| Summary: | 碩士 === 國立屏東科技大學 === 機械工程系所 === 96 === The study proposes three analysis methods to explore the plastic deformation behaviour and characteristics of two-layer and three-layer bounded clad sheet ; one is Slab Method ,the second one is Upper Bound Method , and the third is Finite Element Method.
The frictions of top and bottom dies are assumed as constant sheet friction. And coulomb friction , and those can be different. The shape of outer surface and the compression force can be obtained by the upper bound method , however the stress distributions can not be found , those are able to get by the slab method. The mathematical models based on the slab method and upper bound method are established to investigate the effects of various compression conditions such as clad thickness ratio, shear yield stress ratio, and reduction on various stress distributions and compression forces.
Using the FEM simulation and Taguchi method to explore the compression forming of clad sheet ; and to carry out the experimental plan by L9(34) orthogonal array which includes four various. Control factors the clad thickness ratio, the shear yield stress ratio, the frictional factor ratio or frictional coefficient ratio and the width thickness ratio to explore the effects of the compression characteristics of clad sheet.
For the optimization of compression forming of clad sheet, the SUPERFORM commercial software is used to perform the FEM simulation with constant shear friction and Coulomb friction. The shape of outer surface of clad sheet, the equivalent stress, the equivalent strain, the velocity field, the pressure distribution and the compression force can be simulated by the FEM.
With a view to verifying the results of FEM simulation, the results can be compared to those based on the slab method and the upper bound method.
The acceptance of FEM simulation can be verified by the comparisons of compression forces. Adjusting effectively various compression conditions to control the shape of outer surface to be uniform, the clad sheet is apt to perform the second forming.
The analysis results can be offered to the forging industries at the reference.
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