• 제목/요약/키워드: Displacement function

검색결과 1,012건 처리시간 0.032초

변위구속조건을 고려한 컴플라이언트 메커니즘 설계 (Compliant Mechanism Design with Displacement Constraint)

  • 김영기;민승재
    • 대한기계학회논문집A
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    • 제26권9호
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    • pp.1779-1786
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    • 2002
  • When the topology optimization is applied to the design of compliant mechanism, unexpected displacements of input and output port are generated since the displacement control is not included in the formulation. To devise a more precise mechanism, displacement constraint is formulated using the mutual potential energy concept and added to multi-objective function defined with flexibility and stiffness of a structure. The optimization problem is resolved by using Finite Element Method(FEM) and Sequential Linear Programming(SLP). Design examples of compliant mechanism with displacement constraint are presented to validate the proposed design method.

고속 밀링 가공 시 주축 변위 측정을 통한 절삭력의 실시간 감시 (On-line Cutting Force Estimation by N[ensuring Spindle Displacement in High-Speed Milling Process)

  • 김종혁;김진현;김일해;안형준;장동영;한동철
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2006년도 춘계학술대회 논문집
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    • pp.133-134
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    • 2006
  • A cylindrical capacitive displacement sensor (CCS) was developed and applied for monitoring end milling processes. Dynamic characteristics of a spindle-assembly were measured using the CCS and a designed magnetic exciter. The technique to extract the spindle displacement component caused only by cutting from the measured signals using the CCS was proposed in the paper. Using CCS signals and FRF (Frequency Response Function) derived from dynamics of the spindle tool system, dynamic cutting forces are estimated quantitatively.

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A Study on the Improvement of Stress Field Analysis in a Domain Composed of Dissimilar Materials

  • Song, Kee-Nam;Lee, Jin-Seok
    • Nuclear Engineering and Technology
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    • 제30권3호
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    • pp.202-211
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    • 1998
  • Interfacial stresses at two-material interfaces and initial displacement field over the entire domain are obtained by modifying the potential energy functional with a penalty function, which enforces continuity of the stresses at the interface of two materials. Based on the initial displacement field and interfacial stresses, a new methodology to generate a continuous stress field over the entire domain has been proposed by combining the modified projection method of stress-smoothing and Loubignac's iterative method of improving the displacement field. Stress analysis is carried out on two examples made of dissimilar materials : one is a two-material cantilever composed of highly dissimilar materials and the other is a zirconium-lined cladding tube made of slightly dissimilar materials. Results of the analysis show that the proposed method provides an improved continuous stress field over the entire domain, and accurately predicts the nodal stresses at the interface, while the conventional displacement-based finite element method produces significant stress discontinuities at the interface. In addition, the total strain energy evaluated from the improved continuous stress field converges to the exact value in a few iterations.

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The effect of soil-structure interaction on inelastic displacement ratio of structures

  • Eser, Muberra;Aydemir, Cem
    • Structural Engineering and Mechanics
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    • 제39권5호
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    • pp.683-701
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    • 2011
  • In this study, inelastic displacement ratios and ductility demands are investigated for SDOF systems with period range of 0.1-3.0 s. with elastoplastic behavior considering soil structure interaction. Earthquake motions recorded on different site conditions such as rock, stiff soil, soft soil and very soft soil are used in analyses. Soil structure interacting systems are modeled with effective period, effective damping and effective ductility values differing from fixed-base case. For inelastic time history analyses, Newmark method for step by step time integration was adapted in an in-house computer program. Results are compared with those calculated for fixed-base case. A new equation is proposed for inelastic displacement ratio of interacting system ($\tilde{C}_R$) as a function of structural period of interacting system ($\tilde{T}$), strength reduction factor (R) and period lengthening ratio ($\tilde{T}/T$). The proposed equation for $\tilde{C}_R$ which takes the soil-structure interaction into account should be useful in estimating the inelastic deformation of existing structures with known lateral strength.

