• 제목/요약/키워드: combined loading conditions

검색결과 134건 처리시간 0.026초

파열 시험을 통한 감육곡관의 손상압력에 미치는 원주방향 결함 폭과 굽힘하중의 영향 평가 (Evaluating on the Effects of Circumferential Thinning Angle and Bending Load on the Failure Pressure of Wall-Thinned Elbow through Burst Tests)

  • 김진원;나연수;이성호
    • 한국안전학회지
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    • 제21권6호
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    • pp.14-19
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    • 2006
  • This study performed burst tests using real-scale pipe elbow containing simulated local wall-thinning to evaluate the effects of circumferential thinning angle and bending load on the failure pressure of wall-thinned elbow. The tests were carried out under the loading conditions of internal pressure and combined internal pressure and bending loads. Three circumferential thinning angles, ${\theta}/{\Pi}=0.125,\;0.25,\;0.5$, and different thinning locations, intrados and extrados, were considered. The test results showed that the failure pressure of wall-thinned elbow decreased with increasing circumferential thinning angle for both thinning locations. This tendency is different from that observed in the wall-thinned straight pipe. Also, the failure pressure of intrados wall-thinned elbow was higher than that of extrados wall-thinned elbow with the same thinning depth and equivalent thinning length. In addition, the effect of bending moment on the failure pressure was not obvious.

압전 센서와 액츄에이터를 이용한 단순지지 평판의 능동 진동제어 - I. 이론 (Active Vibration Control of a Simply Supported Plate with Piezoelectric Sensors and Actuators - I. Theory)

  • 노용래
    • 한국음향학회지
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    • 제11권3호
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    • pp.25-39
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    • 1992
  • 압전 센서와 액츄에이터를 이용한 단순지지 평판의 진동제어에 관해 이론적 고찰을 하였다. 적절한 센서, 액츄에이터의 운동방정식을 구한 후 평판으 ㅣ운동 방정식과 결합해 능동 진동제어 시스템을 구성하였으며, 외력과 제어력의 복합 영향을 고려한 평판의 진동 진폭 반응을 해석하였다. 본 방법의 효용성을 보이기 위해 집중 응력과 압전구동기에 의한 모멘트의 두가지 외력에 대한 진동반응을 수치해석 하였으며, 그 결과 압전 센서와 액츄에이터로써 구조물의 외력에 대한 진동반응을 효율적으로 감소시킬 수 있었다. 본 연구에서 고찰된 방법은 임의의 외력 조건과 제어 알고리즘에 적용이 가능하다.

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감육현상을 고려한 가스배관의 파손확률 평가 (Failure Probability Assessment of Gas Pipelines Considering Wall-Thinning Phenomenon)

  • 이상민;윤강옥;장윤석;최재붕;김영진
    • 한국정밀공학회지
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    • 제22권10호
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    • pp.158-166
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    • 2005
  • Pressurized gas pipeline is subject to harmful effects both of the surrounding environment and of the materials transmitted in them. In order to maintain the integrity, reliable assessment procedures including tincture mechanics analysis etc are required. Up to now, the integrity assessment has been performed using conventional deterministic approaches even though there are many uncertainties to hinder a rational evaluation. In this respect, probabilistic approach is considered as an appropriate method for gas pipeline evaluation. The objectives of this paper are to estimate the failure probability of corroded pipeline in gas and oil plants and to propose limited operating conditions under different types of leadings. To do this, a probabilistic assessment program using reliability index and simulation techniques was developed and applied to evaluate failure probabilities of corroded API-5L-X52/X60 gas pipelines subjected to internal pressure, bending moment and combined loading. The evaluation results showed a promising applicability of the probabilistic integrity assessment program.

울진 원자력발전소 5,6호기용 공기정화기에 대한 내진검증 (Seismic Qualification of the Air Cleaning Units for Nuclear Power Plant Ulchin 5&6)

  • 이준근;김진영;정필중
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2001년도 춘계학술대회논문집B
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    • pp.404-409
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    • 2001
  • Seismic qualification of the Air Cleaning Units for nuclear power plant Ulchin 5&6 has been performed with the guideline of ASME Section III and IEEE 344 code. By using the structural and geometrical similarity analysis, the three models to be analyzed is condensed into a single model and, at the same time, the excitation forces and other operating loads for each model are encompassed with respect to different loading conditions. As the fundamental frequencies of the structure are found to be less than 33Hz, which is the upper frequency limit of the seismic load, response spectrum analysis using ANSYS is performed in order to combine the modal stresses within the frequency limit. In order to confirm the structural and electric stability of the major components, modal analysis theory is adopted to derive the required response spectrum at the component locations. As the all combined stresses obtained from the above procedures are less than allowable stresses and no mechanical or electrical failures are found from the seismic testing, the authors confirm the safety of the nuclear equipments Air Cleaning Units studied in this paper.

