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SAE International Journal of Passenger Cars Mechanical Systems
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Fast Characterization of Brake Squeal Behavior

SAE International Journal of Passenger Cars - Mechanical Systems

Technische Universität Berlin-Stefan Schlagner, Utz von Wagner
  • Journal Article
  • 2009-01-3006
Published 2009-10-11 by SAE International in United States
The last decades have shown extensive efforts on the investigation of automotive disk brake squeal. The origin of brake squeal is seen in self-excited vibrations, caused by the friction forces transferring energy from the rotating disk into the brake system. Based on a very simple model, Popp et al. described in 2002 the conditions for positive work of the friction forces (i.e. excitation of squeal), which depends on the phase shift between the in-plane motion (with respect to the disk) of the brake pad and the friction forces. Experiments on active manipulation of this phase shift using pads with integrated piezoceramic actuators, performed by von Wagner et al. in 2004, resulted in successful suppression of disk brake squeal.The authors of the present paper used a variety of models for the investigation of the origin of the excitation mechanism by observing phase relations between the friction forces and the vibrations of the pads. Several measurement techniques based on these theoretical investigations are developed in order to detect parameter regions (e.g. brake pressure, temperature, rotation speed) which…
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Systematic Brake Development Process and Optimized Robust Design of Front Axle Kinematics in Order to Reduce Oscillation Sensitivity

SAE International Journal of Passenger Cars - Mechanical Systems

Audi AG-Jan Muenchhoff
Technische Universitaet Muenchen-Albert Schlecht, Bernd Heissing
  • Journal Article
  • 2009-01-3038
Published 2009-10-11 by SAE International in United States
Brake judder is about oscillations excited by brake application, which are generated in the contact area between brake pad and brake disc and are transmitted by the elements of the suspension to body and steering system. The driver perceives these perturbations as brake pedal pulsations, steering wheel rotational and body vibrations. The evaluation of a suspension concerning brake judder often takes place for the first time in road tests, since established simulation processes with a high significance concerning ride comfort are missing. At such a late moment necessary modifications in the development process are only hardly possible and very expensive. For avoiding brake judder a systematic development process is needed for brake and suspension. Each one can separately be improved in measurably borders so that their assembly is free of cold brake judder. The present paper shows appropriate test and simulation methods to achieve this.
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The Influence of Vibration on Friction

SAE International Journal of Passenger Cars - Mechanical Systems

University of South Florida-Daniel P. Hess
  • Journal Article
  • 2009-01-3015
Published 2009-10-11 by SAE International in United States
This paper summarizes results from the author's work on friction in dry sliding contacts in the presence of vibration. A number of idealized models of smooth and rough contacts are examined. It is shown that vibration can cause up to a 10% reduction in average friction even with continuous contact. A larger reduction in friction occurs when there is intermittent contact loss. This is found to be true for both elastic and plastic contacts, and for adhesive and plowing mechanisms of friction. The results of this work are compared and validated with measurements from experiments. The results presented are fundamental, but applicable to machine components with contacts including brake systems.
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Main Design Factors and Unified Software Structure for Cable Puller and Caliper Integrated Type Electric Parking Brakes

SAE International Journal of Passenger Cars - Mechanical Systems

Hyundai MOBIS-J. S. Cheon, J. W. Jeon, H. M. Jung, I. U. Park, C. H. Park, T.-J. Yeo
  • Journal Article
  • 2009-01-3022
Published 2009-10-11 by SAE International in United States
The main classification of Electric Parking Brakes (EPB) can be made into cable puller and caliper integrated types. In this paper, the main design considerations that need to be made for each type of system will be examined. In terms of mechanical design, actuator design factors including target capacity, system size, and vehicle mounting will be briefly discussed. In terms of software, a unified software structure that can incorporate both types of EPBs will be introduced. This unified approach, made up of fixed and variable modules, allows for more efficient software development for both types of EPB systems. The fixed modules are related to the identical target functions regardless of EPB type, while the variable modules are made up of the different considerations that need to be made depending on the EPB type in order to meet such targets. Finally, some test results of target functions for both types of EPB systems will be given.
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Stability Analysis of a Disc Brake with Piezoelectric Self-Sensing Technique

SAE International Journal of Passenger Cars - Mechanical Systems

Institut für Dynamik und Schwingungen-Marcus Neubauer, Andreas Renner, Jens Twiefel
  • Journal Article
  • 2009-01-3034
Published 2009-10-11 by SAE International in United States
Piezoelectric self-sensing allows to measure frequency response functions of dynamical systems with one single piezoelectric element. This piezoceramics is used as actuator and sensor simultaneously. In this study, a model-based piezoelectric self-sensing technique is presented to obtain potential squealing frequencies of an automotive disc brake.The frequency-response function of the brake system is obtained during operation by measuring the current flowing through the piezoelectric element while the piezoelectric element is driven by a harmonic voltage signal with constant amplitude. The current flow is composed of the part which is required to drive the piezoelectric element as an actuator and a second part which is the sensor signal that is proportional to the vibration amplitude of the attached mechanical system. Typically the first part is dominant and the influence of the mechanical system is marginal.With an idealized mathematical model of the piezoelectric element, the admittance can be calculated and the actuator current eliminated from the measured signal. This software-based solution does not require any additional electrical circuits or precise tuning during the measurements.Potential squealing frequencies which agree…
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Acoustic Analysis of Exhaust Muffler of a 4-Stroke Engine

