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Topic Summary of the Dissertation
 
<Continue>
 

 4.        Two types of FEM analyses are often carried out to simulate heat rolling processes. One of these is the steady-state, Eulerian model by neglecting end effects and using rigid-plastic or viscoplastic behavior. The other is an incremental, updated Lagrangian model used when end effects are being investigated and/or elastoplastic or elastovisoplastic rheology is assumed. Quite a number of investigations have been carried out with various FEM models in the simulation of the rolling process of slab and in stretching grooves. With respect to FEM investigation of shape rolling, a few results have also been published such as the works relating to the rolling of rail, beam and angle steel. Some researcher did the simulation under the application of existing source programs, others tried to, however, directly write their own programs and then analyze the rolling process with the finished program. In a number of investigations some calculated parameters were compared with those of experiment and the FEM was thus examined and optimized. The comparison of local material flow exists, especially in the relatively simple rolling processes such as rolling in stretching grooves. Since the FEM simulation of shape rolling is normally very time consuming, the analysis of the shape rolling was often done through a combination of FEM with other methods (such as slab method, energy method, etc.), in order to cut down the calculation cost. But sometimes such a combination leads to a little sacrifice of the calculation accuracy.

            Most of the published research works for the simulation of shape rolling are inadequate. Many researchers only managed to solve part of the problems of the simulation, or tried to simulate the process with simplified material data and boundary conditions. The dependence of the material data and boundary conditions on the forming parameters such as temperature, strain, strain rate, were not adequately taken into consideration in most of these investigations. Some parameters such as forward and backward slip were often neglected. Only in very few of the investigations were sufficient optimization of boundary conditions and an extensive assessment of the calculation performed, especially with the rolling tests.

 

<To Be Continued>

 

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