Braking Pressure Research Articles

Nonlinear Dynamic Behavior of a Motorcycle’s Forecarriage During Braking

An experimental and numerical experience was carried out to investigate the nonlinear dynamic response of the forecarriage of a motorcycle, paying attention to a particular type of vibration that occurs during the braking. In fact, it was found that, in particular conditions of load on the handlebar, braking pressure, speed and temperature, the first flexural mode of the front fork is strongly excited. Thanks to the numerical model, solutions to these undesired vibrations were identified. Experimental tests were carried out modifying the design parameters of the motorcycles and of the braking system as suggested by the numerical model thus verifying that the purposed solutions were effective.

Analysis of brake squeal noise using the finite-element method: A parametric study

Brake squeal noise has been under investigation by the automotive manufacturers for decades due to consistent customer complaints and high warranty costs. Brake squeal is a problem that has been faced by several numerical and analytical methods in the last decade. Among then, finite-element analysis is proving to be a useful tool to predict the noise occurrence of a particular brake system during the design stage. The finite-element method (FEM) has been employed to analyze the squeal propensity of the disc brake systems. The complex eigenvalue analysis conjugated with FEM has been widely used to detect unstable frequencies in numerical brake systems models. These unstable frequencies are related, in most cases, with high sound pressure levels generated during the brake system operation. This paper summarizes the application of the complex eigenvalue analysis in a finite element model. The effects of the operating parameters (friction coefficient, braking pressure, brake temperature) and wear on the dynamic stability of the brake system are examined. After identifying unstable frequencies and the behavior under different conditions, the performance of some control methods are tested. Changes in material properties and the application of brake noise insulators are presented and its effect discussed.

Wheel-Slip Control of a Passenger Vehicle Using an Electrorheological Valve Pressure Modulator

This paper presents a wheel slip control for the anti-lock brake system (ABS) of a passenger vehicle using a controllable electrorheological (ER) valve pressure modulator. As a first step, the principal design parameters of the ER valve and hydraulic booster are appropriately determined by considering the braking pressure variation during the ABS operation. An electrically controllable pressure modulator is then constructed and its pressure controllability is evaluated empirically. Subsequently, a quarter-car wheel slip model is established and integrated with the governing equation of the pressure modulator. A sliding mode controller to achieve the desired slip rate is then designed and implemented via the hardware-in-the-loop simulation (HILS). Braking control performance and road transition control response are evaluated and presented in the time domain.

Composite friction materials based on organic fibres: Sensitivity of friction and wear to operating variables

Abstract The frictional response of a multi-component friction material is highly complex under a set of dynamically variable loads and speeds. The present paper discusses the sensitivity of friction and wear behaviour of selected composites based on variation in inclusion of organic fibres, viz., aramid, PAN, carbon and cellulose, to braking pressure and sliding speed. The studies on the sensitivity of μ and wear to the operating variables have been carried out on a subscale brake-test-rig, following 4 loads × 3 speeds experimental design. Inclusion of cellulose fibre tended to increase the friction coefficient while aramid fibre improved the wear resistance. The fibres of carbon and PAN made the friction composites least sensitive to dynamic variations in braking pressure and sliding speed. Regression analysis of μ values following an orthogonal L9 (3 × 3) experimental design method revealed that the first order influences of braking pressure and sliding speed were significant while the contribution of their mutual interaction was negligible. Comprehensively, the influence of operating parameters was more dominating as compared to the influence of individual organic fibre variation.

CONTROL PERFORMANCE OF VEHICLE ABS FEATURING ER VALVE PRESSURE MODULATOR

In this work, an electrically controllable anti-lock brake system (ABS) for passenger vehicle is developed by utilizing electrorheological (ER) fluid. A pressure modulator which consists of a cylindrical ER valve and the hydraulic booster is constructed in order to achieve sufficient brake pressure variation during ABS operation. The principal design parameters of the modulator are determined by considering ER properties as well as required braking pressure. After investigating pressure controllability of the modulator, a vehicle model which is integrated with the proposed pressure modulator is formulated to design yaw rate controller. A sliding mode controller is designed to obtain desired yaw rate, and the friction forces between roads and wheels are estimated via the estimator. Braking performances of the proposed ABS under various roads are evaluated through the hardware-in-the-loop-simulation (HILS) and the steering stability during braking operation is demonstrated by undertaking split-μ test.

