Search Results (43)

Brake squeal is an undesirable high-frequency noise caused by vibrations induced by friction in disc brake systems. The noise is strongly affected by temperature, as this influences the material properties of the friction pair and the dynamic behaviour of the brake components. This study investigates the effect of temperature changes on the squeal characteristics of a disc brake system under different operating conditions. Experiments are carried out using a laboratory-scale test setup comprising a rotating disc, pneumatically actuated callipers, and precise measurement equipment. A series of test combinations is performed by systematically varying three parameters: disc surface temperature (40, 55, 70, 85, 100 °C), brake pressure (4.0 bar), and disc rotational speed (50, 100, 150, 200 rpm). Acceleration data are acquired using an accelerometer mounted directly on the calliper, while sound pressure data are measured with a fixed-position microphone located 0.5 m from the disc surface. The collected data are analyzed in the time and frequency domain to identify squeal events and their dominant frequencies. The effect of temperature on brake squeal noise and vibration varies with operating conditions, showing different patterns at low and high disc speed at constant brake pressure. This highlights the importance of considering both thermal and mechanical factors together when addressing brake squeal. Full article

The distributor valve is one of the most important components in the pneumatic braking system of trains. It performs the functions of filling and releasing the brake cylinder. The distributor valve most widely used on Bulgarian railways operates in two positions, respectively, in “freight train” mode (G) and in “passenger train mode” (P). The difference between them is determined by the different times for filling and emptying the brake cylinder. These times affect the moment of engagement of the braking system of each wagon in the train composition. This has a significant impact on the longitudinal forces obtained in the couplers. This paper is dedicated to the analysis of the influence of the distributor valve position on the longitudinal forces. A simulation study of the longitudinal behavior of a train set was carried out in Simulink^®, which consists of a locomotive and 43 freight wagons attached to it, with 80 t gross mass of each wagon. The railway cars are linked by elastic elements with nonlinear characteristics. The results represent the distribution of longitudinal forces in time. They are used for the investigation of the longitudinal dynamics of the train, with the aim of improving the running-dynamic qualities of the train during braking. Full article

Because of their substantial weight and high centers of gravity, commercial vehicles require braking systems that ensure maximum performance and safety. Accurate braking control is vital for preserving safe vehicle dynamics by preventing lateral instability due to excessive deceleration or rear-wheel lock-up. Considering the growing demand for safety in medium-duty commercial vehicles, we introduce a rule-based dynamic braking controller for pneumatic electronic parking brake (EPB) systems. The proposed system is established using a model-based design (MBD) framework involving a V-cycle development process. The rule-based controller is designed to control the braking force based on wheel slip, thereby ensuring both adequate braking distance and lateral stability during emergency braking. Simulations and real-vehicle tests confirmed that the proposed control strategy can maintain lateral stability across varying loading and road-surface conditions. The results highlight the dynamic braking capability of the proposed pneumatic EPB system and its feasibility as an emergency braking solution. The effectiveness of the proposed controller in preventing wheel lock supports the use of MBD for developing safety-aware controllers. Full article

The throughput of the pneumatic brake valve is a key parameter in ensuring fast and safe vehicle braking. The instantaneous value of this parameter determines the short response time of the system to an operator’s force. The scientific objective of this paper was to determine the throughput of brake valve tracts using numerical and experimental methods. These tracts are supposed to provide the tracking and acceleration function of the valve depending on the setting of the correction system. The first numerical method was based on polyhedral meshes using computational fluid dynamics (CFD) and Ansys Fluent software. The second research method—experimental tests on the author’s bench using the reservoir method—consisted of identifying throughputs based on pressure waveforms in the measurement tanks. The determined throughputs were averaged over the range of pressure differences tested and allowed the final calculation of the mass flow rate. The analysis of the obtained results showed an average discrepancy between the two research methods for both tracts, in which the flow in both directions was considered to be 9.43%, taking into account the use of a polyhedral numerical mesh ensuring high-quality results with an optimal simulation duration. The analysis of the pressure distribution inside the working chambers showed local areas of increased pressure and negative pressure resulting from the acceleration of the flow in narrow flow channels and the occurrence of the Venturi effect. Full article

