• Title/Summary/Keyword: 다축

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Dynamic Modeling and Characteristics Analysis of Solid Rocket Motor with Multi Axis Pintle Nozzles (다축 핀틀 노즐을 장착한 고체 추진기관의 동적 모델링 및 특성 분석)

  • Ki, Taeseok;Hong, Seokhyun;Park, Ik-soo
    • Journal of the Korean Society of Propulsion Engineers
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    • v.19 no.3
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    • pp.20-28
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    • 2015

  • Performance parameters of solid rocket motor with multi axis pintle nozzles were analyzed theoretically and modeled. For figuring out the governed variable of dynamic characteristics of system, dynamic analysis was done by using established model. To present characteristics of this system, the model should include not only internal ballistics of propulsion unit but also actuating system to move pintle. For solid rocket motor with multi axis pintle nozzles, not only performance of steady state but also dynamic characteristic of transient state is important design parameter to precise thrust control. Therefore, response time of open-loop system was analyzed by using established model and requirement about response time was satisfied by controlling pressure.

  • https://doi.org/10.6108/KSPE.2015.19.3.020 인용 PDF KSCI

Stress Distribution in Concrete Pavements under Multi-Axle Vehicle Loads Obtained Using Transformed Field Domain Analysis (변환영역 해석법을 통한 콘크리트 도로 포장의 다축 차량 하중에 대한 응력 분포 분석)

  • Kim, Seong-Min;Shim, Jae-Soo;Park, Hee-Beom
    • Journal of the Korea Concrete Institute
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    • v.18 no.5 s.95
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    • pp.695-702
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    • 2006

  • The stress distribution and the critical stresses in concrete pavements were analyzed using formulations in the transformed field domains when dual-wheel single-, tandem-, and tridem-axle loads were applied. First the accuracy of the transformed field domain analysis results was verified by comparing with the finite element analysis results. Then, the stress distribution along the longitudinal and transverse directions was investigated, and the effects of slab thickness, concrete elastic modulus, and foundation stiffness on the stress distribution were studied. The effect of the tire contact pressure related to the tire print area was also studied, and the location of the critical stress occurrence in concrete pavements was finally investigated. From this study, it was found that the critical concrete stress due to multi-axle loads became larger as the concrete elastic modulus increased, the slab thickness increased, and the foundation stiffness decreased. The number of axles did not tend to affect the critical stress ratio except for a small foundation stiffness value with which the critical stress ratio became significantly larger as the number of axles increased. The critical stress location in the transverse direction tended to move into the interior as the tire contact pressure increased, the concrete elastic modulus increased, the slab thickness increased, and the foundation stiffness decreased. The critical stress location in the longitudinal direction was under the axle for single- and tandem-axle loads, but for tridem-axle loads, it tended to move under the middle axle from the outer axles as the concrete elastic modulus and/or slab thickness increased and the foundation stiffness decreased.

  • https://doi.org/10.4334/JKCI.2006.18.5.695 인용 PDF KSCI

Analysis on Creep of Concrete under Multiaxial Stresses Using Microplane Model (미세평면 모델을 적용한 다축응력 상태의 콘크리트 크리프 분석)

  • Kwon Seung-Hee;Kim Yun-Yong;Kim Jin-Keun
    • Journal of the Korea Concrete Institute
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    • v.16 no.2 s.80
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    • pp.195-204
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    • 2004

  • Poisson's ratio due to multiaxial creep of concrete reported by existing experimental works was controversial. Poisson's ratio calculated from measured strain is very sensitive to small experimental error. This sensitivity make it difficult to find out whether the Poisson's ratio varies with time or remain constant, and whether the Poisson's ratio has different value with stress states or not. A new approach method is needed to resolve the discrepancy and obtain reliable results. This paper presents analytical study on multiaxial creep test results. Microplane model as a new approach method is applied to optimally fitting the test data extracted from experimental studies on multiaxial creep of concrete. Double-power law is used as a model to present volumetric and deviatoric creep evolutions on a microplane. Six parameters representing the volumetric and deviatoric compliance functions are determined from regression analysis and the optimum fits accurately describe the test data. Poisson's ratio is calculated from the optimum fits and its value varies with time. Regression analysis is also performed assuming that Poisson's ratio remains constant with time. Four parameters are determined for this condition, and the error between the optimum fits and the test data is slightly larger than that for six parameter regression results. The constant Poisson's ratio with time is obtained from four parameter analysis results and the constant value can be used in practice without serious error.

  • https://doi.org/10.4334/JKCI.2004.16.2.195 인용 PDF KSCI