Influence of Operating Parameters on the Performance of Friction Composites Based on Combinations of Rock Fibers and Organic Fibers

The dynamic frictional response of a multicomponent friction composite is highly complex under a set of variable loads and speeds. The present paper discusses the sensitivity of friction and wear behavior to braking pressure and sliding speed of four selected composites based on a variation of combinations of rock fibers (Basalt and Lapinus) and organic fibers (Aramid and PAN). The studies on the sensitivity of μ and wear to the operating variables were carried out with the help of a pad-on-disc type tribo-test-rig following 4 loads × 3 speeds experimental design. Regression analysis of the μ values following an orthogonal L9 (3 × 3) experimental design method revealed that the first-order influences of braking pressure and sliding speed were significant while the contribution of their mutual interaction was minor. It was observed that aramid fiber proved most beneficial in modifying the selected performance properties except friction stability at higher pressure and speed conditions. Lapinus proved to have an edge over basalt in most aspects. The SEM studies on the worn-pad surfaces revealed the role of contact patches and differential topographic attributes in controlling the friction and wear performance of these composites.

Development of Hydraulic Friction Brake for Railway Rolling Stock (Part I: Static Behavior of Poppet-Type Brake Pressure Control Valve)

Development of Hydraulic Friction Brake for Railway Rolling Stock (Part I: Static Behavior of Poppet-Type Brake Pressure Control Valve)

Development of Hydraulic Friction Brake for Railway Rolling Stock (Part II: Dynamic Analysis and Performance Evaluation of Hydraulic Brake System Using Poppet-Type Brake Pressure Control Valve)

A novel hydraulic brake pressure control (BPC) valve for the railway rolling stock was proposed in the part I of this study. As a second report, this paper is concerned with the dynamic analysis and the performance evaluation of the hydraulic brake system using the BPC valve. In order to analyze the behavior of the BPC valve, a simplified transfer function and a nonlinear model of the valve are derived respectively. By use of simple linear model, it is achieved to determine the initial values of essential parameter simply. In addition, it is also achieved to investigate overall dynamic performance of brake system and to evaluate the effect of design parameters through the numerical analysis using detailed nonlinear model. The validity of mathematical models is confirmed by experiments. Finally, the performance of the hydraulic brake system using newly manufactured BPC valve is confirmed with an actual braking device of the E2 series Shinkansen railway.

Research on Fluid Column Separation of Anti-Lock Braking System (1st Report, Observation of Fluid Column Separation and Research on Influence of Opening Time of Control Valve)

The fluid column separation occurring in the pressure control line of Anti lock Braking System (ABS) of vehicles was analyzed experimentally. As the experimental setup, the ABS for passenger cars installed on the test stand was used. The pressure fluctuation was measured with a pressure sensor installed on the pressure control line. The tube of the connection part of the ABS hydraulic unit and the pressure control line was changed to a transparent pipe, and the vapor column was observed. The fluid column separation occurred when the pressure control valve in the hydraulic unit was operated to increase braking pressure. The mechanism of occurrence of fluid column separation in ABS system and the influence that the time of opening the pressure control valve exerted to pressure fluctuation were analyzed in this paper.

Wear data analysis of friction materials to investigate the simultaneous influence of operating parameters and compositions

The present paper deals with the wear data analysis of friction composites where, the nature and the concentration of the abrasives were varied systematically in steps of 2%. The abrasives selected were; SiC, SiO 2, ZrO 2 and Al 2O 3 in the concentration range of 2–6%. The wear studies on the composites were carried out on a pad-on-disc type tribo-tester. The wear data analysis was carried out based on an orthogonal experimental design following regression analysis method to examine the simultaneous influence of braking pressure, sliding velocity, concentration of abrasives and their interactions. It was observed that the braking pressure was the most influencing factor in controlling the wear performance, whereas the sliding speed effects tended to abate the contributions by the other parameters. The wear performance of such composites was found to be composition dependent with optimal parametric influences that was specific with the nature of the abrasive. Multiple attribute decision-making approach (MADM) was adopted to weigh the influence of each parameter in terms of entropy irrespective of the nature and content of abrasive under the selected operating conditions. The entropy weights have revealed the optimal level of parametric influences for the incremental formulation design and performance optimisation.

