This thesis deals with the development of a mathematical model for an air brake system in the presence of leaks. Brake systems in trucks are crucial for ensuring the safety of vehicles and passengers on the roadways. Most trucks in the US are equipped with S-cam drum brake systems and they are sensitive to maintenance. Brake defects such as leaks are a major cause of accidents involving trucks. Leaks in the air brake systems affect braking performance drastically by decreasing the peak braking pressures attained and also increasing the time required to attain the same, thereby resulting in longer stopping distances. Hence there is a need for detecting leaks in an air brake system. In this thesis, a mathematical model for an air brake system in the presence of leaks is developed with a view towards developing an automatic leak detection system in the near future. The model developed here builds on an earlier research at Texas A&M University in which a "fault free" model of an air brake system is developed, i.e., a mathematical model of an air brake system that predicts how the pressure in the brake chamber evolves as a function of the brake pedal input when there are no leaks in the air brake system.In order to develop a model for an air brake system in the presence of leaks, one must characterize a "leak". A leak may be characterized by the location and its size. Since the pipes are short, the location of the leak does not significantly affect the evolution in the brake pressure as much as its size. For this reason, "effective area" of the leak was chosen as a characteristic of the leak. It was estimated by fitting an empirical relation for leak with leak flow measurement data. The supply pressure and effective area of leak comprised the inputs to the model along with the displacement of the foot pedal (treadle valve plunger). The model was corroborated with the experimental data collected using the setup at Texas A&M University.

Emergency braking of a vehicle is bound with many factors, such as the behaviour of the driver, the drive of the vehicle braking system, the braking mechanisms, the condition of the tyres, and the properties of the pavement. This process involves all parameters of the system “the driver – the vehicle – the road”. In order to investigate the efficiency of braking process upon specific conditions, it is necessary to examine all physical processes that take place in the vehicle on pressing the brake pedal. Upon the completion of the experimental and theoretical investigation on emergency braking of vehicles a general mathematical model of vehicle with hydraulic braking system on its emergency braking had been developed. The dynamic, thermodynamic in solid systems and fluid hydrodynamic processes were assessed. The model enables to examine various cases of emergency braking with assessment of the driver’s reaction, parameters of the vehicle’ technical condition and the pavement condition. A general mathematical model of vehicle with hydraulic braking system that’s computing is realized in the system of the applied software Compaq Visual Fortran Professional system provides possibilities for research the hydrodynamic processes that take place in the system of braking; enables to define more closely the movement parameters of the vehicle in the emergency braking mode and may be applied for analysis of traffic events, improvement of vehicle braking systems as well as a manual for... [to full text]

Emergency braking of a vehicle is bound with many factors, such as the behaviour of the driver, the drive of the vehicle braking system, the braking mechanisms, the condition of the tyres, and the properties of the pavement. This process involves all parameters of the system “the driver – the vehicle – the road”. In order to investigate the efficiency of braking process upon specific conditions, it is necessary to examine all physical processes that take place in the vehicle on pressing the brake pedal. Upon the completion of the experimental and theoretical investigation on emergency braking of vehicles a general mathematical model of vehicle with hydraulic braking system on its emergency braking had been developed. The dynamic, thermodynamic in solid systems and fluid hydrodynamic processes were assessed. Model enables to examine various cases of emergency braking with assessment of the driver’s reaction, parameters of the vehicle’ technical condition and the pavement condition. A general mathematical model of vehicle with hydraulic braking system that’s computing is realized in the system of the applied software Compaq Visual Fortran Professional v 6.3 system provides possibilities for research the hydrodynamic processes that take place in the system of braking; enables to define more closely the movement parameters of the vehicle in the emergency braking mode and may be applied for analysis of traffic events, improvement of vehicle braking systems as well as a manual... [to full text]

