저자명 한 신 
년도 2010 
Three unprecedented dual metal crankshafts for heavy-duty diesel engines up to 3,000 hp are proposed and thoroughly investigated by comprehensive multi-body dynamic finite element analysis and supporting experiments. The dual metal crankshafts are basically made of ductile cast iron and high strength forged steel, and the two dissimilar metals are proven to be seamless by a series of tensile tests using bimetallic specimens. The dual metal approach is made in order to achieve both cost effectiveness and shortened manufacturing lead time simultaneously. The new approach is basically realized by casting of ductile cast iron in a mold assembled with pre-machined steel parts. Historical researches and experiments already proved that the monometallic crankshaft of only ductile cast iron is not able to replace a conventional forged steel crankshaft. Therefore, casting-based crankshaft should be reinforced by high strength structures, especially for critical areas such as the fillets of crank pins and journals. Three dual crankshafts are designed to achieve equivalent structural strength not sacrificing manufacturing advantages of casting. The reinforcing members of forged steel are implemented in three ways for the three dual metal models. The first dual metal approach so-called BM1 crankshaft is to put barrel-shaped steel pipes in the center of both crank pins and journals to complement inferior mechanical properties of ductile cast iron, FCD700. The second duel metal approach named BM2 crankshaft uses reinforcing steel members more extensively than the first one does, putting forged steel pipes in the center and outside of crank pins and journals. The second model is more advanced than the first one because the second one effectively strengthens up the most critical areas of a crankshaft, the fillets of crank pins and journals, by the high strength steel. The third model designated as BM3 crankshaft is quite a bold approach to have only crank webs made of ductile cast iron. Including crank pins and journals, the reset of the body of the third model is all made of forged steel, which is meant to maximize its torsional stiffness and minimize its torsional vibration. The conventional crankshaft and the three proposed dual metal ones are evaluated by state of the art multi-body dynamic analysis. The multi-body dynamic approach proposed in the study is very comprehensive because it includes all the key components of a cranktrain such as a crankshaft, pistons, connecting rods, a flywheel, a pulley and even dynamometer. In addition, hydrodynamic journal bearings and allowable radial clearance of journals are effectively implemented by so-called quasi-hydrodynamic approach which is given in this study. Combination of the quasi-hydrodynamic method and external loading by constant velocity on the dynamometer is quick and effective to simulate closely any cranktrains of either in-line or Vee formation. The proposed multi-body dynamic approach with a full deformable crankshaft is supposed to bear much more accurate results than static analysis with partial portion of a crankshaft, for instance, single or half crank throw. Another competitive advantage of the proposed multi-body approach is no need to consider the worst loading case and the most severely loaded part of a crankshaft, which overcomes all the historical struggles to find them. The proposed multi-body dynamic analysis turned out that the third dual metal crankshaft with the steel crank pins and journals connected by the crank webs of ductile cast iron was capable of replacing conventional monometallic steel crankshaft in term of fatigue safety factor which is calculated by scaled normal stress method. Even in extremely harsh virtual operating condition with maximum gas pressure of 210 bar, the third model was expected to operate normally. On the other hand, other two dual metal designs were not up to the minimum fatigue requirement especially in case of the extreme virtual operating case with 210 bar Pmax. Since modern heavy-duty diesel engines generally have maximum gas pressure up to 210 bar, the successful operation in this condition is prerequisite to realize the ultimate objective of this study. Feasibility of the simulation is proved by an experiment of torsional vibration with actual full-scale operational diesel engine using optical rotary encoder. The natural frequencies of the conventional crankshaft were obtained by the experiment, and the results revealed that there was good agreement of the natural frequencies between the simulation and the experimental results. Consequently, one of the proposed dual metal crankshafts is expected to be able to replace conventional monometallic one finally achieving both cost effective and reduced manufacturing lead time in accordance with the corresponding fatigue performance to the conventional one.
