Friction Noise Research Articles

The onset condition of friction noise in ball joint under concentric loading

This study provides the general methodology describing the propensity of friction noise in ball joint system. The dynamic ball joint model is theoretically proposed under the concentric loading condition with nonlinear friction curve. In ball joint system, contact condition becomes non-conformal due to clearance between the ball head and cup. The results from stability analysis reveal that the ball joint system becomes dynamically unstable under the sufficiently small contact area and a negative friction-velocity slope. It is also shown that the lower bending modes of the beam have the higher propensity for modal instability.

왕복운동에서의 고유주파수 변화에 따른 마찰소음 특성 연구

Experimental study is conducted for investigating the characteristics of friction-induced noise with respect to the variation of system geometry. In this study, a vertically fixed rod is in contact with the reciprocating plate which is controlled by the step motor. Friction noise is generated during the reciprocating motion due to the frictional contact between the plastic pin and the aluminum plate. The frequencies of the friction noise are changed when the height of the rod varies. However, it is found that the vibration modes involved in the friction noise are not changed. It implies that the unstable modes remain unstable regardless of the change of the system geometry, and thus, there are the certain mode shapes which are likely to produce friction noise.

Experimental and numerical studies of friction-induced vibration and noise and the effects of groove-textured surfaces

An experimental and numerical study of friction-induced vibration and noise of a system composed of an elastic ball sliding over a groove-textured surface was performed. The experimental results showed that the impact between the ball and the edges of the grooves may significantly suppress the generation of high frequency components of acceleration and reduce the friction noise. Groove-textured surfaces with a specific dimensional parameter showed a good potential in reducing squeal. To model and understand this noise phenomenon, both the complex eigenvalue and dynamic transient analysis were performed. The dynamic transient analysis for the cases of groove-textured surface with/without filleted edges validated the role of the impact between the ball and the groove edges. Furthermore, a self-excited vibration model with three degrees of freedom was proposed to capture the basic features of the friction system. A small contact angle between the ball and the groove edges, corresponding to the relatively small groove width used in this study, would not cause any instability of the system.

마찰 곡선을 고려한 Pin-on-disk 마찰소음 해석 및 검증

This study provides the numerical finite-element method(FEM) estimating the friction noise induced by the negative slope in the friction-velocity curve. The friction noise due to the friction-velocity curve is experimentally investigated through the pin-on-disk setup. The measured squeal frequency is estimated by FEM. The friction curve is measured by the friction test, then it is applied to the com- plex eigenvalue analysis. The results shows that the experimental squeal frequency can be determined by the FEM analysis. Also, it is emphasized that the negative friction-velocity slope is essential in generating friction noise in the pin-on-disc system.

Bionic Design of Koch Snowflake Surface Texture and Its Effects on Air Frictional Noise of High Speed Train

In order to reduce the air frictional noise at the air-carriage interface of high speed train, a Koch type snowflake surface structure is designed to simulate the fractal structure of snowflake and analyzed with the theory of computational fluid dynamics(CFD) and the method of bionic design for the surface of high speed train. The compressible N-S equation is solved using unstructured hybrid grid and k ?? model and the noise distribution is solved based on broadband noise source. Simulation results demonstrate that the air frictional noise is greatly reduced because of the secondary vortex generated in the Koch snowflake like surface structure. A kind of multi scale surface structure consists of Koch snowflake cells on two scales and a sort of compound surface texture combining cells of Koch snowflake and circular dents are designed in order to further explore the influence of surface texture on the decrease of the noise of high speed train; that multi scale surface texture is better than single texture but compound surface texture is worse than the better one of the single texture in reduction of the air frictional noise, which provide an effective guidance for the study of reducing the air frictional noise of high speed train.

Analysis of Friction Noise and Vibration from the Cushion Frame of a Driver's Seat in Passenger Cars

In this study, the vibration and noise for the cushion frame that directly contacts the driver of the car are investigated. The friction noise from the seat track generating the largest noise is measured and analyzed. Also, vibration measurement and analysis are performed in parallel to locate the position from where the noise is generated. In the next stage, the RPM of motor and the current changes during motor driving are measured. The vibration and noise generated during motor running are also measured and analyzed to examine the interaction between noise from the track and load on the motor. The vibration and noise analysis results are expressed using FFT analysis, octave analysis, spectrum contour map analysis, and sound visualization.

