• 한국기계가공학회지
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• 제17권3호
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• pp.59-64
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• 2018

In general, tracked combat vehicles require excellent output performance of a power unit system to drive on special terrains and in extreme environmental conditions. However, high temperature and pressure are readily applied to the coolant hose in the power unit of the vehicles during high-speed driving under extreme road and weather conditions. These driving conditions can cause the separation phenomenon of the coolant hose in the power unit and consequentially engine overheating during driving. Therefore, a newly designed decompression device for the coolant hose has been proposed and manufactured to solve these problems in the present study. To validate of the newly proposed decompression device, the input and output pressures were measured under the before- and after-improvement conditions using experimental methods for different engine RPMs. In addition, the pre-heater temperature was measured under both conditions. From the experimental results, we expect that the current investigation can help to improve the driving performance of tracked combat vehicles.

• 대한기계학회논문집A
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• 제37권1호
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• pp.1-8
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• 2013

자동차용 냉각기 고무호스는 열과 기계적 하중을 받으면서 국부적으로 형성된 전기적 영향으로 인해 노화와 고장이 발생한다. 본 연구에서는 개선된 시험방법을 이용하여 고무호스의 파괴거동을 재현하였다. 냉각기 고무호스 재료인 카본블랙이 함유된 EPDM 고무를 사용하여 인장응력과 전기화학적 복합 스트레스를 가하여 노화거동을 분석하였다. 노화 시간에 따른 전류 및 저항의 변화거동을 관찰하였으며 인장 변형 스트레스와 전압 및 노화온도 조건에 따른 노화거동을 분석하였다. 고무 시험편을 수직면으로 정밀하게 절단하여 시험편 표면 및 내부의 변화거동을 분석하여 전기화학적 노화거동과 고장메커니즘을 규명하였다.

• 한국자동차공학회논문집
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• 제19권4호
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• pp.107-113
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• 2011

Coolant rubber hoses for automotive radiators under thermal and mechanical loadings can be degraded and thus failed due to the influences of the locally formed electricity. In this study, an advanced test method was developed to simulate the failure problem of the rubber hose. For carbon black filled EPDM (ethylene-propylene dine monomer) rubber used as a radiator hose material the ageing behaviors by the electro-chemical stresses combined with a tensile strain were analyzed. As the tensile strain increased, the current of the rubber specimen reduced indicating an increase of the internal defects and electrical resistance of the rubber specimen. Elongation at break and IRHD hardness rapidly decreased with increasing the ageing time. Both electro-chemical stress and mechanical tensile stress clearly accelerated the degradation of EPDM rubber.