Braking Conditions Research Articles

Personalized Control Strategy of Electronic Brake Booster With Driving Behaviors Identification

To improve the comfort and user acceptance of the intelligent vehicle braking system, this paper proposes a control strategy for the electronic brake booster (Ebooster) that considers differences in driving behaviors. First, a real-vehicle driving data collection platform is built to collect the driving behavior data of 84 drivers under typical vehicle-following braking conditions. Subsequently, the k-means clustering algorithm optimized by particle swarm optimization (PSO) is used to realize the cluster analysis of driving behaviors, and the support vector machine (SVM) algorithm optimized by the genetic algorithm (GA) is used to complete the identification of driving behaviors. Next, through the analysis of the boost characteristics of the self-designed Ebooster, driving behaviors are matched with boost characteristics, and a personalized basic boosting control strategy based on the driver behavior is designed. Finally, a hardware-in-the-loop (HiL) bench and a real-vehicle test platform are designed and built to verify the effectiveness of the personalized control strategy of the Ebooster. The results show that this method can effectively identify the type of driver and make personalized adjustments to the basic boosting strategy of the Ebooster, which effectively improves the personalization of the braking system, resulting in a higher pedal response and user acceptance.

Optimal energy allocation strategy for electric vehicles based on the real-time model predictive control technology

Electric vehicles (EVs) are regarded as the clean transportation due to their wide promising application in the energy conservation and vehicle safety. However, how to allocate the battery energy to four individual in-wheel motors is a challenging job. In this paper, a dynamic energy management strategy of the EV is proposed to optimize the battery energy consumption and to reduce the tire slip loss simultaneously. Basically, nonlinear model predictive control is utilized to identify the tire dynamics and vehicle load. Then, the multi-objective optimization problem with the nonlinear constraints is addressed with the modified particle swarm optimization (MPSO) algorithm in which the inertia weight of particle velocity and the acceleration coefficient are further altered for the real-time calculation. Furthermore, the modification of the global optimal position of the population can effectively avoid the local optima dilemma. The numerical test is implemented under US06 and WLTC03 maneuvers to validate the superiority of the proposed energy strategy. The results demonstrate that the proposed dynamic energy strategy can automatically allocate the torque requirement according to the dynamic load and put more weights on the front wheels in the braking condition. Compared with the typical rule-based strategy, the proposed strategy can conserve 12 ∼ 17% of the battery energy and reduce approximate13% of tire slip loss. Moreover, the modified PSO algorithm can reduce the computational time by 55% which further validates its application value in the real-time energy management of EVs.

Investigations on Pressure Fluctuations in the S-Shaped Region of a Pump–Turbine

Hydraulic pumped storage is a special power generation and electricity shortage technology, which is usually operated with thermal power and nuclear power units, and plays a key role in ultra-high voltage and smart grid. Pressure fluctuations are the main reasons for the instability of the S-shaped region of pump–turbines, which seriously affects their lifespan and operation stability. To reveal the mechanism and propagation law of pressure fluctuations in the S-shaped region as well as numerical simulations at the turbine, the braking and the reverse pump operating conditions of a pump–turbine were carried out. Numerical results were validated using the performance experiments, and the generation mechanism and propagation law of pressure fluctuation were analyzed in detail. The analyses show that high-amplitude pressure fluctuations mainly occur in the braking and reverse pump operating conditions. Under the braking condition, a 0.49-fn low-frequency pressure fluctuation was captured, which is caused by the rotation of the backflow in the vanes. Under the reverse pump condition, a 0.19-fn low-frequency pressure fluctuation was confirmed, which is caused by the periodic rotation of the vortex between the vaneless space. This study has important guiding significance for practical engineering application.

Adaptive distributed finite‐time fault‐tolerant controller for cooperative braking of the vehicle platoon

Vehicle platooning can significantly reduce traffic accidents and enhance transportation safety. Among many subsystems and functionalities equipped in a vehicle platoon, cooperative braking is a safety-critical one. Besides, as actuator faults would deteriorate vehicle safety and stability, they pose a great challenge to the platoon, particularly during cooperative braking. To address the aforementioned problems, this study designed an adaptive distributed finite-time fault-tolerant controller for vehicle platoons under cooperative braking condition. First, based on the graph theory and vehicle longitudinal dynamics, the cooperative braking model of a platoon is constructed. Then, the models of hydraulic braking system and regenerative braking system are developed with malfunction analysis. Based on the vehicle's fault model and the representation of the platoon consensus errors, an adaptive finite-time sliding-mode fault tolerant controller is proposed to maintain consensus between vehicle's states during fault occurring. Further, a distributed adaptive law is presented considering the parameter estimation error and sliding-mode surface. The finite-time convergence property and the stability of the proposed controller are demonstrated. Numerical simulations are conducted under different conditions. The simulation results reflected by the control performance and actuators' responses validate the feasibility and effectiveness of the designed control method.

