Influence of Contact Area Deformation Distribution of Tire on Tire Noise, Rolling Resistance and Dry Grip Performance

Guolin Wang,Kangying Yu,Chen Liang,Ye Mei 한국자동차공학회 2021 International journal of automotive technology Vol.22 No.1

Most tire properties are closely related to the pattern deformation. In order to explore the relationship between tire performance and defined deformation parameters in the contact area between the pneumatic tire and road surface, ten types of 205/55R16 passenger car radial (PCR) tires were selected as the research objects. Using VIC-3D non-contact strain measurement system and by subdividing the contact area, the pattern deformation in contact area under vertical load was tested, and the relevant deformation parameters of the contact area were extracted. Correlation analysis was used to establish the relationship between the identified deformation parameters and tire performance indicators. Then an evaluation method of tire performance based on the deformation parameters was proposed, as well as clarification of the contradictory mechanism between tire noise, rolling resistance and dry grip performance. While the results indicate tire noise having a significant negative correlation with radial deformation in the contact area, rolling resistance coefficient gave a significant positive correlation with its equivalent strain in the XY plane of the contact area, and dry braking distance positively correlates with tensile strain in the Y direction of contact area and negatively correlates with tensile strain in the X direction of the contact area.

복합하중을 받는 외륜 분할 3점 접촉 볼베어링 특성 연구

사진혁,김동혁,리베라 길버트,홍성욱 한국생산제조학회 2024 한국생산제조학회지 Vol.33 No.1

A split-outer-ring three-point contact ball bearing (SO-TCBB) features a removed portion in the circular outer-ring to allow three-point contact. This study introduces a quasi-static model to analyze contact characteristics and predict the occurrence of a phenomenon called truncation of contact area (TCA) in SO-TCBBs. TCA implies that portions of the contact areas between balls and outer-race partially separate, exacerbating premature wear and reduced bearing life. Under pure axial loads, an increase in the axial load leads to earlier occurrence of TCA in the inner ring. Combined loads cause varying contact points and TCA for each ball, with higher radial loads accelerating TCA. Increasing radial load results in an earlier occurrence of TCA. Appropriately increasing the amount of removed portion of the outer ring produces a three-point contact at lower speeds, effectively reinforcing resistance against centrifugal forces at both contact points on the outer ring and impeding the TCA in both inner and outer rings.

