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The purpose of this paper is to develop parallel algorithms for moving boundary simulations by local remeshing and compose them to a fully parallel simulation cycle for the solution of problems with engineering interests.

The moving boundary problems are solved by unsteady flow computations coupled with six-degrees-of-freedom equations of rigid body motion. Parallel algorithms are developed for both computational fluid dynamics (CFD) solution and grid deformation steps. Meanwhile, a novel approach is developed for the parallelization of the local remeshing step. It inputs a distributed mesh after deformation, then marks low-quality elements to be deleted on the respective processors. After that, a parallel domain decomposition approach is used to repartition the hole mesh and then to redistribute the resulting sub-meshes onto all available processors. Then remesh individual sub-holes in parallel. Finally, the element redistribution is rebalanced.

If the CFD solver is parallelized while the remaining steps are executed in sequential, the performance bottleneck of such a simulation cycle is observed when the simulation of large-scale problem is executed. The developed parallel simulation cycle, in which all of time-consuming steps have been efficiently parallelized, could overcome these bottlenecks, in terms of both memory consumption and computing efficiency.

A fully parallel approach for moving boundary simulations by local remeshing is developed to solve large-scale problems. In the algorithm level, a novel parallel local remeshing algorithm is present. It repartitions distributed hole elements evenly onto all available processors and ensures the generation of a well-shaped inter-hole boundary always. Therefore, the subsequent remeshing step can fix the inter-hole boundary involves no communications.

During the industrial design process, a product is usually modified and analyzed repeatedly until reaching the final design. Modifying the model and regenerating a mesh for every update during this process is very time consuming. To improve efficiency, it is necessary to circumvent the computer-aided design modeling stage when possible and directly modify the meshes to save valuable time. The purpose of this paper is to develop a method for mesh modifications.

In contrast to existing studies, which focus on one or a class of modifications, this paper comprehensively studies mesh union, mesh gluing, mesh cutting and mesh partitioning. To improve the efficiency of the method, the paper presents a fast and effective surface mesh remeshing algorithm based on a ball-packing method and controls the remeshing regions with a size field.

Examples and results show that the proposed mesh modification method is efficient and effective. The proposed method can be also applied to meshes with different material properties, which is very different with previous work that is only suitable for the meshes with same material property.

This paper proposes an efficient and comprehensive tetrahedral mesh modification method, through which engineers can directly modify meshes instead of models and save time.

Numerical simulation of the single point incremental forming (SPIF) processes can be very demanding and time consuming due to the constantly changing contact conditions between the tool and the sheet surface, as well as the nonlinear material behaviour combined with non-monotonic strain paths. The purpose of this paper is to propose an adaptive remeshing technique implemented in the in-house implicit finite element code LAGAMINE, to reduce the simulation time. This remeshing technique automatically refines only a portion of the sheet mesh in vicinity of the tool, therefore following the tool motion. As a result, refined meshes are avoided and consequently the total CPU time can be drastically reduced.

SPIF is a dieless manufacturing process in which a sheet is deformed by using a tool with a spherical tip. This dieless feature makes the process appropriate for rapid-prototyping and allows for an innovative possibility to reduce overall costs for small batches, since the process can be performed in a rapid and economic way without expensive tooling. As a consequence, research interest related to SPIF process has been growing over the last years.

In this work, the proposed automatic refinement technique is applied within a reduced enhanced solid-shell framework to further improve numerical efficiency. In this sense, the use of a hexahedral finite element allows the possibility to use general 3D constitutive laws. Additionally, a direct consideration of thickness variations, double-sided contact conditions and evaluation of all components of the stress field are available with solid-shell and not with shell elements. Additionally, validations by means of benchmarks are carried out, with comparisons against experimental results.

It is worth noting that no previous work has been carried out using remeshing strategies combined with hexahedral elements in order to improve the computational efficiency resorting to an implicit scheme, which makes this work innovative. Finally, it has been shown that it is possible to perform accurate and efficient finite element simulations of SPIF process, resorting to implicit analysis and continuum elements. This is definitively a step-forward on the state-of-art in this field.

The purpose of this paper is to present a new simplified local remeshing procedure for the study of discrete crack propagation in finite element (FE) mesh. The proposed technique accounts for the generation and propagation of crack‐like failure within an FE‐model. Beside crack propagation, the technique enables the analysis of fragmentation of initially intact continuum. The capability of modelling fragmentation is essential in various structure‐structure interaction analyses such as projectile impact analysis and ice‐structure interaction analysis.

The procedure combines continuum damage mechanics (CDM), fictitious crack approach and a new local remeshing procedure. In the approach a fictitious crack is replaced by a discrete crack by applying delete‐and‐fill local remeshing. The proposed method is independent of mesh topology unlike the traditional discrete crack approach. The procedure is implemented for 3‐D solid elements in commercial finite element software Abaqus/Explicit using Python scripting. The procedure is completely automated, such that crack initiation and propagation analyses do not require user intervention. A relatively simple constitutive model was implemented strictly for demonstrative purposes.

Well known examples were simulated to verify the applicability of the method. The simulations revealed the capabilities of the method and reasonable correspondence with reference results was obtained. Material fragmentation was successfully simulated in ice‐structure interaction analysis.