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보강(補剛)된 유공판(有孔板)의 좌굴강도해석(挫屈强度解析)(제3보)(第3報) -압축(壓縮) 및 전단좌굴(剪斷挫屈) (The Buckling Analysis of Stiffened Plate with Hole(3rd Report) -compression and shear buckling-)

  • 장창두;나승수
    • 대한조선학회지
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    • 제22권1호
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    • pp.9-20
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    • 1985
  • Generally the stiffened plate in the ship structure is subjected to not only axial load but shear load. With respect to those combined loads buckling analysis in necessary. In this paper, buckling strength is analyzed by using Finite Element Method when the stiffened plate with hole is under loading conditions mentioned above. To obtain the higher buckling strength, we need some reinforcement. The methods of reinforcement are attaching doubler around hole and stiffeners in the arbitrary directions For the sake of convenience those arbitrary directions were selected paralleled($0^{\circ}C$), vertical($90^{\circ}C$)and oblique($45^{\circ}C$) to the edge. Two kinds of method mentioned above are investigated, it is clarified that which of the two is more effective reinforcement. From the viewpoint of buckling strength, following conclusions were obtained. When external load direction is unknown, doubler reinforcement is more effective than those of parallel and vertical stiffener. And oblique stiffener reinforcement is more effective than that of doubler when external load direction is know.

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원자력발전소용 주 제어반의 내진 검증 (Seismic Qualification of the Main Control Board for Nuclear Power Plant)

  • 변훈석;이준근
    • 한국소음진동공학회논문집
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    • 제12권11호
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    • pp.856-863
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    • 2002
  • Seismic qualification of the main control board(MCB) for the nuclear power plant Ulchin 5 and 6 has been performed with the guideline of ASME Section III and IEEE 344 code. As the size and weight of the MCB are too large and heavy to excite using the excitation table, finite element analysis is used in order to investigate the dynamic behaviors and structural integrity of the MCB. As the fundamental frequencies of the equipment are found to be less than 33 Hz, which is the upper frequency limit for the dynamic analysis, response spectrum analysis using ANSYS is performed in order to combine the modal stresses within the frequency limit. In order to confirm the electrical stability of the major components of the MCB. modal analysis theory has been adopted to derive the required response spectra at the component locations. As the all combined stresses obtained from the above procedures are less than the allowable stresses and no mechanical or electrical failures are found from the seismic testing, the authors can confirm the safety of the nuclear equipment MCB under the given seismic loading conditions.

Fully nonlinear inelastic analysis of rectangular CFST frames with semi-rigid connections

  • Bui, Van-Tuong;Vu, Quang-Viet;Truong, Viet-Hung;Kim, Seung-Eock
    • Steel and Composite Structures
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    • 제38권5호
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    • pp.497-521
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    • 2021
  • In this study, an effective numerical method is introduced for nonlinear inelastic analyses of rectangular concrete-filled steel tubular (CFST) frames for the first time. A steel-concrete composite fiber beam-column element model is developed that considers material, and geometric nonlinearities, and residual stresses. This is achieved by using stability functions combined with integration points along the element length to capture the spread of plasticity over the composite cross-section along the element length. Additionally, a multi-spring element with a zero-length is employed to model the nonlinear semi-rigid beam-to-column connections in CFST frame models. To solve the nonlinear equilibrium equations, the generalized displacement control algorithm is adopted. The accuracy of the proposed method is firstly verified by a large number of experiments of CFST members subjected to various loading conditions. Subsequently, the proposed method is applied to investigate the nonlinear inelastic behavior of rectangular CFST frames with fully rigid, semi-rigid, and hinged connections. The accuracy of the predicted results and the efficiency pertaining to the computation time of the proposed method are demonstrated in comparison with the ABAQUS software. The proposed numerical method may be efficiently utilized in practical designs for advanced analysis of the rectangular CFST structures.

