• 한국재료학회지
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• 제19권7호
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• pp.403-406
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• 2009

The friction characteristics of automotive brake friction materials that contained different ceramic content were investigated. Several kinds of raw materials, such as resin-based binder, reinforcing fiber, friction restraint, abrasive, and filling materials were mixed, pressed, and heated in order to make the brake friction materials. The contents of SiC and $BaSO_4$ changed from 5 vol% to 20 vol%, respectively. In addition to this, the content of $Al_2O_3$ adjusted from 1 vol% to 16 vol%. The surface morphology of the SiC containing sample appeared rough while more debris was observed when the contents of SiC increased. This implies that the SiC containing brake composite was not adequate for the automobile. However, the relatively smooth surface was observed in samples that contained the $Al_2O_3$. But the roughness was low with a content of 11 vol% $Al_2O_3$ compared to the other samples. This is consistent with the abrasive properties of the samples. In the case of $BaSO_4$ containing samples, the smoothes surface was observed in the contents of 15 vol% $BaSO_4$. Thus, it was concluded that the 11 vol% $Al_2O_3$ and 15 vol% $BaSO_4$ containing composite would be the optimum content for the brake composite. Similar to the results of the surface morphology, the abrasion resistance consistently decreased when the content of SiC increased. On the contrary, the sample that contained 11 vol% $Al_2O_3$ and 15 vol% $BaSO_4$ showed the highest abrasion resistance compared to the other samples.

• Tribology and Lubricants
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• 제24권4호
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• pp.163-169
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• 2008

Tribological properties of ceramic brake discs were investigated using a commercial friction material. The discs were manufactured by liquid silicon infiltration (LSI) into a C-C preform. The disc surface was modified by two different methods, producing sliding surfaces with chopped carbon fibers and carbon felt. In addition, the composition of the surface was also changed. Friction characteristics of the discs were examined using a 1/5 scale dynamometer. Results showed that the type and composition of the disc surface significantly affected the level of braking effectiveness and high temperature brake performance. The discs with felt surfaces showed higher friction levels than those with chopped fiber surfaces and SiC tended to increase the friction level while C lowered the friction coefficient. The ceramic disc was more sensitive to the deceleration rate than gray iron, showing high speed sensitivity.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.2080-2093
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• 2008

대표적으로 높은 운동에너지를 가지는 고속철도와 항공기의 제동장치에 적용되는 금속계 소결마찰재와 내열강 간의 트라이볼로지 특성 연구를 목적으로 각각 2종류의 고속철도용 금속계 마찰재와 항공기용 금속계 마찰재를 Lab-Scale Dynamometer를 이용하여 시험하였다. 그 결과 철도용 금속계 마찰재가 항공기용 마찰재에 비해 높은 마찰계수 및 마찰계수 안정성을 나타내었고, 마모량도 철도용 금속계 마찰재는 항공기용 마찰재에 비해 약 50%수준에 불과하여 본 시험조건에서는 철도용 소결마찰재가 뛰어난 것으로 나타났다. 또한, 동계 마찰재가 철계 마찰재보다 제동시 급격하게 온도가 상승하며, 냉각도 동계 마찰재가 빨리 되지만, 동계 마찰재라도 마찰재의 기지의 량에 따라 달라지는 것으로 나타났다. 마찰재에 따라 마찰면에 형성되는 산화피막의 안정성은 달라지는 것으로 나타났으며, 산화피막은 $Fe_2O_3$와 $Fe_3O_4$계통이며, 마찰재에 따라서 마모메카니즘이 달라지는 것으로 판단된다.

• 한국소음진동공학회논문집
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• 제18권10호
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• pp.1042-1048
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• 2008

Disc brake noise is an important customer satisfaction and warranty issue for many manufacturers as indicated by technical literature regarding the subject coming from Motor Company. This research describes results of a study to assess disk brake squeal propensity using finite element methods and optimal technique (Kriging). In this study, finite element analysis has been performed to determine likely modes of brake squeal. This paper deals with friction-induced vibration of disc brake system under contact friction coefficient. A linear, finite element model to represent the floating caliper disc brake system is proposed. The complex eigen-values are used to investigate the dynamic stability and in order to verify simulations which are based on the FEM model. In this paper, Kriging from among the meta-modeling techniques is proposed for an optimal design scheme to reduce the brake squeal noise.