Adaptive vehicle control systems are crucial for enhancing safety, performance, and efficiency in modern transportation, particularly as vehicles become increasingly automated and responsive to dynamic environments. This review explores the advancements in bio-inspired actuators and their potential applications in adaptive vehicle control systems. Bio-inspired actuators, which mimic natural mechanisms such as muscle movement and plant tropism, offer unique advantages, including flexibility, adaptability, and energy efficiency. This paper categorizes these actuators based on their mechanisms, focusing on shape memory alloys, dielectric elastomers, ionic polymer–metal composites, polyvinylidene fluoride-based electrostrictive actuators, and soft pneumatic actuators. The review highlights the properties, operating principles, and potential applications for each mechanism in automotive systems. Additionally, it investigates the current uses of these actuators in adaptive suspension, active steering, braking systems, and human–machine interfaces for autonomous vehicles. The review further outlines the advantages of bio-inspired actuators, including their energy efficiency and adaptability to road conditions, while addressing key challenges like material limitations, response times, and integration with existing automotive control systems. Finally, this paper discusses future directions, including the integration of bio-inspired actuators with machine learning and advancements in material science, to enable more efficient and responsive adaptive vehicle control systems. Full article

Open-pit mining involves the use of vehicles with high load capacity and satisfactory mobility. As experience shows, these requirements are fully met by pneumatic wheeled dump trucks, the traction drives of which can be made using thermal or electric machines. The latter are preferable due to their environmental friendliness. Unlike dump trucks with thermal engines, which require fuel to be injected into them, electric trucks can be powered by various options of a power supply: centralized, autonomous, and combined. This paper highlights the advantages and disadvantages of different power supply systems depending on their schematic solutions and the quarry parameters for all the variants of the power supply of the dumper. Each quantitative indicator of each factor was changed under conditions consistent with the others. The steepness of the road elevation in the quarry and its length were the factors under study. The studies conducted show that the energy consumption for dump truck movement for all variants of a power supply practically does not change. Another group of factors consisted of electric energy sources, which were accumulator batteries and double electric layer capacitors. The analysis of energy efficiency and the regenerative braking system reveals low efficiency of regeneration when lifting the load from the quarry. In the process of lifting from the lower horizons of the quarry to the dump and back, kinetic energy is converted into heat, reducing the efficiency of regeneration considering the technological cycle of works. Taking these circumstances into account, removing the regenerative braking systems of open-pit electric dump trucks hauling soil or solid minerals from an open pit upwards seems to be economically feasible. Eliminating the regenerative braking system will simplify the design, reduce the cost of a dump truck, and free up usable volume effectively utilized to increase the capacity of the battery packs, allowing for longer run times without recharging and improving overall system efficiency. The problem of considering the length of the path for energy consumption per given gradient of the motion profile was solved. Full article

Agricultural tractors are equipped with air braking systems to supply and control the braking systems of towed vehicles. This system’s functional and operational characteristics significantly impact the compatibility and speed of the braking system of the tractor–trailer combination and are therefore checked during approval tests. This paper presents a test methodology and a description of the instrumentation and apparatus used to test the air braking systems of tractors under stationary conditions, as required by EU Regulation 2015/68. Sample test results of the trailer air supply system are included, such as checking the system for leaks, checking the pressure at the coupling heads, checking the compressor flow rate and air reservoir capacity, and checking the response time of the tractor control line. Approval authorities and tractor manufacturers can use the work results for quality control or product qualification tests. Full article

