Study Of The Effects Of Deflextion-Angle Of Carrying-Axletree Of Semi-Trailer On The Performance Of Tractor-Semitrailer

With the development of national economic, and the increase in freeway mileage, as well as the guidance of related national laws and regulations , tractor-semi-trailer is more and more being applied to road transportation, and its population is also rapidly increasing. Carrying-axletree's deflexion-angle refers to the angle that the carrying-axletree deviate from its normal position. Carrying-axletree's deflexion-angle has a huge effect on the ride performance of tractor-semi-trailer, not only increase the operating costs of tractor-semi-trailer, but also increase the possibility of traffic accident significantly. Therefore, the measurement and correction of carrying-axletree's deflexion-angle have become necessary. However, because the correction of deflexion-angle is time-consuming, we can't correct the deflexion-angle so long as it has. when carrying-axletree's deflexion-angle should be corrected,this depends on the allowable value of the deflexion-angle of carrying-axletree. Determining the allowable value of the deflexion-angle of carrying-axletree of the semi-trailer have great significance to the transportation enterprise.The purpose of this paper is to determine the allowable value of the deflexion-angle of carrying-axletree of the semi-trailer. Of course, this is built on the quantitative analysis of the deflexion-angle of carrying-axletree on tractor-semi-trailer'ride performance. The main contents included: firstly,build the tractor-semi-trailer model, and then do a series of experiments to validate the model, and then simulate using the model validated to analyse the effect of the deflexion-angle of carrying-axletree of the semi-trailer on the ride and handling performance of tractor-semi-trailer, and derive the relationship between the deflexion-angle of carrying-axletree and the ride and handling performance, ultimately determine the allowable value of the deflexion-angle of carrying-axletree of the semi-trailer.The main contents included:1. Through appropriate simplification, build a tractor-semi-trailer model. Firstly, simplify the tractor-semi-trailer appropriately, and then build tractor-semi-trailer subsystem using ADAMS / View, finally assembly it into a complete tractor-semi-trailer model. Built subsystem of the tractor-semi-trailer model include: chassis model, steering system model, vehicle-bridge model, suspension model, tire model, as well as movement and force.2. Validate the tractor-semi-trailer model through test. To judge the steering and braking performance of the model, we have a steady-state circular test and braking tests on both of them, and then to analyzed and compared the two test results, to judge the level of correlation between the tractor-semi-trailer model and the real vehicle. After compared with the computer model of tractor-semi-trailer and experimental data ,we find that the computer model and the real vehicle have a good correlation, we can use the model to research the deflexion-angle of carrying-axletree of the semi-trailer.3. Simulate using the proven tractor-semi-trailer model, in the end derive the allowable value of the deflexion-angle of carrying-axletree of the semi-trailer. Since the model of the semi-trailer is a biaxial semi-trailer, in order to analyze the effect of the deflexion-angle on the ride and handling performance, we must use experimental design technology of the ADAMS / View to do matrix test with the model, analyze the combinations effect of the two deflexion-angle to the tractor-semi-trailer. Firstly, simulate using the tractor-semi-trailer model with three different conditions: uniform speed linear driving, linear braking and steady static steering, and then use the MATLAB to analyze and deal with the data processed by tractor-semi-trailer model simulation.Finally derived the relationship between the deflexion-angle and the ride and handling performance.The effect of the deflexion-angle of carrying-axletree of the semi-trailer on the ride and handling performance are as follows: when driving in straight line,the jackknifing aggravated with the increase of the deflexion-angle of carrying-axletree of the semi-trailer. When turning,the deflexion-angle of carrying-axletree of the semi-trailer would affect the steering characteristics and the jackknifing angle. When the direction of deflexion-angle of carrying-axletree and the direction of steering are in the same, the tractor-semi-trailer tended to be understeer characteristics and the jackknifing angle increase. on the contrary , the tractor-semi-trailer tended to be oversteer characteristics and the jackknifing angle decrease. When braking in a straight line, with the increase of deflexion-angle of carrying-axletree, the braking distance decreased, but the braking deflection and the jackknifing aggravated. Especially, when the direction of the deflexion-angle of the two carrying-axletree are different, it has a greater effect on braking performance. Use the formula obtained from the foregoing analysis and calculation, and reference for relelated laws and regulations, calculate the allowable value of the deflexion-angle of carrying-axletree of the semi-trailer in straight line driving, straight line braking and turning respectively. The allowable value of the deflexion-angle of carrying-axletree of the semi-trailer are 0.5625 degree,1.661 degree,1.3465 degree. The minimum value of the three allowable value is the deflexion-angle of carrying-axletree of the semi-trailer. So, the deflexion-angle of carrying-axletree of the semi-trailer is 0.6 degree.