• Title/Summary/Keyword: friction connection

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Overdentures using newly designed metal ball attachment containing predetermined gap with stress breakers (일정한 간극으로 새롭게 고안된 완압형 볼 어태치먼트를 이용한 피개의치 수복)

  • Yoo, Jin-Joo;Kim, Man-Yong;Yoon, Joon-Ho
    • The Journal of Korean Academy of Prosthodontics
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    • v.55 no.3
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    • pp.311-318
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    • 2017
  • Several types of attachments have been used for implant supported and/or retained overdentures. Locator is one of the stud type attachments and it has been generally used. However, the colored matrix is resilient and vulnerable to wear, so frequent post-insertion maintenance is needed. To solve this problem, it is necessary to introduce innovative attachment system. Overdentures using Air Gap attachment (AGA) has improved masticatory function and facial esthetics. AGA is made of metal, so it could be more resistant to wear or friction than the other resilient attachments. Nevertheless, AGA plays a role in stress breakers because it allows movement during denture movement with predetermined gap. In addition, both pre-existing implants and natural teeth were successfully used for connection of AGA. AGA could replace other unsplinted type of attachments. Overdentures using AGA could provide satisfactory result in terms of function, esthetics and retention. However, long term follow up is needed.

Evaluation of Ultimate Strength of Shear Connection in Steel Embedded Composite Girders (강재매입형 합성거더 전단연결부의 극한강도 평가)

  • Sim, Chang Su;Kim, Hyeon Ho;Han, Jeong Hoon;Lee, Pil Goo
    • Journal of Korean Society of Steel Construction
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    • v.18 no.4
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    • pp.405-416
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    • 2006
  • In composite girders with steel embedded in concrete as preflex beams, horseshoe connectors and bar connectors are commonly used to achieve composite action. Considering the requirements on the concrete cover in the thin concrete part surrounding a steel member, it has limitations with respect to the use of stud shear connectors, and significant bond and friction resistance can be generated. High horizontal shear strength between the casing concrete and the steel section is needed to introduce prestress to the concrete section in the form of preflex beams.In this paper, experiments on the evaluation of the static strength of horseshoe connectors and bar connectors were conducted and the effects of bonds were also considered. Based on the test results, current design codes were estimated and more general design guidelines that consider the design concept of Eurocode were proposed for the connectors. A strength evaluation according to failure and compared with the test results.

Pull-out Behaviors of Headed Bars with Different Details of Head Plates (Head 플레이트 상세에 따른 Headed Bars의 인발거동에 관한 연구)

  • Park, Hyun-Gyoo;Yoon, Young-Soo;Ryoo, Young-Sup;Lee, Man-Seop
    • Journal of the Korean Society of Hazard Mitigation
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    • v.2 no.2 s.5
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    • pp.95-104
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    • 2002
  • This paper presents the pull-out failure mode on Headed Bars and prediction of tensile capacity, as governed by concrete cone failure. 17 different plate types, three different concrete strengths and three different welding types of specimens were simulated. Test variables are the reinforcing bar diameters connected to headed plate (e.g., 16mm, 19mm and 22mm), the head plate shapes (e.g., circular, square, rectangular), the dimensions of head plates (e.g., area and thickness), the types of welding scheme for connection of reinforcing bars and head plates (e.g., general welding and friction welding). Headed Bars were manufactured in different areas, which shape and thickness are based on ASTM 970-98. Calculation of Embedment length in concrete is based on CSA 23.3-94, and static tensile load was applied. Pullout capacities tested were compared to the values determined using current design methods such as ACI-349 and CCD method. If compare experiment results and existings, Headed bar expressed high strength and bigger breakdown radious than standard by wide plate area and anomaly reinforcing rod unlike anchor.

Slip Behavior of High-Tension Bolted Joints Subjected to Compression Force (압축력을 받는 고장력 볼트 이음부의 미끄러짐 거동)

  • Han, Jin Hee;Choi, Jong Kyoung;Heo, In Sung;Kim, Sung Bo
    • Journal of Korean Society of Steel Construction
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    • v.20 no.2
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    • pp.279-288
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    • 2008
  • In this study, the slip behavior of high-tension bolted joints subjected to compression force is investigated through 3D finite element analysis and experiments. The relation with sliding load, bolt deformation, and failure load are studied with the metal thickness affecting the bolted joint. The post-sliding behavior considering bolt stiffness is presented and compared with the results by finite element and experiments. The finite element model is constructed by solid elements in ABAQUS, in consideration of all the friction effects between metal plates and bolts. The stress-strain relations in the literature are used, and the sliding displacements and axial stresses around the bolt connection are investigated. The flexural buckling of species happened when the plate thickness is less than the bolt diameter. However, the shear failures of bolt occurred in the opposite case.

