Explicit Simulation of Roll Forming Process with EAS Solid-shell Elements

L.M. Lia,Y.H. Peng,D.Y. Li 한국소성가공학회 2010 기타자료 Vol.2010 No.6

Solid-shell elements can be seen as a class of typical double-surface shell elements with no rational degrees of freedom, which are more suitable for analyzing double-sided contact problems than conventional shell elements. In this study, an EAS-based solid-shell element is implemented into the explicit finite element formulation to simulate roll forming process. A twelve-parameter enhanced assumed strain (EAS) method is adopted to solve for the locking pathologies. Accuracy of the explicit solid-shell finite element model is excised through two NUMISHEET benchmark tests. Afterwards, a U-channel forming is simulated with the present explicit model. Numerical results of longitudinal strains and final geometries are compared with experiment as well as calculated by the commercial software ABAQUS. The solid-shell element is found more applicable in dealing with roll-forming process than ABAQUS inherent elements. Potential of the explicit solid-shell model in analyzing cold roll forming process is confirmed.

Arc-length and explicit methods for static analysis of prestressed concrete members

Bulent Mercan,Henryk K. Stolarski,Arturo E. Schultz 사단법인 한국계산역학회 2016 Computers and Concrete, An International Journal Vol.18 No.1

This paper compares the arc-length and explicit dynamic solution methods for nonlinear finite element analysis of prestressed concrete members subjected to monotonically increasing loads. The investigations have been conducted using an L-shaped, prestressed concrete spandrel beam, selected as a highly nonlinear problem from the literature to give insight into the advantages and disadvantages of these two solution methods. Convergence problems, computational effort, and quality of the results were investigated using the commercial finite element package ABAQUS. The work in this paper demonstrates that a static analysis procedure, based on the arc-length method, provides more accurate results if it is able to converge on the solution. However, it experiences convergence problems depending upon the choice of mesh configuration and the selection of concrete post-cracking response parameters. The explicit dynamic solution procedure appears to be more robust than the arc-length method in the sense that it provides acceptable solutions in cases when the arc-length approach fails, however solution accuracy may be slightly lower and computational effort may be significantly larger. Furthermore, prestressing forces must be introduced into the finite element model in different ways for the explicit dynamic and arc-length solution procedures.

Development of Step-Wise Combined Implicit-Explicit Finite Element Method

Jung, Dong-Won 제주대학교 산업기술연구소 2001 尖端技術硏究所論文集 Vol.12 No.1

A combined implicit-explicit scheme for the analysis of sheet forming problems has been proposed in this work. In the finite-element simulation of sheet metal forming processes, the robustness and stability of computation are important requirements. since the computaion time and convergency become major points of consideration in addition to the solution accuracy, due to the complexity of the geometry and boundary conditions. The implicit scheme employs a more reliable and rigorous scheme in considering the equilibrium at each step of deformation, whilst in the explicit scheme the problem of convergency is eliminated at the cost of solution accuracy. The explicit approach and the implicit approach have both merits and demerits. In order to combine the merits of these two methods. a step-wise combined implicit-explicit scheme has been developed. Computations are carried out for the deep drawing of an oil pan by implicit. explicit and combined implicit-explicit schemes. From the comparison between the methods the advantages and disadvantages of the methods are identified and discussed.

Development of Step-Wise Combined Implicit-Explicit Finite Element Method

정동원 濟州大學校 産業技術硏究所 2001 산업기술연구소논문집 Vol.12 No.1

A combined implicit-explicit scheme for the analysis of sheet forming problems has been proposed in this work. In the finite-element simulation of sheet metal forming processes. the robustness and stability of computation are important requirements. since the computaion time and convergency become major points of consideration in addition to the solution accuracy. due to the complexity of the geometry and boundary conditions. The implicit scheme employs a more reliable and rigorous scheme in considering the equilibrium at each step of deformation. whilst in the explicit scheme the problem of convergency is eliminated at the cost of solution accuracy. The explicit approach and the implicit approach have both merits and demerits. In order to combine the merits of these two methods. a step-wise combined implicit-explicit scheme has been developed. Computations are carried out for the deep drawing of an oil pan by implicit. explicit and combined implicit-explicit schemes. From the comparison between the methods the advantages and disadvantages of the methods are identified and discussed.

외연적 유한요소법을 이용한 자동차 Hub Bearing의 Orbital forming 해석

조현직(Hyunjik Cho),구정서(Jeongseo Koo),배원락(Wonrak Bae),임종순(Jongsoon Lim) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

In this paper was analysed the orbital forming of an automotive hub bearing using the explicit finite element method. To find an efficient solution technique on the orbital forming, axisymmetric finite element model s and 3D solid element models were solved and compared numerically. The time scaling and mass scaling techniques were used to reduce long computational time for fine element models in case of using the explicit finite element method. It was found from the numerical results that the axisymmetric element models showed the similar results to the 3D solid element models in forming loads whereas the deformations of them caused by O/F were quite different.