Double displacement coupled forced response for electromechanical integrated electrostatic harmonic drive

  • Xu, Lizhong;Zhu, Cuirong;Qin, Lei
    • Structural Engineering and Mechanics
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    • 제29권5호
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    • pp.581-597
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    • 2008
  • In this paper, the double displacement coupled statics and dynamics of the electromechanical integrated electrostatic harmonic drive are developed. The linearization of the nonlinear dynamic equations is completed. Based on natural frequency and mode function, the double displacement coupled forced response of the drive system to voltage excitation are obtained. Changes of the forced response along with the system parameters are investigated. The voltage excitation can cause the radial and tangent coupled forced responses of the flexible ring. The flexible ring radius, ring thickness and clearance between the ring and stator have obvious influences on the double displacement coupled forced responses.

철근콘크리트 전단벽의 횡하중-횡변위 관계의 일반화 (Generalized Lateral Load-Displacement Relationship of Reinforced Concrete Shear Walls)

  • 문주현;양근혁
    • 콘크리트학회논문집
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    • 제26권2호
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    • pp.159-169
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    • 2014
  • 이 연구에서는 철근콘크리트 전단벽의 횡하중 거동과 연성을 합리적으로 평가하기 위해서 모멘트-곡률관계를 정립하고 이로부터 단순화된 횡하중-횡변위관계를 제시하였다. 최초 휨 균열, 인장철근 항복, 최대내력, 최대내력의 80% 및 인장철근파단시점에서 모멘트와 곡률은 힘의 평형조건과 변형적합조건으로부터 정립되었다. 최대내력 이후의 곡률평가를 위한 압축측연단 콘크리트 변형률은 Razvi and Saatcioglu의 구속된 콘크리트의 응력-변형률 관계를 이용하여 최대응력의 감소계수와 횡보강근 체적지수의 함수로 제시하였다. 모멘트 평가모델은 변수연구를 통하여 인장철근지수, 수직철근지수 및 축력지수의 함수로 일반화하였다. 횡변위는 전단벽의 높이에 따라 분포된 이상화된 곡률로부터 모멘트 면적법을 이용하여 환산하였다. 제시된 횡하중-횡변위관계는 기존 실험 결과와 잘 일치하였으며, 특히 최대내력 이후의 거동을 잘 평가하였다.

장거리 영상기반 변위계측 시스템 검증 (Verification of Long-distance Vision-based Displacement Measurement System)

  • 김홍진;허석재;신승훈
    • 대한건축학회연합논문집
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    • 제20권6호
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    • pp.47-54
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    • 2018
  • The purpose of this study is to verify the long - range measurement performance for practical field application of VDMS. The reliability of the VDMS was verified by comparison with the existing monitoring sensor, GPS, Accelerometer and LDS. It showed the ability to accurately measure the dynamic displacement by tracking a motion of free vibration of target. And using the PSD function of measured data, the results in the frequency domain were also analyzed. We judged that VDMS is able to identify the higher system mode and has sufficient reliability. Based on the reliability verification, we conducted tests for long-distance applicability for actual application of VDMS. The distance from the stationary target model structure was increased by 50m interval, and the maximum distance was set to 400m. From the distance of 150m, the image obtained by the commercial camcorder has an error in the analysis, so the measured displacement comparison was performed between the LDS and the refractor telescope measurement results. In the measurement results of the displacement area of VDMS, the data validity was deteriorated due to the data shift by the external force and the quality degradation of the enlarged image. However, even under the condition that the effectiveness of the displacement measurement data of VDMS is low, the first mode characteristic included in the free vibration of the object is clearly measured. If the influence from the external environment is controlled and stable data is collected, It is judged that reliability of long-distance VDMS can be secured.