번호 제목 저자명 날짜 조회 수
27 Study on Dynamic Tensile Tests of Auto-body Steel Sheet at the Intermediate Strain Rate for Material Constitutive Equations (차체강판의 중변형률 속도에서의 동적 인장시험 및 물성 구성방정식에 관한 연구) 임지호  2005.11.29 25430
26 Analysis of Elasto-Plastic Stress Waves by a Time Discontinuous Variational Integrator of Hamiltonian with a Second-Order Integration Scheme of the Constitutive Model (해밀토니안의 시간 불연속 변분적분기와 구성방정식의 2차 정확도 적분법을 이용한 탄소 조상순  2008.12.15 21645
25 Forming Limit Diagram of Auto-body Steel Sheets at High Strain Rates for Sheet Metal Forming and Crashworthiness (박판성형 및 충돌성능 향상을 위한 고변형률속도에서의 차체강판 성형한계도) 김석봉  2010.07.13 21585
24 A New Ductile Fracture Criterion for the Formability Prediction of Steel Sheets and Its Application to Finite Element Analysis (강판의 성형성 예측을 위한 새로운 연성 파괴 조건 및 유한 요소 해석에의 응용) [1] Yanshan Lou  2012.12.10 20976
23 A Study on the Tension/Compression Hardening Behavior of Auto-body Steel Sheets Considering the Pre-strain and the Strain Rate (초기 변형률 및 변형률 속도를 고려한 차체 강판의 인장/압축 경화 거동에 관한 연구) [1] 배기현  2011.01.11 20274
22 A Study on Material Properties of OFHC Copper Film at High Strain Rates using High-Speed Micro Material Testing Machine (고속마이크로재료시험기를 이용한 무산소동 박판의 고변형률속도 재료물성치 연구) 김진성  2010.07.13 20156
21 Finite Element Inverse Approach and Initial Guess Generation for Sheet Metal Forming Analysis of Complicated Auto-body Members (복잡한 차체부재의 박판성형공정을 위한 유한요소 역해석 및 초기추측치 계산) 김승호  2005.11.29 19050
20 A Study on the Dynamic Failure Model of a Spot Weld under Combined Loading Conditions for Auto-body Crash Analyses (차체용 부재의 충돌해석을 위한 복합하중조건에서 점용접부의 동적 파단모델 연구) [1] 송정한  2008.07.24 18508
19 Optimum Process Design in Sheet Metal Forming Processes using Finite Element Sensitivity Analysis (유한요소 민감도해석을 이용한 박판금속성형에서의 공정변수 최적설계) [1] 김세호  2005.11.29 18448
18 Strain-Rate Dependent Anisotropic Yield Criteria for Auto-body Steel Sheets (자동차용 강판의 변형률속도 의존 이방성 항복함수에 관한 연구) 허지향  2012.12.11 17975
» Evaluation of a cast-joining process of dual metal crankshafts for heavy-duty engines with ductile cast iron and high strength forged steel(구상흑연주철과 고강도 단조강의 주조접합 이종금속을 이용한 중대형 엔진 크랭크샤프트의 평가) 한 신  2010.07.13 17828
16 Dynamic Formulation of Finite Element Limit Analysis for Impact Simulation of Structural Members (구조부재의 충돌해석을 위한 유한요소 극한해석의 동적 수식화) 김기풍  2005.11.29 17725
15 Measurement Uncertainty Evaluation for High Strain Rate Tensile Properties of Auto-body Steel Sheet (자동차용 강판 고속인장물성 데이터의 측정불확도 산출) 정세환  2012.12.10 17703
14 Development of a Nonlinear Degenerated Shell Element with the Drilling Degree of Freedom by the Cubic Polynomial Interpolation and the Assumed Strain Method (드릴링 자유도의 삼차 근사법과 대체변형률법을 이용한 비선형 감절점 쉘 요소의 개발) 이형욱  2005.11.29 17662
13 Rate Dependent Hardening Model for Pure Titanium Considering the Effect of Deformation Twinning (쌍정의 영향을 고려한 티타늄의 변형률속도 의존 경화 모델) 안광현  2012.12.12 17136
12 Finite Element Simulation of 3-dimensional Superplastic blow forming with diffusion bonding (유한요소법을 이용한 초소성 재료의 삼차원 확산 접합 및 압력 성형 해석) 이기석  2005.11.29 16942
11 Microscopic investigation of the strain rate hardening for auto-body steel sheet(차체강판 변형률속도 경화의 미시적 관찰) 윤종헌  2010.07.13 16887
10 Crash Analysis of Auto-body Structures with an Explicit Finite Element Method ( 외연적 유한요소법을 이용한 차체 구조물의 충돌해석 ) 강우종  2005.11.29 16675
9 Shell Element Formulation for Limit Analysis of Thin-Walled Structures ( 박판부재의 붕괴거동해석을 위한 극한해석의 쉘요소 수식화 ) 김현섭  2005.11.29 14689
8 A Study on a Continuum Damage Yield Function to Predict Ductile Fracture of Materials (재료의 연성파단을 예측하기 위한 연속체 손상 항복 함수에 관한 연구) 고윤기  2012.12.10 14565