Experimental Study on the Influence of the Self-Healing Microcapsules on the Friction Noise Performance of Composite Gears Based on Properties of Mechanical Materials

Based on the properties of mechanical materials, the friction noise experiment is conducted on the E-glass-reinforced nylon 6 composite gears in this paper. In the test, by combining the friction testing machine with the noise processing software DASP, the vibration noise signals of the composite gear samples with and without self-healing microcapsules at different friction temperatures were picked. Then the influence the self-healing microcapsules have on the friction noise performance of the composite gear material was analyzed by comparing the obtained signals. The results show that the noise of composite gears with self-healing microcapsules is lower than that of gears without self-healing microcapsules at both different temperatures and different frequencies, which means that the self-healing microcapsules reduce the friction noise of the composite gears.

NCPX 계측방법을 이용한 타이어/노면 사이에서 발생하는 마찰소음에 대한 차량자체에서 발생하는 소음 제거 연구

PURPOSES : The purpose of this study is to eliminate the noise of the vehicle after measuring the friction noise obtained from the NCPX (Noble Close ProXimity) method. The pure friction noise between the tire and road pavement could be determined from filtering the compositeness of sound and the influence of the vehicle noise. METHODS: The noise magnitude could be determined by analyzing the sound pressure level (SPL) and sound power level (PWL) along with the noise frequency of a FFT (Fast Fourier Transform) analysis as well as CPB (Constant Percentage Bandwidth) analysis. RESULTS: When the test for measuring the friction noise originated somewhere between tire and road pavement is performed with NCPX method, it must be fulfilled by attaching the surface microphone near the tire. In this condition, the surface microphone can measure the friction noise occurred at between tire and pavement, the chassis noise from the engine and power transfer units, the fluctuating aerodynamic noise, and the turbulence noise directly affected to the surface microphone. By using the NCPX method, the noise occurred at the vehicle must be eliminated for measuring the friction noise between tire and pavement from the traffic noise. CONCLUSIONS: The vehicle`s testing engine noise depends on the vehicle and road types. The effect of vehicle`s engine noise is less than the friction noise occurred at between tire and pavement at less than 1% effect.

NCPX 계측 방법에 따른 속도별 소음 데시벨 예측 모델 개발에 대한 연구

PURPOSES : The objective of this study is to provide for the overall SPL (Sound Pressure Level) prediction model by using the NCPX (Noble Close Proximity) measurement method in terms of regression equations. METHODS: Many methods can be used to measure the traffic noise. However, NCPX measurement can powerfully measure the friction noise originated somewhere between tire and pavement by attaching the microphone at the proximity location of tire. The overall SPL(Sound Pressure Level) calculated by NCPX method depends on the vehicle speed, and the basic equation form of the prediction model for overall SPL was used, according to the previous studies (Bloemhof, 1986; Cho and Mun, 2008a; Cho and Mun, 2008b; Cho and Mun, 2008c). RESULTS : After developing the prediction model, the prediction model was verified by the correlation analysis and RMSE (Root Mean Squared Error). Furthermore, the correlation was resulted in good agreement. CONCLUSIONS: If the polynomial overall SPL prediction model can be used, the special cautions are required in terms of considering the interpolation points between vehicle speeds as well as overall SPLs.

왕복운동에서의 마찰소음 실험적 연구

The present study provides the characteristics of friction noise under reciprocating sliding. The friction contact is generated between the aluminum plate and plastic, which results in friction noise. The experimental results reveal that the friction noise under reciprocating sliding can be produced as the friction coefficient increases. It is also shown that the vibration modes of the pin with dominant deflection in the sliding direction is participated on the friction noise.

마찰 곡선에 따른 마찰 소음 특성

The characteristics of friction noise due to the friction-velocity curve is experimentally investigated through the pin-on-disk setup. The rotation speed of the disk is controlled in order to produce the sliding speed variation. Then, the friction coefficient and the corresponding friction noise are simultaneously measured with respect to the sliding speed between the steel disk and aluminum pin. The experimental results show that the negative friction-velocity slope is essential in generating friction noise.