Evaluation of adjacent tooth displacement in the posterior implant restoration with proximal contact loss by superimposition of digital models

  • Jo, Deuk-Won;Kwon, Min-Jung;Kim, Jong-Hee;Kim, Young-Kyun;Yi, Yang-Jin
    • The Journal of Advanced Prosthodontics
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    • 제11권2호
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    • pp.88-94
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    • 2019
  • PURPOSE. This study was conducted to investigate patterns of adjacent tooth displacement in the posterior implant with interproximal contact loss (ICL) by 3-D digital superimposition method. MATERIALS AND METHODS. Posterior partially edentulous patients, restored with implant fixed partial prostheses before 2011 and suffered from food impaction of ICL between 2009 and 2011, were included. Two dental casts, at the time of delivery and at the time of food impaction in a same patient, was converted into 3-D digital models through scanning and superimposition was performed to assess chronologic changes of the dentition. Directions of tooth displacement were evaluated and the amount of ICL was calculated. Correlations between the amount of ICL and elapsed time, or between the amount of ICL and age after function, were assessed at a significance level of P<.05. RESULTS. A total number of 13 patients (8 males, 5 females) with a mean age of $65.76{\pm}9.94years$ and 17 areas (4 maxillae, 13 mandibles) were included in this retrospective study. Teeth adjacent to the implant restoration showed complex displacements but characteristic tendency according to the location of the arch. The mean amount of ICL was $0.33{\pm}0.14mm$. Elapsed time from function to ICL was $61.47{\pm}31.27months$. There were no significant differences between the amount of ICL and elapsed time, or age (P>.05). CONCLUSION. Natural teeth showed various directional movements to result in occlusal change in the arch. The 3-D superimposition of chronologic digital models was a helpful method to analyze the changes of dentition and individual tooth displacement adjacent to implant restoration.

다중예각 평면 교차전극을 이용한 입자 크기에 따른 측면방향 변위 (Deterministic Lateral Displacement as a Function of Particle Size Using a Piecewise Curved Planar Interdigitated Electrode Array)

  • 한송이;주영돈;한기호
    • 대한기계학회논문집B
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    • 제36권3호
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    • pp.241-249
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    • 2012
  • 본 논문에서는 유체흐름방향과 예각으로 놓여있는 평면 교차전극 위를 지나가는 입자의 크기에 따른 측면방향 변위에 대하여 소개한다. 아울러, 유체흐름방향과 평면 교차전극 사이의 각도에 따른 측면방향 변위의 변화를 보인다. 본 논문에서는 선전하(line charge) 모델을 이용하여 크기가 다른 세 종류의 형광 polystyrene(PS) 입자의 측면방향 변위를 이론적으로 예측하였다. 크기에 따른 입자의 측면방향 변위의 변화를 이용하여, 크기별로 입자를 연속적으로 분리할 수 있는 측면방향 유전영동 미세분리기를 개발하였다. 3, 5, 10 ${\mu}m$ PS 입자의 혼합물을 이용하여 분리한 실험결과로 부터 개발된 측면방향 유전영동 미세분리기는 3 ${\mu}m$ PS 입자를 99.86%, 5 ${\mu}m$를 98.82%, 10 ${\mu}m$를 99.69%의 높은 효율로 각각 분리할 수 있음을 확인하였다. 이로부터 제안된 측면방향 유전영동 미세분리기는 다종 혼합물로부터 다양한 크기의 입자들을 한 번에 분리하는 기술로 널리 활용될 수 있을 것으로 기대된다.

Sensitivity analysis of variable curvature friction pendulum isolator under near-fault ground motions

  • Shahbazi, Parisa;Taghikhany, Touraj
    • Smart Structures and Systems
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    • 제20권1호
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    • pp.23-33
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    • 2017
  • Variable Curvature Friction Pendulum (VCFP) bearing is one of the alternatives to control excessive induced responses of isolated structures subjected to near-fault ground motions. The curvature of sliding surface in this isolator is varying with displacement and its function is non-spherical. Selecting the most appropriate function for the sliding surface depends on the design objectives and ground motion characteristics. To date, few polynomial functions have been experimentally tested for VCFP however it needs comprehensive parametric study to find out which one provides the most effective behavior. Herein, seismic performance of the isolated structure mounted on VCFP is investigated with two different polynomial functions of the sliding surface (Order 4 and 6). By variation of the constants in these functions through changing design parameters, 120 cases of isolators are evaluated and the most proper function is explored to minimize floor acceleration and/or isolator displacement under different hazard levels. Beside representing the desire sliding surface with adaptive behavior, it was shown that the polynomial function with order 6 has least possible floor acceleration under seven near-field ground motions in different levels.