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The ISO TC22/SWG2 - Brake Lining Committee established a task force to determine and analyze root causes for variability during dynamometer brake performance testing. SAE paper 2010-01-1697 “Brake Dynamometer Test Variability - Analysis of Root Causes” [1] presents the findings from the phases 1 and 2 of the “Test Variability Project.” The task force was created to address the issue of test variability and to establish possible ways to improve test-to-test and lab-to-lab correlation. This paper presents the findings from phase 3 of this effort-description of factors influencing test variability based on DOE study. This phase concentrated on both qualitative and quantitative description of the factors influencing friction coefficient measurements during dynamometer testing.

Electrically Powered Hydraulic Steering (EPHS) was developed in the early 90s and previously applied to vehicle segments B and C (small and medium-sized passenger cars). Till now more than 10 million vehicles are in the field. The advantages consist of the well known power density coming along with the flexible package. Value is added due to the consequent development and usage of electronic control realized in compact physical units. As a result key features for chassis control systems like controllability, high dynamic performance, and low energy consumption are achieved while maintaining mature and robust hydraulic components. Recent market requirements in other segments, e.g. Sport Utility Vehicles (SUV) and Light Commercial Vehicles (LCV) require higher powered motor pump units and lead to the decision to develop products in this direction.

This paper reports the progress that has been made to date on a research program that has as its focus to describe the mechanism of metal pick-up generation on passenger car disc brake pads in correlation with deep rotor scoring. In contrast to other existing generation theories, the new investigation considers other aspects of the initial onset of the metal pick-up.

One of the most important means used for suppressing squeal noise in disc brakes is the application of shims on the pad backplates. In many cases this proves a very efficient tool depending on the type of shim applied in the specific cases. Building up knowledge on the effects of shims have been ongoing for several years, and measuring the important parameters characterizing the shims is crucial for understanding how to develop and implement the shims in an optimal way. Several methods are described in literature for measuring the constrained layer damping effect and one method is described for direct measurement of the shear stiffness and shear damping properties. However, up to now no method has been available that can measure and characterize the normal stiffness and damping properties of shims. This is one of the most important properties of shims as it controls the de-coupling effect in the direction of the normal forces.

An ABS/TC proportional pressure control can be achieved by using some of the control technology applied to an electro-hydraulic brake (EHB) system. This paper describes a new method for reducing the calibration time of an EHB, and this method may be used for potential advanced ABS/TC proportional control systems. A mathematical model is established to analyze the system and by using the model some common physical relationships are identified. Calibration values of a proportional system in certain pressure ranges can be estimated instead of requiring measurement.

Customers of new vehicles expect their vehicle to provide reliable operation. One path vehicle manufacturers have chosen to meet this expectation is to offer their customers advanced braking systems. Antilock Brakes (ABS) and Traction Control (TC) are two advanced braking systems that have evolved to a point at which many OEM's offer them as standard equipment. Size, weight, and performance have also improved to the point of near transparent operation in many cases. The current direction of braking system evolution is in making Vehicle Stability Control (VSC) widely available as well. VSC adds the ability to assist the driver in negotiating understeer and oversteer, by adding corrective braking and engine torque to the vehicle as appropriate. A large percentage of VSC system modeling is related to the sensors chosen to provide driver and vehicle dynamic information to the system's electronic control unit (ECU).

The continuous decrease in background noise levels inside vehicles has made other noise sources easily noticeable. Specifically, foundation brake rattle noise is a growing concern to the customer. This brake rattle is primarily due to rigid body impact between brake components. Currently, vehicle and brake manufacturing companies use different testing procedures to evaluate brake rattle that include laboratory vibration shakers, full vehicle shakers (four post), chassis dynamometers and vehicle road testing. These evaluations are subjective in most cases. A method is needed to replicate and quantify vehicle brake rattle in the laboratory to help determine the acceptability of a brake system at a component level. This approach would also help to identify the root cause for brake rattle and evaluate design changes to address that rattle. Some guidelines for better quantifying brake rattle using shakers will be proposed in this paper.

