스파이럴 그루브 가스시일의 저ㆍ고속 성능특성 해석

이안성(An Sung Lee),양재훈(Jae-Hun Yang),최동훈(Dong-Hoon Choi) 한국트라이볼로지학회 2004 한국트라이볼로지학회 학술대회 Vol.38 No.-

Applying a general Galerkin FE lubrication analysis method to spiral groove dry gas seals, this study analyzes in detail the effects of groove design parameters, such as a number of groove, spiral angle, groove width ratio, groove radius ratio, groove depth ratio. and groove taper ratio, on the lubrication performances of an opening force, leakage, axial stiffness and damping, and angular stiffness and damping at low and high rotating speeds: 3,600 and 15.000 rpm. Results show that, for the primary design consideration performances such as the opening force and axial and angular stiffnesses, a large number of groove, spiral angle of 25°, groove width ratio of 0.46, groove radius ratio of 1.1, groove depth ratio of 1.0, and groove taper ratio of 0.0 are preferred. Where the recommended relatively low values of groove depth and taper ratios are to keep the axial and angular dampings positive or higher than 0 particularly at the high rotating speed.

강성 배분비를 고려한 고강성화 경량화 차체 설계

양희종(Yang, Hee-Jong),김기창(Kim, Ki-Chang),임시형(Lim, Si-Hyung),김찬묵(Kim, Chan-Mook),임홍재(Yim, Hong-Jae) 한국소음진동공학회 2007 한국소음진동공학회 논문집 Vol.17 No.10

Lightweight body due to the decrease of panel thickness and reinforcing member might cause low stiffness. On the other hand, high stiffness body requires an increase of mass. Front pillar section area has been decreased for increasing the driver's visual field. Global vehicle stiffness is affected by stiffness distribution ratio between upper part and lower part at a side body structure. This paper describes a process used to evaluate the stiffness distribution ratio based on strain energy. In addition, optimum design schemes are presented for high stiffness and lightweight body structure considering the investigated stiffness distribution ratio.

Diagrid Core-tube Structure Seismic Performance Based on Equivalent Stiffness Ratio of Inner and Outer Tubes

Chengqing Liu,Dibing Xu 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.4

To study the relationship between the stiffness ratio of the inner and outer tube of the diagrid core-tube structure of high-rise buildings and the redistribution of the storey shear force, the structural ductility, overstrength factor and the seismic performance, a total of 12 kinds of diagrid core-tube structures of equivalent stiffness ratios were established at 71°, 77° and 80° diagonal angles. Based on the static pushover analysis method, combined with the principle of capacity spectrum and demand spectrum, the characteristics and laws of the position change of the weak layer, the redistribution of the storey shear force, the shear lag effect of the bottom compression flange and the overall ductility of the structure are analyzed under the action of the frequent earthquake (70 gal), fortification earthquake (200 gal), rare earthquake (400 gal), extremely rare earthquake (510 gal) and huge earthquake (620 gal). The results show that under different earthquake actions, there is an obvious redistribution of floor shear force in the diagrid core-tube structure, and the storey shear coefficient decreases with the increase of earthquake level and equivalent stiffness ratio. The diagonal angle is the main factor affecting the location of the weak floor and the shear lag effect. The shear lag effect of the structure increases with the increase of the seismic fortification level. The structural ductility with a diagonal angle of 77° is generally optimal. When the equivalent stiffness ratio is 0.64, the structural ductility reaches the optimal value of 1.46, which is 1.1 times that of 71° and 80° diagonal angles. In the structure with the same diagonal angle, the overstrength factor increases with the increase of the equivalent stiffness ratio.

