| Friction effect of asphalt pavement on automobile tires is the important factor to ensure traffic safety.When the vehicle is driving on the road,a tight dynamic coupling system is formed between tire and pavement.And the tire-road coupling friction behavior will have a significant impact on the anti-slip performance of the asphalt pavement.Due to the complexity of friction behavior,friction performance of asphalt pavement is usually studied comprehensively by a combination of experiment and simulation analysis.However,the progress of current research on dynamic simulation of tire-road coupled friction behavior is limited,and the mechanism of dynamic friction behavior of asphalt pavement under tire braking conditions is yet indefinite because of the influence of factors such as algorithms and computational efficiency.Therefore,in order to study the friction performance of asphalt pavement further,the tire-pavement coupling is taken as the focal point.The structural dynamic response of asphalt pavement under wheel load is evaluated comprehensively and the evolution mechanism of friction performance under the driving load is analyzed further through a combination of experiment and numerical simulation.Considering the influence of pavement surface texture,three grading designs were selected,separately continuous dense gradation AC-13,intermittent gradation SMA-13,and open gradation OGFC-13.The basalt,limestone and granite were selected for the coarse aggregate.And then,the following studies were carried out:Firstly,the textures of the asphalt pavements were mesured by sand patch test and profile test.And the correlation among the mean profile depth MPD,the mean texture depth MTD and other texture parameters was analyzed.Then,the British Pendulum Number BPN of pavements were measured by British Pendulum Tester.The relationships between BPN and the texture parameters were studied.And the results show that most of the texture parameters have a good linear relationship with BPN and can be used to evaluate the anti-sliding performance of pavements.Secondly,the friction coefficients of asphalt pavements were measured of by TirePavement Dynamic Friction Analyzer which is independently developed because of the disadvange of British Pendulum Tester that it only can simulate the anti-slip characteristics of the pavements at low speed.This study mainly considers the effects of tire road contact status,pavement texture depth,load,and speed on the tire-road friction behavior.At the same time,the friction coefficient estimation modeling of asphalt pavement was derived based on the relationship among the mean profile depth,mean contact pressure,tire sliding speed,and tire-pavement dynamic friction coefficient T-PDFC.It can provide an important basis for defining the friction behavior between tire and pavement in finite element modeling.Thirdly,three types of pavements modelings(AC,SMA,and OGFC)and PIARC smooth tire modeling with complex mechanical characteristics were formed in the ABAQUS finite element software.And the contact states of tires and pavement under different loads were analyzed.It indicat that contact area and pressure will increase as the load increasing and the contact area and pressure with AC are less than those of SMA and OGFC pavement under the same load.Then,import the exponential friction estimation modeling into the tire-road finite element modeling by the friction user subroutine.And friction coefficient under different conditions was calculated through the steady-state analysis.It is found that the numerical simulation and experimental results reflect the same regulation: When the tire is braked effectively,the friction coefficient will increase as the load increaseing and decrease as the speed increaseing;and there is an optimal slip rate to make the friction coefficient reach the maximum value.Afterwards,the modeling is compared with other friction modelings to prove the superiority and reliability of itself.Finally,a rolling modeling of the tire on the road was created,and the braking distance of the tire on different pavements was studied in this modeling based on the calculated friction coefficient.The results indicat that the better the anti-skid performance of the road surface,the shorter the braking distance of the tire.Besides,for the same pavement,the velocity of tire in ABS braking state was analyzed,it’s found that the deceleration rate of velocity increase totally. |
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