Brake friction composite materials: A review on classifications and influences of friction materials in braking performance with characterizations

Brake friction materials play an important role in automobiles to reduce speed and to stop the vehicles. Advances in friction materials were updated to ensure effective performances in braking systems and to provide the maximum safety and comfort. Presently eco-friendly friction materials have been used as a replacement for conventional friction materials. Many synthetic and natural products were identified and claimed as better alternatives to banned toxic materials like asbestos and copper. Friction materials developed from natural products are eco-friendly and assure a great promise when applied in modern vehicles. To develop innovative formulations, basic knowledge of common ingredients and their effects in friction materials was needed. This review focuses mainly on providing detailed information about the common ingredients used, processing methods and the characteristics of brake friction materials.

DETERMINATION OF FREIGHT WAGON PARAMETERS ACCORDING TO THE SPECIFIED CRITERIA OF THE TRAIN BRAKING EFFICIENCY (four-axle gondola cars, covered cars, platforms, dump cars)

The lack of normative values of the actual coefficients in the new rules of HOST 34434-2018 do not allow to implement and determine the optimal characte-ristics of the brake according to pre-accepted conditions of braking efficiency (braking distance), which causes uncertainty in solving this problem. The uncertainty is that the choice of characteristics of the braking system of the freight wagon has to be done by searching a large number of options. In this regard, the paper provides tools for determining the actual pressing force of the brake pads on the wheels, which complies with the specified braking performance of the freight train. As a tool, universal formulas are used in the form of a power relationship between the actual force of the brake pads and the braking distance of the freight train. The coefficients of universal formulas are obtained on the basis of computer modeling. Numerous examples show that the error in the use of universal formulas in calculation studies does not exceed 1% compared with the calculation method according to HOST 34434-2018. The values of the actual coefficients depending on the axial load of the wagon and the speed at which the braking distances of the freight train satisfy the normative minimum allowable values are given. It is shown that calculation studies performed according to the universal formulas in the EXCEL environment allows to fully automating the computational process. A method for determining the gear ratio of the brake lever of a freight wagon, according to which the specified braking efficiency is performed, is proposed. The proposed procedure allows you to perform a variety of studies to select the optimal parameters of the braking system of freight wagons that meet the specified requirements of braking efficiency, and greatly facilitates the calculation studies. Key words: аctual coefficient, braking distance, speed, axial load, power dependence, coefficients, gear ratio.

Stability analysis of the anti-lock braking system with time delay

A time delay exists between driver input and vehicle braking state response during the working process of the anti-lock braking system (ABS), and the braking performance of vehicles will be further reduced due to the delay of controllers. This paper investigates a systematic method of stability analysis for time delay ABS, and the analysis focuses on the stability and critical delay algorithm of ABS with delay time. Firstly, the dynamic structure and modelling process of ABS are briefly introduced, and PD control algorithm is adopted to improve the control performance. Then, dynamic models of ABS with time delay are derived, and the full delay stability interval and critical time delay algorithm of ABS are deduced by using the generalized Sturm criterion method. Finally, the validity of the critical delay algorithm by the proposed method and the stability and accuracy of ABS with time delay, different road conditions, vehicle speeds and control parameters are illustrated by numerical simulations, and the results show that the critical time delay algorithm of ABS can be verified under different conditions.

Unsettled Issues in Commercial Vehicle Platooning

Platooning has the potential to reduce the energy consumption of commercial vehicles while improving safety; however, both advantages are currently difficult to quantify due to insufficient data and the wide range of variables affecting models. Platooning will significantly reduce the use of energy when compared to trucks driven alone, or at a safe distance for a driver without any automated assistance. Platooning will also reduce stopping distances—multiple states in the US have passed laws authorizing truck platoons to operate at shorter gaps than are authorized for normal, human-driven trucks. However, drivers typically do not currently leave the recommended gaps and, therefore, already gain much of the potential energy savings by drafting lead vehicles, albeit illegally. The automated systems associated with platooning cannot be programmed to flout safety recommendations in the way that human drivers routinely do. Therefore, actual energy savings may be minimal while safety may be greatly improved. More data will be needed to conclusively demonstrate a safety gain. Recommended safe gaps are currently highly generalized and must necessarily assume worst-case braking performance. Using a combination of condition monitoring and vehicle-to-vehicle communications, platooning systems will be able to account for the braking performance of other vehicles within the platoon. If all the vehicles in a platoon have a high level of braking performance, the platoon will be able to operate in a more efficient, tighter formation. Driver acceptance of platooning technology will increase as the systems become more effective and do not displace jobs. The increased loading of infrastructure must also be considered, and there may be requirements for upgrades on bridges or restrictions on platooning operation.

Development of a 125% Load Brake Test Instrument for Elevator

In order to solve the problem of elevator braking test inspection, this paper combs the requirements of relevant national standards and inspection rules on braking performance, and develops an elevator braking test inspection instrument. With the help of the instrument, the elevator braking effect can be expressed quantitatively, and the inspectors can conveniently judge whether the braking test results meet the requirements of elevator inspection rules remotely. A way to standardize and rationalize the test is given. In order to solve the problem of elevator brake test inspection, this paper sorted out the national standards and inspection rules on braking performance, and developed an instrument of elevator brake test inspection. With the help of the instrument, we could quantitatively give the expression on the elevator braking effect, and the inspectors can conveniently judge whether the braking test results meet the requirements of the elevator inspection rules in the remote.

