• Title/Summary/Keyword: Loading Path

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Stress- Strain Behavior Characteristics of Single Work Hardening Model Dependant on the Stress Path (응력경도에 따른 단일항복면구성모델의 응력-변형률 거동 특성)

  • 정진섭;김찬기;박을축
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.38 no.3
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    • pp.70-81
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    • 1996
  • Solutions of geotechnical engineering problems require predictions of deformation and stresses during various stages of loading. Powerful numerical methods are available to make such predictions even for complicated problems. To get accurate results, realistic stress-strain relationships of soils are dependent on a number of factors such as soil type, density, stress level and stress path. Attempts are continuously being made to develope analytical models for soils incorporating all such factors. Isotropic compression-expansion test and a series of drained conventional triaxial tests with several stress path for Baekma river sand were performed to investigate stress-strain and volume change characteristics of Lade's single work hardening model dependant on the stress path. In order to predicted of stress-strain and volumetric strain behavior were determined the values of parameters for the mode by the computer program based on the regression analysis. Predicted stress-strain behavior of triaxial compression tests and optional stress path tests for increasing confining pressure with parameters obtained conventional triaxial compression tests agreed with several test results but the prediction results for decreasing confining pressure reduced triaxial compression tests make a little difference with test results.

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Additional Damage of A17075-T651 under $90^{\circ}C$ Out-of phase Biaxial Loading from Crystal Structure Dependence ($90^{\circ}C$위상차의 이축하중 하에서 A17075-T651의 부가적 손상에 관한 결정구조 의존성에 관한 연구)

  • Lee, Hyun-Woo;Oh, Se-Jong
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.21 no.1
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    • pp.104-111
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    • 1997
  • Accounting for the additional damages come out from non-proportional loading path effect, material damage according to crystal structure dependence was studied. Microscopic observations of damaged material by SEM(Scanning Electron Microscope) showed crystal structure dependence. Biaxial in-phase loaded specimens showed the slips of same direction, which pararell each other, but biaxial 90.deg. out-of-phase loaded specimens showed multiply crossed slips. S. H. Doong and D. F. Socie reported that wavy/planar or planar slip material showed the increase in the cyclic hardening level during non-proportional cycling. From these results, the additional hardening and non-proportional loading effects were related with slip mechanism, and the slip mechanism was related with crystal structure. In the present study, a damage mechanism which accounts for the non-proportional loading effect from crystal structure dependence was considered and applied to A17075-T651.

Fatigue Crack Growth Characteristics of the Pressure Vessel Steel SA 508 Cl. 3 in Various Environments

  • Lee, S. G.;Kim, I. S.;Park, Y. S.;Kim, J. W.;Park, C. Y.
    • Nuclear Engineering and Technology
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    • v.33 no.5
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    • pp.526-538
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    • 2001
  • Fatigue tests in air and in room temperature water were performed to obtain comparable data and stable crack measuring conditions. In air environment, fatigue crack growth rate was increased with increasing temperature due to an increase in crack tip oxidation rate. In room temperature water, the fatigue crack growth rate was faster than in air and crack path varied on loading conditions. In simulated light water reactor (LWR) conditions, there was little environmental effect on the fatigue crack growth rate (FCGR) at low dissolved oxygen or at high loading frequency conditions. While the FCGR was enhanced at high oxygen condition, and the enhancement of crack growth rate increased as loading frequency decreased to a critical value. In fractography, environmentally assisted cracks, such as semi-cleavage and secondary intergranular crack, were found near sulfide inclusions only at high dissolved oxygen and low loading frequency condition. The high crack growth rate was related to environmentally assisted crack. These results indicated that environmentally assisted crack could be formed by the Electrochemical effect in specific loading condition.

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Constitutive Equation for Clay in Overconsolidation State and Under Cyclic Loading (과압밀상태 및 반복하중을 받는 점토지반에 대한 구성모델)

  • 이승래;김주용
    • Geotechnical Engineering
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    • v.10 no.1
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    • pp.7-18
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    • 1994
  • A new model for describing the behavior of clay under monotonic and cyclic loading is proposed. This model uses the hyperbolic representation for the stress -strain relationship in overconsolidated state and it describes undrained effective stress path on the basis of the critical state theory. The developed constitutive model by using an energy dissipation equation can describe the behavior of clay in heavily overconsolidated state as u.ell as lightly overconsolidated state under monotonic loading. In order to extend the model for the behavior of clay under cyclic loading, a shift function of undrained stress spacing ratio is introduced in the constitutive model developed for monotonlc loading. A single additional parameter is required to represent the cyclic effect and it can be reasonably deter mined from the test results. The measured behavior in undrained cyclic triaxial tests has been easily and precisely predicted by the newly developed constitutive model.

