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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.

In the past, each noise shim supplier had its own specifications to describe the properties of their noise shims (often also called as shim or damping shim). Due to that, it was difficult to compare the physical properties of noise shims from different suppliers. The main task was to define common specifications for daily quality/development tests. Traceability in prototype status and production was introduced establishing a clear declaration of noise shim deliveries with batch no. and “use by” date. Harmonization was created through standardized tests and procedures. In addition, a common noise shim database for all noise shim manufacturers was established. A more realistic compressibility test was developed to estimate the additional compressibility of noise shims based on bare pads under cold and hot conditions. These values are important to describe the axial decoupling at low pressure and the maximal displacement at high forces.

In the automotive industry, FMEA occurrence ranking is made to a standard such as SAE J1739. The SAE J1739 standard, as does other comparative standards, provides numerical probability criteria to aid ranking. Problems arise when the part or system under analysis is new, and there is no field data to estimate the probability of failure occurrence. Attempts to use qualitative verbal criteria or to go by the “feel” often result in inconsistency or large variability across and within FMEA projects. This paper presents a case study in which this problem was solved by the development of a tool that enables consistent - and efficient - FMEA occurrence rankings. The tool takes input from the user in the form of multiple-choice answers and calculates the final solution.

The intent of this study was to compare the neck responses measured from the Hybrid III 3 and 6-year-old ATDs in laboratory testing to injuries sustained by three children in a field crash and investigate the appropriateness of recommended in-position neck injury assessment reference values (IARVs), and the regulated out-of-position (OOP) IARVs specified in FMVSS 208 for the Hybrid III 3 and 6-year-old ATDs. This paper principally reports on apparent artifacts associated with the Hybrid III 3 and 6-year-old ATDs, which complicated investigating the appropriateness of the in-position and out-of-position neck IARVs. In tests using 3-point belt restraints, these apparent artifacts included: 1) High neck extension moments, which produced the peak Nij values, without significant observed relative head-to-neck motion, 2) Neck tension forces well in excess of the IARVs that occurred when the ATD's chin contacted the chest.

The noise problem in a multiple-piston hydraulic pump was investigated through computer simulation combining lumped and distributed parameter models (CFD). Analysis results have shown that the source of noise is the turbulence flow and pressure perturbation in the pump gallery caused by check valve flow interference. It was identified that this flow induced noise can be reduced by modifying the check valve characteristic and its flow profile without compromising pump performance.

Steer-By-Wire will be the steering technology of the future. The mechanical connection between the hand wheel and the front axle will become obsolete. Independent electronically controlled actuators will set the road wheel steering angles and will provide force feedback to the driver. This paper presents the approach to establish a production intended steer-by-wire solution in two steps. In a first step a fail safe steer-by-wire system with a mechanical backup is developed which meets the functional and performance requirements of today's passenger vehicles. In the second step this concept is expanded to a future fault tolerant system architecture without any mechanical backup.

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.

Injuries to the knee-thigh-hip (KTH) complex in frontal motor vehicle crashes are of substantial concern because of their frequency and potential to result in long-term disability. Current frontal impact Anthropometric Test Dummies (ATDs) have been shown to respond differently than human cadavers under frontal knee impact loading and consequently current ATDs (and FE models thereof) may lack the biofidelity needed to predict the incidence of knee, thigh, and hip injuries in frontal crashes. These concerns demand an efficient and biofidelic tool to evaluate the occurrence of injuries as a result of KTH loading in frontal crashes. The MADYMO human finite element (FE) model was therefore adapted to simulate bone deformation, articulating joints and soft tissue behavior in the KTH complex.

Interaction of the human arm and deploying airbag has been studied in the laboratory using post mortem human subjects (PMHS). These studies have shown how arm position on the steering wheel and proximity to the airbag prior to deployment can influence the risk of forearm bone fractures. Most of these studies used older driver airbag modules that have been supplanted by advanced airbag technology. In addition, new numerical human body models have been developed to complement, and possibly replace, the human testing needed to evaluate new airbag technology. The objective of this study is to use a finite element-based numerical (MADYMO) model, representing the human arm, to evaluate the effects of advanced driver airbag parameters on the injury potential to the bones of the forearm. The paper shows how the model is correlated to Average Distal Forearm Speed (ADFS) and arm kinematics from two PMHS tests.

Injuries of the Occipitoatlantoaxial (Occ-C2) region (also known as atlanto-occipital injuries) are the most common form of cervical injury in children aged ten years and younger. The crash studied in this paper is unique in that there were three children ages 3, 6 and 7 involved in a frontal crash with a delta V of 28mph with each child receiving a nonfatal Occ-C2 injury of varying degrees. The 3 and 6 year-old children were remarkably similar in height and weight to the 3 and 6 year-old Hybrid III ATD's. Also, unique to this case is the fact that the right rear 6 year-old occupant likely sustained an Occ-C2 injury prior to impact with the frame of the front passenger seat. This crash environment was recreated utilizing MADYMO occupant simulation software. The models for the Hybrid III 3 and 6 year-old ATDs were used to represent the occupants in this crash.

The biomechanical behavior of 4-point seat belt systems was investigated through MADYMO modeling, dummy tests and post mortem human subject tests. This study was conducted to assess the effect of 4-point seat belts on the risk of thoracic injury in frontal impacts, to evaluate the ability to prevent submarining under the lap belt using 4-point seat belts, and to examine whether 4-point belts may induce injuries not typically observed with 3-point seat belts. The performance of two types of 4-point seat belts was compared with that of a pretensioned, load-limited, 3-point seat belt. A 3-point belt with an extra shoulder belt that “crisscrossed” the chest (X4) appeared to add constraint to the torso and increased chest deflection and injury risk. Harness style shoulder belts (V4) loaded the body in a different biomechanical manner than 3-point and X4 belts.

Both frontal and side air bags can inflict injuries to the upper extremities in cases where the limb is close to the air bag module at the time of impact. Current dummy limbs show qualitatively correct kinematics under air bag loading, but they lack biofidelity in long bone bending and fracture. Thus, an effective research tool is needed to investigate the injury mechanisms involved in air bag loading and to judge the improvements of new air bag designs. The objective of this study is to create an efficient numerical model that exhibits both correct global kinematics as well as localized tissue deformation and initiation of fracture under various impact conditions. The development of the model includes the creation of a sufficiently accurate finite element mesh, the adaptation of material properties from literature into constitutive models and the definition of kinematic constraints at articular joint locations.

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.

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.

Recently, during the course of different experimental problem-solving activities on automotive vehicles, several examples have been found in which the identification of the cause of a particular vibration problem related to a specific component or subsystem involves detecting the presence of an impulsive effect on measured time signals. The difficulty in identifying such an effect arises due to the fact that the vibrational response signals measured during operation are dominated by relatively high amplitude harmonics which tend to mask the impulsive component. This article describes two case studies for this type of identification problem, a servo-assisted steering system and a front suspension shock absorber strut.