• Title, Summary, Keyword: 강성

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Optimal Vertical Stiffness of Fastener of Concrete Track in High-Speed Railway (고속철도 콘크리트궤도 체결구 최적 수직강성)

  • Yang, Sin-Chu
    • Journal of the Korean Society for Railway
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    • v.18 no.1
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    • pp.43-52
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    • 2015
  • In this study, to minimize both the costs associated with track maintenance and the energy consumption for train operation, a numerical method that evaluates the optimal vertical stiffness of a fastener for concrete track is presented. A progress model of the track damage is established in order to calculate the concrete track maintenance cost according to the fastener stiffness. Also, the quantitative relationship between the progress of the track damage and the maintenance of the concrete track is derived. The wheel load is more exactly evaluated by using the advanced vehicle-track interaction model, which can precisely consider the behaviors of the track components. An optimal range for the stiffness of the fastener, a range that is applicable to the design of concrete track for domestic high speed lines, is proposed.

Evaluation on Stiffness of High-strength Mortar-filled Sleeve Bar Splice Under Cyclic Loading (반복하중이 작용하는 고강도 모르타르 충전식 슬리브 철근이음에 대한 강성 평가)

  • Kim, Hyong Kee;Chung, Goo Yong
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.17 no.1
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    • pp.85-93
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    • 2013
  • In order to make a more reasonable evaluation on the stiffness of the high-strength mortar-filled sleeve bar splices under cyclic loading, we investigated and analyzed the existing experiment data of 106 full-sized reinforcing bar splices with test variables such as compressive strength of mortar, development length of reinforcement and sleeve type, etc. The following were found: 1) If mortar and the reinforcement development length with $f_{g^*}$(L/d) of more than 340 is used, the cast iron sleeve bar splices for SD350 and SD400 will have the stiffness of higher than A class of the AIJ code. 2) If mortar and the reinforcement development length with $f_{g^*}$(L/d) of more than 400 is used, the cast iron sleeve splices and pipe sleeve splices for SD500 will have the stiffness of higher than A class of the AIJ code.

Joint Stiffness Evaluation in Jointed Plain Concrete Pavement (줄눈 콘크리트 포장의 줄눈강성 산정 연구)

  • Chon, Beom Jun;Lee, Seung Woo;Kwon, Soon-Min;Kim, Seong-Min
    • Journal of The Korean Society of Civil Engineers
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    • v.29 no.1D
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    • pp.49-54
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    • 2009
  • The excellent load transfer at transverse joints ensures the high performance of jointed plane concrete pavements(JPCP). Load transfer efficiency(LTE) is affected by dowel-bars, aggregate interlock and types of underlying layers, and these factors have to be modelled adequately for a reasonable analysis of JPCP. Generally, the joint stiffness has been represented by a spring model for the shear transfer by aggregate interlock or dowels. However dowel-bars, aggregate interlock and types of underlying layers have not been considered together in the design of joints. In this study, the joint stiffness that considered those factors was presented by comparing LTE obtained using FWD(Falling Weight Deflectometer) with theoretical results obtained using the finite element analysis. In addition, the effects of temperature and concrete age, on the joint stiffness were investigated.

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Influence of the joint stiffness on the segment design (이음부 강성계수가 세그먼트 설계에 미치는 영향)

  • Choi, Woo-Yong;Park, Jong-Deok;Lee, Seok-Won
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.16 no.1
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    • pp.63-74
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    • 2014
  • The lining of shield TBM tunnel is composed of segments, therefore segment joints are induced by connecting each segment. Segment joint is considered as joint stiffness in the design of TBM tunnel. Depending on the choice among the different stiffness equations, the joint stiffness values determined can be varied largely. Therefore, the influence of joint stiffness value on the design of segment lining should be verified. In this study, the joint stiffness values were determined firstly by using various equations and total change boundary was justified. Within the change boundary determined, the member forces were calculated by changing the joint stiffness through the numerical analysis and consequently the stability of segment lining was investigated by applying nominal strength. The results showed that the segment joint stiffness did not affect the design of segment lining largely.

New Nonlinear Analysis Algorithm Using Equivalent Load for Stiffness (강성등가하중을 이용한 새로운 비선형해석 알고리즘)

  • Kim, Yeong-Min;Kim, Chee-Kyeong;Kim, Tae-Jin
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.20 no.6
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    • pp.731-742
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    • 2007
  • This paper presents a new nonlinear analysis algorithm, that is, adaptive Newton-Raphson iteration method, The presented algorithm is based on the existing Newton-Raphson method, and the concept of it can be summarized as calculating the equivalent load for stiffness(ELS) and adapting this to the initial global stiffness matrix which has already been calculated and saved in initial analysis and finally calculating the correction displacements for the nonlinear analysis, The key characteristics of the proposed algorithm is that it calculates the inverse matrix of the global stiffness matrix only once irresponsive of the number of load steps. The efficiency of the proposed algorithm depends on the ratio of the active Dofs - the Dofs which are directly connected to the members of which the element stiffness are changed - to the total Dofs, and based on this ratio by using the proposed algorithm as a complementary method to the existing algorithm the efficiency of the nonlinear analysis can be improved dramatically.

