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SAE International Journal of Passenger Cars Mechanical Systems
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Relation between the Weave Mode in Low Speed Range and Slalom Running of Motorcycles

SAE International Journal of Passenger Cars - Mechanical Systems

Yamaha Motor Co., Ltd.-Tomoaki Kishi, Toshifumi Uchiyama, Shigeru Fujii
  • Journal Article
  • 2012-32-0122
Published 2012-10-23 by SAE International in United States
Recently, our research has focused on the weave mode. This is a representative vibration mode of motorcycles and is important when considering maneuverability and stability. In a method of analyzing the weave mode, a disturbance is applied to the handle bars of the motorcycle during running and then the response waveform of the roll angle and other items at that time is used to perform estimations. However, when the motorcycle is driven at low speeds, the steering operations of the rider have a large effect on the running data and this makes estimation difficult. Therefore, it was assumed that weave mode data can be estimated from slalom running data since this possesses almost the same vibration frequency as the weave mode in low speed range.In this research, a simulation was used to investigate the relationship between the weave mode and slalom running. The results of the investigation confirmed that slalom running at a specified speed around pylons placed apart at a specific interval resulted in the same vibration mode as the weave mode in low…
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Performance Enhancement of Road Vehicles Using Active Independent Front Steering (AIFS)

SAE International Journal of Passenger Cars - Mechanical Systems

Concordia University, Montreal-Azadeh Farazandeh, A. K.W. Ahmed, S. Rakheja
  • Journal Article
  • 2012-01-2013
Published 2012-09-24 by SAE International in United States
Technological developments in road vehicles over the last two decades have received considerable attention towards pushing the safe performance limits to their ultimate levels. Towards this goal, Active Front Steering (AFS) and Direct Yaw-moment Control (DYC) systems have been widely investigated. AFS systems introduce corrective steering angles to conventional system in order to realize target handling response for a given speed and steering input. It is thus expected that such an action under severe maneuvers may cause one tire to reach saturation while the other tire may be capable of developing more force. This study, therefore, proposes an Active Independent Front Steering (AIFS) system capable of controlling a wheel independently. At low speeds, the proposed AIFS system will modify the steer angle with speeds while maintaining pro-ackerman geometry similar to an AFS system. In doing so, it will realize a target response defined as one provided by a neutral steer system. However, in a severe maneuver, as the inner tire approaches the saturation limit, the AIFS system controller will only increase the angle of the…
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A Systems Engineering Approach to Requirements Elicitation and Management

SAE International Journal of Passenger Cars - Mechanical Systems

PTC (Parametric Technology Corp)-Christina Perdikoulias, Doug Akers
  • Journal Article
  • 2012-01-2033
Published 2012-09-24 by SAE International in United States
Effective requirements elicitation and management is a common need in supplier-OEM relationships, and continues to play a vital role in all aspects of the product development lifecycle. While traditional methods address the business goals for requirements and provide guidance in ensuring the accuracy of the “Descriptive-Prescriptive-Explanatory” outputs for requirements gathering and documentation, engineering organizations continue to encounter challenges with respect to capturing and communicating change, accommodating the addition of relevant design details and efficient propagation to inform development. These challenges become more difficult to overcome in mechatronic systems, which combine mechanical systems with integrated software.As software development can produce an overwhelming volume of information that requires accurate tracking and proliferation, it cannot be effectively managed using traditional hardware-centric systems. This increased complexity introduced by software-intensive products pushes existing tools to their limits, making the efficient management of information critical to successful product delivery.In this paper, we describe a systems engineering approach to requirements elicitation and management. As systems engineering focuses on the design and management of engineering projects over their lifecycles, it offers an interdisciplinary…
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Role of Accurate Numerical Simulation of Brake Cooldown in Brake Design Process

SAE International Journal of Passenger Cars - Mechanical Systems

Exa Corporation-Devadatta Mukutmoni, Sacha Jelic, Jaehoon Han, Michael Haffey
  • Journal Article
  • 2012-01-1811
Published 2012-09-17 by SAE International in United States
An important metric in the vehicle brake design process, the cool-down time for a brake disk, strongly influences the durability and reliability of brakes. However, the brake cool-down time is a function of many vehicle and chassis factors, making it time consuming and expensive to evaluate and optimize in hardware testing.In this study, we investigate an alternative approach to hardware testing for evaluating brake design cool-down time by implementing a CFD (Computational Fluid Dynamics) simulation based methodology. The simulation cases were all compared with test data and good agreement was observed between test data and simulation over a wide range of design parameters. It is therefore demonstrated that accurate simulation is a promising new approach to the brake design process.
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Dynamic Control of Disc Brake Performance

SAE International Journal of Passenger Cars - Mechanical Systems

SP Lasta a.d, Serbia-Velibor Sovrović
University of Belgrade, Serbia-Dragan Aleksendrić, Velimir Cirovic
  • Journal Article
  • 2012-01-1837
Published 2012-09-17 by SAE International in United States
Since the driver obtains an important feedback of vehicle dynamics and its braking capabilities depending on a brake performance change, it represents an important aspect of vehicle performance and its quality of use. Regarding modern automotive brakes, the extreme demands have been imposed on the friction couple and its tribological performance. Different sensitivity of braking torque, i.e. a disc brake performance versus the influence of the friction couple interaction, under different braking conditions (applied pressure, speed and brake interface temperature), is one of the most important the disc brake properties. That is why, control of braking performance in the sense of providing stable braking performance during a braking cycle and their dynamic adaptation to the driver demands and/or demands imposed by ABS/ESC, are very important. Investigation presented in this paper contributes to the efforts in the direction of intelligent dynamic control of automotive braking systems performance. The dynamic model has been developed in the paper in order to provide dynamic prediction and control of the disc brake performance during a braking cycle. This model provided…
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New Brake By Wire Concept with Mechanical Backup

