• Title/Summary/Keyword: Model material experiment

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Numerical Analysis on External Strengthening Effects in Aged Structures (사용중인 구조물의 보강효과에 대한 해석적 연구)

  • 신승교;임윤묵;김문겸;박동철
    • Proceedings of the Korea Concrete Institute Conference
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    • 2002.05a
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    • pp.455-460
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    • 2002
  • In this study, a numerical analysis that can effectively predict the effect of strengthening of cracked flexural members is developed using axial deformation link elements. Concrete and interface between concrete and repair material are considered as quasi-brittle material. Reinforcing bars and reinforcing steel plates are assumed to perform as elasto-plastic materials. Unloading behavior of axial deformation link element is implemented. In the developed numerical model, a flexural member is intentionally cracked by pre-loading, then, the cracked member is repaired using extra elements, and reloaded. The results from analysis of repaired flexural members agrees well with available experiment results. Also, it was shown that the effect of strengthening and the change of failure mode with respect to the time for strengthening and thickness of repair materials. Based on the results, it was determined that the developed numerical model has a good agreement for determining failure modes and effect of strengthening in cracked flexural members. By utilizing the developed numerical analysis, the time and dimension of external strengthening in an existing cracked flexural member with predition of failure mechanism can be determined.

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A Study on the Reliability Evaluation of Shot Peened Aluminium Alloy Using Accelerated Life Test (가속수명시험을 이용한 쇼트피닝가공 알루미늄 합금의 신뢰성 평가에 관한 연구)

  • Nam, Ji-Hun;Kang, Min-Woo;Cheong, Seong-Kyun
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.30 no.12 s.255
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    • pp.1534-1542
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    • 2006
  • In this paper, the concept of accelerated life test, which is a popular research field nowadays, is applied to the shot peened material. To predict the efficient and exact room temperature fatigue characteristics from the high temperature fatigue data, the adequate accelerated model is investigated. Ono type rotary bending fatigue tester and high temperature chamber were used for the experiment. Room temperature fatigue lives were predicted by applying accelerated models and doing reliability evaluation. Room temperature fatigue tests were accomplished to check the effectiveness of predicted data and the adequate accelerated life test models were presented by considering errors. Experimental result using Arrhenius model, fatigue limit obtain almost 5.45% of error, inverse power law has about 1.36% of error, so we found that inverse power law is applied well to temperature-life relative of shot peened material.

Estimation of the Expected Time in System of Trip-Based Material Handling Systems (트립에 기초한 물자취급 시스템에서 자재의 평균 체류시간에 대한 추정)

  • Cho, Myeon-Sig
    • Journal of Korean Institute of Industrial Engineers
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    • v.21 no.2
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    • pp.167-181
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    • 1995
  • We develop an analytical model to estimate the time a workpiece spends in both input and output queues in trip-based material handling systems. The waiting times in the input queues are approximated by M/G/1 queueing system and the waiting times in the output queues are estimated using the method discussed in Bozer, Cho, and Srinivasan [2]. The analytical results are tested via simulation experiment. The result indicates that the analytical model estimates the expected waiting times in both the input and output queues fairly accurately. Furthermore, we observe that a workpiece spends more time waiting for a processor than waiting for a device even if the processors and the devices are equally utilized. It is also noted that the expected waiting time in the output queue with fewer faster devices is shorter than that obtained with multiple slower devices.

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Design of Low Pressure Driven Soft Actuators for Soft Gripper (소프트 그리퍼를 위한 저압 구동 소프트 액추에이터의 설계)

  • Yoon, Jingon;Yun, Dongwon
    • The Journal of Korea Robotics Society
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    • v.16 no.1
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    • pp.23-28
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    • 2021
  • The gripper with a soft pneumatic actuator uses a soft material, unlike the gripper that uses a rigid body, so it is safer and lighter to interact with objects without advanced control technology. Among the soft pneumatic actuators that have been studied, PneuNets actuators have bellows shape, which enable quick operation and complete bending with only small material deformation at low pressure. In this study, we suggested improved form of PneuNets actuators to obtain the performance of the soft actuator that a larger bending angle and larger bending force at a small pressure. An experiment was designed and conducted to measure the bending angle and bending force according to the pressure. As a result, it was confirmed through experiments that the improved model has a maximum bending angle at a pressure of 5 kPa lower than that of the previous model, and a maximum bending force of 1.97 times at the same pressure.