Static Analysis of Frame Structures Using Transfer of Stiffness Coefficient (강성계수의 전달을 이용한 골조구조물의 정적해석)

  • 최명수;문덕홍;정하용
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.16 no.1
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    • pp.9-18
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    • 2003
  • In static analysis of a variety of structures, the matrix method of structural analysis is the most widely used and powerful analysis method. However, this method has drawback requiring high-performance computers with many memory units and fast processing units in the case of analyzing accurately structures with a large number of degrees-of- freedom. Therefore, it's very difficult to analyze these structures accurately in personal computers. For overcoming the drawback of the matrix method of structural analysis, authors suggest the transfer stiffness coefficient method(TSCM). The TSCM is very suitable to a personal computer because the concept of the TSCM is based on the transfer of the stiffness coefficient for an analytical structure. In this paper, the static analysis algorithm for frame structures is formulated by the TSCM. We confirm the validity of the TSCM through the comparison of computation results by the TSCM, the NASTRAN, the matrix method of structural analysis and the analytical solution.

Stiffness of Bucket Foundation in Sand (사질토 지반에 설치된 버킷기초의 강성)

  • Park, Jeongseon;Park, Duhee;Yoon, Sewoong;Jang, Hwasup;Yoon, Jinam
    • Journal of the Korean GEO-environmental Society
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    • v.18 no.8
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    • pp.5-15
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    • 2017
  • To perform an integrated load analysis carried out to evaluate the stability evaluation of wind turbine generators, the six degree-of-freedom stiffness matrix of foundation, which describes relationships between loads and displacement, is needed. Since the foundation stiffness should accurately reflect the shape of foundation and the condition of soil, it is necessary to calculate the stiffness of the bucket foundation that considers the elasto-plastic behavior of the soil. In this study, finite element analyses were performed for a range of soils and shapes of bucket foundations to estimate the foundation stiffness. Normalized stiffness curves are developed from respective numerical simulations. Proposed results are considered to be useful because they can be directly applied in the design.

Development of Measurement Device for Bending Stiffness of Footwear (신발의 굽힘강성 측정 장비의 개발)

  • Lee, Jong-Nyun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.12 no.3
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    • pp.1078-1084
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    • 2011
  • In design of sport footwear, bending stiffness of its toe part is an important factor though it can be hardly measured. This paper introduces a device for measuring the bending stiffness. The device is simply designed with aluminum frames, one AC motor, two load-cells, one encoder and control hardwares. The mechanism measuring the bending moment of a shoe is described. Then, it was used to observe how the midsole material and design of a sports shoe affect on its bending stiffness. For the experiments, various specimens prepared, where each midsole of the specimens is different in terms of material, thickness and hardness. With those specimens, experiments were performed by using the device and then the bending stiffness was computed by applying the least square curve fitting after the bending moment data were measured. The specimen with Poly-urethane(PU) midsole has the higher bending stiffness than the one with Phylon(PH) midsole, and the midsole thickness affects more on the bending stiffness than the midsole hardness. Based on those results, it can be concluded that the measurement device can provide consistent bending stiffness data to sports footwear and the bending stiffness of a footwear measured by the developed device can be used as a major parameter in the footwear design.

Analysis on the Lateral Stiffness of Coil Spring for Railway Vehicle (철도차량용 코일스프링 횡강성 해석)

  • Hur, Hyun-Moo;Ahn, Da-Hoon
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.9
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    • pp.84-90
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    • 2018
  • In constructing the multi-body dynamics model to analyze the behavior of the railway vehicle, it is very important to understand the properties of the suspension elements that constitute the suspension system. Among them, coil springs, which are mainly used in primary and secondary suspension systems, clearly show the axial stiffness in the drawings, but the lateral properties of the coil springs are not specified clearly, making it difficult to construct a dynamic analysis model. Therefore, in this paper, the model for analyzing the lateral stiffness of the coil spring is examined. A finite element method was applied to analyze the lateral stiffness of the coil spring and numerical analysis was performed by applying the coil spring lateral stiffness analysis model proposed by Krettek and Sobczak. And the test to analyze the lateral stiffness of coil spring was conducted. As a result of comparing with the test results, it was found that the results obtained by applying the lateral stiffness analysis model of Krettek and Sobczak and correcting the correction coefficient are similar to those of the test results.

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
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    • v.21 no.5
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    • pp.103-110
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    • 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.