• Title, Summary, Keyword: 강성변화

Search Result 1,364, Processing Time 0.045 seconds

Parametric Study on the tendency of Stiffness Variation using Variable Stiffness Mechanism (변수변화에 따른 가변강성 메커니즘의 강성변화 경향성에 관한 연구)

  • Ham, KiBeom;Han, Jiho;Jeon, JongKyun;Park, YongJai
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.17 no.6
    • /
    • pp.750-758
    • /
    • 2016
  • In general, a system can be stable when it is designed with a rigid material. However, the use of a rigid system can be limited, such as grasping a glass or using a small surgical instrument. To resolve this limitation, a variable stiffness mechanism was developed using a flexible material. Previous research verified the variable stiffness mechanism where flexible segments and rigid segments were connected alternately in series. However, research into the design parameters of the variable stiffness structure is needed to satisfy the desired stiffness. Therefore, a variable stiffness structure was tested by varying the design parameters to confirm the trend of the stiffness variation. When the radius of the structure becomes larger, the stiffness increases. The stiffness increased with decreasing length of the flexible segments. Under the same design parameters, the length of the flexible segments had a greater effect on the stiffness than the length of the rigid segments. In addition, the stiffness was estimated using the pseudo rigid body model and was compared with the experimental results. This parametric study can be used as a design guideline for designing the variable stiffness mechanism to satisfy the desired stiffness.

콘크리트 함체의 강성변화가 상부구조물의 응답에 미치는 영향

  • Lee, Yeong-Uk;Park, Jeong-A;Chae, Ji-Yong;Choe, Ji-Hun
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
    • /
    • /
    • pp.128-130
    • /
    • 2011
  • 플로팅 구조물은 파랑하중의 영향에 따라 함체가 변형하게 되며, 이러한 변형이 상부구조물에 영향을 주게 된다. 함체의 강성변화 및 파랑의 주기변화에 따라 해석을 수행한 결과 함체의 강성이 증가할수록 모멘트는 감소하며, 축력에 대한 영향은 미미하다. 함체의 강성이 같다면 파랑의 주기가 길어질수록 모멘트는 증가한다.

  • PDF

Influence of Stiffness Coefficients on Optical Performance in Composite Optical Substrate (강성계수가 복합재 광학판 성능에 미치는 영향성 연구)

  • Kim, Kyung-Pyo
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.18 no.11
    • /
    • pp.762-769
    • /
    • 2017
  • The extensional stiffness in quasi-isotropic laminates is uniform in the radial direction, but the bending stiffness varies radially due to the stacking sequence. This paper addresses the directional dependency of the bending stiffness and its radial variation in three types of quasi-isotropic laminate reflectors consisting of unidirectional fiber composite materials (UDM) and randomly distributed composite materials (short fiber, RDM). The extensional stiffness and bending stiffness in optical reflectors using RDM are uniform, while the bending stiffness in those using UDM varies radially from 11% to 26%. Also, the stiffness sensitivity, such as the bend-twist or bend-torsion effect, due to the differences in the stiffness value in the composite, is large. These factors are problematic in the optical field requiring precision surfaces. Utilizing RDM might be one way to eliminate the presence of bending stiffness in composite mirror substrates.

A Study on the Longitudinal Behavior of 2-Span Continuous Railway Bridge (2경간 연속 철도교의 종방향 거동에 관한 연구)

  • Im, Jung-Soon;Jo, Jae-Byung;Bahng, Yun-Suk
    • Journal of Korean Society of Hazard Mitigation
    • /
    • v.1 no.1
    • /
    • pp.81-90
    • /
    • 2001
  • This paper presents the results of the parametric study on the longitudinal behavior of 2-span continuous railway bridge. To perform the main objective of this paper, the effects of pier shaft stiffness, pier height, the size of pier foundation, and the bearing stiffness on the longitudinal behavior of the bridges are studied. Within the limits of this study, the research result has revealed that the variation of the fixed pier is more effective than that of the moved pier. In addition, the control of the hearing stiffness is much less expensive than that of any other parameters.

  • PDF

Analysis of Bridges behavior Considering Pile rigidity and Soil characteristics (말뚝강성과 지반특성을 고려한 교량의 거동해석)

  • An, Zu-Og;Yoon, Young-Man
    • Journal of Korean Society of Hazard Mitigation
    • /
    • v.1 no.3
    • /
    • pp.103-110
    • /
    • 2001
  • The objective of this study is to investigate the behavior of superstructure considering several factors such as change of pile rigidity, soil characteristics, and the constraint condition of support. The results of this study are as follows: 1. Pile-rigidity computed by the rotating deformed plane method is continuously varied up to approximately 5D(D=diameter of pile) below the ground level. This result is consistent with the previous study$^{(12)}$, in which the pile deformation occurs at approximately $3{\sim}6$ times of pile diameter from the ground level. 2. For bridge structure-pile system, analytical results of internal forces and deformations show different values for modified pile rigidity and unchanged pile rigidity. 3. Detaild analysis considering modified pile rigidity is required for the long-span bridge design with structure pile system.