This paper reviews the state of the art of CAE simulation and analysis methods on disc brake squeal. It covers complex modes analysis, transient analysis, parametrical analysis, and operational simulation. The advantages and limitations of each analysis method are discussed. This review can help analysts to choose right methods and decide new lines of method development. For completeness, analytic methods dealing with continuum models are also briefly covered. This review was made from those papers that the authors are familiar with. It is not meant to be all-inclusive even though the best possible effort has been attempted.

It is always a challenging task for the braking industry to maintain consistent friction material behavior during brake system development. Lack of consistency in friction behavior causes significant disruptions in efforts to integrate friction material with the foundation brake system. This is especially true when new friction formulations and/or manufacturing processes are introduced during an application program. Furthermore, every new program has new requirements that introduce new challenges and issues to the brake and friction manufacturers. As issues arise during the Application development, engineers devise countermeasures that often entail new engineering techniques and methods. Sometimes, such countermeasures amount to inventions to cover the inadequacy of lining behavior during brake integration.

This paper provides measurement and analysis on rotor in-plane mode induced squeal. Methodology is presented to simultaneously acquire both temporal and spatial squeal operational deflection shapes (ODS). Rotor accelerations both in the in-plane and out-of-plane directions were measured during squeal along with rotor's normal ODS using a laser vibrometer. Modal measurement and analysis of the rotor and pad in the in-plane and out-of-plane directions were conducted as installed in system condition. The test results indicating rotor modal coupling in the in-plane are provided, and out-of-plane directions, and conclusions on in-plane mode induced squeal are proposed. In addition, the countermeasure for squeal reduction is discussed.

Today's newer friction materials and brake systems are able to operate under extreme conditions that are not normally evaluated with the standard squeal rig procedures. This could cause some discrepancy between the squeal rig test results and the vehicle test results like Los Angeles City Traffic Test (LACT). In some cases the noise behavior of brake systems could change dramatically and take us by surprise with new squeal frequencies being uncovered or get flagged due to high occurrences. This discrepancy could also be a major handicap with respect to developing a noise fix in the lab if the squeal cannot be reproduced. In this paper, we evaluated some case studies where some extreme conditionings especially related to thermal inputs drastically changed the squeal behavior of the brake system.

There has been a rapid increase in popularity of multipurpose All-terrain vehicles (ATV) across the globe over the past few years. SAE BAJA event gives student-community an opportunity to delve deeper into the nitty-gritty of designing a single seat, four-wheeled off road vehicle. The design and development methodology presented in this paper is useful in conceptualization of an ATV for SAE BAJA event. The vehicle is divided into various subsystems including chassis, suspension, drive train, steering, and braking system. Further these subsystems are designed and comprehensively analyzed in software like SolidWorks, ANSYS, WINGEO and MS-Excel. The 3-D model of roll cage is designed in SolidWorks and analyzed in ANSYS 9.0 for front, rear and side impact along with front and side roll-over conditions. Special case of wheel bump is also analyzed. Weight, wall thickness and bending strength of tubing used for roll cage are comprehensively studied.

Modern project management including brake testing includes the exchange of reliable results from different sources and different locations. The ISO TC22/SWG2-Brake Lining Committee established a task force led by Ford Motor Co. to determine and analyze root causes for variability during dynamometer brake performance testing. The overall goal was to provide guidelines on how to reduce variability and how to improve correlation between dynamometer and vehicle test results. This collaborative accuracy study used the ISO 26867 Friction behavior assessment for automotive brake systems. Future efforts of the ISO task force will address NVH and vehicle-level tests. This paper corresponds to the first two phases of the project regarding performance brake dynamometer testing and presents results, findings and conclusions regarding repeatability (within-lab) and reproducibility (between-labs) from different laboratories and different brake dynamometers.