• 제목/요약/키워드: Stiffness Analysis

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동특성 변화를 이용한 구조물의 손상 탐지 해석 (Analysis of a Structural Damage Detection using the Change of Dynamic Characteristics)

  • 이정윤;이정우;이준호
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2003년도 춘계학술대회 논문집
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    • pp.760-763
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    • 2003
  • This study proposed the analysis of damage defection due to the change of the stiffness of structure by using the original and modified dynamic characteristics. The method is applied to examples of a cantilever and 3 degree of freedom by modifying the stiffness. The predicted damage detections are in good agreement with these from the structural reanalysis using the modified stiffness.

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기어이의 변동물림강성을 고려한 비틀림진동해석 (Torsional Vibration Analysis of a Spur Gear Pair with the Variable Mesh Stiffness)

  • 류재완;한동철;최상현
    • 한국정밀공학회지
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    • 제16권12호
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    • pp.99-108
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    • 1999
  • A four-degree-of-freedom non-linear model with time varying mesh stiffness has been developed for the dynamic analysis of spur gear trains. The model includes a spur gear pair, two shafts, two inertias representing load and prime mover. In the model, developed several factors such as time varying mesh stiffness and damping, separation of teeth, teeth collision, various gear errors and profile modifications have been considered. Two computer programs are developed to calculate stiffness of a gear pair and transmission error and the dynamic analysis of modeled system using time integration method. Dynamic tooth and mesh forces, dynamic factors are calculated. Numerical examples have been given, which shows the time varying mesh stiffness ha a significant effect upon the dynamic tooth force and torsional vibrations.

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족관절 근위부 골교정용 기능성 체외고정장치 개발 (Development of a Functional External Fixator System for Bone Deformity near Joints in Legs)

  • 이호중;전경진
    • 한국정밀공학회지
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    • 제22권3호
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    • pp.162-169
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    • 2005
  • The functional external fixator system fur bone deformity near joints in legs using the worm gear was developed for curing the difference angles in fracture bone and the lengthening bar for curing the difference length in fracture bone. Both experiments and FE analysis were performed to compare the elastic stiffness in several loading modes and to improve the functional external fixator system for the bone deformity. The FE model using the compressive and bending FE analysis was applied to the FE analysis due to the angle differences. The results show that the compressive stiffness value in experiment was 175.43N/mm; the bending stiffness value in experiment was 259.74N/mm; compressive stiffness value in FEM was 188.67N/mm; bending stiffness value in FEA was 285.71N/mm. The errors between experiments and FEA were less than 10%. The maximum stress (157MPa) to the angle of clamp was lower than the yield stress (176.4MPa) of SUS316L. The stiffnesses in both axial compressive and bending of the new fixator are about 2 times higher than other products except EBI (2003).

족관절 근위부 골교정용 기능성 체외고정장치 개발 (Development of a Functional External Fixator System for Bone Deformity near Joints in Legs)

  • 전경진;이호중
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2004년도 추계학술대회 논문집
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    • pp.1248-1251
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    • 2004
  • The functional external fixator system for bone deformity near joints in legs using the worm gear was developed for curing the difference angles in fracture bone and the lengthening bar for curing the difference length in fracture bone. Both experiments and FE analysis were performed to compare the elastic stiffness in several loading modes and to improve the functional external fixator system for bone deformity near joints in legs. The FE model using the compressive and bending FE analysis was applied the FE analysis due to the angle differences. The results show that the compressive stiffness value in experiment was 175.43N/mm, the bending stiffness value in experiment was 259.74N/mm, compressive stiffness value in FEM was 188.67N/mm, bending stiffness value in FEA was 285.71N/mm. The errors between experiments and FEA were less than 10%. The maximum stress (157MPa) to the angle of clamp was lower than the yield stress (176.4MPa) of SUS316L. The stiffnesses in both axial compressive and bending of the new fixator are about 2 times higher than other products except EBI (2003).

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마찰기인 접촉 강성을 가지는 2-자유도계 면외 방향 진동 시스템의 선형 안정성 해석 (Linear Stability Analysis of an Out-of-plan Motion of Vibration of a Two Degree-of-freedom with Contact Stiffness)

  • 조용구;신기홍;이현영;오재응;이수갑
    • 한국소음진동공학회논문집
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    • 제15권3호
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    • pp.259-265
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    • 2005
  • A two-degree-of-freedom out-of-plane model with contact stiffness is presented to describe dynamical interaction between the pad and disc of a disc brake system. It is assumed that the out-of-plane motion of the system depends on the friction force acting along the in-plane direction. Dynamic friction coefficient is modelled as a function of both in-plane relative velocity and out-of-plane normal force. When the friction coefficient depends only on the relative velocity, the contact stiffness has the role of negative stiffness. The results of stability analysis show that the stiffness of both pad and disc is equally important. Complex eigen value analysis is conducted for the case that the friction coefficient is also dependent on the normal force. The results further verify the importance of the stiffness. It has also been found that increasing the gradient of friction coefficient with respect to the normal force makes the system more unstable.