• 한국재료학회지
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• 제14권1호
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• pp.59-66
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• 2004

In the present study, ceramic brake pads without fiber phases were manufactured by the low temperature heat treatment below$ 700 ^{\circ}C$. The manufacturing parameters of ceramic brake pads and those levels were investigated by the analysis results of signal-to-noise ratios, ANOVA based upon the Taguchi method. The ceramic brake pads prepared in the Mg experiment had a friction coefficient of 0.30～0.55 very close to the target coefficient (0.35～0.45) of commercial brake pads utilized in the automobiles. The frictional properties of ceramic brake pads could be stabilized with the adjustment of amounts of lubricating additives. The optimum preparation conditions as well as batch formulations for the fabrication of non-fibrous ceramic brake pads were finally determined using Taguchi method in this study.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집A
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• pp.87-92
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• 2000

In this paper, we investigated the braking performance of a composite brake shoe for power car. Laboratory bench test and field tests were carried out to characterize the braking performance by the parameters such as friction coefficient, wear rate, braking temperature and stopping distance. Density distribution was found to have a significant influence on the wear rate. The composite brake shoe with even density distribution showed better braking performance. The braking performance of a composite brake shoe was also compared with that of a cast iron brake shoe which is currently being used. The result indicated the performance of the composite brake shoe is better than the cast iron brake shoe.

• 한국생산제조학회지
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• 제18권5호
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• pp.544-549
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• 2009

Thermal brake judder caused by the high friction heat of the brake disk. Hot thermal judder makes serious problems such as to be unstability to drivers or to decrease braking force of automobile. Because thermal judder vibration makes high vibration occurrence and thermal deformation of brake disk. Therefore it Is necessary to reduce or eleminate thermal Judder phenomenon by understanding and investigation. This paper introduces the thermal deformation arising from friction heat generation in braking and proposes the FEM analysis to predict the distribution of temperature and thermal deformation. the results of the FEM analysis show the deformed shape and temperature distribution of the disk brake. The optimization is performed to minimize the thermal judder of ventilated disc brake that is induced by the thermal deformation of the disk brake.

• Tribology and Lubricants
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• 제23권6호
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• pp.266-271
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• 2007

The brake performance of sintered friction materials for the high speed train was studied. In this study, newly developed sintered materials based on copper were compared with the commercial products for high speed trains. They were tested on a 1/5 scale dynamometer using low carbon steel disks. Effectiveness, fade, and recovery tests were carried out to examine friction performance and the change of disk thickness variation (DTV) during brake applications and noise propensity were also evaluated. Results showed that the two sintered friction materials exhibit similar friction coefficients and braking performance, whereas the newly developed friction material was superior in terms of DTV generation and noise propensity to the commercial friction material. The improvement of the newly developed friction material was attributed to the high graphite content which reduced the stick-slip phenomena and prevented uneven disk wear by producing friction films on the counter disk.

• 한국분말재료학회지
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• 제13권1호
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• pp.62-67
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• 2006

Friction welding of $Al_2O_3$ particulate reinforced aluminum composites was performed and the following conclusions were drawn from the study of interfacial bonding characteristics and the relationship between experimental parameters of friction welding and interfacial bond strength. Highest bonded joint efficiency (HBJE) approaching $100\%$ was obtained from the post-brake timing, indicating that the bonding strength of the joint is close to that of the base material. For the pre-brake timing, HBJE was $65\%$. Most region of the bonded interface obtained from post-brake timing exhibited similar microstructure with the matrix or with very thin, fine-grained $Al_2O_3$ layer. This was attributed to the fact that the fine-grained $Al_2O_3$ layer forming at the bonding interface was drawn out circumferentially in this process. Joint efficiency of post-brake timing was always higher than that of pre-brake timing regardless of rotation speed employed. In order to guarantee the performance of friction welded joint similar to the efficiency of matrix, it is necessary to push out the fine-grained $Al_2O_3$ layer forming at the bonding interface circumferentially. As a result, microstructure of the bonded joint similar to that of the matrix with very thin, fine-grained $Al_2O_3$ layer can be obtained.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.236-240
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• 2005

This paper deals with friction-induced vibration of disc brake system under constact friction coefficient. A linear, finite element model to represent the floating caliper disc brake system is proposed. The complex eigenvalues are used to investigate the dynamic stability and in order to verify simulations which are based on the FEM model, The comparison of experimental and analytical results shows a good agreement and the analysis indicates that mode coupling due to friction force and geometric instability is responsible fur disc brake squeal. And the Front brake system reduced the squeal noise using design of experiment method(DOE). This helped to validate the FEM model and establish confidence in the simulation results. Also they may be useful during real disk brake model.