• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1997년도 추계학술대회논문집; 한국과학기술회관; 6 Nov. 1997
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• pp.101-109
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• 1997

An analytical procedure on the base of the substructure synthesis and assumed modes method is developed to investigate the flexibility effect of bladed disk assembly on vibrational modes of flexible rotor system. In modeling the system, Coriolis forces, gyroscopic moments, and centrifugal stiffening effects are taken into account. The coupled vibrations between the shaft and bladed disk are then extensively investigated through the numerical simulation of simplified models, with varying the shaft rotational speed and the pretwist and stagger angles of the blade. It is found that the Coriolis and inertia forces and the inertia torque, which are induced by the one nodal diameter modes of the bladed disk and vary depending upon the stagger and pretwist angles, lead to the coupled motions of the shaft and the bladed disk.

• 소음진동
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• 제8권1호
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• pp.99-111
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• 1998

An analytical method using the substructure synthesis and assumed modes method is developed to investigate the effect of flexibility of bladed disk assembly on vibrational modes of flexible rotor system. In modeling the system, Coriolis forces, gyroscopic moments, and centrifugal stiffening effects are taken into account. Then the coupled vibrations between the shaft and bladed disk are extensively investigated using simplistic models, as the shaft rotational speed and the pretwist and stagger angles of blade are varied.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 춘계학술대회논문집
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• pp.132-139
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• 2008

The blade vibration problem of bladed disk is the most critical subject to consider since it directly affects the stable performance of the engine as well as life of the engine. Especially, due to complicated vibration pattern of the bladed disk, more effort was required for vibration analysis and test. The research of measuring the vibration of the bladed disk, using NSMS(Non-intrusive stress measurement) instead of Aeromechanics testing method requiring slip ring or telemetry system with strain gauge, was successful. These testing can report the actual stresses seen on the blades; detect synchronous resonances that are the source of high cycle fatigue (HCF) in blades; measure individual blade mis-tuning and coupled resonances in bladed disks. In order to minimize the error being created due to heat expansion, the tip timing sensor is installed parallel to the blade trailing edge, yielding optimal result. Also, when working on finite element analysis, the whole bladed disk has gone through three-dimensional analysis, evaluating the family mode. The result of the analysis matched well with the test result.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년 영문 학술대회
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• pp.871-876
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• 2008

The blade vibration problem of bladed disk is the most critical subject to consider since it directly affects the stable performance of the engine as well as life of the engine. Especially, due to complicated vibration pattern of the bladed disk, more effort was required for vibration analysis and test. The research of measuring the vibration of the bladed disk, using NSMS(Non-intrusive stress measurement) instead of Aeromechanics testing method requiring slip ring or telemetry system with strain gauge, was successful. These testing can report the actual stresses seen on the blades; detect synchronous resonances that are the source of high cycle fatigue(HCF) in blades; measure individual blade mis-tuning and coupled resonances in bladed disks. In order to minimize the error being created due to heat expansion, the tip timing sensor is installed parallel to the blade trailing edge, yielding optimal result. Also, when working on finite element analysis, the whole bladed disk has gone through three-dimensional analysis, evaluating the family mode. The result of the analysis matched well with the test result.

• 소음진동
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• 제8권3호
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• pp.477-484
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• 1998

An analytical procedure on the base of the substructure synthesis and assumed modes method is developed to investigate the flexibility effect of bladed disk assembly on vibrational modes of flexible rotor system. In modeling the system, Coriolis forces, gyroscopic moments, and centrifugal stiffening effects are taken into account. The coupled vibrations between the shaft and bladed disk are then extensively investigated through the numerical simulation of simplified models, with varying the shaft rotational speed and the prewist and stagger angles of the blade. It is found that the Coriolis and inertia forces and the inertia torque, which are induced by the one nodal diameter modes of the bladed disk and vary depending upon the stagger and prewist angles, lead to the coupled motions of the shaft and the bladed disk.

