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Optimization of Die Profile in Screw Extrusion Process for an Arbitrary Profile by Considering Viscoelastic Effects of the Material

Fadaei Naeini, Vahid | 2013

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 44971 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Asghari, Mohsen
  7. Abstract:
  8. In this thesis, equations related to large deformation of a polymer were derived by considering viscoelastic effects. To express type of material behavior which includes elastoplastic and viscoelastic property at the same time, two-layer viscoplastic model was used. An axisymmetric model was used for modeling problem in finite element software. By derivation of parameters related to two layer model and entering them in finite element software and also entering other properties required to model the forming process, modeling was performed by special profile connecting input and output sections. Due to favorable properties of spline functions, profiles used in die geometry, were selected from spline category. Then by parameterization of some of these functions, modeling for some special cases and determination of objective function values for these cases, some relations between objective function and optimization parameters were derived. Spline functions connecting input and output sections were defined by one position point at the first case and two at the second case. To develop a relationship between objective function values and optimization parameters, a fitting method for surfaces in 3D space using MATLAB was selected in one position point case, and a neural network in two position point case and optimization was performed for two cases separately. Optimization results demonstrated that more number of position points can achieve more optimized values for objective function
  9. Keywords:
  10. Objective Function ; Die Profile ; Screw Extrusion ; Viscoelastic Effects ; Nonlinear Finite Element Method ; Optimization

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