Alingment of braking performance for truck and trailer as an important factor in road construction

Alingment of braking performance of truck trailer is an important parameter that affects its braking stability. This shows particular in critical situations or during braking on a surface with reduced adhesion. Alingment of braking performance can be automatic, which is one of quality of electronical brake systems. Further on, can be forcible, which is being executed during service a diagnostic work.This contribution is focused on analysis alingment of braking performance. Describing technical conditions, internal and external factors which affect it. Due to magnitude of this problematics, is in this article evaluated the optimization of braking affects truck trailers in the start-up phase. The analysis of the process – start-up braking effect has justification from the reason, that has primary influence on the stability truck trailer during braking and this can be the cause of collision situations or also traffic accidents. The parameter of alingment of braking performance has a primary influence on the braking stability of the truck trailers, which significantly affects road safety and is also important for the economy of the truck trailers. your abstract here… The abstract should include the purpose of research, principal results and major conclusions. References should be avoided, if it is essential, only cite the author(s) and year(s) without giving reference list. Prepare your abstract in this file and then copy it into the registration web field. Braking distance is an important factor in the road construction. Therefore, it must be taken into account when designing these buildings.

Sistem Kendali Eddy Current Brakes Dinamometer menggunakan Linear Quadratic Regulator (LQR)

ABSTRAKMakalah ini memberikan analisis perbandingan antara teknik kendali klasik yaitu kendali PID dengan teknik kendali modern pada sistem Eddy current brakes dinamometer. Eddy current brakes merupakan sistem pengereman modern yang membutuhkan sebuah sistem kendali untuk menunjang kinerja pengereman. Selama ini kendali PID lebih sering digunakan, namun di beberapa kondisi dinilai kurang optimal. Dengan demikian, diperlukan pengembangan kendali yang modern dan optimal yaitu full state feedback Linear Quadratic Regulator (LQR). Perbandingan respon waktu pengereman disimulasikan menggunakan Matlab/Simulink. Hasil simulasi menunjukkan respon waktu pengereman pada kendali LQR lebih baik dibandingkan dengan kendali PID, dengan Ts = 2.12 detik, Tr = 1.18 detik, dan tanpa overshoot. Adapun kendali PID, meskipun menghasilkan Ts = 0.27 detik dan Tr = 0.18 detik, namun demikian masih terdapat overshoot sebesar 0.7%.Kata kunci: Eddy brakes, PID, LQR, Matlab ABSTRACTThis paper provides a comparative analysis between PID control as a classical control technique and modern control technique in the dinamometer Eddy current brakes system. Eddy current brakes is a modern braking system that requires a control system to support the braking performance. PID control is often used to be implemented but in some conditions it is less optimal. Therefore, it is necessary to develop a modern and optimal control, such as a full state feedback Linear Quadratic Regulator (LQR). The comparison of the braking time responses were simulated using Matlab/Simulink. The simulation results show that the response of LQR control is better than the PID, with Ts = 2.12 seconds, Tr = 1.18 seconds, and without overshoot. On the other side, PID control, although having Ts = 0.27 seconds and Tr = 0.18 seconds, there is still an overshoot about 0.7%.Keywords: Eddy brakes, PID, LQR, Matlab

Development of a device for determining the coefficient of adhesion of a tire simulator with a flat support surface

To ensure optimal braking performance, i.e. minimum braking distance while maintaining the stability of the car at the limit of controllability, anti-lock systems are currently installed on cars. The relative fraction of the rest friction in the contact spot, which is used to form the longitudinal reaction of the support surface at the appropriate value of the slip coefficient, in relation to the total fraction of the rest friction in the contact spot is a constant value for any type and condition of the road surface. The coefficient of adhesion in physical essence is the coefficient of friction at rest. The proposed device for determining the coefficient of adhesion of a tire simulator with a flat horizontal support surface will simplify the design and increase the measurement accuracy. Keywords: coefficient of adhesion, a device for determining the coefficient of adhesion, a device

A thermomechanical model for the analysis of disc brake using the finite element method in frictional contact

In this work, numerical simulations of the transient thermal and the static structural analysis were performed here sequentially, with the coupled thermo-structural method. Numerical procedure of calculation relies on important steps such that the CFD thermal analysis has been well illustrated in 3D, showing the effects of heat distribution over the brake disc. Three different brake disc materials were selected in this simulation and a comparative analysis of the results was conducted in order to derive the one with the best thermal behavior. Finally, the resolution of the coupled thermomechanical model allows us to visualize other important results of this research such as; the deformations, and the equivalent Von Mises stress of the disc, as well as the contact pressure of the brake pads. Following our analysis and the results we draw from it, we derive several conclusions. The choice allowed us to deliver the best suitable of the brake rotor to ensure and guarantee the good braking performance of vehicles.