The normalized operation of 30,000-ton heavy-haul trains is of significant importance for enhancing the transportation capacity of heavy-haul railways. However, with the increase in train formation size, traditional braking strategies result in excessive longitudinal impulse when combined pneumatic and electric braking is applied on long, steep gradients. This presents a serious challenge to the braking safety of the train. To this end, this paper establishes a longitudinal dynamic model of a 30,000-ton heavy-haul train based on vehicle system dynamics theory, and validates the model’s effectiveness through line test data. On this basis, the influence of two braking parameters, namely, the distribution of the magnitude of the electric braking force and the matching time of pneumatic braking and electric braking, on the longitudinal dynamic behavior of heavy-haul trains is studied. Thereby, an optimized combined pneumatic and electric braking strategy is formulated to reduce the longitudinal impulse of the trains. The results show that setting reasonable braking parameters can effectively reduce the longitudinal impulse, with the braking matching time having a significant impact on the longitudinal impulse. Specifically, when using a strategy where the electric braking forces of three locomotives are set to 90 kN, 300 kN, and 300 kN, with a 30 s delay in applying the electric braking force, a better optimization effect is achieved. The two proposed braking strategies reduce the maximum longitudinal forces by 20.27% and 47.83%, respectively, compared to conventional approaches. The research results provide effective methods and theoretical guidance for optimizing the braking strategy and ensuring the operational safety of 30,000-ton heavy-haul trains. Full article

This study presents the design and analysis of a proportional solenoid used in electro-pneumatic brake systems for heavy vehicles. The solenoid was designed using a traditional method, and its static and dynamic characteristics were investigated both theoretically and experimentally. ANSYS 2024 R1 Maxwell was employed for theoretical static analysis, focusing on the effects of the geometric dimension parameters in the fixed and moving pole contact regions on the force–displacement characteristics. The optimal dimensions for proportionality were determined under constraint parameters. The static analysis results provided the magnetization curve data, which were used to create Look-Up Tables for a dynamic model in MATLAB R2024b-Simulink, and this method reduced the simulation time and increased the dynamic simulation accuracy. Following static analysis, a prototype electromagnet was manufactured and tested. The solenoid achieved a constant magnetic force of 45 ± 3 N with a current of 1.3 A over a working range of 1–3 mm. The dynamic model, incorporating data from ANSYS, yielded results that closely matched the experimental findings. Full article

The present study aimed to enhance the efficiency and efficacy of the Al/Cu joint production process implemented by the company VEMID Ltd., Jagodina, Serbia, by attaining sound joints within a very short welding time. For this purpose, the present study aimed at investigating the accuracy and the quality of the continuous drive friction welding (CDFW) process, as well as the optimum combination of CDFW parameters with highest joint efficiency in terms of investigated properties. The accuracy was estimated through an analysis of temperature–time curves recorded during CDFW using an infrared camera. The quality was evaluated through an investigation of the properties of Al/Cu joints produced using different friction (66.7, 88.9, and 133.3 MPa) and forging (88.9, 222.2, and 355.6 MPa) pressures and a constant total welding time (4 s) and rotational speed (2100 rpm). Thermal imaging with an infrared camera demonstrated that the actual total welding time was 15% longer compared to the nominal value. This was attributed to the slow pressure response of the pneumatic brake system. The relative changes in the maximum surface temperature (T_MS) during the CDFW process corresponded to changes in welding pressures, indicating the potential of the thermal imaging method for monitoring and assessing this process. A preliminary investigation demonstrated that Al/Cu joints produced using welding pressures less than 88.9 MPa often displayed the presence of non-joined micro-regions at the Al/Cu interface and a significant thickness of interfacial Al₂Cu (up to 1 µm). However, when friction pressure was set at 66.7 MPa, an increase in the forging pressure to 222.2 MPa eliminated the presence of non-joined micro-regions and reduced the thickness of Al₂Cu to 0.5 µm on the average level. These Al/Cu joints achieved the highest joint efficiencies in terms of strength (100%) and ductility (61%). They exhibited an electrical conductivity higher than 92% of the theoretical value. A further increase in any welding pressure produced similar or deteriorated properties, accompanied by an increase in the consumption of raw materials and energy. Such turn of events was counterproductive to the original goal of increasing the efficiency and efficacy of the CDFW process. Full article

