Practical estimation of veering effects on high-rise structures: a database-assisted design approach

Yeo, DongHun Techno-Press 2012 Wind and Structures, An International Journal (WAS Vol.15 No.5

Atmospheric boundary layer winds experience two types of effects due to friction at the ground surface. One effect is the increase of the wind speeds with height above the surface. The second effect, called the Ekman layer effect, entails veering - the change of the wind speed direction as a function of height above the surface. In this study a practical procedure is developed within a database-assisted design (DAD) framework that accounts approximately for veering effects on tall building design. The procedure was applied in a case study of a 60-story reinforced concrete building, which also considered the dependence of veering effects on the orientation of the building. Comparisons are presented between response estimates that do not account for veering, and account for veering conservatively. For the case studied in this paper veering effects were found to be small.

Practical estimation of veering effects on high-rise structures: a database-assisted design approach

DongHun Yeo 한국풍공학회 2012 Wind and Structures, An International Journal (WAS Vol.15 No.5

Atmospheric boundary layer winds experience two types of effects due to friction at the ground surface. One effect is the increase of the wind speeds with height above the surface. The second effect, called the Ekman layer effect, entails veering - the change of the wind speed direction as a function of height above the surface. In this study a practical procedure is developed within a databaseassisted design (DAD) framework that accounts approximately for veering effects on tall building design. The procedure was applied in a case study of a 60-story reinforced concrete building, which also considered the dependence of veering effects on the orientation of the building. Comparisons are presented between response estimates that do not account for veering, and account for veering conservatively. For the case studied in this paper veering effects were found to be small.

Study on localization influences of frequency veering on vibration of mistuned bladed disk

Hongyuan Zhang,Huiqun Yuan,Wenjun Yang,Tianyu Zhao 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.11

Reduced-order models of the bladed disk of the aero-engine compressor were established by adopting Prestressed component mode synthesis (PCMS) method. The frequency veering characteristics of the tuned bladed disk were analyzed. From the aspect of the strain energy, the forced vibration response of the mistuned bladed disk was analyzed, along with calculation of the contribution degree factors, the localization factors and frequency veering distances, finding the influences of the frequency veering distance, the contribution degree factors and the localization. The results show that frequency veering has significant influence on vibration localization of the mistuned bladed disk; in the region of frequency veering, the degree of vibration localization of the mistuned bladed disk is relatively high; along with the changes of the frequency veering distance, the contribution degree of the strain energy of the blades of localization of the mistuned bladed disk shows the certainty of regularity.

해상표적의 변침과 대함유도탄의 중기유도 오차분석 연구

김인수 한국군사과학기술학회 2020 한국군사과학기술학회지 Vol.23 No.6

This paper presents the results of new error analysis on the veering of marine target with the concept of frequency of occurrence, and shows how to apply the midcourse guidance errors of anti-ship missile. The veering error would be a dominant factor in the midcourse guidance errors with flight time increase. This study suggests the reasonable application method of the veering error based on the characteristics of abnormal error, and describes the tailoring method including trade-off between the midcourse guidance range of veering target and the value of frequency of occurrence on veering error.

시각장애인의 직선보행 시 나타나는 비어링 현상에 대한 운동학적 연구 -단일사례연구-

임가영 ( Ga-young Lim ),류지선 ( Ji-seon Ryu ) 한국체육대학교 체육과학연구소 2015 스포츠사이언스 Vol.32 No.2

이 본 연구는 시각장애인의 실제 보행 시 나타나는 좌·우 하지 관절의 움직임을 살펴보고 그 차이가 시각장애인의 비어링의 정도에 미치는 영향을 분석하고자 하는 데 목적이 있다. 본 연구의 대상자는 전 맹의 시력을 가졌으며, 시력상실 외에 다른 신체적 장애가 없는 건강한 남성 1명(체중: 85kg, 신장: 171cm, 나이: 37세, 주동발 및 주동손: 오른쪽)이 참여하였다. 대상자는 지팡이를 사용하여 8m의 직선거리 보행을 총 4번 실시하였으며, 대상자의 동작은 8대의 적외선 카메라(sampling frequency of 100Hz)를 이용하여 촬영하였다. 하지관절의 좌우 차이를 비교하기 위하여 보행의 한 주기 동안 엉덩관절, 무릎관절, 발목관절의 관절각과 분절각을 분석하였으며, 몸통분절의 좌우 회전에 대한 비어링 거리와의 관계를 분석하기 위하여 전체구간 동안의 몸통분절각이 분석되었다. 본 연구 결과 지지구간에서 모든 하지 관절의 왼쪽 분절각이 오른쪽 분절각에 비해 크게 나타난 반면, 왼쪽 관절각이 오른쪽 관절각에 비해 작게 나타났다. 또한 스윙구간 동안 오른쪽 무릎관절에서 분절각과 관절각의 내측회전이 나타났다. 몸통분절의 좌우 회전각은 의미 있는 현상이 나타나지 않았지만 비어링 거리는 오른쪽지지구간보다 왼쪽 지지구간에서 더 크게 나타났다. The purpose of this study was to confirm the kinematic patterns between the left and right during the blind walking. Participant who is blind: He (body mass: 85 kg, height: 171 cm, age: 37 yrs, preferred hand and foot:: right) participated in this study. A three-dimensional motion analysis was performed on the participants using eight infrared cameras(sampling frequency of 100 Hz). The participant walked four times in a straight line 8m using the cane. The kinematic data is analyzed that ankle, knee and hip of segment and joint angle in order to compare right and left. Also, the relevance between trunk segment angle of right-left rotation and veering distance during whole phase. The results were as follows; All lower extremity``s left segment angles are higher than right segment angles. But all lower extremity``s left joint angles are lower than right joint angles. Also, They were internal rotation in the right lower extremity``s segment and joint angle during swing phase. The trunk segment angle of right-left rotation couldn``t appeared significance. However the veering distance is higher left stance phase than right stance phase.

