• Title, Summary, Keyword: stiffness

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A Study on Tire Labeling Performance for Tire Stiffness Design (타이어 기본강성 설계에 따른 타이어 라벨링 성능변화 연구)

  • Kang, Young Kyu;Kim, GunHo;Jang, InSung;Oh, YagJeon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.265-267
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    • 2013
  • Tire labeling is an important issue to reduce $CO_2$ and to secure the safety of tire/vehicle on wet road. A basic study on the effects of tire basic stiffness design on tire labeling performance has been done through experimental test. The pass-by noise is affected by tire structural design. The tire with lower side part stiffness and lower tread part stiffness has the lowest PBN level and the best wet grip. And the tire with higher tread part stiffness and higher side part stiffness has the better RR performance. Also it is observed that the trade-off between RR and wet grip exists for various tire stiffness design.

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Stiffiness Analysis and Optimization of Strand and Wire Rope (스트랜드와 와이어 로프의 강성해석 및 최적화)

  • Heo, Seong-Pil;Yang, Won-Ho;Seong, Gi-Deuk;Jo, Myeong-Rae
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.5
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    • pp.1246-1253
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    • 2000
  • Wire ropes are widely used in cable car, suspension bridge and elevator, etc. and there has been a growing need for ropes of large diameter. The theoretical procedures to obtain the stiffness coefficients of wire ropes, using previously reported theory, are programmed and the verification of the program is made. The effects of lay angle on the stiffness of strand are researched and comparisons on stiffness of rope are made according to the lay type. Axial stiffness optimization problems with coupling and torsional stiffness constraints are formulated and the effects of constraints on other stiffness coefficients on axial stiffness optimization are investigated.

Stiffness modeling of RC columns reinforced with plain rebars

  • Ozcan, Okan
    • Structural Engineering and Mechanics
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    • v.50 no.2
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    • pp.163-180
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    • 2014
  • Inaccurate predictions of effective stiffness for reinforced concrete (RC) columns having plain (undeformed) longitudinal rebars may lead to unsafe performance assessment and strengthening of existing deficient frames. Currently utilized effective stiffness models cover RC columns reinforced with deformed longitudinal rebars. A database of 47 RC columns (33 columns had continuous rebars and the remaining had spliced reinforcement) that were longitudinally reinforced with plain rebars was compiled from literature. The existing effective stiffness equations were found to overestimate the effective stiffness of columns with plain rebars for all levels of axial loads. A new approach that considers the contributions of flexure, shear and bond slip to column deflections prior to yielding was proposed. The new effective stiffness formulations were simplified without loss of generality for columns with and without lap-spliced plain rebars. In addition, the existing stiffness models for the columns with deformed rebars were improved while taking poor bond characteristics of plain rebars into account.

Development of On-Line Bending Stiffness Tester (1) - Theoretical Background - (종이 휨강성 자동 측정방식의 개발과 그 이용(1) - 이론적 배경 -)

  • Seo Yung-Bum;Jung Tae-Young
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.38 no.1
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    • pp.21-26
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    • 2006
  • A simple method of on-line stiffness measurement using the wrinkling behavior of paper web between rollers was developed. The theory and calculating equation were presented, and the theoretical maximum error associated with the equation was also presented. We called the stiffness measured by Taber tester as 'Taber stiffness', and by wrinkling behavior as 'wrinkle stiffness', respectively, for comparison. By using this method, on-line complete control of paper stiffness will be possible in near future. Special care about shear wrinkle and paper dimensional effects were addressed.

Identifying stiffness irregularity in buildings using fundamental lateral mode shape

  • Vijayanarayanan, A.R.;Goswami, Rupen;Murty, C.V.R.
    • Earthquakes and Structures
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    • v.12 no.4
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    • pp.437-448
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    • 2017
  • Soft or extreme soft storeys in multi-storied buildings cause localized damage (and even collapse) during strong earthquake shaking. The presence of such soft or extremely soft storey is identified through provisions of vertical stiffness irregularity in seismic design codes. Identification of the irregularity in a building requires estimation of lateral translational stiffness of each storey. Estimation of lateral translational stiffness can be an arduous task. A simple procedure is presented to estimate storey stiffness using only properties of fundamental lateral translational mode of oscillation (namely natural period and associated mode shape), which are readily available to designers at the end of analysis stage. In addition, simplified analytical expressions are provided towards identifying stiffness irregularity. Results of linear elastic time-history analyses indicate that the proposed procedure captures the irregularity in storey stiffness in both low- and mid-rise buildings.

Investigation for the Restriction of the Stiffness and Mechanical Impedance of the Shipboard Floor and Foundation Considering Dynamic Stiffness of the Anti-vibration Mount (방진 마운트의 동적 강성을 고려한 선체 바닥 및 받침대의 강성과 임피던스 규제에 대한 고찰)

  • Han, Hyung-Suk;Son, Yoon-Jun
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.19 no.3
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    • pp.320-326
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    • 2009
  • The mechanical impedance and stiffness of the foundation of shipboard equipments and hulls supported by anti-vibration mount are very important so that the anti-vibration mount can accomplish its performance effectively. But, it is frequently argued how much stiffness and mechanical impedance are necessary for those foundations and hulls. In this research, it is discussed by evaluating the dynamic stiffness of the commercial anti-vibration mounts used in a naval vessel. Consequently, in this research, the minimum level of the mechanical impedance and stiffness of the foundation of shipboard equipments and hulls are suggested considering the dynamic stiffness of the mount which varies as frequency.