  • PDF

An Analytical Model for Calculating Initial Stiffnesses of Double Angle Connections (더블앵글 접합부의 초기강성 산정을 위한 해석모델)

  • Yang, Jae-Guen;Kim, Ki-Hwan;Kim, Ho-Keun
    • Journal of the Korean Association for Spatial Structures
    • /
    • v.4 no.4
    • /
    • pp.55-63
    • /
    • 2004
  • Double angle connections are commonly used for the construction of the low-rise steel framed buildings. Several experimental tests lave been conducted to investigate the effect of the number of bolts on the rotational stiffness of a double angle connection. Several parameters are obtained by performing regression analysis. An analytical model has been introduced to calculate the initial stiffness of a double angle connection in this research.

  • PDF

An Efficient Partial Reanalysis Algorithm for the Locally Changed Structures (부분적 강성 변화에 따른 효율적 부분 재해석 알고리즘)

  • Kim Chee-Kyeong
    • Journal of the Computational Structural Engineering Institute of Korea
    • /
    • v.17 no.4
    • /
    • pp.459-467
    • /
    • 2004
  • This paper presents an efficient reanalysis algorithm, named PRAS (Partial Reanalysis algorithm using Adaptable Substructuring), for the partially changed structures. The algorithm recalculates directly any displacement or member force under consideration in real time without a full reanalysis in spite of local changes in member stiffness or connectivity_ The key procedures consists of 1) partitioning the whole structure into the changed part and the unchanged part, 2) condensing the internal degrees of freedom and forming the unchanged part substructure, 3) assembling and solving the new stiffness matrix from the unchanged part substructure and the changed members.

Vibration Fatigue Analysis of Spot Welded Component considering Change of Stiffness due to Fatigue Damage (피로손상의 누적에 따른 강성변화를 고려한 점용접부의 진동피로해석)

  • Kang, Ki-Weon
    • Journal of the Korea Convergence Society
    • /
    • v.5 no.1
    • /
    • pp.1-8
    • /
    • 2014
  • The purpose of this paper was to evaluate the fatigue life to apply the vibration fatigue analysis considering the stiffness change of the spot welding due to fatigue damage accumulation. For this, the mechanical and fatigue properties of base and spot welded standard specimens were obtained through the tensile and constant amplitude fatigue test. The transfer function of the spot-welded structure was obtained from the frequency response analysis and fatigue analyisis was performed under the condition of PSD=0.11. A vibration fatigue analysis that considered changes in the frequency response due to the fatigue damage that is, failure of some wleding point was conducted on spot-welded structure. The fatigue life of the spot-welded structure was determined by combining the transfer function, the S-N curve of the tensile-shear spot-welded joint and the input PSD.

Transformation of Load Transfer Soil Arch in Geosynthetics-Reinforced Piled Embankment: A Numerical Approach (성토지지말뚝공법의 아치형 응력전달구조 변화에 대한 수치해석적 분석)

  • Lee, Taehee;Lee, Su-Hyung;Lee, Il-Wha;Jung, Young-Hoon
    • Journal of the Korean Geotechnical Society
    • /
    • v.32 no.6
    • /
    • pp.5-16
    • /
    • 2016
  • In the geosynthetics-reinforced piled embankment the effects of soft soil stiffness, friction angle of the fill material, tensile stiffness of geosynthetics, and height of the embankment on the load transfer soil arch measured by the critical height were numerically investigated. Results from parametric studies show that the magnitude of the soft soil stiffness is the most influencing factor on the critical height. The contour charts of the critical height with respect to the combination of the soft soil stiffness and other parameters were presented. The charts show that the critical height sensitively varies with the combination of the soft soil stiffness and the height of embankment. Under the sufficiently low stiffness of soft soil, the critical height sensitively varies with the friction angle of the fill material. Once the geosynthetic layer is placed, however, the magnitude of the tensile stiffness of the geosynthetic layer hardly influences the critical height of the soil arch.

Design and Manufacturing of Robotic Dolphin with Variable Stiffness Mechanism (가변강성 메커니즘을 적용한 로봇 돌고래 설계 및 제작)

  • Park, Yong-Jai
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.21 no.5
    • /
    • pp.103-110
    • /
    • 2020
  • Bio-inspired underwater robots have been studied to improve the dynamic performance of fins, such as swimming speed and efficiency, which is the most basic performance. Among them, bio-inspired soft robots with a compliant tail fin can have high degrees of freedom. On the other hand, to improve the driving efficiency of the compliant fins, the stiffness of the tail fin should be changed with the driving frequency. Therefore, a new type of variable stiffness mechanism has been developed and verified. This study, which was inspired by the anatomy of a real dolphin, assessed a process of designing and manufacturing a robotic dolphin with a variable stiffness mechanism. By mimicking the vertebrae of a dolphin, the variable stiffness driving part was manufactured using subtractive and additive manufacturing. A driving tendon was placed considering the location of the tendon in the actual dolphin, and the additional tendon was installed to change its stiffness. A robotic dolphin was designed and manufactured in a streamlined shape, and the swimming speed was measured by varying the stiffness. When the stiffness of the tail fin was varied at the same driving frequency, the swimming speed and thrust changed by approximately 1.24 and 1.5 times, respectively.