| Budget Amount *help |
¥3,200,000 (Direct Cost: ¥3,200,000)
Fiscal Year 2001: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2000: ¥2,400,000 (Direct Cost: ¥2,400,000)
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| Research Abstract |
In metal forming operations, there are many surface phenomena and problems which are very complicated and difficult to characterize quantitatively by the usual mathematical methods. As a measure to overcome such problems, a fractal approach was introduced in the present investigation. In the beginning, a practical fractal method applicable to various surface phenomena was proposed. Next, it was aimed to develop a simulator which can predict free surface profiles of any press-formed products and thus serves to provide such surface information as needed for process design. Finally, various applications of the fractal approach were presented. Main results obtained are as follows.
1. Fractal Characteristics of Free Surface Profile of Sheet Metals under Biaxial Tension
Two fractal analyses applicable to metal sheets and other objects were presented. The uniaxial and biaxial tension test that caused various strain ratios were conducted on metal sheets, and their free surface were examined by e
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mploying those fractal analyses. An important rule was found that the fractal dimension of surfaces is uniquely determined from the equivalent strain independently of the strain (or stress) ratios.
2. Development of Simulator for Prediction of Free Surface Profiles of Sheet-Formed Products
A method for simulating the surface roughening phenomenon caused by plastic deformation is presented. The strain dependence of the fractal parameters required for simulation can be unifiably expressed with the equivalent strain, irrespective of the strain ratio. Based on the result, a simulator for predicting surface profiles of any press-formed products is proposed, and shown to be valid.
3. Various Applications of Fractal Approach
The fractal approach was applied to characterization of adhesion particles caused on the tool surface in forging, a quantitative estimation of fracture surfaces for mild steel and an analysis of the nanofractal structure of material surfaces. Thus, the fractal analyses developed in the present investigation was shown to be useful. Less
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