Correlation Between Dynamic Stiffness of Resilient Materials and Lightweight Floor Impact Sound Reduction Level (완충재 동탄성계수와 경량바닥충격음 저감량의 상관성)

  • Kim, Kyoung-Woo;Jeong, Gab-Cheol;Sohn, Jang-Yeul
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.18 no.8
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    • pp.886-895
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    • 2008
  • Resilient materials are generally used for the floating floors to reduce the floor impact sound. Dynamic stiffness of resilient material have a close relation with the floor impact sound reduction. In this study, to examine the relationship between dynamic stiffness and lightweight impact sound level, the dynamic stiffness and floor impact sound level of 51 resilient materials were measured. The impact sound level of each of these resilient materials, whose dynamic stiffness was measured, was measured before and after installation, and the level difference (${\Delta}L$) was analyzed. The result of test showed that the dynamic stiffness of resilient materials decreased, the lightweight impact sound level also decreased, and there was a correlation between the dynamic stiffness and the lightweight impact sound, especially in the low frequency domain.

Force Chain Stability Analysis in Jamming Mechanism for Variable Stiffness Actuator (가변 강성 엑츄에이터인 재밍 메커니즘의 힘 체인 안정성 분석)

  • Lee, Jeongsu;Cho, Youngjun;Koo, Jachoon
    • The Journal of Korea Robotics Society
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    • v.14 no.4
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    • pp.326-332
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    • 2019
  • In the case of conventional soft robots, the basic stiffness is small due to the use of flexible materials. Therefore, there is a limitation that the load that can bear is limited. In order to overcome these limitations, a study on a variable stiffness method has been conducted. And it can be seen that the jamming mechanism is most effective in increasing the stiffness of the soft robot. However, the jamming mechanism as a method in which a large number of variable act together is not even theoretically analyzed, and there is no study on intrinsic principle. In this paper, a study was carried out to increase the stability of the force chain to increase the stiffness due to the jamming transition phenomenon. Particle size variables, backbone mechanisms were used to analyze the stability of the force chains. We choose a jamming mechanism as a variable stiffness method of a soft robot, and improve the effect of stiffness based on theoretical analysis, modeling FEM simulation, prototyping and experiment.

Proposal for Optimal Core Outrigger Position Reflecting Lateral Stiffness of Rigid Frame (강성골조의 수평강성을 반영한 코어 아웃리거 구조시스템의 최적위치에 대한 제안)

  • Kim, Hyong-Kee
    • Journal of the Architectural Institute of Korea
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    • v.36 no.8
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    • pp.137-144
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    • 2020
  • The aim of this study is to propose the more reasonable and more comprehensive method than existing methods to predict the optimal core outrigger position in high-rise building. To attain this goal, a 54 existing analysis data about the optimal position of core outrigger system were analyzed and studied. In this analysis data, the major parameters were the outrigger stiffness, the shear wall stiffness, the stiffness of column linked in outrigger, the stiffness of frame, lateral stiffness ratio between rigid frame and shear wall, and so on. This research made a proposal concerning the method of predicting the optimum core outrigger position reflecting the effect of frame stiffness. Also the research results presented in this paper offered the valuable data of structural design for looking for the optimal location of outrigger system in high-rise building.

Study on Application of Equivalent Stiffness Modeling Method for Static Aeroelastic Analysis of Large Scale Wind Turbine Rotor System (대형 풍력로터시스템의 정적 공탄성해석을 위한 등가강성모델링 기법 적용에 관한 연구)

  • Cha, Jin-Hyun;Ku, Tae-Wan;Kim, Jeong;Kang, Beom-Soo;Song, Woo-Jin
    • Journal of the Korean Society for Precision Engineering
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    • v.29 no.11
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    • pp.1236-1244
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    • 2012
  • A equivalent stiffness modeling has been performed for extracting the equivalent stiffness properties which are orthotropic elastic model from a large scale wind turbine rotor blade so that structure model can be constructed more simply for the three dimensional static aeroelastic analysis. In order to present the procedure of equivalent stiffness modeling, NREL 5MW class wind turbine rotor having the three stiffness information which are flapewise, edgewise and torsional stiffness was chosen. This method is based on applying unit moment at the tip of the blade as well as fixing all degree of freedom at the blade root and calculating the displacement from the load analysis to obtain the elastic modulus corresponding to equivalent stiffness referred to the NREL reports on blade divided into 5 sections respectively. In addition, one section was divided into 3 parts and the trend functions were used to make the equivalent stiffness model more correctly and quickly. Through the comparison of stiffness between the reference values and calculated values from equivalent stiffness model, the investigation of the accuracy on the stiffness values and the efficiency for constructing the model was conducted.