• 대한기계학회논문집A
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• 제24권4호
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• pp.926-936
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• 2000

Actual and strict definition of the shift quality for the powertrain system equipped an automatic transmission must be understood through the acceleration change of the vehicle body, which the driver directly feels as a shift shock. For this reason, it is necessary to concurrently analyze the characteristics of the powertrain system and the vehicle body. This paper presents the mathematical model of the vehicle body, which is based on the equivalent lumped system, to append to the developed model of the powertrain system. The concept of tire slip is also introduced for the experimental relationship between tire/road and driving force. Using the developed dynamic simulation programs, shift transients characteristics are analyzed. Theoretical results are compared with experimental ones from real car tests in equal conditions in order to prove the validity of presented model. In these tests, the system to measure the vehicle acceleration is used with various speeds and engine throttle sensors. It is expected that the presented modeling techniques can provide good predictions of the vehicle driving comfortability.

• 대한기계학회논문집 C: 기술과 교육
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• 제5권2호
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• pp.115-126
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• 2017

본 논문은 특수 차량용 동력 전달계 부품인 구동축의 가속 수명 시험을 수행하는 것이다. 동력 전달계 부품의 수명 평가를 위하여 사용환경의 주행 부하 스펙트럼의 데이터가 필요하나, 특수 차량의 경우 부하 스펙트럼을 구할 수 없는 경우가 대부분이다. 따라서, 본 논문에서는 차량 데이터와 특수 주행로 조건에 기반하여 주행 부하 로드 스펙트럼을 모델링하고 시뮬레이션 하였다. 가속 수명 시험에는 역승 모델을 적용하였고, 마이너 법칙을 사용하여 등가 토크를 구하였으며, 구동축 가속 수명 시험을 위하여 교정 가속법을 사용하였다. 피로시험은 세 수준의 스트레스로 수행하였으며, 사용자 스트레스 수준의 수명은 외삽법을 사용하여 예측 하였고, 실제 시험 결과와 부하 스펙트럼 데이터와의 비교로 수명을 검증하였다.

• 기계와재료
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• 제23권3호
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• pp.190-198
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• 2011

하이브리드 굴삭기는 에너지 재생 및 연비향상을 위하여 기존의 유압부품들 중 일부를 전기부품으로 대체하여 시스템을 구성하고 있다. 따라서, 하이브리드 굴삭기의 신뢰성을 평가하고 보장하기 위해서는 기계적인 부하와 전기적인 부하가 복합적으로 영향을 미쳐 발생되는 고장모드를 고려하여 신뢰성평가기법을 개발하여야 한다. 특히 하이브리드 굴삭기는 가혹한 실외 환경조건에서 운용되므로 새롭게 개발되는 부품들에 대하여 설계 결함을 조기에 발견하기 위한 복합 내환경 시험과 초가속 수명시험이 수행되어야만 한다. 본 연구에서는 FMEA, FMECA, FTA 및 HALT 등의 다양한 신뢰성 기법을 사용하여 하이브리드 굴삭기의 신뢰성평가기법을 개발하였고, 개발대상 하이브리드 굴삭기의 주요 동력전달 파트인 선회구동 시스템에 대한 신뢰성평가장비를 개발하고 구축하였다. 본 연구에서 개발된 하이브리드 굴삭기 신뢰성평가기법은 하이브리드 자동차의 부품들에 대한 신뢰성평가에도 유용하게 사용될 수 있을 것으로 기대된다.

• 동력기계공학회지
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• 제16권6호
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• pp.45-51
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• 2012

In this paper, the algorithm for the static analysis of an axisymmetric cylindrical shell by using the finite element-transfer stiffness coefficient method (FE-TSCM) is suggested. TE-TSCM combining both the modeling procedure of the finite element method (FEM) and the transfer procedure of the transfer stiffness coefficient method (TSCM) has the advantages of FEM and TSCM. After computational programs are made by both FE-TSCM and FEM for the stress analysis of the axisymmetric cylindrical shell, we compare the numerical results by FE-TSCM with those of FEM for two computational models in order to confirm the trust of FE-TSCM.

• 동력기계공학회지
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• 제17권2호
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• pp.46-55
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• 2013

In this paper, the computational algorithm for free vibration analysis of an axisymmetric cylindrical shell is formulated by the Sylvester-transfer stiffness coefficient method (S-TSCM) which combines the Sylvester's inertia theorem and the transfer stiffness coefficient method. After the computational programs for obtaining the natural frequencies and natural modes of the axisymmetric cylindrical shell are made by the S-TSCM and the finite element method (FEM), the computational results which are natural frequencies, natural modes, and computational times by both methods are compared. From the computational results, we can confirm that S-TSCM has the reliability in the free vibration analysis of the axisymmetric cylindrical shell and is superior to FEM in the viewpoint of computational times.

