Papers by Keyword: Adaptive Remeshing

Abstract: The adaptive discretization technique for static discrete models of random geometry based on Voronoi cells is developed here. It is based on adding randomly located nodes into the highly stressed regions and updating the discretization based on those nodes before the crack may initiate in or propagate through the regions.

Abstract: Metal orthogonal cutting and blanking are two important forming processes which include material removing. During finite element analyzing, the nonlinear problems of boundary, material and geometry must be considered to obtain the accurate calculating results. In this paper, we present an advanced adaptive remeshing procedure which has the capacities to simulate material removing processes in three dimensions. The sizes of finite elements are well adapted to local conditions which have the high distributions of physical fields using priori and posteriori error estimates. Based on constraint Delaunay Kernel, the unit mesh strategy is proposed to improve the mesh quality. By optimizing of both mesh edges and mesh elements, the mesh shape qualities are strictly controlled as the regular tetrahedrons. In this paper, Johnson-cook model is considered to simulate the elastic-visco-plastical material behaviors. The damage initiation is also judged by Johnson-cook criterion. The finite elements which reach the criterion will be killed and the material removing processes finished step by step. The proposed adaptive remeshing scheme is well present using the simulation of metal orthogonal cutting, milling and blanking processes.

Abstract: Metal orthogonal cutting process involves complex geometry deformation and mate-rial characteristics as large thermal-visco-plastic ow include ductile damage. Simultaneously,the contact with friction occurs in the same zone. To build the nite element model for metalcutting, the nite element mesh will be severely distorted at the region with high gradientof stress/strain/temperature eld. In this paper, a Adaptive remeshing procedure which inte-grates the 3D OPTIFORM mesher, ABAQUS/Explicit solver and eld node-node eld transferalgorithm are proposed to solve these problems. The thermal-mechanical simulation for metalorthogonal cutting is realized to demonstrate our numerical simulation approach. Some simu-lation results are illustrated include continuous chip forming process, thermal-mechanical elddistribution and cutting force in di erent rank angles, cutting speeds and friction conditions.

Abstract: Drilling is the source of major cost and time elements in airframe assembly due to hole quality, burr formation, and tool life problems plaguing the industry. Aerospace applications focus on holes for rivets loaded in shear in aluminum, titanium and composite stack-ups. Optimal chip flow and tool life are often in competition with burr formation, general hole quality, and cycle time. Physics-based modeling of drilling processes can provide insight and information not readily available or easily obtained from experiments, and in a much faster time frame. A three-dimensional finite element-based model of drilling is presented which includes fully adaptive unstructured meshing, tight thermo-mechanical coupling, deformable tool-chip-workpiece contact, interfacial heat transfer across the tool-chip boundary, and constitutive models appropriate for high strain-rate, large strain and high temperature deformation.

Abstract: In this work, an adaptive remeshing scheme is presented in order to simulate with accuracy sheet metal forming processes. During simulations of metal forming processes, large plastic deformations with ductile damage occur and severe mesh distortion takes place after a few incremental steps. Hence frequent remeshing of the part must be performed in order to carry out the finite element analysis. The necessary steps to remesh the damaged structure during the simulation of the sheet metal forming process are given. The adaptive remeshing based on refinement and coarsening techniques, is controlled by geometrical and physical size maps. This remeshing strategy has been coupled with a projection method in order to avoid problems of contact between the part and the rigid tools. The influence of the remeshing is studied on numerical examples which show the capacity of the proposed procedure.

Abstract: This paper presents an advanced numerical methodology which aims to improve virtually any metal forming processes. It is based on elastoplastic constitutive equations accounting for non-linear mixed isotropic and kinematic hardening “strongly” coupled with isotropic ductile damage. During simulation of metal forming processes, where large plastic deformations with ductile damage occur, severe mesh distorsion takes place after a finite number of incremental steps. Hence an automatic mesh generation with remeshing capabilities is essential to carry out the finite element analysis. Besides, when damage is taken into account a kill element procedure is needed to eliminate the fully damaged elements in order to simulate the growth of macroscopic cracks. The necessary steps to remesh a damaged structure in finite element simulation of forming processes including damage occurrence (initiation and growth) are given. An important part of this procedure is constituted by geometrical and physical error estimates. The meshing and remeshing procedures are automatic and are implemented in a computational finite element analysis package (ABAQUS/Explicit solver using the Vumat user subroutine). Some numerical results are presented to show the capability of the proposed procedure to predict the damage initiation and growth during the metal forming processes.