퍼포본드 FRP-콘크리트 합성보의 휨/전단거동에 관한 외연적 비선형 유한요소해석 연구

유승운 한국산학기술학회 2020 한국산학기술학회논문지 Vol.21 No.11

In this study, the flexural/shear behavior characteristics of perfobond FRP-concrete composite beams using an FRP plate with perforated webs as formwork and reinforcement are analyzed through an analytical method. Compared with the existing experimental results, we have proved its usefulness and use it in future practice. When the nonlinearity is very large in this case, the nonlinear finite element analysis by an explicit method will be effective. The concrete damage plasticity (CDP) model adopted in this study is considered to be able to adequately simulate the nonlinear behavior of concrete, and the determination of several variable factors required in the model is compared with the experimental results and values used in the study. This recommendation will require review and adjustment for more diverse cases. The effect of the perfobond of the composite beam with perforated web is considered to be somewhat effective in terms of securing the initial stiffness, but in the case of the apex, it is considered that the cross-sectional loss and the effect of improving the bonding force should be properly arranged. The contact problem, such as slipping of the FRP plate and concrete, is considered to be one of the reasons that the initial stiffness is slightly larger than the test result, and the slightly difference from the experimental results is attributed to the separation problem between concrete and FRP after the peak. 본 연구에서는 천공된 웨브를 가진 FRP판을 거푸집 및 보강재로 활용한 퍼포본드 FRP-콘크리트 합성보의 휨/전단 거동 특성을 해석적인 방법으로 거동특성을 파악한다. 기존 실험결과와 비교하여 그 유용성을 입증하고 차후 실무에 활용하고자 한다. 본 사례와 같이 비선형성이 매우 큰 경우에는 외연적 방법에 의한 비선형 유한요소해석이 효과적일 것이다. 본 연구에서 채택한 콘크리트손상소성(concrete damage plasticity: CDP)모델은 콘크리트의 비선형적 거동을 적절히 모사할 수 있는 것으로 사료되며, 모델에서 필요한 여러 변수 인자의 결정은 실험결과와 비교하여 연구에서 사용한 값들을 추천하나, 보다 다양한 케이스에 대한 검토 및 조정이 필요할 것이다. 웨브가 천공된 합성보의 퍼포본드의 효과는 초기강성의 확보 측면에서 다소 효과가 있는 것으로 판단되나 정점에서의 경우 단면 손실과 결합력 증진 효과를 적절히 안배해야 할 것으로 사료된다. FRP 판과 콘크리트의 미끄러짐 등의 접촉문제는 초기 강성이 실험결과보다 다소 크게 나타난 이유 중에 하나라 판단되며 정점 이후 콘크리트와 FRP 의 분리문제 등이 실험결과와 다소 차이를 보인 원인으로 생각한다.

자동차 휠 베어링 설계 시 3축성형한계를 고려한 크랙 예측

이인하(I. H. Lee),안정호(J. H. An),송민우(M. W. Song),송가형(G. H. Song),곽호택(H. T. Kwak) 한국소성가공학회 2016 한국소성가공학회 학술대회 논문집 Vol.2016 No.4

In this study, orbital forming process, assembly method of automotive wheel bearing hub and inner ring, was analytically implemented using the STAMPACK™ that is based on explicit finite element method. CPU time significantly reduced beside implicit finite element method and STAMPACK™ analysis showed similar results with the test data. Additionally, It predicted crack and found solution plan using TFD(triaxiality fracture diagram).

Combined finite volume and finite element method for convection-diffusion-reaction equation

Sutthisak Phongthanapanich,Pramote Dechaumphai 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.3

A combined finite volume and finite element method is presented for solving the unsteady scalar convectiondiffusion-reaction equation in two dimensions. The finite volume method is used to discretize the convection-diffusionreaction equation. The higher-order reconstruction of unknown quantities at the cell faces is determined by Taylor's series expansion. To arrive at an explicit scheme, the temporal derivative term is estimated by employing the idea of local expansion of unknown along the characteristics. The concept of the finite element technique is applied to determine the gradient quantities at the cell faces. Robustness and accuracy of the method are evaluated by using available analytical and numerical solutions of the two-dimensional pure-convection, convection-diffusion and convectiondiffusion-reaction problems. Numerical test cases have shown that the method does not require any artificial diffusion to improve the solution stability.

PANEL DASH LHD 차체판넬 스템핑공정 해석에 관한 연구

정동원,황재신 제주대학교 공과대학 첨단기술연구소 2003 尖端技術硏究所論文集 Vol.14 No.1

The static implicit finite element method and the dynamic explicit finite element method are applied effectively to analyze total auto-body panel stamping processes, which include the forming stage. Analyzed complicated and abnormal Large size auto-body panel using common use program called Auto Form. Analysis results examining possibility and validity of spot application that is useful of finite element law refer. In this work, brief descriptions of the formulation and the factor study are presented. Further, the simulated results for the total auto-body panel stamping processes are shown and discussed. Its application is being increased especially in the automotive industrial area for the cost reduction, weight saving, and improvement of strength.

대형 차체판넬 스템핑공정에서의 동적 외연적 탄소성 유한요소해석

정동원(Dong-Won Jung),김귀식(Gui-Shik Kim),양동열(Dong-Yol Yang) 한국해양공학회 1998 韓國海洋工學會誌 Vol.12 No.1

In the present work the elastic-plastic FE formulations using dynamic explicit time integration schemes are used for numerical analysis of a large auto-body panel stamping processes. For analyses of more complex cases with larger and more refined meshes, the explicit method is more time effective than implicit method, and has no convergency problem and has the robust nature of contact and friction algorithms while implicit method is widely used because of excellent accuracy and reliability. The elastic-plastic scheme is more reliable and rigorous while the rigid-plastic scheme require small computation time.<br/> In finite element simulation of auto-body panel stamping processes, the robustness and stability of computation are important requirements since the computation time and convergency become major points of consideration besides the solution accuracy due to the complexity of geometry and boundary conditions. The performance of the dynamic explicit algorithms are investigated by comparing the simulation results of forming of complicate shaped autobody parts, such as a fuel tank and a rear hinge, with the experimental results.<br/> It has been shown that dynamic explicit schemes provide quite similar results to the experimental results. It is thus shown that the proposed dynamic explicit elastic-plastic finite element method enables an effective computation for complicated auto-body panel stamping processes.