Study On The Impact Of Vehicle Braking Performance From Deicing Salt

In Northern China, winter is quite long and there is always large amount of snow. Therefore to remove snow by manual and mechanical forces can far meet the needs of the development of modern transportation. So since 1970s, many cities in China has begun to use deicing salt to remove ice and snow on the roads in order to ensure the smooth flow of road and safety of pedestrians and vehicles in snowy days. However, to what extent will deicing salt affect vehicle's braking performance is rarely studied in China. This paper, combined with the actual situation of Harbin in the use of deicing salt, from the actual process of automotive brake, has studied the actual effect of the use of deicing salt to cars'braking performance.Of the three indexes for evaluating Vehicle's braking performance, braking efficiency is the most basic, and braking distance is the most intuitive parameters. By melting ice and snow to change the road adhesion coefficient, the effect of deicing salt is mainly improvement the car's braking performance to some extent. Therefore, this article mainly studies the real impact of the use of deicing salt makes to cars'braking distance.Firstly, this paper describes management methods and use of deicing salt as well as evaluation indexes of vehicle braking performance, and also analyzes the structure of the vehicle braking system theoretically. Then, by analyzing the stress the whole vehicle and the wheels bear when the car brakes, effect made by adhesion coefficient on the braking performance and the braking process, a mathematical model on calculating the braking distance through adhesion coefficient is obtained. Also a simulation system for calculating braking distance has been set up by using development environment GUIDE of MATLAB graphical user interface. By setting the parameters, the simulation of braking distance of car for different road conditions in different speed can be made, and curve of Initial braking speed and braking distance of the car model can be output. Finally, on the one hand, work out the braking distances of cars, vans and buses with different initial braking speed, on (compacted road) road with ice and snow and on road after using deicing salt respectively by adopting the simulation system set before. On the other hand, considering the real situation of Harbin on the use of deicing salt, referring to China's GB12676-1999 brake regulations----"Automobile Braking System Structure, Performance and Test Methods "---- a set of experimental programs have been developed:first, braking test the Bora car on (compacted) snow and ice road; and then spread deicing salt on the road artificially; after the work of deicing salt, test the car's braking distance on the road again. Through this experiment, both the adhesion coefficient and the car's braking distance under two road conditions are reached. Studies show that after using deicing salt, adhesion coefficient between the tire and road has been improved, and has increased by 86% and 92% compared with that of tire and compacted road with snow over it, thereby reducing the car's braking distance; when the vehicle is traveling on compacted road with snow and ice in a speed of more than 20km/h, it will easily get braking deviation; while when the vehicle is running on the road after the effect of deicing salt, it is easy to get braking deviation when the speed is more than 30km/h. So even if deicing salt has made braking distances shorter, people still need to control the speed while driving in order to ensure safety. At the same time application experiment has verified the correctness and practicability of the simulation system, and provided a theoretical basis for speed limits for driving in different road conditions.