Στόχος της εργασίας είναι η μοντελοποίηση και ο έλεγχος με τη χρήση υπολογιστή του συστήματος της πέδησης του αυτοκινήτου καθώς και της επιτάχυνσης (γκάζι - throttle) του κινητήρα. Για την πέδηση μελετήθηκε και υλοποιήθηκε στο Simulink το μοντέλο που περιγράφεται στην εργασία των Humair Raza, Zhigang Xu, Bingen Yang και Petros A. Ioannou με τον τίτλο “Modeling and Control Design for a Computer-Controlled Brake System”. Για την πέδηση και την επιτάχυνση, ενοποιημένα σε ένα ενιαίο μοντέλο που περιγράφει το όχημα, μελετήθηκε η εργασία των P. Ioannou και Z. Xu με τίτλο “Throttle and Brake Control Systems for Automatic Vehicle Following”, και στη συνέχεια υλοποιήθηκαν στο Simulink τα μοντέλα για την πέδηση και το throttle. Στην συνέχεια δοκιμάσαμε τους ελεγκτές εφαρμόζοντας διάφορες εισόδους (σενάρια φρεναρίσματος) και λάβαμε τις αναμενόμενες από τη θεωρία εξόδους, επαληθεύοντας έτσι την ορθότητά τους. / The aim of this study is to model and control with the computer the car brake system and the engine throttle. For the brake system we studied and implemented in the Simulink the model described in the work of Humair Raza, Zhigang Xu, Bingen Yang and Petros A. Ioannou titled "Modeling and Control Design for a Computer-Controlled Brake System ". For the braking and the acceleration, consolidated into a single model describing the vehicle, we studied the work of P. Ioannou, Z. Xu entitled "Throttle and Brake Control Systems for Automatic Vehicle Following ", and then we implemented the models in Simulink. Then we tried applying different controllers inputs (braking and acceleration scenarios) and we verified the models' correctness.

Design of braking system for Formula Student vehicle. Braking system is one of the most important control system in every vehicle, even more in race car application. Only perfectly working braking system is capable bring the best results. In this diploma thesis are list of used parts with basic force calculation, design of pedal assembly in accordance with the rules of Formula Student, options for measuring and dataloging from ride for next development.

This thesis draws up a basic overview of the current groups pedal cars. It focuses on creating a computer model of the pedal group with the help of the mathematical model and simulation stress of individual components and proposed relief.

Objective of this thesis is design of brake system of new car Formula Student class – Dragon 3. This car was built by students of faculty of mechanical engineering on Brno university of technology. Brake parts selection is described as well as designing hydraulic brake line circuits optimized for stable braking behavior on tracks of Formula Student competitions. One of main parts of this thesis is design of front and rear custom brake discs with related parts. These parts are FEM analyzed. In the end the whole brake system fitted on Dragon 3 car is tested on track and its performance is analyzed too.

No / Braking system characteristics, brake system performance and brake system component design parameters that influence brake pedal ‘feel’ in a passenger car have been studied using the simulation modelling package AMESim, in particular to model the linear and nonlinear characteristics of internal components. A passenger car hydraulic brake system simulation model incorporating the brake pedal, booster, master cylinder, brake lines and calipers has been developed to predict brake system response to assist in the design of braking systems with the desired brake pedal force / travel characteristic characteristics to create good brake pedal ‘feel’. This has highlighted the importance of system components, in particular the master cylinder and caliper seal deformation, and the operating characteristics of the booster in determining the brake pedal force / travel characteristic. The potential contribution of these 3 components to brake pedal ‘feel’ improvement has been investigated, and the results of the AMESim model have been verified using experimental measurement data. The model can be used in the future to provide an accurate prediction of brake system response at the design stage thereby saving time and cost.