피팅 상태에 따른 RGP 렌즈와 각막과의 간극 비교

박은혜,김소라,박미정 한국안광학회 2012 한국안광학회지 Vol.17 No.3

Purpose: In this study, the effect of lens fitting status on the contact area between spherical/aspherical RGP lens and the cornea having different astigmatic degree and corneal type was investigated for guiding the proper selection of RGP lens. Methods: Spherical and aspherical RGP lenses were applied on ninety eyes (25.12±3.52years) having with-the-rule astigmatism by different fitting status. Then, their central, mid-peripheral and peripheral areas of fluorescein pattern were calculated and compared for the quantitative evaluation of the contact area between spherical/aspherical RGP lens. Results: The central and peripheral areas with the alignment fitting was significant different based on lens design. However, the central area didn't show any significant difference by lens design and corneal type when fitted in steep or flat. When analyzed by the corneal shape, both lenses with alignment and flat fitting had significant difference in central and peripheral areas. However, the central, mid-peripheral and peripheral areas with steep fitting didn’t show the difference by corneal types. When analyzed by the astigmatic degree, the central and peripheral areas with alignment fitting changed proportionally to the increase of corneal astigmatism regardless of corneal shape. With steep and flat fitting, however, the central, mid-peripheral and/or peripheral areas in round- and symmetric bowtie-typed corneas showed the conflicting result when compared to those of alignment fitting when analyzed by the astigmatic degree. Conclusions: In this study, it was confirmed that the contact areas of cornea and RGP lens fitted steep and flat status were largely affected by the corneal type and corneal astigmatism rather than RGP lens fitted in alignment status. Also, this result commonly occurred in both spherical and aspherical RGP lenses. 목적: 본 연구에서는 형상 및 난시도가 상이한 각막에 구면 및 비구면 RGP 렌즈를 피팅 상태를 달리하여 착용시켰을 때 각막과 렌즈와의 간극에 미치는 영향을 알아보아 적절한 RGP 렌즈의 선택에 도움이 되고자 하였다. 방법:직난시를 가진 25.12±3.52세의 90안에 구면과 비구면 RGP 렌즈를 각기 다른 피팅 상태로 착용시키고 플루레신 염색의 정량적인 분석을 위하여 중심부, 중간주변부 및 주변부로 나눠 면적을 계산하여 각막과 콘택트렌즈의 간극을비교하였다. 결과: 양호한 피팅 시 중심부와 주변부 면적은 렌즈 디자인에 따른 유의한 차이가 있었으나 스팁 혹은플랫하게 피팅되었을 때의 중심부 면적은 각막형상과 렌즈 디자인에 따른 차이는 없었다. 각막 형상에 따라 분석하였을 때 양호한 피팅과 플랫 피팅에서는 두 렌즈 디자인 모두에서 중심부와 주변부 면적이 각막 형상에 따라 통계적으로 유의하게 달라졌으나, 스팁 피팅에서는 차이가 없었다. 각막 난시도에 따라 분석하였을 때 각막형상에 상관없이 각막난시가 증가함에 따라 일정하게 중심부 및 주변부의 면적이 변하는 양호한 피팅의 경우와는 달리 스팁 피팅과 플랫한 피팅의 경우는 원형 각막과 대칭나비형 각막에서의 면적 변화 양상이 상이하였다. 결론: 본 연구에서는 RGP 렌즈를 스팁이나 플랫하게 피팅 되었을 경우 양호한 피팅시 보다 각막난시나 각막 형상에 따른 렌즈와 각막과의 간극 변화가 더 커지며 이러한 결과는 구면 RGP 렌즈와 비구면 RGP 렌즈 모두에서 공통적으로 나타나는것임을 알 수 있었다.

Contact Area-Dependent Electron Transport in Au/n-type Ge Schottky Junction

Kim, Hogyoung,Lee, Da Hye,Myung, Hye Seon Materials Research Society of Korea 2016 한국재료학회지 Vol.26 No.8

The electrical properties of Au/n-type Ge Schottky contacts with different contact areas were investigated using current-voltage (I-V) measurements. Analyses of the reverse bias current characteristics showed that the Poole-Frenkel effect became strong with decreasing contact area. The contribution of the perimeter current density to the total current density was found to increase with increasing reverse bias voltage. Fitting of the forward bias I-V characteristics by considering various transport models revealed that the tunneling current is dominant in the low forward bias region. The contributions of both the thermionic emission (TE) and the generation-recombination (GR) currents to the total current were similar regardless of the contact area, indicating that these currents mainly flow through the bulk region. In contrast, the contribution of the tunneling current to the total current increased with decreasing contact area. The largest $E_{00}$ value (related to tunneling probability) for the smallest contact area was associated with higher tunneling effect.

A Study on Ball-Race Contact in Angular Contact Ball Bearing during Rotation

리베라 길버트(Gilbert Rivera),통반칸(Van-Canh Tong),홍성욱(Seong-Wook Hong) Korean Society for Precision Engineering 2021 한국정밀공학회지 Vol.38 No.11

Angular contact ball bearings (ACBBs) are widely used in rotating machinery due to their heavy load-carrying capacity and excellent accuracy in high-speed operation. However, employing an ACBB requires a careful analysis because the characteristics of the ACBB significantly depend on the operating condition. The ball-race contact condition of an ACBB is one of the most important factors that can change its properties. This study deals with the ball-race contact behavior concerning several important parameters, such as rotational speed, unloaded contact angle, and external loading. Between the ball and race under loading, an elliptical contact area is formed, in which pure rolling lines may exist. In the region other than the pure rolling lines, sliding dominates due to differential slippage in the elliptical contact area. We investigated the behavior of ball-race contact in terms of the pure rolling lines. A computational procedure was presented to determine the pure rolling lines. Through simulations, it was found that rotational speed, unloaded contact angle, axial preload, and radial load significantly affected the number and locations of pure rolling lines. The presented results are useful for investigating and estimating the sliding friction torque for ACBBs.

