage and elastic-plastic stage with the same roughness or different and contact capability are analyzed.Through the study,for rough surfaces with the same roughness,in the elastic contact stage,the relationship between non-dimensional area and displacement and the non-dimensional load is linear;however,in elastic-plastic stage,the relationship is approximately linear only if elastic-plastic tangential direct modulus Et is large enough.For turning surfaces with roughness R_a=0.8,R_a=1.6 and R_a=3.2,in the same load case,contact area of the rough surface with roughness R_a= 3.2 is the largest, and displacement in Z direction of rough surface with roughness and contact pressure R_a=1.6 are the largest respectively;in elastic stage,the relationship between non-dimensional area and displacement and the non-dimensional load is not linear, whereas in elastic-plastic stage,when elastic-plastic tangential direct modulus Et equals 100GPa,the relationship is approximately linear;in addition,the varieties of non-dimensional contact pressures with non-dimensional load in three models(OEPPLNPLSLNEPP) for the same rough surface with the same roughness are studied respectively in this dissertation.The conclusions show that,in the same load case, the contact pressures of OEPP and NEPP models are less than that of NPLS model.Some discoveries have been made when researching the problems of thermo-mechanical coupling of real roughness interface.With the increasing of slide distance, the distribution of equivalent stress and the distribution of temperature are gradually increasing respectively,while the fluctuate is appeared in the distribution of contact press, because the temperature is climbing too fast to transmit into inside;different stress distribution are obtained with different contact materials,but there are not too big difference between them.When the contact materials are different,the primary factors are the elastic modulus of materials.Equivalent stress and temperature are increasing respectively with the increasing of load,velocity and friction coefficient.This research has active significance and value for reference in engineering,such as improving the capability of surface contact,and predicting quantificationally the friction and wear of practicality machine system,and developing high-capability frictional materials and processing and manufacturing initial surface of friction pairs.