Phase-Specific Verbal Cue Effects on Countermovement Jump Performance.

Krzyszkowski, J, Chowning, LD, and Harry, JR. Phase-Specific Verbal Cue Effects on Countermovement Jump Performance. J Strength Cond Res 36(12): 3352-3358, 2022-The aim of this study was to determine whether countermovement vertical jump (CMVJ) phase-specific cues can improve jump performance and phase-specific force-time characteristics. Twenty-nine subjects (14 males and 15 females) performed 15 total CMVJ trials (5 per condition) while being provided with a control and phase-specific (unloading phase and eccentric braking phases) foci of attention. Jump height, reactive strength index-modified, countermovement depth, time-to-takeoff, and CMVJ subphase force-time characteristics were compared between each phase-specific verbal cues and the control condition using paired samples t-tests ( α = 0.05) and Cohen's d effect sizes ( d ; large >1.2). Female ( d = 0.242; p = 0.012) and male ( d = 1.96; p = 0.047) subjects achieved greater jump heights in the control condition compared with the unloading phase condition. Females demonstrated a faster unloading phase, less unloading force, greater unloading yank, and greater braking force during the unloading condition, as well as greater eccentric braking force during the eccentric braking condition compared with the control condition ( p ≤ 0.014; d ≥ 0.242). Males exhibited less body mass unloading, greater unloading yank, faster eccentric braking time, greater eccentric braking force, and greater eccentric braking yank for both the unloading and eccentric braking conditions compared with the control condition ( p ≤ 0.047; d ≥ 0.196). Collectively, these results suggest that phase-specific foci of attention do not acutely improve jump performance but can enhance phase-specific force-time characteristics in recreationally active individuals. Specifically, practitioners should consider using an eccentric braking phase instruction for individuals need to improve eccentric braking force generation.

Influence of electrical part of traction transmission on dynamic characteristics of railway vehicles based on electromechanical coupling model

With the continuous development of rail transit industry and the acceleration of train speed, higher requirements are established for the operation quality of high-speed trains and the reliability of transmission system. In the process of train running, speed fluctuation and vibrations from various parts of the driving devices are common, which could be greatly affected by the traction torque. During traction transmission, the harmonic vibration torque exists in traction motor due to that the motor is connected with non-sinusoidal alternating current. In order to study the vibration influence of the electrical component of traction transmission system on the rail vehicles, i.e., bogie and car-body, an electro-mechanical coupling dynamic model for rail transit vehicles was established by explicitly incorporating the electric-induced traction into the transmission model. The dynamics responses of the vertical, lateral and longitudinal acceleration on vehicle components, such as axle box and car-body were quantitative analyzed. By comparison with field test, it was observed that there was a vibration peak of 12-times of the fundamental rotor frequency on the bogie frame and axle box, which existed at conditions of traction, uniform speed and braking. However, the vibration acceleration exhibit nearly little difference with or without traction force, especially at low frequency domain < 100 Hz.

Balancing Injury Risk and Power Development by Weighted Jump Squat Through Controlling Eccentric Loading.

Songsupap, T, Newton, RU, and Lawsirirat, C. Balancing injury risk and power development by weighted jump squat through controlling eccentric loading. J Strength Cond Res 35(11): 2999-3005, 2021-Weighted jump squat (WJS) training is highly effective for increasing neuromuscular power but entails higher injury risk than traditional resistance training because of the impact of landing. Braking mechanisms can be used to control the landing impact; however, the optimal eccentric loading condition that balances injury risks and power output is still unclear. The purpose of this study was to assess different eccentric braking conditions. Twenty-two male varsity basketball players aged 20.8 ± 1.1 years and a 1 repetition maximum (1RM) of back squat-to-body mass ratio of 2.0 ± 0.2 participated in the study. The subjects performed 2 sets of WJS of 6 repetitions with additional 30% of 1RM load under 4 randomly assigned conditions: (a) traditional load, no braking (B0), (b) 25% braking load reduction during landing (B25), (c) 50% braking load reduction during landing (B50), and (d) 100% braking load reduction during landing with release at touchdown (B100R). A repeated measures analysis of variance was used to determine differences of dependent variables: peak power output, peak force, peak velocity, and impulse. B100R resulted in statistically lower eccentric peak force and impulse for the first 50 milliseconds than the other 3 conditions (p < 0.05), but the largest concentric peak power. Furthermore, B0 resulted in statistically lower concentric peak power and peak velocity than the other 3 conditions (p < 0.05). We suggest that B100R was a more favorable loading condition that balanced injury risk and power production in WJS.