강성계수의 전달을 이용한 일정 단면을 갖는 비틀림 축계의 고유진동수 민감도 해석 (Sensitivity Analysis for Natural Frequency of Torsional Shafting with Constant Cross Section Using Transfer of Stiffness Coefficient)

  • 최명수;변정환
    • 동력기계공학회지
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    • 제16권2호
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    • pp.11-16
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    • 2012
  • In this paper, the authors formulate the sensitivity analysis algorithm for the natural frequency of a torsional shafting by expanding the transfer stiffness coefficient method. The basic concept of the present algorithm is based on the transfer of sensitivity stiffness coefficient, which is the derivative of stiffness coefficient with respect to design parameter, at every node from the first node to the last node in analytical model. The effectiveness of the present algorithm is confirmed by comparing the results of the sensitivity analysis and those of the reanalysis for the natural frequencies of a torsional shafting with a constant cross section. In numerical calculation, the design parameter is the diameter of the shaft element of the torsional shafting.

파랑하중을 받는 부유체의 강성에 따른 응답 고찰 (Response Analysis of Floating Structure under Wave Loads Considering Stiffness)

  • 김병완;김영식;홍사영;경조현;조석규
    • 한국전산구조공학회:학술대회논문집
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    • 한국전산구조공학회 2006년도 정기 학술대회 논문집
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    • pp.941-948
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    • 2006
  • In this paper, the effect of stiffness on hydroelastic responses of plate-like floating structure under wave loads are studied. Direct method is used for the numerical analysis. In the numerical analysis, structural equation is formulated by finite element method(FEM) and higher order boundary element method(HOBEM) is employed for the analysis of fluid flow. A 1000m-long VLFS(Very Large Floating Structure) is considered in numerical analyses. By analyzing VLFS for various cases of stiffness, the characteristics of hydroelastic responses with the variation of stiffness are investigated.

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새로운 개념의 비반복적 비점증적 비선형해석 (New Non-iterative Non-incremental Nonlinear Analysis)

  • 김치경;황영철
    • 한국전산구조공학회:학술대회논문집
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    • 한국전산구조공학회 2006년도 정기 학술대회 논문집
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    • pp.514-519
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    • 2006
  • This paper presents a new nonlinear analysis algorithm which uses the equivalent nodal load for the element stiffness. The equivalent nodal load represents the influence of the stiffness change such as the addition of elements, the deletion of elements, and/or the partial change of element stiffness. The nonlinear analysis of structures using the equivalent load improves the efficiency very much because the inverse of the structural stiffness matrix, which needs a large amount of computation to calculate, is reused in each loading step. In this paper, the concept of nonlinear analysis using the equivalent load for the element stiffness is described and some numerical examples are provided to verify it.

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변동물림강성/감쇠와 마찰을 고려한 기어구동계의 동특성 해석 (Dynamic Analysis of a Gear Driving System with Time-varying Mesh Stiffness/Damping and Friction)

  • 김우형;정태일;정진태
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2006년도 춘계학술대회논문집
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    • pp.224-231
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    • 2006
  • A six-degree-of-freedom dynamic model with time-varying mesh stiffness/damping and friction has been developed for the dynamic analysis of a gear driving system. This model includes a spur gear pair, bearing, friction and prime mover. Using Newton???s method, equations of motion for the gear driving system were derived. Two computer programs are developed to calculate mesh stiffness, transmission error and friction force and analyze the dynamics of the modeled system using a time integration method. The influences of mesh stiffness/damping, bearing, and friction affecting the system were investigated by performing eigenvalue analysis and time response analysis. It is found that the reduction of the maximum peak magnitude by friction is decided according to designing the positions of pitch point and maximum peak in the responses.

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부재간 결합부의 동적 특성 분석 및 강성 예측 (Analysis of the Dynamical Characteristics and Prediction of Stiffness for the Joint between Members)

  • 윤성호
    • 한국기계가공학회지
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    • 제18권2호
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    • pp.58-64
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    • 2019
  • This paper describes the analysis of dynamic characteristics and prediction of the stiffness for the joint between structural members. In the process of deriving the governing equations, the stiffness values responsible for the moment and shear force were modelled by using linear and torsional springs in the middle of a clamped-clamped beam. The sensitivities of the natural frequency and modal assurance criterion were investigated as a function of the dimensionless linear and torsional spring stiffness. The reliability of the predictions for the linear and torsional stiffness values was verified by the inverse computations of the stiffness matrix. The predictive and exact theoretical stiffness values were compared for the stiffness element in the finite element formulation, and their results show an excellent correlation. It is strongly anticipated that although the proposed methodology is currently limited to the analytical utilization, it will provide a useful tool to estimate unknown joint stiffness values based on the experimental natural frequency and mode shape.