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김유종(Yujong Kim),허훈(Hoon Huh) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
Mechanical properties of two kinds of auto-body steel sheets are presented over a wide range of strain rates and temperatures. Tensile tests were conducted at different strain rates and temperatures to determine constitutive models for the two materials. At high temperature, strain rate sensitivity is negative and Portevin?Le Chatelier effect is observed because of dynamic strain ageing (DSA). Widely known constitutive models such as Zerilli-Armstrong and Khan-Huang-Liang models cannot describe DSA effect. Therefore, the models are modified in order to describe material strengthening due to DSA at high temperature. The modified constitutive models give good correlations with experimental data over a wide range of strain rates and temperatures including the range in which material strengthening due to DSA occurs.
Rigid Axle Type 이 적용된 차량의 Brake Judder 개선에 관한 연구
김유종(Yujong Kim),정현범(Hyunbum Jung) 한국자동차공학회 2002 한국자동차공학회 Symposium Vol.2002 No.11
Brake-induced vibration of a vehicle such as brake judder has received considerable attention in recent years and<br/> sometimes has been the subject of recall after marketmore and more because it makes comfort and ride performance<br/> poor and gives customers complaints.<br/> In this study, we try to introduce a reduction case of brake judder transferred to the drivers and passengers via<br/> suspension, steering system and vehicle body using a variety of analysis and modification of rear axle. And we<br/> suggest optimal stiffened rear axle without increasing weight.
점용접부 파단을 고려한 ULSAB-AVC 모델의 충돌해석
김유종(Yujong Kim),하지웅(Jiwoong Ha),허훈(Hoon Huh),임지호(Jiho Lim) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11
Finite element crash analysis can be a great method to design a safe and reliable car in the design process. Today, auto makers try to enhance the accuracy of crash analysis by considering spot-weld failure during the analysis because it has a great effect on the crashworthiness of a car. In this study, the effect of spot-weld failure on the crash analysis of a car is investigated. Spot-weld failure models with different failure criteria are employed to the ULSAB-AVC models and the crashworthiness is evaluated and compared for each models. The intrusion distance and the intrusion velocity of the center pillar are measured for each model after the crash analysis following US-NCAP side impact test The result shows that the crashworthiness of the ULSAB-AVC model is dramatically changed by adopting spot-weld failure models with different spot weld failure criteria.
하지웅(Jiwoong Ha),김유종(Yujong Kim),허훈(Hoon Huh),임지호(Jiho Lim) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11
This paper propose an alternative methodology to construct the dynamic failure model of a spot weld under combined loading conditions for auto-body crash analyses using cross-tension and lap-shear tests. In order to construct the failure model proposed by Song and Huh, failure tests of spot welds should be carried out at intervals of 15˚ from 0˚ to 90˚ or cross-tension and pure-shear tests. But this methodology is not practical because of too difficult and a large number of experiments. In order to substitute lap-shear tests for pure-shear tests, correlation equation between failure loads of pure-shear and lap-shear tests is derived from stress distribution that was assumed around a nugget at failure of a spot weld. Using failure loads of lap-shear and cross-tension tests and β-norm 1.45, Song and Huh’s dynamic failure model of a spot weld is constructed simply. With the failure model which is constructed by the alternative methodology, FE analyses in which are failure loads and failure behaviors of the spot weld are investigated carried out.
이종화(Jongwha Lee),곽철원(Chelwon Kwak),김유종(Yujong Kim),박병일(Byungil Park),이민성(Minsung Lee),이학준(Hakjoon Lee),박상원(Sangwon Park),조성식(Sungshik Cho),김민정(Minjung Kim) 한국자동차공학회 2011 한국자동차공학회 학술대회 및 전시회 Vol.2011 No.11
Generally, vehicle test has been widely adopted by means to evaluate and improve rattle noise of steering system. But it consumes a lot of time and development cost, as well as difficult to ignore the variation of vehicles. This paper proposes systematic approach method to evaluate rattle noise of power steering system instead of vehicle test and also identifies rattle noise phenomenon according to the size of steering system using acoustic holography method. On this study, noise contribution analysis using anti-rattle spring and yoke clearance drew appropriate design guide to reduce rattle noise. Test result using mode analysis of gearbox housing and tuning parameter of MDPS shows that improvement of mechanical system is important to reduce rattle noise. In the future, additional studies will be conducted to reduce rattle noise based on this research.