• EDISON SW 활용 경진대회 논문집
• /
• 제5회(2016년)
• /
• pp.217-221
• /
• 2016

In this paper, a springboard for diving is analysed to find out how much force a diver should apply to reach specific height when the diver jumps. The springboard is presumed to Co-rotational plane cantilever beam(CR-beam), so EDISON program related to Co-rotational framework is used. The force of the person is supposed to sine function and the demanded height is fixed. Same velocity makes same height regardless of diver's weight. So, the velocity of springboard when the feet of a diver are separated from the springboard is a main factor of the analysis. The result shows that there is no association between deformation and weight and also between velocity and weight. That is, the required force to reach a optimal height is fixed whatever the diver's weight is.

• 한국전산구조공학회논문집
• /
• 제28권5호
• /
• pp.485-490
• /
• 2015

구조의 기하학적 비선형해석을 위해 대표적으로 Total Lagrangian, Updated Lagrangian 정식화 기법이 있다. 이러한 고전적인 정식화 과정은 요소의 변형률을 가정하는 방법에 따라 그리고 요소의 절점 수에 따라 추가의 수학적 정식화 과정이 요구된다. 하지만 비교적 최근에 정립된 Co-roational(CR) 이론은 기 존재하는 보, 판, 쉘 요소에 독립적으로 요소 절점자유도에 따라 일정하게 적용하여 대변위, 작은 변형률을 갖는 구조의 기하비선형 해석을 가능케 한다. 본 논문에서는 회전자유도를 갖는 삼각평면요소에 대한 CR 기법을 정식화하였고 동적해석으로 확장하여 이를 상용프로그램과 검증하였다. 해석에 사용한 삼각평면요소는 OPtimal Triangular(OPT) 평면요소이다.

• 한국항공우주학회지
• /
• 제44권9호
• /
• pp.775-780
• /
• 2016

본 논문에서는 비선형 다물체 동역학 해석에 적용 가능한 구조해석을 개발하였다. 비선형 구조 해석을 위해 Co-rotational 이론 기반의 유한요소를 개발하였다. 그리고 국부 Lagrange 승수를 활용한 영역분할해석 기법을 적용하여 대용량/다물체 해석이 가능한 구조해석 알고리듬을 개발하였다. 기 개발한 구조 해석은 외팔보 및 다물체 구조에 대한 비선형 정적 해석 예제에 적용하였다. 병렬 계산에 따른 성능 평가는 희박행렬 계산 라이브러리인 PARDISO와 비교하였다. 이를 통해 기 개발 구조해석의 계산 속도 향상을 확인하였다.

• Structural Engineering and Mechanics
• /
• 제67권6호
• /
• pp.629-641
• /
• 2018

The paper describes the development of a two-dimensional (2D) co-rotational nonlinear beam finite element that includes advanced path-following capabilities for detecting bifurcation instability in elasto-plasticity of steel elements subjected to fire without introducing imperfections. The advantage is twofold: i) no need to assume the magnitude of the imperfections and consequent reduction of the model complexity; ii) the presence of possible critical points is checked at each converged time step based on the actual load and stiffness distribution in the structure that is affected by the temperature field in the elements. In this way, the buckling modes at elevated temperature, that may be different from the ones at ambient temperature, can be properly taken into account. Moreover, an improved displacement predictor for estimating the displacement field allowed significant reduction of the computational cost. A co-rotational framework was exploited for describing the beam kinematic. In order to highlight the potential practical implications of the developed finite element, a parametric analysis was performed to investigate how the beam element compares both with the EN1993-1-2 buckling curve and with experimental tests on axially compressed steel members. Validation against experimental data and numerical outcomes obtained with commercial software is thoroughly described.

• 제어로봇시스템학회논문지
• /
• 제14권9호
• /
• pp.886-892
• /
• 2008

In this paper, a closed-loop observer to extract the center of mass (CoM) of a bipedal robot is suggested. Comparing with the simple conversion method of just using joint angle measurements, it enables to get more reliable estimates by fusing both joint angle measurements and F/T sensor outputs at ankle joints. First, a nonlinear-type observer is constructed to estimate the flexible rotational motion of the biped in the extended Kalman filter framework. It adopts the flexible inverted pendulum model which is appropriate to address the flexible motion of bipeds, specifically in the single support phase. The predicted estimates of CoM in terms of the flexible motion observer are combined with measurements (that is, output of the CoM conversion equation with joint angles). Then, we have final CoM estimates depending on the weighting values which penalize the flexible motion model and the CoM conversion equation. Simulation results show the effectiveness of the proposed algorithm.