타이어의 접지 면적과 비선형 접지압력을 고려한 연성포장내의 거동 분석

조명환(Jo Myoung-Hwan),김낙석(Kim Nakseok),정진훈(Jeong Jin-Hoon),서영국(Seo Youngguk) 대한토목학회 2006 대한토목학회논문집 D Vol.26 No.4D

포장을 설계하고 설계 수명을 산정하거나 현재 공용중인 포장의 유지ㆍ관리를 위한 상태 평가를 수행해야하는 경우 포장의 거동 분석은 중요한 입력 변수로 작용하게 된다. 포장의 거동을 예측하기 위해서는 정확한 타이어의 접지면적과 타이어의 압력이 필요하다. 따라서 본 연구에서는 실제 측정된 타이어의 형상을 측정하여 PCA에서 제안한 타이어의 형상과 비교하고, 측정된 타이어의 접지면적과 타이어의 종류에 대한 타이어 압력분포를 사용하여 3차원 유한요소해석을 통하여 포장의 거동을 예측하고 예측된 포장의 거동과 실제 포장의 거동을 비교ㆍ분석하였다. 해석 결과 표층의 경우 타이어의 형상과 비선형 압력분포의 영향을 크게 받으며, 이러한 타이어의 특성을 고려함으로써 현장 거동을 보다 잘 설명할 수 있는 것으로 나타났다. 하지만 중간층의 경우 타이어의 영향이 크지 않은 것으로 나타났으며, 실제 현장 거동과 비교했을 때 타이어 하부 에서는 큰 차이를 보여주어 실제 포장의 거동을 보다 정확하게 예측하기 위해서는 이 부분을 보다 명확하게 설명을 할 수 있어야 할 것으로 나타났다. The important elements in pavement design criteria are the stress and strain distributions. To obtain reasonable stress and strain distribution, tire contact area and tire pressures are very important. In this study, finite element analysis was used to identify the three-dimension states using nonlinear tire contact pressure and measured tire contact area. Measured tire contact area was quite different from the assumed tire contact area, and it resulted in different strain states under the tire. At the surface course, considering tire rib and nonlinear tire pressure, the pavement response presented accurate data compared to the predicted one. However, at the binder course, tire effects were generally negligible and it showed that the predicted pavement response was different compared to the measured one.