Design of Improved Disturbance Observer for Stabilized Platform Servo System

In order to reduce the influence of frictional interference and measurement noise on stabilized platform tracking performance, disturbance observer (DOB) is applied to platform servo system. In view of the non-ideal performance of classical disturbance observer about suppressing measurement noise, a novel improved DOB which uses an additional control signal to compensate system outputs is proposed based on the structure of classical DOB, and robust stability of the improved DOB when existing model perturbation is analyzed in detail. Simulation results show that the improved DOB can suppress external disturbances and model perturbation well, and the suppression performance of measurement noise is improved, too.

Biomimetic touch perception of edge finish of ophthalmic lens

The functional texture of polished edge of an ophthalmic lens is controlled by the characteristics of the finishing process by which the surface edge is produced. In order to assess the selection of edge surface finish for production purposes, tribo-acoustic sensor that mimics human sensory perception is used. The assumptions underlying the methods are that certain sounds, such as the old and surprisingly sensitive fingernail test, have a close association with somatosensory precepts. In this paper, an existing sensor was modified and adapted, via biomimetic knowledge transfer of sensory perception in humans (touch perception). If an artificial finger with smooth surface slides over an edge of polished lenses, the friction induced micro-wear traces, waviness (termed macro-roughness) and the form (hills and valleys) population varies. In touch perception tests, we showed that the texture stimulus (friction noise) delivered to artificial finger depends on the edge finish quality. The results also revealed that the effects of the edge finish on touch are frequency dependent—only sounds with the same frequency as the vibrotactile frequency enhanced tactile detection. These results demonstrate that texture finish influences touch perception in highly systematic way and suggest that similar coding of wear traces produce by polishing may underlie the processing information of quality assessment and selection of the edge ophthalmic glass.

Catastrophic Wear of Tibial Component of Total Knee Replacement Due to Neglected Dislocation of Polyethylene Insert: A Case Report

We report a case of 69-year-old female patient who presented with a dislocated insert causing tibial component failure and catastrophic metallosis after 4 years of prosthesis implantation. In case of a trauma history, surgeons must suspect friction noise and motion loss as clinical symptoms indicating dislocation of the insert at the initial postoperative period. Timely diagnosis can prevent catastrophic consequences.

Mechanism of the Effect of Groove-textured Surface on the Friction Vibration and Noise

Groove-textured surface with parallel regular intervals is manufactured on compacted graphite iron materials(brake disc material). Experimental test and numerical simulation(ABAQUS/Explicit) are performed to investigate the influence of grooved surface texturing on friction noise, by comparing the case of smooth surface. The test results show that significant friction noise is generated from the smooth surface, while nearly no friction noise can be measured from the groove-textured surface under the current testing conditions. The results can be well simulated by using finite element software ABAQUS/Explicit. Combing the results of experimental test and numerical simulation, it is showed that the groove-textured surface in this test can effectively interrupt the continuous contact of the friction surfaces when the counterface ball slid across the edge of the groove-textured surface. This will suppress the generation of high frequency components of the friction force and vibration acceleration, disturb the self-excited vibration of the friction system, and finally significantly reduce the friction noise.

THE INFLUENCE OF ROAD CHARACTERISTICS AND TIRES ON VEHICLE NOISE

Frictional noise from the contact between tires and pavement contributes significantly to overall traffic noise. The level depends on the type and condition of tires and pavement. Frictional noise is generally greatest at high speed and during quick braking. In this paper was analyzed the influence of roar characteristics and tire types over the noise produced by the vehicles. There ware made noise measurements with a specific vehicle, in different conditions (on asphalt and concrete roads and with summer and winter tires). The measurements ware made considering Noise Romanian Standard. Keywords— Asphalt, Concrete, Noise, Pollution, Tire, Vehicle.