SAE International Journal of Passenger Cars - Mechanical Systems

MOBIS-Jae Seung Cheon, Jongsung Kim, Jaehan Jeon
  • Journal Article
  • 2012-01-1800
Published 2012-09-17 by SAE International in United States
Brake-By-Wire (BBW) is a term used to describe next generation brake systems that rely on motor driven electro-mechanical calipers in place of conventional hydraulic components such as the booster, master cylinder, hydraulic unit, and parking brake. Instead the system configuration is simplified to a pedal simulator, electro-mechanical calipers that require no boosting, and electric control units. The active, highly-responsive, and independent control of the brake actuators at each wheel allows for great control flexibility and improved brake performance. It is also very well-suited for easy integration with cooperative regenerative braking and driver assistance functions.Although such potential and innovations have driven the interest and research into BBW systems through the years, it has yet to be successfully introduced in series production mainly due to the underlying perception of the lack of reliability of electronic components and overall cost concerns.In the current investigation, a new concept of BBW system is proposed as a step towards overcoming such hurdles. The proposed concept provides a mechanical backup function that does not deter the system from the original performance benefits…
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Optimized Caliper Design for Low Drag Using DFSS Method

SAE International Journal of Passenger Cars - Mechanical Systems

GM Korea Company-Namyeul Ryu
Korea Delphi Automotive Systems Corp.-Junghan Kim, Youngtaek Kim
  • Journal Article
  • 2012-01-1835
Published 2012-09-17 by SAE International in United States
Limiting residual drag torque and fluid displacement is a major requirement of a caliper brake as they are related to the fuel efficiency and the safety of a vehicle. However, it is difficult to simultaneously reduce both the drag torque and the fluid displacement since improving one tends to degrade the other.This paper investigates a caliper with a high residual drag torque. DFSS (Design for Six Sigma) method was implemented to identify all major factors and the design optimization was performed to achieve a low drag caliper. The prototype was created with the desirable design factors identified in the study and the dynamometer tests confirmed that it is possible to achieve a low drag caliper without sacrificing the fluid displacement.
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Complex Eigenvalue Analysis and Brake Squeal: Traps, Shortcomings and their Removal

SAE International Journal of Passenger Cars - Mechanical Systems

TU Darmstadt-Gottfried Spelsberg-Korspeter, Peter Hagedorn
  • Journal Article
  • 2012-01-1814
Published 2012-09-17 by SAE International in United States
Among many NVH problems brake squeal continues to be a difficult topic for design engineers and scientists. Both the experimental and the simulation approaches so far have failed to provide robust and reliable guidelines for the design of squeal free brakes. On the experimental side the problem clearly lies in the wide range of operating conditions which the brake encounters in its lifetime, in which it should be squeal free. From lab experiments alone, it is hardly possible to judge how far the system is from squeal, which implies that an extremely wide range of conditions is mandatory. Brake squeal simulation presents different challenges. Once a model for the brake has been formulated, including the excitation mechanism(s), it should be possible to check the robustness of a given design and system parameters against squeal. Complex eigenvalue analysis has become a standard industrial tool for squeal prediction, and is routinely applied to the simulation models. Despite many years of research and development along these lines, the reliability of squeal prediction is still not adequate. This lack…
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Differential Effects of Dimensions on Various Vibration Modes of Brake Disc Rotors

SAE International Journal of Passenger Cars - Mechanical Systems

KIRIU Corp.-Toshikazu Okamura, Hiroyuki Yumoto, Masanori Imasaki
  • Journal Article
  • 2012-01-1822
Published 2012-09-17 by SAE International in United States
The propensity of brake squeal depends significantly on the vibrational characteristics of disc rotors. In this study, we focused on the differential effects of disc dimensions on the natural frequencies of various vibration modes. We analyzed the results of the CAE factorial experiments presented in our previous paper, which were conducted on four disc rotors with different designs such as front-and back-vented and solid discs. As a result, the effects of disc dimensions on natural frequencies were confirmed to depend on vibration modes, their orders (or the number of nodal diameters), and the basic design of disc rotors. The dimensions that change the stiffness of the friction ring such as ventilation-path width and fin thickness had larger effects on the out-of-plane circumferential modes of high orders than those of low orders. The dimensions around the necking, on the other hand, had a large effect on the low-order modes. The significance of these effects depends on the basic design of disc rotors as well. The effects of some typical dimensions on natural frequencies obtained from CAE…
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Research for Brake Creep Groan Noise with Dynamometer

SAE International Journal of Passenger Cars - Mechanical Systems

Hyundai Motor Company-Taeho Jung, Seung Chung
  • Journal Article
  • 2012-01-1824
Published 2012-09-17 by SAE International in United States
This paper deals with creep groan noise in vehicles which is a low frequency vibration problem at 20∼500Hz that appears in low brake pressures and extremely low speed especially in automatic transmission car, where there is a transition from static to dynamic condition. The vibration causing the noise is commonly thought to result from friction force variation between brake disc and pad in stick-slip phenomena. Simulation results are confirmed through dynamometer testing. Then presented noise contribution factor analysis by experimental approach between chassis components.
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