• 한국소음진동공학회논문집
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• 제15권4호
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• pp.429-436
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• 2005

터보기계에서 mistuning은 구조적, 기하학적인 측면에서의 blade와 blade 사이의 미소한 특성차이를 의미하며, blade의 제작과정이나 운전 중 발생하는 마모의 차이에 의해 발생한다고 알려져 있다. Blade사이에서 발생하는 이러한 미소한 차이가 강제 진동 시 아주 큰 국부진동을 야기 시킬 수 있다는 사실이 여러 논문들에 의해 확인되었다. 최근에는 조화패턴의 intentional mistuning 배열을 사용하여 제작 및 사용 중에 발생하는 unintentional mistuning에 의한 blade의 강제진동 응답을 줄일 수 있다는 연구가 발표되었다. 따라서 본 논문에서는 두 가지 형태의 blade(A와 B)를 사용하고, blade감쇠와 coupling 효과를 고려하여 bladed disk의 강제진동응답을 줄일 수 있는 intentional mistuning의 최적배열패턴을 인공지능 알고리즘의 하나인 유전알고리즘과 steepest descent법을 이용하여 구하고자 한다. 그리고 단순 bladed disk와 17-bladed로 된 산업체 로터의 수치예제를 통하여 intentional mistuning 된 bladed disk의 이점을 증명하려고 한다.

• 한국추진공학회지
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• 제14권5호
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• pp.15-23
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• 2010

블레이드 디스크에는 진동 저감을 위해 종종 마찰 감쇠기가 같은 부가적인 감쇠 요소가 부착된다. 마찰 감쇠기가 있는 블레이드 디스크의 강제 진동 해석 시스템이 개발 및 검증되었다. 비선형 진동 해석 방법인 다중 조화 방법과 주기 구조물의 효율적인 해석을 위한 주기 경계 조건이 사용되었으며 집중된 구조 비선형성인 마찰 감쇠기가 있는 구조물의 거동을 모사하기 위하여 가상 질량법으로 얻어진 모드 형상이 사용되었다. 이러한 모드와 일반적인 고유 모드의 상대적인 수렴성이 비교되었다.

• 한국소음진동공학회논문집
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• 제20권1호
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• pp.29-35
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• 2010

This paper studies causes of the L-1 blade damage of a low pressure turbine, which was found during the scheduled maintenance, in 500 MW fossil power plants. Many failures of turbine blades are caused by the coupling of aerodynamic forcing with bladed-disk vibration characteristics. In this study the coupled vibration characteristics of the L-1 turbine bladed-disk in a fossil power plant is shown for the purpose of identifying the root cause of the damage and confirming equipment integrity. First, analytic and experimental modal analysis for the bladed-disk at zero rpm as well as a single blade were performed and analyzed in order to verify the finite element model, and then steady stresses, natural frequencies and corresponding mode shapes, dynamic stresses were calculated for the bladed-disk under operation. Centrifugal force and steady steam force were considered in calculation of steady and dynamic stress. The proximity of modes to sources of excitation was assessed by means of an interference diagram to examine resonances. In addition, fatigue analysis was done for the dangerous modes of operation by a local strain approach. It is expected that these dynamic characteristics will be used effectively to identify the root causes of blade failures and to perform prompt maintenance.

• Journal of Computational Design and Engineering
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• 제2권4호
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• pp.197-205
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• 2015

Bladed disk (BLISK) is a vital part in jet engines with a complicated shape which is exclusively machined on a five-axis machine and requires high accuracy of machining. Poor quality of tool orientation (e.g., false tool positioning and unsmooth tool orientation transition) during the five-axis machining may cause collision and machine vibration, which will debase the machining quality and in the worst case sabotage the BLISK. This paper presents a reference plane based algorithm to generate a set of smoothly aligned tool orientations along a tool path. The proposed method guarantees that no collision would occur anywhere along the tool path, and the overall smoothness is globally optimized. A preliminary simulation verification of the proposed algorithm is conducted on a BLISK model and the tool orientation generated is found to be stable, smooth, and well-formed.

• 한국유체기계학회 논문집
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• 제10권1호
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• pp.14-19
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• 2007

일반적으로 터보 기계에서 mistuning은 구조적, 기하학적인 면에서의 blade와 blade사이의 미소한 특성의 차이를 의미하며, 이러한 미소한 차이가 강제 진동 시, 발생하는 진동 에너지가 몇 개의 blade 또는 하나의 blade에 집중되어 매우 큰 진동을 야기 시킬 수 있다는 사실이 여러 논문들에 언급되고 있다. 또한 mistuning에 대한 blade 시스템의 강제진동응답의 감도를 줄이기 위하여, intentional mistuning개념을 설계단계에 도입하려고 하는 연구도 진행되고 있다. 따라서 본 논문에서는 두 가지 형태의 blade만을 사용하여 bladed disk의 강제진동응답을 최소화 할 수 있는 intentional mistuning의 pattern 최적화에 미치는 mistuning intensity 영향을 조사하였고 최적화 알고리즘으로 유전알고리즘을 사용하였다.