• Transactions of the Korean Society of Automotive Engineers
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• v.24 no.3
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• pp.365-371
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• 2016

The electromechanical brake (EMB) is one of future brake systems due to its many advantages. For implementation of the EMB, the correct feed back about clamping force is necessary. Keeping commercialization of the EMB in mind, it is strongly demanded that an expensive load cell measuring the clamping force is replaced with an estimation algorithm. In addition, an estimation of the kissing point where the brake pads start to come into contact with a disk wheel is proposed in this paper. With these estimation algorithms, the clamping force can be expressed as a polynomial characteristic curve versus the motor angle. Also, a method for calibration of measured values by the load cell is proposed and used for an actual characteristic curve. Lastly, the performance of the proposed algorithms is evaluated in comparison with the actual curve on a developed EMB test bench.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.11
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• pp.6406-6411
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• 2014

This paper presents the analytical-FE (finite element) squeal model, which can provide the efficient simulation time and accuracy. The system geometry and the extraction of the vibration modes were constructed using the finite element method. Instead, the friction contact model was derived from theoretical contact kinematics of the rotating disc and the stationary pads. This modeling procedure was incorporated into the perturbed equations of motion based on the finite elements of the system. Throughout the analytical-FE squeal model, the accuracy of linear stability analysis and the simulation time of FE squeal analysis were improved. In addition, the sensitivity of contact stiffness on brake squeal and the mode-coupling mechanism were provided by the system parameter study.

• Journal of the Korean Society for Railway
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• v.17 no.4
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• pp.223-227
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• 2014

The brake pad is one of the basic brake elements of a railway vehicle. It accomplishes braking action by friction between a pad and a brake disc. Because the brake pad must endure specified high pressure, the compressive strength is managed as the main performance factor. The standards for measuring the compressive strength of brake pads are KRS, KRCS, and KRT. These standards specify the size of the test piece for measuring compressive strength as $20mm{\times}10mm{\times}15mm$ ($W{\times}D{\times}H$). To reduce the uncertainty of the compressive strength, factors of uncertainty were analyzed. The results show that changing the dimensions of the cross section was useful to reduce the uncertainty. The uncertainty due to the new cross-sectional dimension shows the effectiveness of reducing uncertainty.

• Tribology and Lubricants
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• v.34 no.2
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• pp.55-59
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• 2018

This paper proposes a new type of electro-mechanical wedge brake for commercial vehicles. The brake operates on a novel mechanism for self-boosting braking friction forces using eccentric shafts, and involves wedges that are inserted between the rampbridge and traverse; this self-boosting mechanism is explained herein. A dynamic analysis using ADAMS was conducted, and the findings are reported. The constraint and contact conditions are explained to verify the precision of the dynamic analysis. The dynamic analysis shows that in the proposed mechanism, the self-boosting effect occurs as desired. However, it is also noted that the system has a limitation in terms of the production of unlimited braking forces that can jam the roller inside the wedges. After demonstrating the self-boosting effect, dynamic analyses are performed for several values of the wedge angles and friction coefficients between the brake pads and disks. Conventionally, a lower wedge angle has been suggested owing to its provision of a larger clamping force for given friction coefficients. However, it is noted that lower wedge angles can lead to a higher probability of occurrence of undesirable high braking forces, which can jam the roller into the wedge; thus, a larger wedge angle is preferable for avoiding the undesirable jamming phenomena. These analysis results are presented and discussed herein.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1998.10a
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• pp.330-336
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• 1998

The friction and wear characteristics of automotive friction materials reinforced with carbon fibers were studied using a direct drive brake dynamometer. Two types of model friction materials, a low-metallic and an NAO type, were prepared and each of the materials was modified by substituting 5 vol% of carbon fibers with other reinforcing fiber used in the model formulations. Drag tests were carried out to investigate the friction properties of these materials at various braking conditions. Results showed that the modified friction materials were improved in the friction stability and the wear resistance.

• KSTLE International Journal
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• v.7 no.2
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• pp.56-60
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• 2006

By the increasing amount of vehicles, the increase of car accident served as a major momentum for remind the importance of braking system. The adequate design of a passenger car braking system, which is directly related to the safety of a car, is very important since the safety is an essential design parameter of a car to keep men and car from the damage. The thermal behaviors of the ventilated disk has been investigated based on the air cooling effects during repeat braking operations. In this study, the temperature and velocity fields of 3-D unsteady simulated model are obtained using a software package "FLUENT". The numerical results show that there exits a temperature nonuniformity between the disk faces contacting with pads.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.11
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• pp.1692-1696
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• 2004

This paper presents the thermally induced hot spot characteristics of rubbing surface in the friction pad disk brake. During the braking period, the rubbing surface with irregular asperities that are strongly engaged in rough surface, wear, and deformed surface due to a friction heating may produce an irregular distorted geometry of the disk surface. The tribological interactions between the disk and the pads are unstable if the contact stress is severe, in which the irregularity develops the contact pressure distribution, leading eventually to localized contact, high temperature and formation of hot spots. The computed results of contact spots that are simulated using a coupled thermal-mechanical analysis present sinusoidal distortions and localized extrusions of the disk surface, which are strongly related to a hot spot in the practical disk brake.

• Tribology and Lubricants
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• v.13 no.3
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• pp.10-19
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• 1997

Frictional characteristics of two different types of automotive friction materials were studied. They were non-asbestos organic and semi-metallic friction materials. The two friction materials were tested using an inertial brake dynamometer to investigate friction stability, rooster tailing phenomena, temperature change during drags and stops. Results show that the level of the friction force is strong functions of time, temperature, and speed regardless of the type of friction materials. In particular, rooster tailing effects are pronounced in the case of semi-metallic friction materials compared to non-asbestos organic friction materials. The phenomena appear strongly dependent on raw materials contained in the friction materials.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2010.10a
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• pp.344-345
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• 2010

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.242-243
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• 2012