Effect of Nitrogen Implantation on Metal Transfer during Sliding Wear under Ambient Conditions

Nitrogen implantation in Interstitial-Free steel was evaluated for its impact on metal transfer and 1100 Al rider wear. It was determined that nitrogen implantation reduced metal transfer in a trend that increased with dose; the Archard wear coefficient reductions of two orders of magnitude were achieved using a dose of 2e17 ions/cm2, 100 kV. Cold-rolling the steel and making volumetric wear measurements of the Al-rider determined that the hardness of the harder material had little impact on volumetric wear or friction. Nitrogen implantation had chemically affected the tribological process studied in two ways: directly reducing the rider wear and reducing the fraction of rider wear that ended up sticking to the ISF steel surface. The structure of the nitrogen in the ISF steel did not affect the tribological behavior because no differences in friction/wear measurements were detected after postimplantation heat treating to decompose the as-implantedε-Fe3N toγ-Fe4N. The fraction of rider-wear sticking to the steel depended primarily on the near-surface nitrogen content. Covariance analysis of the debris oxygen and nitrogen contents indicated that nitrogen implantation enhanced the tribo-oxidation process with reference to the unimplanted material. As a result, the reduction in metal transfer was likely related to the observed tribo-oxidation in addition to the introduction of nitride wear elements into the debris. The primary Al rider wear mechanism was stick-slip, and implantation reduced the friction and friction noise associated with that wear mechanism. Calculations based on the Tabor junction growth formula indicate that the mitigation of the stick-slip mechanism resulted from a reduced adhesive strength at the interface during the sticking phase.

Applications of Nanostructured Materials as Additives in Space Fluid Lubricants

With an extended service life expectancy of space crafts, fluid lubricants attracted intense interests of the fields of tribology, due to their long life under EDH conditions, higher thermal conductance, lower frictional and torque noise, and rapid processing compared to the solid lubricants. However, there are still some disadvantages of fluid lubricants, such as finite vapor pressure, narrow range of operating temperature, degradation of some oils, viscosity temperature-dependence and so on. So far, there have existed some space fluid lubricants, such as PFPE, MAC, PAO and mineral oil based lubricants. It seems that there will be a challenge for a new type of fluid lubricants to come out without any limits above. Recent arisen nanostructured materials assisted in improvement of the research of space fluid lubricants, and the results indicated that some nanostructured materials exactly promoted the tribological properties of fluid lubricants. This paper reviewed recent development of nanostructured materials as additives in space fluid lubricants.

Características acústicas dos fones [s] e [∫] de adultos e crianças com desenvolvimento fonológico típico

OBJETIVO: Comparar as produções de [s] e [∫] de adultos e crianças com desenvolvimento fonológico típico, considerando os parâmetros acústicos: duração do ruído fricativo, banda de frequências de concentração do ruído, frequência de corte de ruído de fricção e transição formântica da vogal seguinte. MÉTODOS: Participaram do estudo 26 sujeitos, divididos em dois grupos: Grupo de adultos (GA) - composto por 17 adultos jovens (média de idade: 23,61±3,44 anos), sem alterações em aspectos fonológicos da língua e; Grupo de crianças com desenvolvimento fonológico típico (GDFT) - composto por nove crianças (média de idade: 7,12±0,74 anos), com desenvolvimento fonológico típico. Foi realizada uma triagem fonoaudiológica e, após, coleta de dados para análise acústica e, para isso, foram utilizadas pseudopalavras inseridas em frases-veículo. Foram analisadas 624 produções dos sujeitos e os achados foram submetidos à análise estatística. RESULTADOS: Os parâmetros de banda de frequências e transição formântica apresentaram diferenças entre os grupos GA e GDFT. Na comparação entre as posições na palavra, os parâmetros de duração, frequência de corte e transição formântica apresentaram diferença. Os parâmetros de frequência de corte, banda de frequências e transição formântica apresentaram diferença na comparação entre os pontos de articulação de [s] e [∫]. CONCLUSÃO: Para a maioria dos parâmetros acústicos estudados, as produções de GA e GDFT mostraram-se semelhantes. Para alguns parâmetros, porém, puderam-se observar diferenças entre os grupos, entre as posições na palavra e entre os pontos de articulação dos fones estudados.

1208 湿式摩擦機構における摩擦振動と騒音の発生メカニズムに関する実験的検討(G02-3 トライボロジーと摩擦振動,G02 機械材料・材料加工部門)

1208 湿式摩擦機構における摩擦振動と騒音の発生メカニズムに関する実験的検討(G02-3 トライボロジーと摩擦振動,G02 機械材料・材料加工部門)