• 대한기계학회논문집
• /
• 제16권5호
• /
• pp.992-998
• /
• 1992

본 연구에서는 그립부의 비틀림 모멘트를 최소화하는 안정타점영역을 정의하 였으며 전달매트릭스법에 의한 수치해석과 실험적 모드해석법을 실제의 골프클럽에 적 용하여 모드 파라메타를 구한 다음 그 파라메타변경에 따른 안정타점영역 변화를 예측 함으로써 안정타점영역을 확장시키는 방법에 대해 연구하였다.

• 대한기계학회논문집A
• /
• 제22권1호
• /
• pp.190-197
• /
• 1998

Equations of motions of a pretwisted rotating blade with a concentrated mass in an arbitrary position are derived. The flapwise and chordwise equations are coupled to each other due to the pretwist angle of the blade. As the angular speed, hub radius ratio, pretwist angle and concentrated mass vary, the vibration characteristics of the blade change. It is found that eigenvalue lociveering phenomena occur between two closing loci due to the pretwist angle. The effect of the pretwist angle on the critical angular speed and location of the concentrated mass on the natural frequencies are also investigated.

• 대한기계학회논문집A
• /
• 제20권7호
• /
• pp.2174-2181
• /
• 1996

Equations of chordwise and flapwise bending motions of pretwisted rotatin cantilever beams are derived. The two motions are coupled to each other due to the pretwist angle of the beam cross section. As the angular speed, hub radius ratio, and pretwist angle vary, the vibration characteristics of the beam change. It is found that engenvalue loci veering phenomena and associated mode shape variations occur between two vibration modes due to the pretwist angle. The effect of the pretwist angle on the critical angular speed is also investigated.

• 한국소음진동공학회논문집
• /
• 제22권7호
• /
• pp.659-666
• /
• 2012

A nonlinear dynamic model for the shaft-disk-blade unit is developed in this study. In this regard, the rotating flexible blade, with a pre-twist angle, attached to a rigid disk driven by a shaft which is flexible in torsion is developed. The rotor-blade coupled model is derived using Lagrange equation in conjunction with the assumed mode method to discretize the blade deformation. The equations of motion are analyzed based on the small deformation theory for the blade and shaft torsional deformation to obtain the system natural frequencies for various system parameters.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 1996년도 춘계학술대회논문집; 부산수산대학교, 10 May 1996
• /
• pp.227-232
• /
• 1996

For analyzing the torsional vibration of a complicated multi-branched geared system, we constructed the transfer matrix using the modified Hiber Branch Method and performed the modal analysis using the .lambda.-matrix method. We compared the developed transfer matrix method with the Lagrangian method and noticed that the result of two methods are in agree with each other.

• 항공우주기술
• /
• 제7권2호
• /
• pp.205-212
• /
• 2008

본 논문에서는 스마트무인기 로터시스템의 공진, 로터 공탄성 안정성 및 휠플러터 안정성 해석을 위한 모델링 데이터와 최종 해석결과를 기술하였다 향후 날개구조 설계변경 가능성을 고려하여 날개 빔, 코드 및 비틀림 강성이 훨플러터 안정성에 미치는 영향이 분석되었다. 파라메트릭 분석 결과 날개의 비틀림 강성 및 빔강성의 변화가 코드방향 강성에 비하여 빔모드 댐핑값에 훨씬 큰 영향을 미치는 것으로 분석되었다. 최종 설계된 로터시스템은 공진가능성이 없고, 스마트무인기 TR-S4 로터/파일론/날개에 대하여 로터 공탄성 안정성 및 훨플러터 안정성이 보장됨을 해석적으로 확인하였다.

• 동력기계공학회지
• /
• 제7권2호
• /
• pp.23-28
• /
• 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.

• 한국소음진동공학회논문집
• /
• 제12권2호
• /
• pp.116-123
• /
• 2002

Applying a general coupled lateral and torsional vibration finite element model of gear pair element, this paper intends to look into in detail the coupled lateral and torsional vibration characteristics of a turbo-chiller rotor bearing system, having a bull-pinion speed increasing gear. Investigations have been carried out systematically by comparing the uncoupled and coupled natural frequencies and their mode shapes upon varying the gear mesh stiffness with considerations on rotating speeds, and also by comparing the strain energies of lateral and torsional vibration modes. Results hale shown that some modes may hale the coupled lateral and torsional mode characteristics as the gear mesh stiffness Increases over a certain value, and moreover that their associated dominant modes may be different from their initial modes, j.e., a certain dominant mode may change from an initial torsional one to a lateral one or from an initial lateral one to a torsional one.

• 소음진동
• /
• 제5권2호
• /
• pp.215-224
• /
• 1995

In this paper, the three-dimensional finite element model is established to investigate the structural dynamic characteristics of rotor blade using a finite element analysis. Six natural frequencies and mode shapes are calculated by computer simulation. The first three flapping modal frequencies, the first two lead-lag modal frequencies, and the first feathering modal frequency are validated through comparison with the modal test results of the fixed rotor blade. The computer simulation results are found in good agreement with experimentally measured natural frequencies. The important results are obtained as follows: (1) Natural frequencies are changed due to the variation of rotational speed and fiber angle of rotor blade, (2) Weak coupling between flapping mode shape and lead-lag mode shape are detected, (3) Centrifugal force has more effect on flapping modal frequency than lead-lag modal frequency.

• 소음진동
• /
• 제9권1호
• /
• pp.103-112
• /
• 1999

A new modeling and analysis technique for one-dimensional distributed parameter systems is presented. First. discretized equations of motion in Laplace domain are derived by applying discretization methods for partial differential equations of a one-dimensional structure with respect to spatial coordinate. Secondly. the z and inverse z transformations are applied to the discretized equations of motion for obtaining a dynamic matrix for a uniform element. Four different discretization methods are tested with an example. Finally, taking infinite on the number of step for a uniform element leads to an exact dynamic matrix for the uniform element. A generalized modal analysis procedure for eigenvalue analysis and modal expansion is also presented. The resulting element dynamic matrix is tested with a numerical example. Another application example is provided to demonstrate the applicability of the proposed method.