• Tribology and Lubricants
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• 제15권2호
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• pp.193-198
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• 1999

Applying design methodology, new type friction tester has been developed. Functional analysis has been executed and functional structure were constructed during the conceptual design. Optimal solution has been selected and a proto model has been manufactured according to the conceptual design. Using the tester developed in the laboratory, frictional characteristics of natural rubbers have been experimentally analyzed. Friction coefficient has been calculated from the measured normal force and friction force under various speeds, loads, and temperatures. The corelations between the various operating conditions and friction coefficients have been verified. Especially, drag friction due to the visco-elastic behavior of the rubber has been observed in this analysis.

• 한국지반공학회논문집
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• 제24권2호
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• pp.87-97
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• 2008

단단한 모래 입자와 연약한 고무 입자로 이루어진 Engineered soils을 고결화 시킨 후 $K_o$ 상태에서의 거동 특성을 분석하였다. 고결화 효과에 따른 영향 및 모래부피비에 따른 영향을 파악하기 위하여 다양한 모래부피비를 가지는 비고결화 및 고결화 시료를 준비하여, 수직 응력에 따른 변형 및 탄성파 속도를 측정하였다. 탄성파 속도 측정은 벤더 엘리먼트와 PZT 엘리먼트를 이용하였다. 고결화 이 후 응력에 따른 수직 변형율의 기울기는 이중 선형 관계를 보이며 고결화 결합 파괴 이후에는 비고결화 시료와 비슷한 기울기를 가진다. 정규화된 수직 변형량은 응력에 따라 capillary force, cementation, decementation 구간으로 나눌 수 있다. 근접장 내에서 측정된 전단파 신호의 첫 번째 움직임은 압축파의 도달과 일치하였다. 고결화에 의해 탄성파 속도는 수직 응력의 증가 없이 급격한 증가를 보였으며, 고결화 이후 추가적인 응력 증가에도 일정한 값을 보였다. 고결화 파괴 후 지속적인 수직 응력의 증가에 따라 탄성파속도는 증가하였다. 고결화는 비고결화 시료에서 나타나는 유사고무, 유사모래, 전이 3가지의 거동을 방해한다. 고무-모래 혼합재의 고결화 결합의 파괴 메커니즘은 모래부피비에 따라 다르며 낮은 모래부피비의 시료는 입자 모양의 변화가, 높은 모래부피비 시료에서는 입자 구조의 변화가 고결화 결합의 파괴가 주요한 원인이다. 본 연구를 통해 연약한 고무 입자와 단단한 모래 입자의 혼합재인 Engineered soils의 거동은 고결화 및 고결화 파괴에 따라 비고결화 시료와 구분됨을 알 수 있었다.

• 한국지반공학회논문집
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• 제27권3호
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• pp.85-94
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• 2011

다양한 모래부피비($sf=V_{sand}/V_{total}$)를 가지는 시료를 조성하여 변형률 크기에 따른 모래-고무 혼합재($D_{sand}/D_{rubber}=1$)의 거동을 분석하였다. 공진주시험, 압밀시험, 그리고 직접전단시험을 실시하였다. 변형률 크기에 따라 모래와 고무는 혼합재 전체 거동을 서로 다르게 제어한다. $sf{\geq}0.4$의 혼합재는 비선형 전단강성의 감소가 관찰되는 반면, $sf{\leq}0.2$의 낮은 모래부피비를 가지는 혼합재는 상당히 높은 탄성한계변형률을 보인다. 고무 입자가 force chain의 역할을 수행할 때 수직변형은 급격한 증가를 보인다. 혼합재 내의 고무부피비가 감소함에 따라 혼합재의 강도는 증가하는 경향을 보이며 $sf{\leq}0.8$의 혼합재는 전단변형에 따라 부피 수축 거동을 보인다. 고무 입자는 변형률 크기에 따라 혼합재 내에서 서로 다른 역할을 수행한다: 미소변형률 영역에서는 혼합재 내의 접촉수 증가 및 소성의 제어; 중간변형률 영역에서는 force chain의 좌굴 방지; 그리고 대변형률 영역에서는 혼합재의 부피수축 거동을 이끈다.

