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장훈(Hoon Chang),조성산(Sung-San Cho),이창수(Changsoo Lee),신천세(Chunse Shin),한병기(Byounggi Han),이경우(Kyungwoo Lee) 한국자동차공학회 2008 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Engine head bolts are used to assemble the head, block and gasket of engine. Preload of the head bolts affects significantly the performance and durability of engine. A computer-aided engineering (CAE) approach to assess the appropriateness of head bolt preload has been developed. This paper introduces a finite element (FE) model of head/block/gasket/bolt structure, a FE analysis scheme to mimic the engine running condition, and a method to assess the performance and durability of the structure. Some experimental and analysis data are presented to demonstrate the reliability of the approach. A systematic procedure to determine the optimal bolt preload using the approach is discussed. The approach will be employed at the stage of engine development after further verification and improvement of the approach.
Crevice Corrosion Study of Materials for Propulsion Applications in the Marine Environment
( F Deflorian ),( S Rossi ),( M Fedel ),( C Zanella ),( D Ambrosi ),( E Hlede ) 한국부식방식학회(구 한국부식학회) 2015 Corrosion Science and Technology Vol.14 No.6
The present work addresses crevice and galvanic corrosion processes occurring at the cylinder head gasket/cylinder head interface and cylinder head gasket/cylinder liner interface of four-stroke medium-speed diesel engines for marine applications. The contact between these systems and the marine environment can promote formation of demanding corrosion conditions, therefore influencing the lifetime of the engine components. The electrochemical behavior of various metals and alloys used as head gasket materials (both ferrous alloys and copper alloys) was investigated. The efficacy of corrosion inhibitors was determined by comparing electrochemical behavior with and without inhibitors. In particular, crevice corrosion has been investigated by electrochemical tests using an experimental set-up developed starting from the requirements of the ASTM G-192-08, with adaptation of the test to the conditions peculiar to this application. In addition to the crevice corrosion resistance, the possible problems of galvanic coupling, as well as corrosive reactivity,were evaluated using electrochemical tests, such as potentiodynamic measurements. It was possible to quantify,in several cases, the corrosion resistance of the various coupled materials, and in particular the resistance to crevice corrosion, providing a basis for the selection of materials for this specific application.
ASSESSMENT OF AN ENGINE CYLINDER HEAD-BLOCK JOINT USING FINITE ELEMENT ANALYSIS
조성산,신춘세,이창수,장훈,이경우 한국자동차공학회 2010 International journal of automotive technology Vol.11 No.1
An engine cylinder head-block joint is a gasketed, bolted joint. Assessment of sealing performance and fatigue durability of the joint during engine development relies entirely on the engine dynamometer test because the rig test cannot mimic the engine run condition and finite element analysis employs gasket and bolt models that are too simple to provide the stress data for fatigue assessment. This paper introduces finite element-based assessment of the gasket and the bolt and a model that improves the analysis accuracy without increasing computation time. Experimental data for the deformation of joint members under thermo-mehanical load are presented to demonstrate the accuracy of the model.
FINITE ELEMENT MODELING AND PARAMETER STUDY OF HALF-BEAD OF MLS CYLINDER HEAD GASKET
CHO S. S.,HAN B. K.,LEE J. H.,CHANG H.,KIM B. K. The Korean Society of Automotive Engineers 2006 International journal of automotive technology Vol.7 No.1
Half-beads of multi-layer-steel cylinder head gaskets take charge of sealing of lubrication oil and coolant between the cylinder head and the block. Since the head lifts off periodically due to the combustion gas pressure, both the dynamic sealing performance and the fatigue durability are essential for the gasket. A finite element model of the halfbead has been developed and verified with experimental data. The half-bead forming process was included in the model to consider the residual stress effects. The model is employed to assess the dependence of the sealing performance and the fatigue durability on the design parameters of half-bead such as the width and height of bead and the flat region length. The assessment results show that the sealing performance can be enhanced without significant deterioration of the fatigue durability in a certain range of the half-bead width. In the other cases the improvement of sealing performance is accompanied by the loss of the fatigue durability. Among three parameters, the bead width has the strongest influence.
실린더 라이너 보어 변형 저감을 위한 실험 및 해석적 접근
강동우(Dong-woo Kang),이경은(Kyoung-eun Lee),임규운(Gyu-un Im) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12
The development of modern diesel engines is characterized by the increase in specific power. Consequently, the peak firing pressure (PFP) of the internal combustion engine is also increased. In order to seal the combustion gas completely, axial forces of cylinder head bolts become greater resulting in the severe bore distortion not to mention the structural instability of cylinder head and block. Especially the bore distortion should be kept within certain criteria because the severe bore distortion may cause various problems like blow-by, LOC (Lubricant Oil Consumption), fuel economy and engine noise. This study focuses on the development of a reliable CAE approach to predict the bore distortion in the early stage of the engine development and also discusses the effect of the gasket properties which are considered to be the most sensitive factor on the bore distortion.
이병하(Byungha Lee),조미희(Mihui Jo) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
In the engines of automobiles, knowledge on the thermo-elasticity a priori is very informative in the design stage. Especially, increasing demands on engine performance and fuel economy have resulted in progressively higher loadings on internal components of combustion engines. Therefore the durability assessment should be requested in the cylinder head and block design. In this study, an efficient and reliable analysis technique for the cylinder head, gasket and block compound by using computer modeling and numerical method was described. Commercial software GT Power<SUP>TM</SUP> and Fluent<SUP>TM</SUP> were used to find the gas side and coolant side thermal loading condition. ABAQUS<SUP>TM</SUP> software was followed to predict the temperature and stress of the engine with utilization of estimated coefficients. FE-Fatigue<SUP>TM</SUP> was used for fatigue safety factor.
FATIGUE DURABILITY ASSESSMENT OF FULL-BEAD OF MLS GASKET USING FINITE ELEMENT ANALYSIS
CHO S.-S.,HAN B. K.,LEE J.-H.,CHANG H.,KIM B. K. The Korean Society of Automotive Engineers 2005 International journal of automotive technology Vol.6 No.5
A full-bead of multi-layer-steel engine head gasket, taking charge of the dynamic sealing of combustion chamber, is susceptible to fatigue failure. The fatigue durability of full-bead was assessed with the finite element analysis results and the high-cycle multi-axial fatigue theory. The assessment aimed to reveal the effects of the forming parameters and dimensions of full-bead. The results show that the selection of embossing parameters producing less deformation of bead plate is beneficial for the improvement of durability while the flatting has marginal influence. The fatigue durability also improves with the increase in the width of full-bead and the radial length of bore-side flat region. However, the dimensional effects are limited due to the occurrence of snap-through.
MLS 가스켙 완전양각의 치수 및 성형공정과 피로수명의 관계
조성산(Sung-San Cho),한병기(Byungkee Han),이정현(Jung-Hyun Lee),장훈(Hoon Chang),김범근(Beomkeun Kim) 한국자동차공학회 2004 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
A full-bead of multi-layer-steel engine head gasket, taking charge of the dynamic sealing of combustion chamber, is susceptible to fatigue failure. The dependence of full-bead fatigue life on the forming parameters and dimensions of full-bead were estimated with the finite element analysis and the high cycle multi-axial fatigue theory. The results show that the selection of embossing parameters producing less deformation of bead plate increases the fatigue life while the flatting operation has marginal influence. The fatigue life is also enhanced with the increase in the width of full-bead and the radial length of bore-side flat region. However, the dimensional effects are limited due to the snap-through of full-bead.