Andreea-Catalina Cristescu

The study of the tribological behavior of the braking system in auto vehicles requires knowing the characteristics of the material in contact and, in the work process, the friction pair brake disc pads. Material structural analysis is necessary because the wear process depends both on the friction-pair chemical composition (brake disc pads) and on the work process parameters (pressing force, rotational speed, traffic conditions, etc.). The material of the brake discs is generally the same, gray cast iron, and the brake pads can be semimetallic (particles of steel, copper, brass, and graphite, all united with a special resin), organic materials (particles of rubber, glass, and Kevlar, all joined with the help of a resin), composite materials that contain different constituents, and ceramic materials (rarely have small copper particles). Therefore, the purpose of this paper is to analyze the crystalline structure, tribological behavior (at friction and wear), and the mechanical properties of the materials of the brake disc–pad friction pair specific to the field through study and analysis.

The study of the tribological behavior of the braking system in auto vehicles requires knowing the characteristics of the material in contact and, in the work process, for the friction pair, brake disc-pads. Materials structural analysis is necessary because the wear process depends on the friction pair chemical composition, and brake disk-pads, respectively on the work process parameters (pressing force, rotational speed, traffic conditions, etc.). The material of the brake discs is generally the same gray cast iron, but the brake pads can be semi-metallic (particles of steel, copper, brass, and graphite, all united with a special resin), organic materials (particles of rubber, glass, and kevlar all joined with the help of a resin), composite materials that contain different constituents and ceramic materials (rarely have small copper particles). Therefore, the purpose of the paper is to know the crystalline structure and the mechanical properties of the brake pad materials, through specific studies and analyses, with important implications on the friction and wear behavior.

The importance of utilizing an optimal and efficient braking system is emphasized in this study. Braking system optimization and efficiency were practically determined through successive tests on the brake dynamometer, according to road safety regulations. Subsequently, the results were correlated with practical tests involving consecutive braking at different speeds, tracking both the time and distance of braking. The coefficient of friction (COF) was established for each braking instance by utilizing the braking force measured on the brake dynamometer. This paper aims to highlight the genuine impact of the braking system by measuring and establishing its braking efficiency depending on the car’s speed, time, and distance of braking.

The growing number of vehicles leads to increasingly intense and congested traffic, which will additionally put demand on the braking system, and drivers behave more aggressively. As a result, the braking system must be durable and efficient. For this purpose, the study of the braking system behavior in conditions of intense and moderate traffic is required to increase the safety of traffic participants—respectively, to demonstrate the need for more frequent replacement of some braking system elements. Thus, a series of successive tests were performed on a vehicle, through which the degree of wear of the brake pads and discs was monitored periodically, resulting in the efficiency evolution of the braking system. The tests were carried out both in the laboratory (on a dynamometer) and in traffic to establish the efficiency of the braking system according to some parameters considered essential. The experimental tests showed that the recommendations regarding the frequency of replacement of brake pads and discs are inconsistent with their actual wear. Therefore, the aim of this paper is to establish the braking system efficiency of a vehicle, subject to testing depending on the vehicle mass, travel speed, distance driven, and braking time, based on experimental tests, on stand and in-traffic, according to the road safety regulations. The validation of the braking system efficiency of the tested vehicle was done by measuring the stopping distance and time in relation to the initial speed, the mass of the vehicle, the number of kilometers traveled, and conditions of intense and moderate traffic.

The vehicles number continuously growing lead to increasingly intense and congested traffic and it will additionally demand the braking system, and drivers behave more aggressively and as result is required that the braking system to be durable and efficient. For this is necessary the study the braking system behavior in conditions of intense and moderate traffic to increase the safety of traffic participants, respectively to demonstrate the need for more frequent replacement of some braking system elements. Thus, on a vehicle were performed a series of successive tests, through which the degree of wear of the brake pads and discs was monitored periodically and as a result the efficiency evolution of the braking system. The tests were carried out both in laboratory (on dynamometer) and in traffic to establish the efficiency of the braking system according to some parameters considered essential. The experimental tests showed that the recommendations regarding the frequency of replacement of brake pads and disks are inconsistent with their actual wear. Therefore, the aim of this paper is the establishment of the braking system efficiency of an auto-vehicle, subject to testing depending on the auto-vehicle mass, travel speed, distance driven, and braking time, based on experimental on stand and in-traffic tests, according the road safety regulations.

For road safety, braking system performance has become a very important requirement for car vehicle manufacturers and passengers. To this end, vehicle designers must understand the characteristics of tribological behavior and the causes of their variation in properties. This paper analyzes the tribological behavior (at friction and wear) of the most recent material couples of the braking disk-pad system affected by their structural change through the implications on the braking system stability, reliability and suitable characterizations. Obtaining information to design a very efficient braking system and assessing the influence of the material’s structural changes on its stability has become a necessity. This has been made possible by using several methods of testing a brake disk-pad couple on various devices intended for this purpose. The materials of the contact surface disk-brake pad with their tribological performance (friction, wear), especially the friction coefficient, present particular importance. Also, system components’ reliability, heat transfer and the noise and vibration of the brake disk-pad couple are vital to the correct operation of the braking system and should be given special attention. The test results obtained define the friction patterns and the influence of structural changes and other environmental factors that can be used in computer analysis.