자연과학편 : 배구경기에서 타점 위치 및 블로킹 위치에 따른 오픈면적 시뮬레이션

이기청(KiChungLee),김관호(KwanHoKim) 한국체육학회 2014 한국체육학회지 Vol.53 No.4

남자 프로배구 경기를 대상으로 스파이크 하는 순간 공의 타점 위치와 블로킹에 따른 오픈면적을 알아보았다. 오픈면적을 계산하는 프로그램은 비주얼 베이직과 비주얼 C⁺⁺을 이용해 개발하였다. 블로킹이 없는 상황에서는 오픈공격과 후위공격은 높이 330 cm 정도에서 네트로부터는 가급적 가까운 지점이 유리하며 특히 후위공격은 어택라인으로부터 120 cm 들어온 지점이 오픈면적을 넓게 확보하는 것으로 나타났다. A 속공은 가급적 네트와 가까운 지점에서 310 cm의 높이에서 공격하는 것이 오픈면적을 효율적으로 확보하는 것으로 나타났다. 블로킹이 있는 상황에서는 오픈공격은 블로킹과의 높이 차이를 약 20 cm 정도 유지하고, A 속공은 블로킹 보다 빠른 공격을 수행하는 것이 공격성공의 확률을 높일 수 있을 것으로 판단된다. 후위공격은 두 명 이상의 블로킹이 참여하지 않는 상태에서 공격이 이루어질 수 있도록 하는 것이 중요한 것으로 판단된다. 한편 오픈공격과 후위공격은 블로킹이 네트로부터 다소 떨어져서 하는 것이 오픈면적을 작게 하는 것으로 나타났지만, A 속공의 경우에는 약 10 cm 정도 오버블로킹을 하는 것이 적절할 것으로 판단된다. This study has analyzed the open area according to the ball contact position and blocking position by men’s volleyball games. The program of calculating the open area was developed using Visual Basic and Visual C++. The area for Open spike and Back attack without blocking, which is 330 cm heights and the range as near as possible from the net, has the advantage and the area in 120 cm from the attack line secured the open area widely for Back attack. The A quick in the nearest area from the net and 310 cm secured the open area efficiently. Open spike that kept the heights about 20 cm from the blocking and the A quick that was faster than the blocking will raise successful attack probability when there was the blocking. Attack the rear without more than 2 blocking will be a crucial point. The blocking a little far from the net for Open spike and Back attack had the small open area. The blocking over about 10 cm for A quick, however, appropriate.

Pin-on-Disc식 미끄럼마모시험 시 마모 거동에 미치는 접촉면적 및 하중 조합의 영향

이한영(Lee, Han-Young) 한국트라이볼로지학회 2013 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.29 No.2

The effects of contact pressure on the sliding wear behavior of mild steel in a pin-on-disc type apparatus were investigated. Sliding wear tests were conducted with various combinations of the load and apparent area of contact. The wear behavior of mild steel as a function of sliding speed was independent of contact pressure. However, the wear rate at different sliding speeds was influenced by the load regardless of the apparent area of contact. This was attributed to the fact that there may be no difference in the real area of contact for any combination of the load and apparent area of contact.

마이크로 구동기를 이용한 탄소나노튜브 어레이의 접촉 면적에 따른 점착력 측정

최정욱 ( Jung Wook Choi ),김종백 ( Jong Baeg Kim ) 정보저장시스템학회 2014 정보저장시스템학회논문집 Vol.10 No.1

Adhesion between carbon nanotube (CNT) arrays is measured and characterized for number of different contact areas. The CNT arrays are directly grown on an electrostatic microactuator, and they make contact with each other during the growth process. The pull-out force is precisely applied by the microactuator while the contact status is identified by measuring electrical resistance between the CNT arrays. We have designed different contact areas of 1000, 6000, and 8500 μm2 between the CNT arrays, and the corresponding adhesion increases from 0.9 to 3.7 μN as the contact area increases.

이용자의 과거 위치 정보와 이용자별 SLA(Sevice Level Agreement)를 지원하는 동적 예측서비스 기반의 접촉 지역 추천(S-RCA) 기법

조경래,이지형 (사)디지털산업정보학회 2013 디지털산업정보학회논문지 Vol.9 No.2

In this paper, We collected location based services of the user’s past moving paths through the GPS. Using the collected by location-based services through the analysis of the similarity between the user’s of service level agreement recommended of mobile contact area(SLA)proposed that can be. S-RCA method based on Service Level Agreement of the users in order to provide the service user’s path distance, time, and to predict the direction of the movement paths and collect. The data collected by the interests and requirements of users through classification with the same interests and the needs of users to move between the analysis of the similarity between the path is used to analyze the results of analysis of the path-specific tolerance range (distance, time, and space) is determined according to the difference in the contact area. From a small area of the error range for users first to recommended and through their smartphones recommended contact area (S-RCA) to meet with the other party to make a choice of recommended methods. We verify through experiments that proposed method(S-RCA) a valid and reliable mobile contact area were recommended.