Bifurcation and Chaotic Behaviors of Vehicle Brake System Under Low Speed Braking Condition

Bifurcation and Chaotic Behaviors of Vehicle Brake System Under Low Speed Braking Condition

Experimental Investigation on Coupled Vibration Features of Suspended Monorail Train–Bridge System under Constant Speed and Braking Conditions

Suspended monorail transportation (SMT) plays an important role in alleviating the urban traffic pressure, and its vehicle–bridge dynamic features are significantly different from those of the traditional railway. To grasp the coupled vibration features of suspended monorail train–bridge system (SMTBS), this paper presents a comprehensive experimental investigation on the vehicle–bridge vibrational responses under different operating conditions. First, based on the Chengdu SMT test line in China, a full-scale field measurement of the coupled vibration responses of the SMTBS is elaborately conducted under constant speed conditions. Then, the vibrational responses of the SMTBS are analyzed in the time and frequency domains to reveal its coupled vibration features and vibration transmission characteristics. Further, considering an extreme train operating condition, the vibrational responses of the SMTBS are tested and analyzed under train emergency braking; and the vibration features of the vehicle and bridge are examined for emergency braking, along with several key indexes evaluated for the train braking performance. Results show that the vibrational accelerations transmitted from the frame to the center pin and then to the carbody will be significantly decreased in turn, and the vibrational dominant frequencies of the bogie, center pin, and carbody mainly fall with 0–100[Formula: see text]Hz, 0–50[Formula: see text]Hz, and 0–20[Formula: see text]Hz, respectively. Under moving train loads, the box beam produces plentiful high-frequency vibrations and the vibrations transmitted from the driving track to the top plate are drastically reduced. The train braking significantly intensifies the car-body longitudinal vibration; however, it has small influences on the car-body vertical and lateral vibrations.

Study & Improvement of Occupant Out-of-position Injuries Under Pre-crash Braking Condition

Although the impact strength can be reduced by AEB and other active safety technologies, the occupants may move forward under braking condition and reduce the protection space of the restraint system. The out-of-position displacement and injuries of occupants under braking conditions are studied by sled tests. The injury characteristics of the out-of-position occupant are obtained. By orthogonal tests, the influence of out-of-position on the injury of different body regions are analysed. MADYMO active human body simulation model is established, and the characteristics of the occupant forward displacement under different braking waveforms are studied by single variable method. By using the active seatbelt, the occupant’s forward displacement is restrained. With the use of Central Composite Design (CCD) method, the response surface model of the occupant’s neck displacement relative to the pretension force and pretension time of the active seatbelt is established. The effects of pretension force and pretension time on out-of-position displacement are studied, and the optimal design is carried out to obtain the parameter combination.

Strength Analysis and Optimization of Tank Truck Based on ANSYS

With the vigorous development of the oil industry, the number of tank trucks has increased significantly in recent years. Accidents such as explosion and leakage of oil tank truck during transportation are common. Therefore, it is particularly important to study the stress analysis, strength optimization and safety reliability of oil tank truck. This paper establishes the three-dimensional parametric model of the tank car by the solid works software and changes the thickness and height of the wave preventer, and analyze the influence of the thickness and height of the wave preventer on the tank car under the starting and braking conditions by the ANSYS software. The deformation diagram, strain nephogram and stress nephogram under different working conditions were compared and analyzed to optimize the dimension parameters of the wave preventer. The results show that the optimal thickness and height of the wave preventer are10-15mm and 990-110mm. It can not only meet the oil transportation safety of tank truck, but also save the manufacturing cost, which provides important reference value for the design of tank truck.

Theoretical study on energy recovery rate of regenerative braking for hybrid mining trucks with different parameters

Based on the theory of the traditional hydraulic braking system of mining trucks and under the condition of safety, in order to maximize the regenerative braking energy recovery of hybrid mining trucks, a regenerative braking force distribution and control strategy for rear wheel parallel hybrid mining truck is proposed in this paper. Influences of charging current, battery state of charge value and braking force distribution on regenerative braking energy recovery is studied. ADVISOR is used for truck modeling and simulation under typical mining braking conditions. The results show that the maximum regenerative braking energy recovery rate is 65.01% when the initial charging current is 10A, 30A, 50A and 70A, respectively. The results indicate that the regenerative braking control strategy can solve the problems of braking safety performance and maximize the regenerative braking recovery rate.