Uncertainty Evaluation of the Estimated Release Rate for the Atmospheric Pollutant Using Monte Carlo Method (Monte Carlo 방법을 이용한 대기오염 배출률 예측의 불확실성 평가)

  • Jeong, Hyo-Joon;Kim, Eun-Han;Suh, Kyung-Suk;Hwang, Won-Tae;Han, Moon-Hee
    • Journal of Environmental Science International
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    • v.15 no.4
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    • pp.319-324
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    • 2006
  • Release rate is one of the important items for the environmental impact assessment caused by radioactive materials in case of an accidental release from the nuclear facilities. In this study, the uncertainty of the estimated release rate is evaluated using Monte Carlo method. Gaussian plume model and linear programming are used for estimating the release rate of a source material. Tracer experiment is performed at the Yeoung-Kwang nuclear site to understand the dispersion characteristics. The optimized release rate was 1.56 times rather than the released source as a result of the linear programming to minimize the sum of square errors between the observed concentrations of the experiment and the calculated ones using Gaussian plume model. In the mean time, 95% confidence interval of the estimated release rate was from 1.41 to 2.53 times compared with the released rate as a result of the Monte Carlo simulation considering input variations of the Gaussian plume model. We confirm that this kind of the uncertainty evaluation for the source rate can support decision making appropriately in case of the radiological emergencies.

A STUDY ON THE ACCURACY OF DENTAL CAST AND DIE MATERIALS USING PHOTO-SCANNING (사진 주사(走査)를 이용한 치과용 모형재의 정확도에 관한 연구)

  • Yang, Seong-Wook;Lim, Ju-Hwan;Cho, In-Ho
    • The Journal of Korean Academy of Prosthodontics
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    • v.34 no.2
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    • pp.320-334
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    • 1996
  • Dental cast and die materials are essential material using in almost dental prsthodontic procedure and it's most important requirement is accuracy for reqorducing the oral anatomical structures. In this study, 5 abutments A, B, C, D, E were fabricated on the metal master model to simulate the arch form and specimens were poured with 4 cast materials. Inter-abutment distances, A-B, A-C, A-D, A-E, B-C, B-D were calculated using the photo-scanning and the deviations from the metal master model were also evaluated. The results were as follows; 1. The distance between A-B, A-C, A-D, A-E, B-C, B-D of the abutments A, B, C, D, E of each cast material was calculated. And after comparing the deviations between the metal master model. $Fujirock^{(R)}$ showed the lowest value with $0.20{\pm}0.22mm$, and the deviation increased in the order of $Suprastone^{(R)}$, Epoxy $Die^{(R)}$, Die $Keen^{(R)}$. There was significant difference between $Fujirock^{(R)}$ and Epoxy $Die^{(R)}$, Die $Keen^{(R)}$. 2. In each calculation area, the difference in measurements between cast material and metal master model showed singificant difference between A-B and Cross arch measure-ments of A-D, B-D, A-E(p<0.05). 3. The difference in measurements between cast material and metal master model in the A-B area showed $Fujirock^{(R)}$ to be the lowest with $0.05{\pm}0.04$mm and increased in the order of Die $Keen^{(R)}$, $Suprastone^{(R)}$, Epoxy $Dies^{(R)}$. There was significant difference between $Fujirock^{(R)}$ and $Suprastone^{(R)}$, Epoxy $Die^{(R)}$ (p<0.05). 4. The difference in measurements between cast material and metal master model in the B-C area showed $Fujirock^{(R)}$ to bo the lowest with $0.17{\pm}0.11$mm and increased in the order of $Suprastone^{(R)}$, Die $Keen^{(R)}$, Epoxy $Dies^{(R)}$. There was significant difference between $Fujirock^{(R)}$ and Die $Keen^{(R)}$, Epoxy $Die^{(R)}$(p<0.05). 5. The difference in measurements between cast material and metal master model in the B-D area showed $Fujirock^{(R)}$ to bo the lowest with $0.13{\pm}0.07$mm, Epoxy $Dies^{(R)}$and increased in the order of $Suprastone^{(R)}$, Die $Keen^{(R)}$. There was significant difference between $Fuji-rock^{(R)}$ and Die Keen(p<0.05). 6. In this experiment, Epoxy $Dies^{(R)}$ showed mean contraction in every calculation area. And when reconstruction cross arch restorations it is thought that distortion should be considered in every cast material.