• 동력기계공학회지
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• 제9권3호
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• pp.58-65
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• 2005

This paper deals with the free vibrations of truncated conical shell with uniform thickness by the transfer influence coefficient method. The classical thin shell theory based upon the $Fl\ddot{u}gge$ theory is assumed and the governing equations of a conical shell are written as a coupled set of first order differential equations using the transfer matrix. The Runge-Kutta-Gill integration and bisection method are used to solve the governing differential equations and to compute the eigenvalues respectively. The natural frequencies and corresponding mode shapes are calculated numerically for the truncated conical shell with any combination of boundary conditions at the edges. And all boundary conditions and the intermediate supports between conical shell and foundation could be treated only by adequately varying the values of the spring constants. Numerical results are compared with existing exact and numerical solutions of other methods.

• 동력기계공학회지
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• 제2권1호
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• pp.59-66
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• 1998

The authors have studied vibration analysis algorithm which was suitable to the personal computer. Recently, we presented the transfer stiffness coefficient method(TSCM). This method is based on the concept of the transfer of the nodal dynamic stiffness coefficients which are related to force and displacement vectors at each node. In this paper, we describes the general formulation for the longitudinal and flexural coupled vibration analysis of a beam type structure by the TSCM. And the superiority of the TSCM to the finite element method(FEM) in the computation accuracy, cost and convenience was confirmed by results of the numerical computation and experiment.

• 동력기계공학회지
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• 제5권4호
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• pp.82-89
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• 2001

To design a structural or a mechanical system with the best performance, the main procedure of a typical design usually consists of repeated modifications of design parameters and the investigation of the system response for each set of these parameters. But this procedure requires much time, effort and experience. Sensitivity analysis can provide systematic information for improving performance of a system. The author has studied on the development of the structural analysis algorithm and suggested recently the transfer stiffness coefficient method(TSCM). This method is very suitable algorithm to a personal computer because the concept of the TSCM is based on the transfer of the nodal stiffness coefficients which are related to force and displacement vectors at each node. In this paper, a new sensitivity analysis algorithm using the concept of the TSCM is formulated for the computation of state variable sensitivity in static problems. The trust of the proposed algorithm is confirmed through the comparison with the computation results using existent sensitivity analysis algorithm and reanalysis for computation models.

• 대한기계학회논문집A
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• 제37권5호
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• pp.601-607
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• 2013

본 논문은 Matlab/simulink 기반 휠로더 시뮬레이션 모델의 개발과 검증에 대한 논문이다. 휠로더 시뮬레이션 모델의 개발 및 검증은 실제 휠로더의 생산단계에 앞서 휠로더의 성능을 평가하고 개선하기 위한 목적을 두고 있다. 휠로더 시뮬레이션 모델은 전체적으로 주행부/유압부 동력전달계 모델, 주행부/작업장부 동역학 모델을 포함한 4 가지 모델로 나뉘어져 있다. 휠로더의 주행 및 작업성능을 평가하고 개선하기 위해서는 언급된 4 가지 모델의 통합 시뮬레이션이 필요하며 통합된 시뮬레이션 모델은 성능평가 외의 연료효율의 최적화, 하이브리드 시스템 및 지능형 휠로더 모델의 개발로써 작업효율 향상에 기여할 수 있을 것이다. 본 논문에 제안된 시뮬레이션 모델은 주행부와 작업부 실험 데이터와의 비교를 통해 검증 되었다.

• 동력기계공학회지
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• 제7권2호
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• pp.23-28
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• 2003

It is very important to analyze the torsional vibration for the propulsion shafting of ship. The authors have developed the transfer stiffness coefficient method(TSCM) as a vibration analysis algorithm. The concept of the TSCM is based on the successive transfer of stiffness coefficient. The effectiveness of the TSCM was verified through many applications. In this paper, the TSCM is applied to the torsional free vibration analysis for the propulsion shafting of an actual shin with a diesel engine. In order to calculate the additional torsional stresses of the propulsion shafting the torsional forced vibration for the shafting is analyzed by using both the modal analysis method and the results of the torsional free vibration analysis by the TSCM. The accuracy of the present method is confirmed by comparing with the vibration analysis results of engine maker.