Optimization Parameters of Disc Brake

Abstract: In recent time due to high performance of electronic component the heat generation is increasing drastically. Due to this scenario heat dissipation becomes a major issue in efficiency promation and stable operation. Silicon based microchannel heat sink fabricated using semiconductor production technique plays important role in cooling devices. The effect of the thermophysical properties of working fluids on the performance of microchannel is tested or we can say investigated. For this purpose the different working fluids are selected. water, hepthane, ammonia, methanol, and ethanol. The disc brake is a device for slowing or stopping the rotation of a wheel. Repetitive braking of the vehicle leads to heat generation during each braking event. Transient Thermal and Structural Analysis of the Rotor Disc of Disk Brake is aimed at evaluating the performance of disc brake rotor of a car under severe braking conditions and there by assist in disc rotor design and analysis. Disc brake model and analysis is done using ANSYS workbench 14.5. The main purpose of this study is to analysis the thermo mechanical behavior of the dry contact of the brake disc during the braking phase. The coupled thermal-structural analysis is used to determine the deformation and the Von Mises stress established in the disc for the both solid and ventilated disc with two different materials to enhance performance of the rotor disc. A comparison between analytical and results obtained from FEM is done and all the values obtained from the analysis are less than their allowable values. Hence best suitable design, material and rotor disc is suggested based on the performance, strength and rigidity criteria. Keywords- disc break, thermal analysis, structure analysis.

Influence of Contact Plateaus Characteristics Formed on the Surface of Brake Friction Materials in Braking Performance through Experimental Tests.

This work applies a procedure for analysis and characterization of the surface of brake friction materials, correlating them with the tribological and thermal properties achieved in different vehicle braking conditions. Experiments were performed in a vehicle under two real conditions of braking operation, simulated flat track descent and emergency braking. Characteristics of the plates formed on the surfaces of the friction materials were analyzed by scanning electron microscopy (SEM) and correlated with the performance during braking, as measured by the coefficient of friction at the interface of the friction pair and temperature. As a result, the formation of the primary and secondary plateaus in these two different braking operating conditions was observed, and the relationship between the characteristics of the plateaus formed on the surface and the surface roughness parameters and performance measurements during braking.

ОЦЕНКА ВЛИЯНИЯ СИСТЕМЫ НАКОПЛЕНИЯ ЭНЕРГИИ НА УРОВЕНЬ НАПРЯЖЕНИЯ НА ШИНАХ АКТИВНОГО ПОСТА СЕКЦИОНИРОВАНИЯ ПОСТОЯННОГО ТОКА

The work purpose is to estimate and investigate processes of the regenerative braking impact upon a voltage level on object buses of the system of traction power supply at electricity storage systems. In the investigation there are used methods of imitation modeling and analytical ones allowing the fulfillment of calculations for different conditions of the electric traction load formation within the limits of inter-substation areas under consideration. The work novelty consists in the approach to the estimation of the working mode impact of electricity storage systems upon the voltage level on buses of the objects of traction power supply under conditions of regenerative braking and charge characteristics changes. In the course of the investigation there are obtained the following results: the work cyclicity change estimation of a storage system is carried out; the dependence of a charge depth change upon rated power consumption is defined; charge characteristics for conditions of charge predominance in the diagram are calculated; the character of voltage changes on object buses of the system of traction power supply is defined; the necessity of charge characteristic adaptation depending on conditions of regenerative braking use is defined. The regenerative braking use makes an impact upon charge characteristics formed from the condition of charge predominance in the diagram of a charge degree at the rated interval and allows increasing currents of the second stage of the charge characteristics allowing the decrease voltage loss at charge realization caused by adjacent traction substations at the first stage.

Comparison of noise generated from simplex and duplex configurations of drum brake using non-linear vibro-acoustic models

The drum brakes used on the rear wheels of automobiles have various configurations. These contribute to the differences in kinematic (geometry) and dynamic (contact, friction) aspects, eventually leading to significantly different vibration and acoustic response. This work attempts to estimate the difference in the vibro-acoustic noise generated by the drum brake's simplex and duplex variants using a combination of non-linear analytical vibration models and a numerical acoustic model. Four degrees-of-freedom lumped parameter models developed for the simplex and the duplex configurations with conformal contact predict the contact and reaction forces during braking. These forces act as the sources for the finite element based acoustic models developed for the two configurations to obtain the sound pressure to force transfer functions. The sound pressure levels are estimated by the product of the predicted forces with the respective transfer functions in the frequency domain. The sound pressure levels of the simplex and duplex drum brakes are quantitatively compared under different braking conditions, and the results are presented. It is expected that this vibro-acoustic analysis will help in designing quieter drum brakes.

