• 한국해양공학회지
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• 제12권3호통권29호
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• pp.19-30
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• 1998

In this paper, the dynamic analysis of a dolphin system for mooring a floating structure such as barge mounted plant is studied. The characteristics of the soil-pile system are simplified by a set of equivalent spring elements at the mudline. To evaluate the equivalent spring constants, the finite difference method is used. Since the characteristics of the soil-pile system are nonlinear in case of soft foundation, the nonlinear dynamic analysis technique is needed. The Newmark $beta$ method incorporating the modified Newton-Raphson method(initial stiffness method) is used. A numerical analysis is performed on two mooring dolphin systems on soft foundation and rock foundation. In case of the rock foundation, the characteristics are found to be nearly linear, so the linear dynamic analysis may be sufficient to consider the foundation effect. But in case of soft foundation, the non-linearity of the foundation appears to be very signigicant, so the nonlinear dynamic analysis si needed.

• 대한조선학회논문집
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• 제45권2호
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• pp.168-174
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• 2008

To calculate the fluid-structure interaction(FSI) problem rationally, it should be the basic technology to analyse each domain of fluid and structure accurately. In this paper, a new FSI analysis algorithm was introduced using the 3D solid finite element for structural analysis and CFD code based on the HCIB method for viscous flow analysis. The fluid and structural domain were analysed successively and alternatively in time domain. The structural domain was analysed by the Newmark-b direct time integration scheme using the pressure field calculated by the CFD code. The results for example calculation were compared with other research and it was shown that those coincided each other. So we can conclude that the developed algorithm can be applied to the general FSI problems.

• Earthquakes and Structures
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• 제16권3호
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• pp.359-368
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• 2019

This paper focuses on the study of dynamic analysis of thick plates resting on Winkler foundation. The governing equation is derived from Mindlin's theory. This study is a parametric analysis of the reflections of the thickness / span ratio, the aspect ratio and the boundary conditions on the earthquake excitations are studied. In the analysis, finite element method is used for spatial integration and the Newmark-${\beta}$ method is used for the time integration. While using finite element method, a new element is used. This element is 17-noded and it's formulation is derived from using higher order displacement shape functions. C++ program is used for the analyses. Graphs are presented to help engineers in the design of thick plates subjected to earthquake excitations. It is concluded that the 17-noded finite element is used in the earthquake analysis of thick plates. It is shown that the changes in the aspect ratio are more effective than the changes in the aspect ratio. The center displacements of the reinforced concrete thick clamped plates for b/a=1, and t/a=0.2, and for b/a=2, and t/a=0.2, reached their absolute maximum values of 0.00244 mm at 3.48 s, and of 0.00444 mm at 3.48 s, respectively.

• 한국전산구조공학회논문집
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• 제15권4호
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• pp.567-578
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• 2002

본 논문은 8절점 고체요소를 이용하여 항공기 충돌에 의한 원전 격납건물의 동적 거동을 분석하고 그 결과를 기술하였다. 콘크리트의 재료적 특성을 표현하기 위하여 Drucker-Prager항복기준을 바탕으로 항복면과 파괴면을 형성하였다. 이때 항복면과 파괴면은 콘크리트의 소성변형이 누적되면 가변하는 것으로 가정하였다. 철근의 재료특성은 변형도에 의존적인 탄성/점소성모델을 이용하여 표현하였다. 표준고체요소의 성능저하를 방지하기 위하여 Hughes가 제시한 B bar법을 바탕으로 변형도-변위관계 행렬을 형성하였다. 동적 시간이력해석을 수행하기 위하여 안정적인 수렴성을 가지는 암시적인 Newmark법을 도입하였다. 마지막으로 시간이력해석을 통하여 콘크리트 균열변형도의 수준과 충돌하는 항공기의 종류에 따른 격납건물의 동적거동변화를 조사하고 이를 정량적으로 기술하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.250-251
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• 2014

This paper investigates the stick-slip phenomena on spinning shaft. The modeling of the shaft is considered only torsional direction with nonlinear friction. The friction is adopted a negative friction-velocity slope. Based on the model, a nonlinear equation of motion is derived and analyze the stick-slip phenomena. In order to analyze the time dependent response, the nonlinear formulations are numerically solved by nonlinear Newmark method. The numerical results reveal the stick-slip phenomena on the spinning shaft system.