Characterization of Stiffness Coefficients of Silicon Versus Temperature using “Poisson’s Ratio” Measurements

Chun-Hyung Cho,Ho-Young Cha,Hyuk-Kee Sung 대한전자공학회 2016 Journal of semiconductor technology and science Vol.16 No.2

The elastic material constants, stiffness constants (c11, c12, and c44), are three unique coefficients that establish the relation between stress and strain. Accurate knowledge of mechanical properties and the stiffness coefficients for silicon is required for design of Micro-Electro-Mechanical Systems (MEMS) devices for proper modeling of stress and strain in electronic packaging. In this work, the stiffness coefficients for silicon as a function of temperature from -150℃ to +25℃ have been extracted by using the experimental measurements of Poisson’s ratio (n) of silicon in several directions.

Dynamic Characteristics and Responses of Tall Building Structures with Double Negative Stiffness Damped Outriggers

Sun, Feifei,Duan, Ningling,Wang, Meng,Yang, Jiaqi Council on Tall Building and Urban Habitat Korea 2021 International journal of high-rise buildings Vol.10 No.3

Dynamic characteristics of tall building structures with double negative stiffness damped outriggers (2NSDO) are parametrically studied using the theoretical formula. Compared with one negative stiffness damped outrigger (1NSDO), 2NSDO can achieve a similar maximal modal damping ratio with a smaller negative stiffness ratio. Besides, the 2NSDO can improve the maximum achievable damping ratio to about 30% with less consumption of an outrigger damping coefficient compared with the double conventional damped outriggers (2CDO). Besides, the responses of structures with 2NSDO under fluctuating wind load are investigated by time-history analysis. Numerical results show that the 2NSDO is effective in reducing structural acceleration under fluctuating wind load, being more efficient than 1NSDO.

CFT 트러스 거더의 휨강성 및 진동특성

정철헌(Chung Chul-Hun),송나영(Song Na-Young),김인규(Kim In-Gyu),진병무(Jin Byeong-Moo) 대한토목학회 2009 대한토목학회논문집 A Vol.29 No.1A

본 연구에서는 CFT 트러스 거더의 자유진동실험 결과를 토대로 주요 코드에서 규정하고 있는 CFT(concrete filled tube) 합성단면의 초기 휨강성 산정식을 평가하였다. 각 코드에서 규정하는 합성단면 초기 휨강성 산정식에 의한 CFT 트러스 거더의 자유진동 해석결과와 실험결과를 비교하였으며, 그 결과 CFT 트러스 거더의 자유진동실험 결과는 ACI의 휨강성 산정식을 적용하는 경우의 해석결과와 잘 일치하는 결과를 보였다. 이를 반영하여 f/L비 변화에 따른 CFT 트러스 거더의 자유진동해석을 수행하여 f/L비가 CFT 거더의 고유진동수에 미치는 영향을 분석하였다. CFT 트러스 거더의 f/L비는 거더의 전체강성에 영향을 주기 때문에 고유진동수를 변화시킨다. 수평모드에서의 고유진동수는 f/L비가 증가하면 감소하지만, 연직 모드에서의 고유진동수는 f/L비가 증가하면 선형적으로 증가하는 경향을 보였다. The primary objective of the present study was to attempt to quantify the effect of the existing codes for CFT composite section on initial section flexural stiffness, based on the measured vibration frequency of CFT truss girders. The formulae for the initial flexural stiffness of the composite sections in the different codes are compared with the free vibration test results. The results of the free vibration test on the CFT truss girders are in good agreement with the analysis results when used in ACI formulae. The free vibration analysis of CFT truss girders for different f/L ratios was conducted to determine how the natural frequency of the CFT truss girder is affected by different f/L ratios. The presence of the f/L ratios in CFT truss girders alters its frequencies of vibration because of the global stiffness of the CFT girders. The frequency in horizontal modes decreases as the f/L ratio increases. However, the frequency in vertical modes increases as the f/L ratio increases.

