• 한국정밀공학회지
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• 제24권7호
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• pp.106-111
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• 2007

In this paper, the transient brake time was studied on the van type vehicle with accelerometer. Experiments were carried out on the asphalt(new and polished), unpacked road(earth and gravel) and on wet or dry road conditions. The transient brake time is not effected bzy the vehicle speed. The transient brake time is about 0.41$\sim$0.43second on the asphalt road surface and the error range is within 0.1$\sim$0.16second. For the asphalt road condition, the transient brake time is not effected by both new asphalt road surface and the polished asphalt road surface. With compared by dry and wet road surface condition, the transient brake time of wet condition is longer than dry road condition and compared with unpacked road condition and packed road condition, unpacked road condition is shorter than packed road condition. It is considered that the transient brake time is effected by the road surface fraction coefficient. In other words, the transients brake time increases as friction coefficient decreases.

• 한국항공운항학회지
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• 제14권3호
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• pp.16-22
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• 2006

The friction and wear of tire determined by frictional behavior of tire tread that translate driving force, cornering force and braking force between automobile and road as a result of frictional behavior of each tread block. The tire tread block is representative case of rubber block doing frictional behavior. In this paper, frictional behavior of rubber block under compressive force and shear force was analytically obtained by using slip starting position parameter instead of friction coefficient which is uncertain to express exact value between rubber and other surfaces yet. And local coefficients of friction were calculated as a function of compressive force, shear force, shear modulus of rubber, shape factor and slip starting position.

• 한국도로학회논문집
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• 제12권3호
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• pp.131-137
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• 2010

본 논문에서는 국내 공항 활주로에 적합한 마찰계수 측정 및 고무 퇴적물 제거에 대한 합리적 기준 개발을 위해 관련 해외 기준 및 연구결과에 관한 문헌을 조사하였다. 그리고 2007년 8월부터 2009년 7월까지ASFT(Airport Surface Friction Tester)장비를 이용하여 인천국제공항 활주로의 마찰계수를 측정하고 항공기 집중 착륙 지점에 대한 분석을 실시하였다. 타이어 고무의 퇴적 및 제거에 따른 마찰계수의 변화를 분석하였고 이에 미치는 계절적 영향을 포장 형식별로 조사하였다. 고무 퇴적물 제거 작업을 주기적으로 수행해도 활주로 표면의 마찰계수는 장기적으로 시간에 따라 점차 감소되는 것으로 확인되었다. 여름철 마찰계수의 변화가 다른 계절에 비해 컸으며 아스팔트 포장이 콘크리트 포장보다 계절적 영향에 민감했다. 매크로한 표면조직을 갖는 아스팔트 포장의 마찰계수가 마이크로한 표면조직을 갖는 재령 초기 콘크리트 포장의 마찰계수보다 큰 것으로 나타났다. 타이어 고무의 퇴적 및 제거에 따른 마찰계수의 변화도 아스팔트 포장에서 더 큰 것으로 확인되었다.

• 한국자동차공학회논문집
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• 제22권4호
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• pp.105-110
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• 2014

This paper presents the hysteresis friction of a sliding elastomer on various types of surfaces. The hysteresis friction is calculated by means of an analytical model which considers the energy spent by the local deformation of the rubber due to surface asperities. By establishing the fractal character of the surfaces, the contribution to rubber friction of roughness at different length scales is accounted for. High resolution surface profilometer is used in order to calculate the main three surface descriptors and the minimal length scale that can contribute to hysteresis friction. The results show that this friction prediction can be used in order to characterize in an elegant manner the surface morphology of various surfaces and to quantify the friction coefficient of sliding rubber as a function of surface roughness, load and speed.

• 대한기계학회논문집A
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• 제41권7호
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• pp.585-590
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• 2017

주행중인 차량의 거동은 지면과 타이어의 접촉면에 발생하는 힘과 토크에 의해 결정된다. 타이어에 작용하는 힘과 토크를 계산하기 위하여 다양한 타이어 모델들이 사용되고 있으며, 본 연구에서 사용하는 브러쉬 모델(brush model)은 타이어의 물리적 특성을 이용하여 지면과의 접촉면에 발생하는 힘과 토크를 구하는 모델이다. 브러쉬 모델은 힘과 토크를 계산하는데 다른 타이어 모델에 비하여 적은 수의 계수를 필요로 하지만, 힘과 토크를 계산하는데 낮은 자유도를 가지기 때문에 시험 데이터를 정확하게 표현하는데 한계가 있다. 본 논문에서는 이러한 단점을 개선하기 위하여 타이어 마찰계수 및 특성계수에 최소한의 변수를 추가한 개선된 모델을 제안하고, 이의 유효성을 검증하였다.

