作者: X.F. Xu, L.M. Tang, G.Q. Tong

摘要: A comparative study of different element formulations in simulating superplastic forming
with the MARC finite element code is performed in the paper. Simulations were accomplished with
solid, shell, membrane elements to predict forming characteristics and pressure-time curves. Finite
element analysis (FEA) predictions of SPF pressure-time curves were found to be greatly affected by
the element type and the strain rate control algorithms. Two strain rate control algorithms were
applied in the present study: an algorithm based on limiting the rate of deformation with the average
strain rate of all the elements, i.e. the build-in method in MARC, and a second algorithm which limits
the rate of deformation based on the average strain rate of the elements with the 20 highest strain rates.
The resulting pressure-time curves for each of these formulations were compared with respect to each
type of element. Under the guide of the analysis, the die was fabricated and the AA5083 bracket was
successfully manufactured. Good agreement was obtained between predicted and measured thickness
in the part.

281

作者: Yoshitaka Wada, Takuji Hayashi, Masanori Kikuchi, Fei Xu

摘要: Due to more complex and severe design restrictions, more effective and faster finite
element analyses are demanded. There are several ways to compute FE analysis efficiently: parallel
computing, fast iterative or direct solvers, adaptive analysis and so on. One of the most effective
analysis ways is the combination of adaptive analysis and multigrid iterative solver, because an
adaptive analysis requires several meshes with difference resolutions and multigrid solver utilizes
such meshes to accelerate its computation. However, convergence of multigrid solver is largely
affected by initial shape of each element. An effective mesh improvement method is proposed here. It
is the combination of mesh coarsening and refinement. A good mesh can be obtained by the method to
be applied to an initial mesh, and better convergence is achieved by the improved initial mesh.

833

摘要: A new triangular element of Hermitian type, i.e., the degrees of freedom includes differentiation of value as well as value itself, is proposed and XFEM formulation is demonstrated. Some numerical examples are also shown.

405

作者: Hong Liang Li, Jin Gui Lu, Zhao Xin Xuan, Jian De Zhang

摘要: This paper is involved in triangulating surface of the hollow cylinder. The strategy is proposed for generating surface triangulation elements for the hollow cylinder at first. The strategy of adjusting the surface triangulation elements which are adjacent to the crossing cures in the hollow cylinder, is discussed. The computer implementation on the strategy proposed in this paper is given and the numerical example is performed. The example of the hollow cylinder verifies the correctness of the strategy proposed in this paper.

1444

作者: Biao Feng, Hong Shuai Liu, Ri Qing Lan

摘要: The traditional constraint model employed in Interface Stress Element Method is cumbersome due to the using of additional virtual elements. To remedy this, a new constraint model without virtual elements was proposed, based on the introductions of constrained interface, formula for stress mode on bound boundary and governing equations considering geometric boundary conditions. With the elimination of virtual elements, constraints can be treated more naturally and simply. Programs based on this model were developed and numerical examples were provided to demonstrate the validity and convenience of the presented technique.

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