油圧制御による鉄道車両ブレーキに関する研究 : 第2報,ポペット形圧力制御弁の動特性(機械力学,計測,自動制御)

The poppet-type Brake Pressure Control valve (BPC valve) was proposed in the first report for use in hydraulic control systems for the friction brake of railway rolling stock. In this study, a simplified transfer function of the valve is determined to analyze the effects and choose the parameters for the valve. In order to shorten the trial-and-error process to determine the best valve parameters, mathematical simulations are performed. The validity of the mathematical model and effectiveness of actual orifices is studied experimentally. Simulations of pressure response and stability of the valve in the presence of disturbances are confirmed experimentally. The performance of the actual brake system is studied using a caliper brake device from the Shinkansen railway. The results show that the performance of brake pressure control can be improved by the hydraulic system with the developed BPC valve.

Design of the Electronic Brake Pressure Modulator Using a Direct Adaptive Fuzzy Controller in Commercial Vehicles for the Safety of Braking in Fail.

In the brake systems, it is important to reduce the rear brake pressure in order to secure the safety of the vehicle in braking. So, there was some research that reduced and controlled the rear brake pressure exactly like a L.S.P.V and a E.L.S.P.V. However, the previous research has some weaknesses: the L.S.P.V is a mechanical system and its brake efficiency is lower than the efficiency of E.L.S.P.V. But, the cost of E.L.S.P.V is very higher so its application to the vehicle is very difficult. Additionally, when a fail appears in the circuit which controls the valves, the fail results in some wrong operation of the valves. But, the previous researchers didn't take the effect of fail into account. Hence, the efficiency of them is low and the safety of the vehicle is not confirmed. So, in this paper we develop a new economical pressure modulator that exactly controls brake pressure and confirms the safety of the vehicle in any case using a direct adaptive fuzzy controller.

A Study on Hydraulic Control of a Friction Brake for Railway Rolling Stock. 1st Report. A Development of a Poppet Type Brake Pressure Control Valve.

The utilization of a hydraulic system on the friction brake of railway rolling stock permits a small size and fast response of control system. In spite of these advantages, the inner leakage of the conventional control valve for friction brake results in a reliability problem. In this study, a poppet type pressure control valve is developed. The poppet type valve is proposed for preventing inner leakage, and the displacement-pressure characteristic is designed to eliminate the need for a pressure transducer. The compensation methods for the operating force and the change caused by wear of the poppet valve are determined. The experimental results confirm the design constraints, and show that the proposed valve is valid for the specific system.

Technical Note: External torque application on antilock brake systems

The possibility of shortening the braking distance by the application of an additional driving torque linked to a control mechanism working with an ABS system is investigated in this work. In the ABS control cycle, the reacceleration of the locking wheels is provided only by decreasing the braking pressure. An external tractive torque can be used to shorten the time for acceleration during the phase of lowering of the braking pressure. The engine of the vehicle or an additional electric motor could be used as a source of external tractive force. The possibility of decreasing the braking distance by such a system is investigated by using a mathematical model. The effect of the additional accelerating torque is analysed with a simulation model and it is concluded that an increase of up to 10 per cent in braking distance may be obtained.

Hydraulic anti-lock braking control using the hybrid sliding-mode pulse width modulation pressure control method

This study integrates the discrete on-off operation of hydraulic high-speed solenoid valves and the pulse width modulation (PWM) method to achieve a quasi-continuous braking pressure control. Sliding-mode control is applied here due to the non-linear nature of the solenoid valve. The hybrid compensating method presented here compensates for the mechanical and electrical delay of solenoid valves, obtaining more precise control results and keeping the robustness of the sliding controller. Following verification of the braking pressure controller on a test stand, an anti-lock braking controller of a passenger car is designed by use of tyre tangential deceleration feedback. This anti-lock braking controller is also verified on a dynamic test stand. Braking experiments on both dry and wet road surfaces are simulated.