• Tribology and Lubricants
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• 제28권1호
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• pp.1-6
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• 2012

In this paper, a three elastic body sliding contact problem is modeled to investigate more precise wear mechanisms related with the sealing surface. A 3-D finite element contact model, a small spherical elastic particle, PTFE seal and steel surface, is solved using a nonlinear finite element code MARC. The deformed seal and steel surface shapes, von-Mises and principal stress distributions are obtained for different seal sliding distances. The entrapped small particle within PTFE seal results in very high stresses on the steel surface which exceeded its yield strength and produce plastic deformation such as groove and torus. The sealing surface could also be worn down by sub-surface fatigue due to intervening small particles together with the well-known abrasive wear. Therefore the proposed contact model adopted in this paper can be applied in design of various sealing systems, and further studies are required.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 추계학술대회논문집
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• pp.266-269
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• 2006

Tire is in charge of a lot of function, which is supporting vehicle load, transferring traction and. brake, absorbing impact by road etc. As the silence of vehicle increase more important, the importance of tire noise is more raised. In recent, the study on reduction of tire noise is generally processed. Tire noise is divided in structure home noise and all borne noise. Tire tread properties have a lot of multiplicity. Rubber properties are caused by changing or tread hardness. That change Elastic Modulus and Loss Modulus, which is related by tire noise. In the study, we found that road noise is affected by tread hardness

• Elastomers and Composites
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• 제57권3호
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• pp.114-120
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• 2022

The tensile properties of the extruded PC film were measured in the extrusion direction and perpendicular to the extrusion direction. The measured properties were the elastic modulus and Poisson's ratio at the glass transition temperature of PC. The measured orthotropic properties of the film were used for the computer simulation of vacuum forming. In this simulation, three mold shapes were tested: dome, trapezoid, and cubic, and the vacuum was applied between the mold surface and the heated film. The stress, strain, thickness, and stretch ratio distributions of the film in different mold shapes were observed and compared. The thermoforming simulation method used in this study and the obtained results, considering the determined orthotropic properties, can be applied to the thermoforming of various three-dimensional shapes.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1994년도 Proceedings of the Korea Automatic Control Conference, 9th (KACC) ; Taejeon, Korea; 17-20 Oct. 1994
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• pp.587-592
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• 1994

To realize artificial device with sensing ability of the human skin, a mono-material tactile sensor with three sensing functions made of some elastic thin electro-conductive rubber sheet with eight latticed patch elements is proposed. This trial sensor provides the information of three kinds of model material characteristics such as thermal property, hardness property and the surface situation of materials by setting up three kinds of surface models as test materials. It can be finally expected to estimate unknown model materials by analyzing the data of the sensor.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1996년도 봄 학술발표회 논문집
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• pp.180-185
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• 1996

Construction activities and operation of transportation facilities have caused unfavorable effects such as civil petitions associated with vibration-induced damages or nuisances. The objedtive of this research is to develop vibration-controlled concrete containing foams, latex, rubber powders, plastic resins and etc as a concrete mixture. As the first step to achieve this research, preliminary mix designs have been carried out to find out an appropriate mix proportion above 200kg/㎠ in uniaxial compressive strength, and investigate their dynamic mechanical characteristics such as dynamic elastic moduli, material damping ratio, Poisson's ratio, resonant frequency and etc.

• Elastomers and Composites
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• 제38권2호
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• pp.175-179
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• 2003

For the total description of mechanical behaviors of elastomers, it is necessary to know the so-called rheological constitutive equation i.e. the strain-energy density function (W) in case of elastomers, which necessitates biaxial tensile results of elastic body. This paper first describes the experimental results of biaxial tensile measurements on poly(siloxane) model networks. W was estimated from its differential form i.e. the $1^{st}$ differential of W is stress. The W was found to reproduce the experimental stress-strain results, and the W estimated for silica filled poly(siloxane) networks suggest a different behavior between conventional precipitated silica and in situ formed silica. The difference suggests the different surface property of the two silicas.

• 한국자동차공학회논문집
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• 제10권1호
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• pp.153-161
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• 2002

This paper develops a finite element model for crashworthiness analysis ova small-sized bus. The full vehicle finite element model is composed of 31,982 shell elements,599 beam elements,42 bar elements, and 34,204 nodes. The model uses four material models (such as elastic, elastic-plastic(steel), rigid. and elastic-plastic (rubber) material model) of PAM-CRASH. The model uses four contact types to define sliding interfaces in ten areas. A frontal crash test using an actual vehicle with 30mph velocity to a rigid barrier is carried out. Vehicle pulses at lower part of left and right b-pillar are measured, and deformed shapes of frame and driver seat's lower left area are photographed. A frontal crash simulation using the developed full vehicle finite element model is performed with PAM-CRASH installed in super computer SP2. The simulation is performed with the same conditions as the test. The measured vehicle pulses and photographed deformed shapes from the test are compared to ones from the simulation to validate the reliability of the developed model.