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Behavior of Surface Flashover Depending on Shape and Gap Distance of End Shield in Vacuum Interrupter (진공인터럽터 내부 End Shield형상과 갭거리에 따른 연면방전거동)

  • Yoon, Jae-Hun;Lim, Kee-Jo
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.23 no.2
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    • pp.169-173
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    • 2010
  • Because of power consumption increase, global warming, and limitation of installation, not only high reliability and interruption capability but also compact and light power apparatuses are needed. In this paper, E field calculation and experiment were processed to identify the influence of the shape of end shield and gap distance. It is expected that the results of FEM simulation and experiments could be the basic data to develop VI. the results of FEM simulation and experiments are as following. Firstly, maximum E fields were compared by means of finite element method as a function of the shape of end shield. 3 types of models were used to analyze maximum E field of each model and the influence of shape of shield could be identified. As a result, proposed L type shield could reduce the maximum E field by 20%. Secondly, the influence of the gap distance between end shields on E field was analyzed. As the gap distance become short the gap distance between inner walls of ceramic also become short. And the maximum E field concentrated on inner wall of ceramic finally increased. Thirdly, the experiment was conducted by fabricating each prototype. As a result, no creepage occurred in shieldless model. In other words, creepage occurred in the shield-installed models. And creepage inception voltages were different from each other because of the difference of maximum E field. Fourthly, The equation that shows relation between calculated E field and measured creepage inception voltage was proposed as a result of FEM analysis and experiment. It is concluded that when designing VI this equation could be important data to reduce time and cost by identifying indirectly the optimal gap distance and the shape of shield required to prevent creepage.

Experiment of Turbine Blade Hot Forging Process using Model Material and SLA Prototype Die Set (모델재료와 SLA 시금형을 이용한 터빈블레이드 열간단조공정의 모사실험)

  • Park, K.;Shin, M.C.;Yang, D.Y.;Cho, J.R.;Kim, J.S.
    • Transactions of Materials Processing
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    • v.4 no.4
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    • pp.335-344
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    • 1995
  • In this paper, an experimental study of a hot forging process is carried out using plasticine and the die set manufactured with the aid of rapid prototyping. In order to manufacture the die set, Stereolithography Apparatus(SLA) which is most widely used rapid prototyping system is introduced. Turbine blade forging is performed using palsticine and the SLA prototype die set. Through the experiment, it has been shown that SLA prototype is suitable to the die set for the plasticine workpiece, and the formability and the forming load of turbine blade forging are predicted.

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Valuing Amenity attributes of Farm Village using Choice Experiment - Valuing Rurality- (농촌마을 어메니티 자원의 속성별 가치 평가 - 농촌다움의 가치평가 -)

  • Jung, Hyunhee
    • Journal of Korean Society of Rural Planning
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    • v.20 no.4
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    • pp.243-252
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    • 2014
  • This study strengthens importance of farm land has possessed rurality. Thus the amenities of farm village were offered to the symbolical attributes of rurality and it was extracted four amenities attributes for valuing the amenities. Possessing the importance of rurality for agricultural and rural development and rural tourism evaluated each attribute by Choice Experiment(CE) for sustainable development make full use of rurality. Applying for Conditional-Logit model estimated the value of attributes then consumer's benefit feeling form each attributes was offered to the value of a unit change. Through this study, I wish to apply for the direction of rural development as important material and the compensation in the operation of agricultural output offering social benefit as political reference materials.

Multi-spring model for 3-dimensional analysis of RC members

  • Li, Kang-Ning;Otani, Shunsuke
    • Structural Engineering and Mechanics
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    • v.1 no.1
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    • pp.17-30
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    • 1993
  • A practical multi-spring model is proposed for a nonlinear analysis of reinforced concrete members, especially columns, taking into account the interaction of axial load and bi-directional bending moment. The parameters of the model are determined on the basis of material properties and section geometry. The axial force-moment interaction curve of reinforced concrete sections predicted by the model was shown to agree well with those obtained by the flexural analysis utilizing realistic stress-strain relations of materials. The reliability of the model was also examined with respect to the test of reinforced concrete columns subjected to varying axial load and bi-directional lateral load reversals. The analytical results agreed well with the experiment.