Mode localization and frequency loci veering in an aircraft with external stores

Liu, J.K.,Chan, H.C. Techno-Press 1999 Structural Engineering and Mechanics, An Int'l Jou Vol.8 No.2

This paper presents an investigation of the mode localization and frequency loci veering phenomena in an aircraft with disordered external stores. Two theoretical analyses are carried out to study the occurring mechanism of the two phenomena: condensation technique in the subspace spanned by modes of interest and geometric mapping theory in the complex plane. Two simple criteria for predicting the occurrence of the mode localization and frequency loci veering are put forward. The prediction of the phenomena by our theoretically proposed criteria is in good agreement with that obtained through numerical calculations of characteristic solutions of the disordered system.

수평형 마이크로 자이로스코프의 비어링 현상 및 동특성

정호섭,박규연 한국소음진동공학회 2001 소음 진동 Vol.11 No.1

The vibratory gyroscope can effectively measure the angular velocity as the oscillating and position-sensing mode are exactly tuned. The veering Phenomenon impedes the exact tuning, which is caused by the mode coupling of two modes. In this paper, the gyroscope's structure with two frames is introduced to minimize the veering phenomenon that destabilizes the tuning process of oscillating and position-sensing mode. Experimental results show that the Proposed structure can achieve the mode intersection without veering phenomenon.

Dynamic analysis of an axially moving robot manipulator supported by bearings

김재원,정진태 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.7

In this study, a robot manipulator is modelled as a cantilever beam, which moves in an axial direction, has a lumped mass at the end, and is supported by intermediate springs. Considering the tip mass and intermediate springs in the modeling, we derive the equations of motion in which the rigid-body motion is coupled with the flexible motions, and then analyze the transverse vibrations of the beam. Furthermore, we study the tip mass effects on the natural frequencies and the corresponding mode shapes. The natural frequency loci veering is analyzed for variations in the tip mass and the spring position/stiffness. In addition, we investigate the exchange and localization of modes around these veering regions as well as the parameter effects on the mode shapes. Using a Short-time Fourier transform (STFT), the relationship between the dynamic characteristics and dynamic responses are described. It is found that the dynamic characteristics of the beam are dependent on the veering distance. It is also shown via dynamic responses that the mode exchanges occur when a veering distance is close.

Mode localization and veering of natural frequency loci in two circular plates coupled with a fluid

Jeong, Kyeong-Hoon Techno-Press 2006 Structural Engineering and Mechanics, An Int'l Jou Vol.22 No.6

An analytical method for the free vibration of two circular plates coupled with an inviscid and compressible fluid is developed by the Rayleigh-Ritz method. The fluid is bounded by a rigid cylindrical vessel and two circular plates with an unequal thickness and diameter. It was found that the theoretical results could predict well the fluid-coupled natural frequencies with an excellent accuracy when compared with the finite element analysis results. As the fluid thickness increases or the plate thickness difference increases, an abrupt curve veering in the natural frequency loci of the neighboring modes and drastic changes in the corresponding mode shapes are observed. The mode localization frequently appears in the higher modes and in the wide gap between the plates because of a decrease in the fluid coupling owing to the fluid dispersion effect.

On mode localization of a weakly coupled beam system with spring-mass attachments

Huang, M.,Liu, J.K.,Lu, Z.R. Techno-Press 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.42 No.1

There are a large number of papers in the literature dealing with the free vibration analysis of single/multi-span uniform beam with multiple spring-mass systems, but that of coupled multi-span beams carrying spring-mass attachments is rare. In this note, free vibration analysis of a weakly coupled beam system with spring-mass attachments is conducted. The mode localization and frequency loci veering phenomena of the coupled beam system are investigated. Studies show that for weakly coupled beam system with spring-mass attachments, the mode localization and frequency loci veering will occur once there is a disorder in the system.