| Summary: | 碩士 === 國立清華大學 === 化學工程學系 === 87 === In this study, a Galerkin finite element numerical algorithm with splitting technique is developed to simulate the blow molding process, the Oldroyd-B viscoelastic fluid model is used as the constitutive equation to describe the isothermal forming process of homogeneous and incompressible plastic preform. It is implemented to predict the velocity profile, pressure field, stress and part thickness distribution. Mold contact problem will be discussed after that. The results will compare with the experimental data to ensure the finally solutions.Compare the simulation results with the experimental data, preform blow pressure can be exactly predicted. The material characteristic relaxation parameter has enormously affected on the stretch in axial direction, but less affected in axial direction. As the relaxation parameter increase from 0.1 to 0.5, the stretch amount in axial direction increase one times. But as it increase from 0.5 to 2.5, the stretch amount in axial direction increase less than 0.2 times. The reason for this phenomena maybe the strain-hardening effects. Based on the simulation results, the larger the relaxation parameter, the lower needed blown pressure, and can get longer part. From the part thickness distribution, we can find it is difficult to attain part average thickness. We also know that, the inertia effects in the blow molding process simulation can be neglected because its large viscosity.
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