Investigation of Thermal Response of Disc Brake System: A Review

A comprehensive review of the thermal response of disc brake system has been made. Extensive research has been carried out on the operating problems, the material for the rotor, design of the rotor and the braking conditions of the disc brake systems and numerous methods of improvement are proposed. Various ventilation patterns have been studied in order to enhance thermal efficiency, and structural performance reductions have been found in most cases. Which creates need for the design of discs with optimal thermal and structural characteristics, so that disc brake performance can be enhanced without compromising in strength and other parameters of the disc brake system. It is expected that this exhaustive and comprehensive review will help the research fraternity in identifying the research gaps for their future work. The prime purpose of this paper is to provide an exhaustive overview of developments going on in this field. The proposed research work attempts to develop and modify the system which uses the effective method to minimise the temperature and weight of disc brake rotor by thermo-mechanical analysis to optimise the performance of Disc brake. The proposed design of disc brake offers a promising solution to improve the braking efficiency by 15%and overall reduction in weight of disc brake by 10%.

Development and tribological studies of a novel metal‐ceramic hybrid brake disc

AbstractCeramic matrix composite (CMC) friction materials show promising tribological properties. Typically, carbon ceramic brake discs consist of a C/SiC rotor which is joined to a brake disc bell. Within this work, a novel metal‐ceramic hybrid brake disc, consisting of C/SiC friction segments which are mounted by screws onto an aluminum carrier body, was designed and investigated. A prototype was built which was tribologically tested with three different brake pad materials, LowMet reference, modified SF C/SiC as well as C/C. A constant starting sliding velocity of 20 m/s and braking pressures of 1, 2, and 3 MPa were investigated. To simulate emergency braking conditions 10 consecutive brake applications were carried out in close succession for each brake pad material and braking pressure. The C/C brake pad material showed the highest average coefficient of friction followed by the LowMet and C/SiC material. However, the wear rates of the C/C and LowMet material were orders of magnitude higher compared to the C/SiC material.

Analysis of deep crack formation and propagation in railway brake discs

While surface crack formation and propagation in Electric Multiple Unit (EMU) brake discs has been an active research topic, relatively few studies have considered similar behavior in deep cracks which become unstable. Moreover, most analyses assume nominal design conditions which does not reflect changes which may have been occurred during service. In the present study, a steel brake disc was analyzed after a deep crack was discovered during a maintenance check. The objective was to identify the impetus for deep crack propagation and characteristic semi-elliptical shape. Finite element (FEM) and extended finite element (XFEM) models which included residual stress effects from service were used to analyze the thermo-mechanical history and resulting crack propagation. The simulated and actual fracture surfaces demonstrated satisfactory agreement and showed that the crack preferentially initiated at the bolt hole corners and that transient temperature differences between adjacent hot spots help to define the crack orientation. It was also found that unstable propagation along the axial direction was due to a steep temperature gradient. Service induced distortion was also found to indicate the presence of internal stresses which can have a strong effect on crack behavior. It is expected that the findings will contribute toward a better understanding of how braking conditions and service effects influence unstable crack behavior in EMU brake discs.

Braking behaviors of Cu-based PM brake pads mating with C/C–SiC and 30CrMnSi steel discs under high-energy braking

Exploring braking behaviors of powder metallurgy (PM) brake pads mating with different brake discs is conducive to promoting the development of high-speed trains. In this study, the braking behaviors and wear mechanisms of Cu-based PM brake pads mating with C/C–SiC and 30CrMnSi steel disc, respectively, under high-energy braking condition have been investigated. Results show that compared with PM-30CrMnSi brake pair, the coefficient of friction (COF) and stability coefficient of PM-C/C–SiC brake pair are increased by 28.9% and 13.9%, respectively, and the PM pad wear rate and braking time are reduced by 31.0% and 29.5%. Moreover, PM-C/C–SiC brake pair does not exist obvious tail warping in braking curve, which can be attributed to the formation of dense tribo-layer and the lubrication of carbon fibers. TEM analysis shows that the tribo-layer of PM-C/C–SiC brake pair is composed of nanostructured oxide layer and plastic deformation layer. Besides, a ~600 nm thick oxide layer containing nano-sized Cu/Fe oxides and ZrSiO4 particles greatly improves COF and wear resistance of PM pad. The dominant wear mechanisms of PM-C/C–SiC brake pair are delamination and oxidation wear, whilst those of PM-30CrMnSi brake pair are abrasive and adhesive wear.