• 대한기계학회논문집B
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• 제37권3호
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• pp.229-235
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• 2013

유연한 혈관벽을 가진 경동맥 분지관을 흐르는 혈액의 유동을 해석하기 위하여 비정상상태, 비압축성, 뉴턴 유체를 가정한 3차원 유한요소해석을 수행하였다. 유체영역은 P2P1 유한요소를 사용하였으며, 격자의 움직임을 모사하기 위하여 arbitrary Lagrangian-Eulerian 기법을 적용하였다. Newmark 관계식을 이용하여 고체영역의 선형탄성 방정식의 변수들을 속도에 관한 방정식으로 간략화하였으며, 유체와 고체의 운동에 관하여 완전 결합된 공식을 얻었다. 맥동의 한 주기 동안에 혈관벽의 유연성이 유동장에 큰 영향을 미치며, 경동맥 분지각이 커짐에 따라 경동맥 공동에서 유동장의 정체영역이 더 넓게 분포한다는 연구결과를 얻었다.

• 대한조선학회논문집
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• 제38권3호
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• pp.47-53
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• 2001

선박이 파랑중에 충격력을 받거나 불규칙한 외력을 받았을 경우에 시간영역에서의 운동방정식을 해석하는 것이 편리하다. 본 연구에서는 주파수영역에서 3차원 Green함수를 이용한 패널방법을 사용하여 부가질량, 파랑감쇠계수, 1차항 파강제력과 시간평균된 표류력을 계산하였고, 기억효과를 포함한 시간영역의 운동방정식에서 Newmark-$\beta$방법을 사용하여 수치적분하였다. 계산 예로 계열 60 선박($C_B=0.7$)을 선정하여 불규파중에서 전진할 때의 6자유도 운동, 선수미에서의 가속도, 갑판침수 횟수 및 선저 노출 횟수 등을 계산하였다. 또한 2차항 파강제력을 운동방정식에서 고려하여 파도중에서 추력증가에 대해서 검토하였다.

• Interaction and multiscale mechanics
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• 제3권4호
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• pp.299-308
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• 2010

The indirect approach for measuring the bridge frequencies from the dynamic responses of a passing vehicle is a highly potential method. In this study, the effect of road surface roughness on such an approach is studied through finite element simulations. A two-dimensional mathematical model with the vehicle simulated as a moving sprung mass and the bridge as a simply-supported beam is adopted. The dynamic responses of the passing vehicle are solved by the finite element method along with the Newmark ${\beta}$ method. Through the numerical examples studied, it is shown that the presence of surface roughness may have negative consequence on the extraction of bridge frequencies from the test vehicle. However, such a shortcoming can be overcome either by introducing multiple moving vehicles on the bridge, besides the test vehicle, or by raising the moving speed of the accompanying vehicles.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 추계학술대회논문집
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• pp.575-580
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• 2000

Recently it is increased by degrees to construct complex and large lattice structure such as bridge, tower and crane structures. It is very important problem to know dynamic properties of such structures. Authors presented new dynamic response analysis algorithm for rectilinear structure already. This analysis algorithm is combined transfer stiffness coefficient method with Newmark method. Presented method improves the computational accuracy remarkably owing to advantage of the transfer stiffness coefficient method. This paper formulates dynamic response analysis algorithm for plane lattice structure expanding rectilinear structures.

• Steel and Composite Structures
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• 제3권3호
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• pp.169-184
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• 2003

This paper presents a generic modelling of composite steel-concrete beams with elastic shear connection. It builds on the well-known seminal technique of Newmark, Siess and Viest, in order to formulate the partial interaction formulation for solution under a variety of end conditions, and lends itself well for modification to enable direct quantification of effects such as shrinkage, creep, and limited shear connection slip capacity. This application is possible because the governing differential equations are set up and solved in a fashion whereby inclusion of the kinematic and static end conditions merely requires a statement of the appropriate constants of integration that are generated in the solution of the linear differential equations. The method is applied in the paper for the solution of the well-studied behaviour of simply supported beams with partial interaction, as well as to provide solutions for a beam encastr$\acute{e}$ at its ends, and for a propped cantilever.