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Prediction of Thickness and Loading Noise from Aircraft Propeller (항공기용 프로펠러에서의 두께 및 하중소음 예측)

  • Ryu, Ki-Wahn
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.33 no.2
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    • pp.39-45
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    • 2005
  • The aim of this research is to predict the thickness and loading noise of the round-tip shaped Hartzell propeller currently used in the general aviation aircraft. Before implementing the noise analysis, the pressure distribution on the propeller was obtained by using the free wake panel method and unsteady Bernoulli's equation. The noise signal at observer position can be obtained by using the FW-H equation. The noise prediction results for the propeller indicates that the thickness noise has s symmetric directivity pattern with respect to the tip path plane, while the noise due to loading shows higher noise directivity toward downstream than the upstream direction from the rotor plane. The loading noise is dominant rather than the thickness noise in normal operating condition.

Stochastic ship roll motion via path integral method

  • Cottone, G.;Paola, M. Di;Ibrahim, R.;Pirrotta, A.;Santoro, R.
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.2 no.3
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    • pp.119-126
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    • 2010
  • The response of ship roll oscillation under random ice impulsive loads modeled by Poisson arrival process is very important in studying the safety of ships navigation in cold regions. Under both external and parametric random excitations the evolution of the probability density function of roll motion is evaluated using the path integral (PI) approach. The PI method relies on the Chapman-Kolmogorov equation, which governs the response transition probability density functions at two close intervals of time. Once the response probability density function at an early close time is specified, its value at later close time can be evaluated. The PI method is first demonstrated via simple dynamical models and then applied for ship roll dynamics under random impulsive white noise excitation.

Nonlinear Analysis of RC Structures Using Volume Control Method (체적 제어법을 이용한 철근 콘크리트 구조물의 비선형 해석)

  • Song Ha-Won;Nam Sang-Hyeok;Lee June-Hee;Lim Sang-Mook
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2006.04a
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    • pp.891-897
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    • 2006
  • The volume control method which utilize a pressure node added into a finite shell element can overcome the drawbacks of conventional load control method and displacement control method. In this study, an improved volume control method is introduced for effective analysis of path-dependant behaviors of RC structures subjected to cyclic loading. RC shell structures including RC hollow columns are anlayized by discretizing the structures with layered shell elements and by applying in-plane two dimensional constitutive equations for concrete layers and reinforcement layers of the shell elements. The so-called path dependant volume control method is verified by comparing analysis results with other data including experimental results.

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Development of Obstacle Database Management Module for Obstacle Estimation and Clustering: G-eye Management System (장애물 추정 및 클러스터링을 위한 장애물 데이터베이스 관리 모듈 개발: G-eye 관리 시스템)

  • Min, Seonghee;Oh, Yoosoo
    • Journal of Korea Multimedia Society
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    • v.20 no.2
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    • pp.344-351
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    • 2017
  • In this paper, we propose the obstacle database management module for obstacle estimation and clustering. The proposed G-eye manager system can create customized walking route for blind people using the UI manager and verify the coordinates of the path. Especially, G-eye management system designed a regional information module. The regional information module can improve the loading speed of the obstacle data by classifying the local information by clustering the coordinates of the obstacle. In this paper, we evaluate the reliability of the walking route generated from the obstacle map. We obtain the coordinate value of the path avoiding the virtual obstacle from the proposed system and analyze the error rate of the path avoiding the obstacle according to the size of the obstacle. And we analyze the correlation between obstacle size and route by classifying virtual obstacles into sizes.

Path-dependant Nonlinear Analysis of RC shell Structures using Volume Control Method (체적제어법을 이용한 철근콘크리트 쉘구조물의 경로의존 비선형 해석)

  • 송하원;이준희;변근부
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2003.10a
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    • pp.585-590
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    • 2003
  • To overcome the drawbacks of conventional load control method and displacement control method, the so-called volume control method was developed by utilizing a pressure node added into a finite shell element. In this study, an improved volume control method which can analyze path-dependant behaviors of RC shell structures subjected to cyclic loading effectively is developed. RC shell structures are discretized with layered shell elements and in-plane two dimensional constitutive equations for concrete and reinforcements are implemented for each layer of the shell elements. Validity of the so-called path dependant volume control method is also verified by comparing analysis results with other data including experimental results.

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