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Increasing usage of metals in engineering structures has made the metal forming process become superior in the solid mechanic researches. Meanwhile, the physical theories are of high significance due to the individual features. The crystal plasticity theory is one of these theories. This theory predicts the texture evolution and deformation of these materials by modeling the plastic deformation mechanisms of crystal material’s micro-structure (such as metals). Connecting with micro-structure enables this theory to predict the anisotropy of single crystals, and also the prediction of some phenomena in polycrystals which are aggregate of single crystals, is possible. Presenting a suitable work hardening model which contains the anisotropy behaviors of single-crystals is very important. In this paper, at first, the principles of crystal plasticity are explained, and then by evaluating several experimental results and the most commonly used work hardening models, a new work hardening model will be presented. This model adapts better with experimental results, compared to the previous models. The scope of this research is specifically for crystal materials with FCC structure, nevertheless, some part of this research is applicable to the other structures.

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In this paper, the drawing process of the sheet metal through the wedge shaped die has been analyzed by upper bound method using stream function. First, a new deformation model has been introduced in which inlet and outlet shear boundaries are considered flexible. Then, the optimized geometry of the deformation zone has been determined through the effect of work hardening of the sheet material depending on the process conditions. According to the suggested stream function, velocity field, strain rates and power terms have been calculated. The analytical results have been compared with the results of the published analytical data and the finite element simulation results. Furthermore, the effect of work hardening exponent has been investigated on the deformation zone, drawing force and optimum die angle. It has been shown that by increasing the work hardening exponent, inlet and outlet shear boundaries of deformation zone are being inclined to the inlet zone of the die and the required drawing stress is decreased. In addition, by increasing the friction factor, inlet and outlet shear boundaries are being inclined to outlet zone of the die, and by increasing reduction in thickness, inlet and outlet shear boundaries of deformation zone are being inclined to the inlet zone of the die. It is shown that the analytical results have been improved up to ten percent in comparison to the published data.

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The slab method can predict rapidly the rolling force and torque in metal forming processes and a large amount of CPU time can be saved. Up to now, the work hardening effect has not been considered in the slab analysis for forging process of double-layer clad sheet. Evaluation of considering or eliminating the work hardening effect of material behavior in the slab analysis of three layer clad sheet forging process and investigating the subsequent effects on the process outputs are a novel subject considered in this paper. The pressure distribution as well as the forging force are investigated for both conditions. In addition, three layer clad sheet forging process is simulated entirely using ABAQUS/Explicit software. The results have showed that considering the work hardening will result into having larger stresses and forces in the process. Moreover, the results of considering the work hardening have better agreements with those from simulation. Finally, some experiments were performed on forging process of two layer Al/Cu clad sheet to evaluate the bonding quality of sheets. Therefore, forging process can be used for producing multi-layer clad sheets in various industries.