Prediction Model for Brake-Drum Temperature of Large Trucks on Consecutive Mountain Downgrade Routes Based on Energy Conservation Law

Menghua Yan,Jinliang Xu

doi:10.1155/2018/4587673

Abstract

Excessively high brake temperature may lead to brake fading and failure, resulting in truck runaway down a graded descent. The accurate prediction of the changes in the brake-drum temperature on downgrades can provide theoretical guidance for truck accident countermeasures, such as determining the maximum safe speeds and the locations of truck escape ramps. By analyzing truck accident mechanisms during graded descents and selecting the initial brake-drum temperature, downgrade percentage and length, and the truck weight and speed as independent variables, with the brake-drum temperature as a dependent variable, the downgrade process of a truck can be divided into two stages: speed control at the grade section and emergency braking at the grade end. The energy conversion process in the forms of brake and nonbrake forces in the two stages are analyzed, based on the energy conservation law. A prediction model for the brake-drum temperature of large trucks on consecutive mountain downgrade routes is established, using the heat quantity formula. The model’s numerical calculation explicitly demonstrates the effect of all the variables. The brake-drum temperature is positively related to the truck weight, and the percentage and length of the downgrade. The temperature increase in the control speed phase is negatively related to the truck speed, whereas that in the emergency braking phase is positively related. The relationship curves between the variables show that the brake-drum temperature does not change significantly with the truck speed. However, the brake-drum temperatures, under different truck weights, downgrade lengths, and percentages, at the same speed, differ considerably. Compared to the existing empirical fitting model based on specific test data, the proposed model clearly shows the effects of main variables. The proposed model can be used for determining the safe truck speeds and locations of truck escape ramps to provide guidance for drivers and builders.

Highlights

Consecutive mountain-highway downgrade routes are prone to severe truck accidents caused by brake failure towing to high temperature
The number of truck accidents accounted for only 4% of the total number of motor vehicle accidents in 2016 in the US [1] due to heavy truck weight, large kinetic truck energy, and the large inertia of the truck, the amount of energy requiring dissipation during a truck accident was considerable
This study intends to establish a prediction model for the brake-drum temperature, with a full theoretical foundation and extensive application scope to clearly demonstrate the effect of the main parameters, including the ambient temperature, initial brake-drum temperature, truck weight and speed, and grade percentage and length, while enabling the user to customize the parameters according to the actual conditions

Summary

Introduction

Consecutive mountain-highway downgrade routes are prone to severe truck accidents caused by brake failure towing to high temperature. In 1989, the US Department of Transportation and Federal Highway Administration published a user manual on the grade severity rating system (GSRS) [8] This system establishes a two-stage brake temperature model, based on experimental data during the speed control stage, and the energy conversion law during the emergency stop stage. This study intends to establish a prediction model for the brake-drum temperature, with a full theoretical foundation and extensive application scope to clearly demonstrate the effect of the main parameters, including the ambient temperature, initial brake-drum temperature, truck weight and speed, and grade percentage and length, while enabling the user to customize the parameters according to the actual conditions. The approach presented here is based on the energy conservation law and aims to establish a temperature prediction model suitable for the brake drums of trucks on consecutive mountain downgrade routes, using a theoretical derivation method.

Mathematical Model

Brake-Drum Temperature Prediction Model during the Speed Control Stage

Results

Discussion and Conclusion