Application of Horizontal Subgrade Reaction Modulus to Bridge Abutment Design after Soil Improvement (연약지반 개량후 교대구간 수평지반반력계수 적용 사례)

  • Kim, Kyung-Tae;Park, See-Boum;Kim, Chang-Hyun;Lee, Jong-Bum;Yoon, Yea-Won
    • Proceedings of the Korean Geotechical Society Conference
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    • 2006.03a
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    • pp.1228-1236
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    • 2006
  • In soft ground, There are many case that Bridge Abutment is constructed after soil improvement in order to reduce the Negative Friction and prevent from Lateral Soil movements of Bridge Abutment. That section of Horizontal Subgrade Reaction $Modulus(K_h)$ derivation has much important mean due to Horizontal Stability of Abutment. It is come from behavior of Pile and Soil within depth of $1/\beta$. After Soil Improvement, however, If Bridge Abutment was construction, It's not impossible to carry out Field Investigation After Ground of Improved at design stage. Therefore, It's not able to derivate Horizontal Subgrade Reaction $Modulus(K_h)$. Therefore, in this case of study compare with Field Construction Test Data in order to derivation of Horizontal Subgrade Reaction $Modulus(K_h)$ and Reliability in terms of ground of Bridge Abutment by Sand Compaction Pile(SCP) during design of The 2nd Bridge Connection Road of Incheon International Airport. In this paper determine, Soil Property(The rate of strength increase, $c_u$ so on) and Horizontal Subgrade Reaction $Modulus(K_h)$ after soil improvement at design stage.

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Study on Rib's Structural Details of Double Baseplate Connection Through Numerical Analysis (수치해석을 통한 이중 베이스플레이트 연결부의 리브 구조 상세에 대한 연구)

  • Hwang, Won Sup;Kim, Hee Ju;Ham, Jun Su;Hwang, Seung Hyun
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.17 no.2
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    • pp.45-53
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    • 2013
  • In this study, steel-pier's structural behavior by design variables of ribs were analyzed in order to improve structural details of ribs supporting double base plates. A numerical analysis was conducted using commercial FE analysis program. Anchor bolts and reinforced bars were made of BEAM element, and coefficient of friction was applied to contact surfaces. After that, the analytical result was compared with experiment of previous study to verify analysis methods. Steel-pier's load-displacement relation was analyzed according to various rib's design variables (rib's central angle, height, thickness) by using proven analysis methods, and proper rib's design ranges were proposed.

Capsule Train Dynamic Model Development and Driving Characteristic Analysis Considering the Superconductor Electrodynamic Suspension (초전도 유도 반발식 부상특성을 고려한 캡슐트레인 동특성 해석 모델 구축 및 주행 특성 분석)

  • Lee, Jin-Ho;Lim, Jungyoul;You, Won-Hee;Lee, Kwansup
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.21 no.7
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    • pp.38-45
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    • 2020
  • A magnetically levitating capsule train, which runs inside the sub-vacuum tube, can reach ultra-fast speeds by dramatically reducing the aerodynamic drag and friction. The capsule train uses the superconductor electrodynamic suspension (SC-EDS) method for levitation. The SC-EDS method has advantages, such as a large levitation gap and free of gap control, which could reduce the infra-construction cost. On the other hand, disadvantages, such as the large variation of the levitation-guidance gap and small damping characteristics in levitation-guidance force, could degrade the running stability and ride comfort of the capsule train. In this study, a dynamic analytical model of a capsule train based on the SC-EDS was developed to analyze the running dynamic characteristics. First, as important factors in the capsule train dynamics, the levitation and guidance stiffness in the SC-EDS system were derived, which depend non-linearly on the velocity and gap variation. A 3D dynamic analysis model for capsule trains was developed based on the derived stiffness. Through the developed model, the effects of the different running speeds on the ride comfort were analyzed. The effects of a disturbance from infrastructure, such as the curve radius, tube sag, and connection joint difference, on the running stability of the capsule train, were also analyzed.

