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Research Area

        Due to limitation of natural resources, producing high strength and lightweight parts with environmentally friendly process is a great challenged in the materials and manufacturing industries. The major research work related is to develop the material with better mechanical properties without adding expensive alloying elements or applying secondary processes like heat treatment and to introduce a new manufacturing process guaranteeing better quality of the products employing with the conventional material.

1.       Severe Plastic Deformation process

 

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Fig.1) Schematic illustrations of the die geometry for the Equal Channel Angular Pressing process (left) and Hybrid process (right)

 

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Fig.2) The comparison of stress-strain curves with different route and number of pass (left) and with different materials processing and number of pass (right)

 

 

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Fig.3) Change of ultimate tensile strength, elongation of fracture and reduction area with wire-drawing and hybrid process

 

 

2.       Micro-structural Analysis

Cellular Automata

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Fig.1) Non-isothermal hot compression test

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Fig.2) The comparison of average grain size and flow stress curves obtained by the isothermal hot compression tests and CA analysis

 

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Fig.3) The comparison of average grain sizes at each position and morphology of grains

 

 

Crystal Plasticity FE simulation

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Fig.1) Procedure of Euler angles and hardness mapping for the fully coupled analysis of the subsequent compression after the three-pass ECAE: (a) half FE model, (b) full FE-model, and (c) cylindrical upsetting specimen extracted.

 

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Fig.2) Deformed shapes after the subsequent upsetting of the three-pass ECAEed specimen (route C with an aspect ratio of 2.7) at different strokes: (a)1 mm, (b) 2 mm, (c) 3 mm, (d) 4 mm, (e) 5 mm, and (f) 6 mm. (g) The final shape with various side views

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Fig.3) Comparison of the predicted (1 1 1) pole figures with the corresponding experiments after the single pass ECAE in the work of Li et al. (2006): (a) upper deformation path, (b) middle deformation path, and (c) lower deformation path.

 

        Friction is a highly non-linear phenomenon affected by a number of process parameters such as material property, characteristics of lubricant, deformation speed, temperature, surface condition, tool geometry, environmental factors, and their interactions. Although there have been a number of friction tests, it is still unclear whether these techniques are useful enough to differentiate the effect of these parameters on friction separately. So, it is proposed by Y.T. Im that a novel test method called tip test based on a combination of simple compression and backward extrusion at room temperature.

 

1.       Friction measurement

Tip test

 

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Fig.1) Schematic representation of a tip test

 

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Fig.2) Comparison of the load and stroke curves for the tip test for AL7075-O with a deformation speed of 0.1 mm/s between the experiment and simulation for the smooth (left) and rough counter punch (right)

 

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Fig.3) Effect of the process variables on the friction owing to (a)-(c) the hardness of the deforming material, and (d)-(f) the deformation speed



CAMPlab_연구실 소개자료(전산모사).pdf

CAMPlab_연구실 소개자료(실험 및 전산모사).pdf