The procedure for modelling discrete crack propagation and fragmentation of initially intact quasi‐brittle materials based on local remeshing has not been presented previously. The procedure is well suited for simulation of fragmentation and is implemented in a commercial FE‐software.

Applies an updated Lagrangian finite element analysis with automatic remeshing scheme to three‐dimensional hot extrusion through landless square dies. The remeshing procedure is composed mainly with decision for remeshing, transfer of state variables and mesh generation. The procedure is carried out fully automatically. In the procedure, it is difficult to generate the mesh automatically, considering the physical characteristics. Accomplishes mesh generation by introducing the modular concept. The mesh generated by the modular concept has advantages, especially for three‐dimensional problems, such as economic computational time and consideration of physical characteristics. Classes the profiles of orifice into two cases; and develops the orifice adaptive module for each case and then carries out numerical examples by using the orifice adaptive modules.

A new method of three‐dimensional remeshing is proposed for thermo‐viscoplastic finite element analysis of connecting rod forging. In the method, the deformed body to be remeshed is divided into a surface‐adaptive layer (SAL) and a core region. At the surface layer of hexahedral elements, the arrangement of nodal points is made by normal projection of boundary nodes in order to retard the mesh degeneracy, since the arrangement of boundary nodes can be easily achieved by using the information of the die surface patch. After generating the mesh automatically at the surface‐adaptive layer, the core region is automatically meshed by introducing a body‐fitted mapping technique. In order to show the effectiveness of the method in the three‐dimensional problem, forging of a connecting rod has been simulated as a practical example. The complete simulation of connecting rod forging has been carried out by using the thermo‐viscoplastic finite element method and the remeshing scheme. The analysis of transient heat transfer has been carried out for the workpiece by the finite element method, while the boundary element method has been used for the die.

Gives a bibliographical review of the finite element meshing and remeshing from the theoretical as well as practical points of view. Topics such as adaptive techniques for meshing and remeshing, parallel processing in the finite element modelling, etc. are also included. The bibliography at the end of this paper contains 1,727 references to papers, conference proceedings and theses/dissertations dealing with presented subjects that were published between 1990 and 2001.

In the finite element analysis of a hot forging process with hexahedral elements, flash region is difficult to analyze because of the thin shape. In this paper, a hot forging process is effectively analyzed by constructing a locally fine mesh in the flash region.

When remeshing is decided by an error estimation and flash is generated, the boundary patch of the mesh is constructed and expanded in the normal direction of the flash region. After hexahedral mesh is constructed in the expanded patch with master grid approach, the boundary patch is compressed to the original shape and the nodes in the boundary are moved to the relative position of the boundary patch. Then, a locally fine mesh is constructed in the flash region. The quality of mesh on the boundary is again improved by adding surface element layer. Therefore, the hot forging process can be effectively analyzed by constructing the adaptive hexahedral mesh in the flash region.

The results show that the locally fine mesh can be constructed in the hexahedral mesh generation procedure by constructing mesh in the expanded patch and compressing the mesh according to the original boundary patch without affecting the compatibility of element. Then, it is applied to the analysis of a hot forging process and it has been shown that the analysis result of the proposed technique can save the analysis time remarkably relative to that of the fine mesh, while maintaining the analysis accuracy of the fine mesh.

In the finite element analysis of a hot forging process, the flash region is very difficult to analyze because it is difficult to construct locally fine mesh with hexahedral elements. A new adaptive mesh generation technique using hexahedral elements is suggested to overcome such difficulty and applied to the analysis of a hot forging process.

In metal forming, there are problems with recurrent geometric characteristics and without explicitly prescribed boundary conditions. In such problems, so‐called recurrent boundary conditions must be introduced. The present study deals with non‐steady‐state three‐dimensional finite element analysis for helical extrusion of twisted clover and trocoidal gear sections through a curved die. A boundary‐directed remeshing scheme based on the modular remeshing technique has been proposed to reduce the errors arising in mapping of variables between old and new mesh systems. The computed extrusion pressures in reaching the near steady‐state loading stage are compared with the results of the experiments as well as the steady‐state analysis. The three‐dimensional deformed pattern involving warping at the extruded end due to torsional deformation mode is demonstrated. For twisted clover and trocoidal gear sections, the twisted angle of an extruded product is smaller than that of the die, and the simpler the shape of the sections, the larger the amount of the deviation.

An easy and robust grid‐based approach is proposed to construct the fully hexahedral mesh in three‐dimensional case and its application for the mesh regeneration or remeshing during the finite element simulation of a metal forming process is presented to show the validity and effectiveness of the scheme. The proposed scheme enables the construction of the provisional mesh by superimposing the regular cubical grid over the object to be meshed and removing the exterior grid points and cells. Because the constructed provisional mesh has the discrete rugged boundary that is quite different from the boundary geometry of the object to be meshed, the nodes on the boundary of the provisional mesh are projected onto the object boundary. The main disadvantage of the mesh constructed by grid‐based approaches is its severely distorted elements on the boundary owing to the projection of the rugged boundary onto the object boundary. In order to improve the quality of boundary elements, some layers of elements on the boundary surface are constructed and the nodes are repositioned by mesh smoothing. Consequently, the quality of boundary elements is effectively improved.