The Design of an Auto Tuning PI Controller using a Parameter Estimation Method for the Linear BLDC Motor (선형 추진 BLDC 모터에 대한 파라미터 추정 기법을 이용하는 오토 튜닝(Auto Tuning) PI 제어기 설계)

  • Cha Young-Bum;Song Do-Ho;Koo Bon-Min;Park Moo-Yurl;Kim Jin-Ae;Choi Jung-Keyng
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.10 no.4
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    • pp.659-666
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    • 2006
  • Servo-motors are used as key components of automated system by performing precise motion control as accurate positioning and accurate speed regulation in response to the commands from computers and sensors. Especially, the linear brushless servo-motors have numerous advantages over the rotary servo motors which have connection with the friction induced transfer mechanism such as ball screws, timing belts, rack/pinion. This paper proposes an estimation method of unknown motor system parameters using the informations from the sinusoidal driving type linear brushless DC motor dynamics and outputs. The estimated parameters can be used to tune the controller gain and a disturbance observer. In order to meet this purpose high performance Digital Signal Processor, TMS320F240, designed originally for implementation of a Field Oriented Control(FOC) technology is adopted as a controller of the liner BLDC servo motor. Having A/D converters, PWM generators, rich I/O port internally, this servo motor application specific DSP play an important role in servo motor controller. This linear BLDC servo motor system also contains IPM(Intelligent Power Module) driver and hail sensor type current sensor module, photocoupler module for isolation of gate signals and fault signals.

Numerical Analytic Study considering the Behavior Characteristics between Individual Blocks in Block-Type Retaining Walls (블록식 보강토 옹벽에서 개별 블록간 거동특성을 고려한 수치해석적 연구)

  • Hwang, Sungpil;Park, Byungsuk;Woo, Yong-Hoon;Park, Sangki;Kim, Wooseok
    • The Journal of Engineering Geology
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    • v.31 no.4
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    • pp.579-588
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    • 2021
  • Reinforced earth retaining walls have been widely used in recent years, as they are superior from the landscape perspective than normal concrete retaining walls. However, as reinforced earth retaining walls are made of various materials depending on site, existing design methods cannot secure stability, and a variety of problems have occurred. Studies on the design and stability analysis methods, which are different from existing methods, have been conducted to address these problems. This study conducted a stability investigation using numerical analysis, and blocks of reinforced earth retaining walls were individually applied, which is different from pre-existing numerical analyses. To verify the input values of the numerical analysis when applying individual blocks, real-scale experiments of the friction characteristics between the blocks and the connection properties between the blocks and stiffener were conducted. The applicability of the block conditions, which were the same as those of real sites, was verified through numerical analysis, and will be used for the stability review and design of various combinations of blocks and stiffeners.

Dynamic response of segment lining due to train-induced vibration (세그먼트 라이닝의 열차 진동하중에 대한 동적 응답특성)

  • Gyeong-Ju Yi;Ki-Il Song
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.25 no.4
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    • pp.305-330
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    • 2023
  • Unlike NATM tunnels, Shield TBM tunnels have split linings. Therefore, the stress distribution of the lining is different even if the lining is under the same load. Representative methods for analyzing the stress generated in lining in Shield TBM tunnels include Non-joint Mode that does not consider connections and a 2-ring beam-spring model that considers ring-to-ring joints and segment connections. This study is an analysis method by Break-joint Mode. However, we do not consider the structural role of segment lining connections. The effectiveness of the modeling is verified by analyzing behavioral characteristics against vibration loads by modeling with segment connection interfaces to which vertical stiffness and shear stiffness, which are friction components, are applied. Unlike the Non-joint mode, where the greatest stress occurs on the crown for static loads such as earth pressure, the stress distribution caused by contact between segment lining and friction stiffness produced the smallest stress in the crown key segment where segment connections were concentrated. The stress distribution was clearly distinguished based on segment connections. The results of static analysis by earth pressure, etc., produced up to seven times the stress generated in Non-joint mode compared to the stress generated by Break-joint Mode. This result is consistent with the stress distribution pattern of the 2-ring beam-spring model. However, as for the stress value for the train vibration load, the stress of Break-joint Mode was greater than that of Non-joint mode. This is a different result from the static mechanics concept that a segment ring consisting of a combination of short members is integrated in the circumferential direction, resulting in a smaller stress than Non-joint mode with a relatively longer member length.