A software-based measurement system for testing and analysis of automotive brake squeal

A software-based measurement system using both analogue data acquisition and digital communication via a general-purpose interface bus (GPIB) board has been developed for analysis and evaluation of disc brake squeal. The system is built around a computer and based on commercial software. Brake pressure and torque, rotational speed, five different temperatures, and sound emission are logged once a second. If the sound is characterised as a squeal it is saved to file together with the other parameters. The measurement system is very flexible, allowing for different types of instruments and sensors to be used by adapting the software. Furthermore, the same software is used for evaluation of the collected data. Mechanically, the equipment consists of a complete front wheel suspension where the original brake disc and caliper are mounted in a steel tube chassis. The brake disc is driven by a DC electric motor, while a hydraulic system provides the brake pressure. Brake pressure and rotational speed can be controlled independently.

Nonlinear Model for Aircraft Brake Squeal Analysis: Stability Analysis and Parametric Studies

Results are presented from analyses of primary squeal-mode vibration in aircraft brake systems. System stability is investigated by determining the eigenvalues of linearized perturbation equations at each steady-state operating point of the nonlinear system. Time-history responses are obtained by integrating the complete set of nonlinear dynamic equations. Results are given from analyses conducted using two versions of the nonlinear squeal model, a single-wheel model representing a typical dynamometer configuration, and a fore-aft wheel pair model representing one side of a main landing-gear truck. In general, the model predicts system instability at low braking pressures and stability at high braking pressures. The effects on stability of variations in brake pressure, friction coefficient, and torsional stiffness are shown. The nonlinear squeal model indicates that system instability can occur with a constant friction coefficient and that system stability decreases with increasing brake-friction coefficient. It is shown that proper selection of brake heat stack mechanical properties and design geometry can produce a stable system. Results indicate that a fore-aft brake pair will be more unstable than a single brake, which is in agreement with dynamometer and airplane test data.

High-temperature destruction of composite materials during intense heat and gasdynamical action

High-temperature destruction of polymer composite materials during interaction with gas flows has been investigated experimentally. The braking pressure of the flow varied from 5 to 25 MPa. The basic laws of the destruction under high pressure were established. The condition of thermomechanical destruction of the materials studied under a pressure of 15 to 25 MPa was determined. A physical model of the high-temperature destruction of polymer composite materials subjected to intense heat and gasdynamical action was developed.

A fuzzy logic controller for an ABS braking system

Anti-blocking system (ABS) brake controllers pose unique challenges to the designer: a) For optimal performance, the controller must operate at an unstable equilibrium point, b) Depending on road conditions, the maximum braking torque may vary over a wide range, c) The tire slippage measurement signal, crucial for controller performance, is both highly uncertain and noisy, d) On rough roads, the tire slip ratio varies widely and rapidly due to tire bouncing, and e) The braking system contains transportation delays which limit the control system bandwidth. A digital controller design was chosen which combines a fuzzy logic element and a decision logic network. The controller identifies the current road condition and generates a command braking pressure signal, based on current and past readings of the slip ratio and brake pressure. The controller detects wheel blockage immediately and avoids excessive slipping. The ABS system performance is examined on a quarter vehicle model with nonlinear elastic suspension. The parallelity of the fuzzy logic evaluation process ensures rapid computation of the controller output signal, requiring less time and fewer computation steps than controllers with adaptive identification. The robustness of the braking system is investigated on rough roads and in the presence of large measurement noise. This paper describes design criteria, and the decision and rule structure of the control system. The simulation results present the system's performance on various road types and under rapidly changing road conditions.

Brake Pressure Apportioning Valves

The increasing popularity of front wheel drive cars and the requirements of the European braking regulations have resulted in a corresponding increase in the use of brake pressure apportioning valves. These valves are suitable for conventional braking systems where the driver can push harder on the brake pedal, after the front wheels have locked, to obtain extra retardation from the rear wheels. However, the recent introduction of low-cost front-controlled anti-lock systems has limited the level of rear retardation and has made it necessary to optimize the braking utilization for all conditions of loading and road surface friction levels.