시스템 동바리의 수직재와 수평재 연결부 경계조건에 따른 거동 분석

김경윤 ( Gyeoung Yun Kim ),원정훈 ( Jeong-hun Won ),김상효 ( Sang-hyo Kim ) 한국안전학회 2017 한국안전학회지 Vol.32 No.3

This study examined the effect of rotational stiffness of joints between vertical and horizontal members in system supports. In order to prevent repeated disasters of system supports, it is important to examine the accurate behavior of system supports. Among various factors affecting the complex behavior of system supports, this study focused on the stiffness of joints between vertical and horizontal members. The considered joint was modelled by a rotational spring, but the translational displacements were fixed. The stiffness of rotational spring was calculated by utilizing the usable experimental data. In addition, the hinge connection condition, which is generally considered in design and only restrict the translational displacements, was modelled to compare the results. The case with the rotational stiffness in joints showed 3.5 times buckling loads compared to the case without the rotational stiffness. Thus, the structural behavior of the vertical member in system supports was similar to the vertical member with the fixed condition. For the combined stresses of vertical members, the combined stress ratios were reduced 5~6% by considering the rotational stiffness of connecting parts. However, for the horizontal member where showed relatively small stress range, the stresses were increased 2.3~7.6 times by considering the rotational stiffness in connecting parts.

Study on midtower longitudinal stiffness of three-tower four-span suspension bridges with steel truss girders

Jin Cheng,Hang Xu,Mingsai Xu 국제구조공학회 2020 Structural Engineering and Mechanics, An Int'l Jou Vol.73 No.6

The determination of midtower longitudinal stiffness has become an essential component in the preliminary design of multi-tower suspension bridges. For a specific multi-tower suspension bridge, the midtower longitudinal stiffness must be controlled within a certain range to meet the requirements of sliding resistance coefficient and deflection-to-span ratio. This study presents a numerical method to divide different types of midtower and determine rational range of longitudinal stiffness for rigid midtower. In this method, influence curves of midtower longitudinal stiffness on sliding resistance coefficient and maximum vertical deflection-to-span ratio are first obtained from the finite element analysis. Then, different types of midtower are divided based on the regression analysis of influence curves. Finally, rational range for longitudinal stiffness of rigid midtower is derived. The Oujiang River North Estuary Bridge which is a three-tower four-span suspension bridge with two main spans of 800m under construction in China is selected as the subject of this study. This will be the first three-tower four-span suspension bridge with steel truss girders and concrete midtower in the world. The proposed method provides an effective and feasible tool for engineers to design midtower of multi-tower suspension bridges.

The empirical corner stiffness for right-angle frames of rectangular and H-type cross-sections

Kwon, Young-Doo,Kwon, Soon-Bum,Gil, Hyuck-Moon,Cho, Hui-Jeong Techno-Press 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.51 No.3

Until now, the finite corner stiffness of the right-angle frames used as horizontal girders in a bonnet, have not been considered during the design process to result in not a precise result. This paper presents a design equation set for right-angle frames used as horizontal girders in a bonnet assuming rigid corner stiffness. By comparing the center stresses of the right-angle frame according to the design equation set with the results of the finite element method, the master curves for the empirical corner stiffness can be determined as a function of slenderness ratio. A second design equation set for a right-angle frame assuming finite corner stiffness was derived and compared with the first equation set. The master curves for the corner stiffness and the second design equation set can be used to determine the design moments at the centers of the girder so that the bending stresses can be analyzed more precisely.

The empirical corner stiffness for right-angle frames of rectangular and H-type cross-sections

권영두,권순범,길혁문,조희정 국제구조공학회 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.51 No.3

Until now, the finite corner stiffness of the right-angle frames used as horizontal girders in a bonnet, have not been considered during the design process to result in not a precise result. This paper presents a design equation set for right-angle frames used as horizontal girders in a bonnet assuming rigid corner stiffness. By comparing the center stresses of the right-angle frame according to the design equation set with the results of the finite element method, the master curves for the empirical corner stiffness can be determined as a function of slenderness ratio. A second design equation set for a right-angle frame assuming finite corner stiffness was derived and compared with the first equation set. The master curves for the corner stiffness and the second design equation set can be used to determine the design moments at the centers of the girder so that the bending stresses can be analyzed more precisely.