SAE International Journal of Passenger Cars - Mechanical Systems

Engineering Research Centre, Tata Motors Ltd.-Abhishek Vishwakarma
Indian Institute of Technology-P. Chandramouli, V. Ganesan
  • Journal Article
  • 2009-01-1980
Published 2009-06-15 by SAE International in United States
A one-dimensional analysis was performed to analyze a three-pass muffler with perforated tubes for Transmission Loss, using numerical decoupling approach. Effect of mean flow on transmission loss inside the muffler was studied. To account for the three-dimensional nature of acoustic waves at higher frequencies, a three dimensional finite element analysis was done using SYSNOISE. The Transmission loss results of the three-dimensional analysis were compared with those of one-dimensional analysis for no flow case and shown to agree reasonably for lower frequency range.
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Biomechanical Evaluation of Headwear System Prototypes using Digital Human Modeling

SAE International Journal of Passenger Cars - Mechanical Systems

HumanSystems Incorporated-Kent W. McKee
  • Journal Article
  • 2009-01-2267
Published 2009-06-09 by SAE International in United States
Digital human modeling allows for the evaluation of equipment designs before physically building and testing prototypes. This paper presents an example of how digital human modeling was used to perform biomechanical studies on four new designs for future infantry headwear systems. Range of Motion (ROM) and cervical spine forces and moments were compared using static and dynamic simulations in a virtual environment. Results confirmed that headwear system prototypes with optimal overall mass and Centre of Mass (CM) location, as determined by previous human subject trials, exerted the least amount of biomechanical loading. Facial protection was favorable when considering forces and moments in the cervical spine, however when considering ROM, the rigid prototype mandible guards used in this evaluation are not recommended. The shape of a more accommodating mandible guard was developed, and the option to remove facial protection for some tasks was recommended.
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Dynamic Analysis of Car Ingress/Egress Movement: an Experimental Protocol and Preliminary Results

SAE International Journal of Passenger Cars - Mechanical Systems

INRETS-Julien Causse, Elodie Chateauroux, Gilles Monnier, Xuguang Wang
PSA Peugeot-Citroen-Lisa Denninger
  • Journal Article
  • 2009-01-2309
Published 2009-06-09 by SAE International in United States
This paper focuses on full body dynamical analysis of car ingress/egress motion. It aims at proposing an experimental protocol adapted for analysing joint loads using inverse dynamics. Two preliminary studies were first performed in order to 1/ define the main driver/car interactions so as to allow measuring the contact forces at all possible contact zones and 2/ identify the design parameters that mainly influence the discomfort.In order to verify the feasibility of the protocol, a laboratory study was carried out, during which two subjects tested two car configurations. The experimental equipment was composed of a variable car mock-up, an optoelectronic motion tracking system, two 6D-force plates installed on the ground next to the doorframe and on the car floor, a 6D-Force sensor between the steering wheel and the steering column, and two pressure maps on the seat. Motions were reconstructed from measured surface markers trajectories using inverse kinematics. Joint loads were calculated by an inverse dynamic approach using a recursive Newton-Euler procedure.The validation of the computing method and the relevance of a dynamic approach are…
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Inverse Dynamic Reconstruction of Truck Cabin Ingress/Egress Motions

SAE International Journal of Passenger Cars - Mechanical Systems

INRETS-Gilles Monnier, Elodie Chateauroux, Xuguang Wang
VOLVO 3P-Christophe Roybin
  • Journal Article
  • 2009-01-2286
Published 2009-06-09 by SAE International in United States
This paper investigates the feasibility of calculating joint forces and moments during a whole body truck cabin ingress/egress motion. For such a task, it is difficult to evaluate a future truck instep as the influences of the architecture parameters are complex over the motion and the discomfort feeling. In order to evaluate the future product at an early stage of the design process, Digital Human Models (DHMs) are interesting tools. However, most existing DHM simulation packages can only efficiently evaluate the kinematics of postures where the dynamics of the whole motion is necessary for such a task. The enhancement of DHMs towards a dynamic analysis and modeling is therefore necessary.In this study, the motions of subjects entering and exiting an adjustable truck cabin were measured by mean of an opto-electronic motion capture system and six load sensors. The joint angles were then calculated using an inverse kinematics method. And the joint loads were calculated using a classical Newton-Euler inverse dynamics method during the period when all the contact loads are measured. The comparison of the…
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Estimation of Mass and Inertia Properties of Human Body Segments for Physics-based Human Modeling and Simulation Applications

SAE International Journal of Passenger Cars - Mechanical Systems

The University of Iowa-Rajeev Penmatsa, Rajankumar Bhatt, Kimberly Farrell, Brent Rochambeau, Carl Fruehan, Uday Verma, Steven Beck, Karim Abdel-Malek
  • Journal Article
  • 2009-01-2301
Published 2009-06-09 by SAE International in United States
This paper describes an effective integrated method for estimation of subject-specific mass, inertia tensor, and center of mass of individual body segments of a digital avatar for use with physics-based digital human modeling simulation environment. One of the main goals of digital human modeling and simulation environments is that a user should be able to change the avatar (from male to female to a child) at any given time. The user should also be able to change the various link dimensions, like lengths of upper and lower arms, lengths of upper and lower legs, etc. These customizations in digital avatar's geometry change the kinematic and dynamic properties of various segments of its body. Hence, the mass and center of mass/inertia data of the segments must be updated before simulating physics-based realistic motions. Most of the current methods use mass and inertia properties calculated from a set of regression equations based on average of some population. In this paper, we calculate avatar-specific mass and inertia properties from the scans of digital human. The mesh of the…
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