Pastilhas de freio para sistemas de freios automotivos correspondem a um dos materiais compósitos mais complexos já que eles contêm muitos componentes, cada qual com uma grande variedade de propriedades físicas e químicas. Esta natureza multi-fase é necessária para satisfazer a grande variedade de demandas relativas à performance. As condições de processamento também possuem grande influência nas propriedades deste complexo compósito. As pastilhas de freio usadas neste trabalho foram sem amianto do tipo semi-metálica contendo muitos elementos, incluindo resina fenólica, fibra de reforço, lubrificantes sólidos, abrasivos e cargas. Este trabalho tem como objetivo principal esclarecer a influência entre as variáveis de processo e de composição nas propriedades de compressibilidade a frio, densidade, dureza, flexão e coeficiente de atrito. Para isso foram utilizados planejamentos de experimentos fracionados e completos. O planejamento de experimentos fracionado, 25-1, indicou que a quantidade de resina fenólica e a temperatura do molde são os fatores mais significativos para a compressibilidade. O planejamento de experimentos completo, 24, mostrou mais uma vez, que a quantidade de resina e a temperatura do molde, bem como as suas interações, são fatores significativos na determinação da compressibilidade. O terceiro planejamento de experimentos, 2³, concentrou-se nas propriedades da resina, já que a mesma mostrou-se muito influente na determinação das propriedades dos materiais de atrito. Os resultados mostraram que é possível controlar as propriedades tribológicas e a compressibilidade das pastilhas de freio dentro de certa escala de valores. Assim, este trabalho mostra que é possível aplicar técnicas estatísticas para racionalizar o projeto de materiais de atrito. / Submitted by Marcelo Teixeira (mvteixeira@ucs.br) on 2014-05-14T18:07:18Z No. of bitstreams: 1 Dissertacao Ademir R Menetrier.pdf: 3142797 bytes, checksum: 973f28293a5f77372f68c6146e790438 (MD5) / Made available in DSpace on 2014-05-14T18:07:18Z (GMT). No. of bitstreams: 1 Dissertacao Ademir R Menetrier.pdf: 3142797 bytes, checksum: 973f28293a5f77372f68c6146e790438 (MD5) / Brake pads for automotive brake systems represent one of the most complex composite materials since they contain many components with widely varying physical and chemical properties. This multiphase nature is necessary to satisfy a wide variety of performance related demands. Processing conditions also have a major influence on the properties of these complex composites. Brake pads used in these studies were semi-metallic non-asbestos friction materials containing many different ingredients, including phenolic resin, reinforcing fibers, solid lubricants, abrasives and fillers. In this work, the influence of composition and process parameters on the compressibility, density, hardness, flexure strength and coefficient of friction were investigated. The designs of experiments selected for this study were fractional and full varieties. In the initial fractional design of experiments, we found both the quantity of resin and the mold temperature to be dominant influences on the compressibility. A full design of experiments again indicated that the quantity of resin and mold temperature, as well as their interaction, are the dominant players in determining the compressibility. A third design of experiments concentrated on the resin properties since this factor was the most influential in determining the properties of friction materials. The results show that it is possible to control both the tribological properties and the compressibility of the pads within a rather large range of values. Thus, the work shows that it is possible to use statistical methods to rationalize brake pad design.

Pastilhas de freio para sistemas de freios automotivos correspondem a um dos materiais compósitos mais complexos já que eles contêm muitos componentes, cada qual com uma grande variedade de propriedades físicas e químicas. Esta natureza multi-fase é necessária para satisfazer a grande variedade de demandas relativas à performance. As condições de processamento também possuem grande influência nas propriedades deste complexo compósito. As pastilhas de freio usadas neste trabalho foram sem amianto do tipo semi-metálica contendo muitos elementos, incluindo resina fenólica, fibra de reforço, lubrificantes sólidos, abrasivos e cargas. Este trabalho tem como objetivo principal esclarecer a influência entre as variáveis de processo e de composição nas propriedades de compressibilidade a frio, densidade, dureza, flexão e coeficiente de atrito. Para isso foram utilizados planejamentos de experimentos fracionados e completos. O planejamento de experimentos fracionado, 25-1, indicou que a quantidade de resina fenólica e a temperatura do molde são os fatores mais significativos para a compressibilidade. O planejamento de experimentos completo, 24, mostrou mais uma vez, que a quantidade de resina e a temperatura do molde, bem como as suas interações, são fatores significativos na determinação da compressibilidade. O terceiro planejamento de experimentos, 2³, concentrou-se nas propriedades da resina, já que a mesma mostrou-se muito influente na determinação das propriedades dos materiais de atrito. Os resultados mostraram que é possível controlar as propriedades tribológicas e a compressibilidade das pastilhas de freio dentro de certa escala de valores. Assim, este trabalho mostra que é possível aplicar técnicas estatísticas para racionalizar o projeto de materiais de atrito. / Brake pads for automotive brake systems represent one of the most complex composite materials since they contain many components with widely varying physical and chemical properties. This multiphase nature is necessary to satisfy a wide variety of performance related demands. Processing conditions also have a major influence on the properties of these complex composites. Brake pads used in these studies were semi-metallic non-asbestos friction materials containing many different ingredients, including phenolic resin, reinforcing fibers, solid lubricants, abrasives and fillers. In this work, the influence of composition and process parameters on the compressibility, density, hardness, flexure strength and coefficient of friction were investigated. The designs of experiments selected for this study were fractional and full varieties. In the initial fractional design of experiments, we found both the quantity of resin and the mold temperature to be dominant influences on the compressibility. A full design of experiments again indicated that the quantity of resin and mold temperature, as well as their interaction, are the dominant players in determining the compressibility. A third design of experiments concentrated on the resin properties since this factor was the most influential in determining the properties of friction materials. The results show that it is possible to control both the tribological properties and the compressibility of the pads within a rather large range of values. Thus, the work shows that it is possible to use statistical methods to rationalize brake pad design.