With the development of safety technologies for intelligent commercial vehicles, electronic pneumatic braking systems (EBSs) have been widely used. However, EBS actuators may fail during vehicle operation and thus create safety problems. For this reason, we propose a path-tracking fault-tolerant control strategy under EBS actuator failure in intelligent commercial vehicles. First, in order to be able to characterize different types of brake actuator faults during the EBS differential braking process of a vehicle, a comprehensive fault coefficient for calculating the degree of fault is designed, and a BES generalized fault model is established. Second, the faults are introduced into the fault-tolerant controller through the comprehensive fault coefficients for braking torque calculation and braking pressure allocation. Thus, a vehicle path model with the complete fault coefficients as variable parameters is established. Then, based on the LPV system gain scheduling, a path-tracking LPV/H∞ fault-tolerant controller under EBS actuator faults in commercial vehicles is designed, which is used to solve the safety problem arising from sudden EBS actuator faults. Finally, we conducted experimental validation through hardware-in-the-loop tests. The results demonstrate that the control strategy designed in this paper redistributes the braking torque and synergizes with the steering system to enhance vehicle stability, thereby improving vehicle safety in the EBS failure mode. Full article

The optimization of the brake systems is crucial for vehicle performance and safety of Formula SAE (FSAE) race cars. This study introduces a specialized brake test bench designed to enhance the understanding and testing of these systems. The bench integrates a rotating mechanical system mounting a brake disc-caliper group, which is driven by an electric motor, a pneumatic brake pedal assembly to simulate real braking conditions, and a comprehensive array of sensors that facilitate the measurement of critical parameters, such as rotation speed, braking torque, oil pressure, and disc temperature. Its structure, sensor integration, and control electronics are fully described, demonstrating the capability to replicate on-track scenarios in a controlled environment. The results underscore the utility of the bench in providing precise and consistent testing conditions essential for analyzing the efficiency, durability, and safety of the braking systems of FSAE race cars. Full article

In the electronic brake system (EBS) of commercial vehicles, due to the compressibility of gas, it is difficult to achieve accurate control in the pneumatic pipeline. To address this issue, a vertical load estimator based on unscented particle filtering (UPF) was designed, which can estimate vertical load during the running of the vehicle. Then, the EBS dynamics model was established based on software, including a brake signal sensor, single-channel bridge control module, ABS solenoid valve, and dual-channel bridge control module. Finally, based on the characteristics of the EBS valve, the control algorithm of the valve was studied, and the algorithm was tested using a hardware-in-the-loop experiment. The experiment results showed that the designed algorithm could improve braking performance. Full article

Fast and precise pressure control for an electropneumatic brake system is essential for ensuring the safe operation of trains. However, the nonlinearity and uncertainties of the system make controller design challenging. This paper proposes a prescribed performance control method integrating an extended state observer to address this issue. A thermodynamical model of the brake cylinder is first built based on the pneumatic characteristics of the braking system, considering multiple modes, coupling effects, and input saturation. Then, an extended state observer is designed to estimate model uncertainty due to temperature variation and disturbances and to achieve online compensation of the model. A feedback control law with a specified prescribed performance function is developed based on the updated thermodynamic model to guarantee the transient and steady-state performance of the pressure control. A parameter adaptive method is also utilized to handle input saturation. The observer’s bounded convergence and stability analysis of the closed-loop control system is given using the Lyapunov theory. Compared experimental results are provided to verify the effectiveness of the proposed method. Full article

Currently, braking control systems used in regional railways are open-loop systems, such as metro and tramways. Given that the performance of braking can be influenced by issues such as wheel sliding or the properties of the friction components present in brake systems, our study puts forward a novel closed-loop mechanism to autonomously stabilize braking performance. It is able to keep train deceleration close to the target values required by the braking control unit (BCU), especially in terms of the electrical–pneumatic braking transform process. This method fully considers the friction efficiency characteristics of brake pads and encompasses running tests using rolling stock. The test results show that the technique is able to stabilize the actual deceleration at a closer rate to the target deceleration than before and avoid wheel sliding protection (WSP) action, especially during low-speed periods. Full article