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엄밀한 동적 요소를 이용한 유한 요소 동적 모델의 개선
김종욱,홍성욱,박종혁 金烏工科大學校 産業技術開發硏究院 1999 産業技術開發硏究 Vol.15 No.-
Although the finite element method has become an indispensible tool for dynamic analysis of structures, there still remains a problem to quantify the errors associated with discretization. To improve the modeling accuracy, the present paper proposes a method to make a combined use of finite elements and exact dynamic elements. To this end, the dynamic modeling of beams with the finite element method (FEM)are compared with the exact dynamic element modeling (EDEM). Exact interpolation functions for a Timoshenko beam element, as functions of Laplace variables, are derived using the exact dynamic elements, tested and compared with those for the finite element modeling. A Timoshenko frame with a tapered section is tested to demonstrate the design procedure with the proposed method. the numerical study shows that the combined use of finite element model and exact dynamic element model is very useful.
초기 변형이 있는 일반 회전체 베어링계의 동조 진동응답해석
홍성욱,박종혁,서용규 金烏工科大學校 1996 論文集 Vol.17 No.-
Rotating machinery often encounter excessive vibration due to various sources. Among others, synchronous excitation such as rotating unbalance and initial deformation is acknowledged as essential source affecting the forced vibration of rotor-bearing systems. In the present paper synchronous response is considered in the presence of initial deformation as well as unbalance. The present paper considers general, flexible rotor bearing system, instead of simple rotors as usually adopted in the literature. The present paper intends to reveal the peculiar effects due to initial deformation in general rotor bearing systems which include rotation speed dependent elements and anisotropic nature. Two numerical examples are provided to illustrate the physics of rotor-bearing systems with initial deformations.
조종환,홍성욱,김종욱,박종혁 金烏工科大學校 産業技術開發硏究院 1998 産業技術開發硏究 Vol.14 No.-
Continuous system modeling and analysis are often desirable for understanding of the physics of structures as well as sensitivity analysis or design. The present paper proposes a comprehensive modeling procedure to obtain exact solutions for general beam-like structures. The proposed method considers a Timoshenko beam model. The proposed method provides exact eigensolutions and frequency response functions (FRFs) of general multi-stepped beam structures. Two example are provide for illustrating the proposed method. The first numerical example compares the proposed method with FEM in order to verify the proposed method. The other example demonstrates the applicability of the proposed method with a multi-stepped beam structure. The numerical study proves thar the proposed method is very efficient and useful for the analysis of beam-like structures.
A Study on the Synchronous Response of General Rotor-Bearing Systems due to Initial Deformation
Hong, Seong-Wook,Seo, Yong-Gyu,Park, Jong-Heuck The Korean Society of Mechanical Engineers 2001 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.15 No.9
Rotating machinery often encounters excessive vibration due to various excitation sources. Among others, the synchronous excitation due to rotating unbalance and initial deformation is acknowledged to be one of the major sources of vibration in rotor-bearing systems. In this paper, a synchronous response analysis method in the presence of the initial deformation is proposed to investigate the peculiar effect of the initial deformation on the response of general flexible rotor-bearing systems with rotational speed dependency and the anisotropy. Experiments are performed and compared with computational results to verify the proposed analysis method. Two numerical examples are also provided to illustrate the characteristics of the synchronous response of general rotor-bearing systems due to the initial deformation.