Hygrothermal sound radiation analysis of layered composite plate using HFEM-IBEM micromechanical model and experimental validation

  • Binita Dash;Trupti R Mahapatra;Punyapriya Mishra;Debadutta Mishra
    • Structural Engineering and Mechanics
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    • 제89권3호
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    • pp.265-281
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    • 2024
  • The sound radiation responses of multi-layer composite plates subjected to harmonic mechanical excitation in hygrothermal environment is numerically investigated. A homogenized micromechanical finite element (FE) based on the higher-order mid-plane kinematics replicating quadratic function as well as the through the thickness stretching effect together with the indirect boundary element (IBE) scheme has been first time employed. The isoparametric Lagrangian element (ten degrees of freedom per node) is used for discretization to attain the hygro-thermo-elastic natural frequencies and the modes of the plate via Hamilton's principle. The effective material properties under combined hygrothermal loading are considered via a micromechanical model. An IBE method is then implemented to attain structure-surrounding coupling and the Helmholtz wave equation is solved to compute the sound radiation responses. The effectiveness of the model is tested by converging it with the similar analytical/numerical results as well as the experimentally acquired data. The present scheme is further hold out for solving diverse numerical illustrations. The results revealed the relevance of the current higher-order FE-IBE micromechanical model in realistic estimation of hygro-thermo-acoustic responses. The geometrical parameters, volume fraction of fiber, layup, and support conditions alongside the hygrothermal load is found to have significant influence on the vibroacoustic characteristics.

Spring rod를 사용한 척추경 나사못과 동반 시술된 Flexible cage의 생체역학적 효과 (Biomechanical Efficacy of a Combined Flexible Cage with Pedicle Screws with Spring rods: A Finite Element Analysis)

  • 김영현;박은영;김원현;황성필;박경우;이성재
    • 대한의용생체공학회:의공학회지
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    • 제38권1호
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    • pp.9-15
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    • 2017
  • Recently, flexible cages have been introduced in an attempt to absorb and reduce the abnormal load transfer along the anterior parts of the spine. They are designed to be used with the pedicle screw systems to allow some mobility at the index level while containing ROM at the adjacent level. In this study, a finite element (FE) study was performed to assess biomechanical efficacies of the flexible cage when combined with pedicle screws with flexible rods. The post-operated models were constructed by modifying the L4-5 of a previously-validated 3-D FE model of the intact lumbar spine (L2-S1): (1) Type 1, flexible cage only; (2) Type 2, pedicle screws with flexible rods; (3) Type 3, interbody fusion cage plus pedicle screws with rigid rods; (4) Type 4, interbody fusion cage plus Type 2; (5) Type 5, Type 1 plus Type 2. Flexion/extension of 10 Nm with a compressive follower load of 400N was applied. As compared to the Type 3 (62~65%) and Type 4 (59~62%), Type 5 (53~55%) was able to limit the motion at the operated level effectively, despite moderate reduction at the adjacent level. It was also able to shift the load back to the anterior portions of the spine thus relieving excessively high posterior load transfer and to reduce stress on the endplate by absorbing the load with its flexible shape design features. The likelihood of component failure of flexble cage remained less than 30% regardless of loading conditions when combined with pedicle screws with flexible rods. Our study demonstrated that flexible cages when combined with posterior dynamic system may help reduce subsidence of cage and degeneration process at the adjacent levels while effectively providing stability at the operated level.

A numerical method for evaluating fire performance of prestressed concrete T bridge girders

  • Zhang, Gang;Kodur, Venkatesh;Song, Chaojie;Hou, Wei;He, Shuanhai
    • Computers and Concrete
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    • 제25권6호
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    • pp.497-507
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    • 2020
  • This paper presents a numerical method for evaluating fire performance of prestressed concrete (PC) T shaped bridge girders under combined effect of structural loading and hydrocarbon fire exposure conditions. A numerical model, developed using the computer program ANSYS, is employed to investigate fire response of PC T shaped bridge girders by taking into consideration structural inherent parameters, namely; arrangement of prestressing strands with in the girder section, thickness of concrete cover over prestressing strands, effective degree of prestress and content of prestressing strands. Then, a sequential thermo-mechanical analysis is performed to predict cross sectional temperature followed by mechanical response of T shaped bridge girders. The validity of the numerical model is established by comparing temperatures, deflections and failure time generated from fire tests. Through numerical studies, it is shown that thickness of concrete cover and arrangement of prestressing strands in girder section have significant influence on the fire resistance of PC T shaped bridge girders. Increase in effective degree of prestress in strands with triangular shaped layout and content in prestressing strands can slow down the progression of deflections in PC T shaped bridge girder towards the final stages of fire exposure, to thereby preventing sudden collapse of the girder. Rate of deflection based failure criterion governs failure in PC T shaped bridge girders under most hydrocarbon fire exposure conditions. Structural inherent parameters incorporated into sectional configuration can significantly enhance fire resistance of PC bridge girders; thus mitigating fire induced collapse of these bridge girders.