• 한국자동차공학회논문집
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• 제22권3호
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• pp.130-135
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• 2014

In this paper, a new estimation method is proposed to calculate steering rack axial force using a 3 dimensional tire mesh model when a car is standing on the road. This model is established by considering changes of camber angle and contact patch between the tires and the ground according to steering angle. The steering rack bar axial force is estimated based on the static equilibrium equations of forces and moments. A tire friction force is supposed to act on the center point of the contact patch, and the proportional coefficient of friction depending on contact patch is suggested. Using the proposed estimation method, rack axial force sensitivity analysis is evaluated according to changes of suspension geometry. Then optimal motor power of Motor Driven Power Steering(MDPS) is evaluated using suggested rack forces.

• 한국기계가공학회지
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• 제19권10호
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• pp.87-97
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• 2020

In general, tires require various sensors and power supply devices, such as batteries, to obtain information such as pressure, temperature, acceleration, and the friction coefficient between the tire and the road in real time. However, these sensors have a size limitation because they are mounted on a tire, and their batteries have limited usability due to short replacement cycles, leading to additional replacement costs. Therefore, vibration energy harvesting technology, which converts the dynamic strain energy generated from the tire into electrical energy and then stores the energy in a power supply, is advantageous. In this study, the output voltage and power generated from piezoelectric elements are predicted through finite element analysis under static state and transient state conditions, taking into account the dynamic characteristics of tires. First, the tire and piezoelectric elements are created as a finite element model and then the natural frequency and mode shapes are identified through modal analysis. Next, in the static state, with the piezoelectric element attached to the inside of the tire, the voltage distribution at the contact surface between the tire and the road is examined. Lastly, in the transient state, with the tire rotating at the speeds of 30 km/h and 50 km/h, the output voltage and power characteristics of the piezoelectric elements attached to four locations inside the tire are evaluated.

• 대한교통학회지
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• 제28권3호
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• pp.119-130
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• 2010

교통사고의 재구성 해석은 도로와 사고흔적, 자동차 손상 등 다양한 자료들을 분석함으로서 이루어진다. 대부분의 자료들은 사고 해석에서 변수로 작용하며, 측정으로부터 구해지는 자료들은 조사자와 도구, 주어진 환경 등에 의해 측정 오차가 발생된다. 따라서 사고해석에서는 측정 오차에서 비롯되는 불확실성이 항상 존재한다. 본 연구는 불확실성이 존재할 가능성이 매우 높은 도로 기하구조와 타이어 흔적 등 길이와 마찰계수 등에 대해 반복 측정 실험을 함으로서 교통 사고해석에서의 불확실성을 정량화하였다. 또한 자동차 충돌 변형량의 사진 계측에 대한 불확실성에 대해서도 해석 결과를 제시하였다. 이러한 통계학적 분포들은 사고 재구성 불확실성을 추정하기 위해 입력 계수의 적절한 범위를 결정하는 것을 도울 수 있다.

• 한국기계가공학회지
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• 제10권5호
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• pp.110-116
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• 2011

Water on a road surface can lower the coefficient of friction of vehicle tires and it involves lots of risks. One way to prevent water from staying is to cut many "rain grooves" into the edges of the pavement parallel. Such grooves, however, can exert unwanted side forces, particularly on passenger tires, which cause "Groove Wander" making the drivers uncomfortable. The "Groove Wander" is somewhat related to vehicle geometry, but is more strongly related to interaction between road grooves and tire tread's longitudinal grooves. This thesis tries to examine principles to estimate "Groove Wandering" effect focusing on the design of longitudinal groove. Additionally, it studied how to reduce pipe resonance longitudinal grooves form in the contact patch.

• 한국자동차공학회논문집
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• 제15권5호
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• pp.174-179
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• 2007

The transient brake time or distance is one of very important factors to guess the vehicle speed to inspect an automobile accident. But, it is usual that the vehicle speed is estimated by using only skid mark without considering the transient brake distance. Deceleration and the friction coefficients of tire and road surface play an important role in calculating the brake distance. In this paper, a scheme is presented to estimate more accurate automobile speed. The scheme contains the effect of the transient brake distance on the speed. Experiment was carried out on the asphalt, unpacked road to get relationships between the speeds and the skid mark distances, and to get the transient brake time. The experimental results were utilized to construct the equation to approximate more realistic vehicle speeds.