Modeling the real contact area plays a key role in every tribological process,such as friction,adhesion,and wear.Contact between two solids does not necessarily occur everywhere within the apparent contact area.Consid...Modeling the real contact area plays a key role in every tribological process,such as friction,adhesion,and wear.Contact between two solids does not necessarily occur everywhere within the apparent contact area.Considering the multiscale nature of roughness,Persson proposed a theory of contact mechanics for a soft and smooth solid in contact with a rigid rough surface.In this theory,he assumed that the vertical displacement on the soft surface could be approximated by the height profile of the substrate surface.Although this assumption gives an accurate pressure distribution at the interface for complete contact,when no gap exists between two surfaces,it results in an overestimation of elastic energy stored in the material for partial contact,which typically occurs in many practical applications.This issue was later addressed by Persson by including a correction factor obtained from the comparison of the theoretical results with molecular dynamics simulation.This paper proposes a different approach to correct the overestimation of vertical displacement in Persson’s contact theory for rough surfaces with self-affine fractal properties.The results are compared with the correction factor proposed by Persson.The main advantage of the proposed method is that it uses physical parameters such as the surface roughness characteristics,material properties,sliding velocity,and normal load to correct the model.This method is also implemented in the theory of rubber friction.The results of the corrected friction model are compared with experiments.The results confirm that the modified model predicts the friction coefficient as a function of sliding velocity more accurately than the original model.展开更多
In this paper,a discrete tire model of comering properties for road vehicles relating to tire grip performance,which is important for driving stability and safety,is presented.The proposed tire model combines realisti...In this paper,a discrete tire model of comering properties for road vehicles relating to tire grip performance,which is important for driving stability and safety,is presented.The proposed tire model combines realistic rubber friction related to velocity and tire grip performance with deformation of the carcass.The model can describe the stress and strain of the carcass and tread,and the rubber friction coefficient at each point of the contact patch,which is affected by the di stribution of the slip velocity.Meanwhile,the model incorporates the effects of the viscoelastic rubber material and power spectrum of the road,which are explicitly reflected in the rubber friction model.First,an improved rubber friction model based on the Persson theory of rubber friction is introduced in this paper.A discrete analytical tire model,which considers carcass compliance and the discretization of the tread,is then proposed.In addition,important phenomena of tire properties arising from the carcass compl iance and rubber friction are analyzed and the effectiveness of the discrete analytical tire model is validated experimentally.The proposed model provides a new way to optimize the grip performance of a tire by adjusting the tire or rubber physical parameters even before the tire is made.展开更多
We study the friction when a rectangular tire tread rubber block is sliding on an ice surface at different temperatures ranging from−38 to−2℃,and sliding speeds ranging from 3μm/s to 1 cm/s.At low temperatures and l...We study the friction when a rectangular tire tread rubber block is sliding on an ice surface at different temperatures ranging from−38 to−2℃,and sliding speeds ranging from 3μm/s to 1 cm/s.At low temperatures and low sliding speeds we propose that an important contribution to the friction force is due to slip between the ice surface and ice fragments attached to the rubber surface.At temperatures above−10℃ or for high enough sliding speeds,a thin premelted water film occurs on the ice surface and the contribution to the friction from shearing the area of real contact is small.In this case the dominant contribution to the friction force comes from viscoelastic deformations of the rubber by the ice asperities.We comment on the role of waxing on the friction between skis and snow(ice particles).展开更多
文摘Modeling the real contact area plays a key role in every tribological process,such as friction,adhesion,and wear.Contact between two solids does not necessarily occur everywhere within the apparent contact area.Considering the multiscale nature of roughness,Persson proposed a theory of contact mechanics for a soft and smooth solid in contact with a rigid rough surface.In this theory,he assumed that the vertical displacement on the soft surface could be approximated by the height profile of the substrate surface.Although this assumption gives an accurate pressure distribution at the interface for complete contact,when no gap exists between two surfaces,it results in an overestimation of elastic energy stored in the material for partial contact,which typically occurs in many practical applications.This issue was later addressed by Persson by including a correction factor obtained from the comparison of the theoretical results with molecular dynamics simulation.This paper proposes a different approach to correct the overestimation of vertical displacement in Persson’s contact theory for rough surfaces with self-affine fractal properties.The results are compared with the correction factor proposed by Persson.The main advantage of the proposed method is that it uses physical parameters such as the surface roughness characteristics,material properties,sliding velocity,and normal load to correct the model.This method is also implemented in the theory of rubber friction.The results of the corrected friction model are compared with experiments.The results confirm that the modified model predicts the friction coefficient as a function of sliding velocity more accurately than the original model.
基金supported by National Natural Science Foundation of China(Grant Nos.51875236 and 61790561)China Automobile Industry Innovation and Development Joint Fund(Grant Nos.U1664257 and U1864206).
文摘In this paper,a discrete tire model of comering properties for road vehicles relating to tire grip performance,which is important for driving stability and safety,is presented.The proposed tire model combines realistic rubber friction related to velocity and tire grip performance with deformation of the carcass.The model can describe the stress and strain of the carcass and tread,and the rubber friction coefficient at each point of the contact patch,which is affected by the di stribution of the slip velocity.Meanwhile,the model incorporates the effects of the viscoelastic rubber material and power spectrum of the road,which are explicitly reflected in the rubber friction model.First,an improved rubber friction model based on the Persson theory of rubber friction is introduced in this paper.A discrete analytical tire model,which considers carcass compliance and the discretization of the tread,is then proposed.In addition,important phenomena of tire properties arising from the carcass compl iance and rubber friction are analyzed and the effectiveness of the discrete analytical tire model is validated experimentally.The proposed model provides a new way to optimize the grip performance of a tire by adjusting the tire or rubber physical parameters even before the tire is made.
文摘We study the friction when a rectangular tire tread rubber block is sliding on an ice surface at different temperatures ranging from−38 to−2℃,and sliding speeds ranging from 3μm/s to 1 cm/s.At low temperatures and low sliding speeds we propose that an important contribution to the friction force is due to slip between the ice surface and ice fragments attached to the rubber surface.At temperatures above−10℃ or for high enough sliding speeds,a thin premelted water film occurs on the ice surface and the contribution to the friction from shearing the area of real contact is small.In this case the dominant contribution to the friction force comes from viscoelastic deformations of the rubber by the ice asperities.We comment on the role of waxing on the friction between skis and snow(ice particles).
