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The heating stage is of primary importance in stretch blow molding and thermoforming processes. Computational methods using the finite element technique for modeling the radiation heating stage of thick gauge plastic preforms and thin gauge, roll-fed plastic sheets are presented and discussed. The theoretical approach as well as the experimental validation are also presented. For stretch blow molding, the energy absorbed by the preform is adjusted by accounting for the selective heating process. An oriented preform is heated from two sides on a mandrel with a pre-defined pattern. This results in a controlled, optimized and uniform material distribution on the bottle which is essential to meet the growing needs of the packaging industry. For this purpose, preferential heating combined with the use of universal preforms produces a range of standard bottles having excellent aesthetic features without sacrificing the physical properties.

A numerical simulation model for predicting the fuel hydrocarbon permeation as well as the barrier layer thickness optimization for multilayer plastic fuel tanks is presented. The diffusion model is based on Fick's laws of diffusion for a steady/unsteady state permeation regime through a multilayer polymeric wall under isothermal condition. A continuum approach based on an homogenization technique is used to model solvent diffusion through an n layer film. The hydrocarbon flux determination through the multilayer film is solved using homogenization techniques that ensure continuity of partial pressure at the polymer-polymer inter-diffusion interface. Since the pinch-off zone is known to be the major source of emission per unit area, a method has been developed to automatically detect it at the end of the extrusion blow molding process and the diffusion model is adapted to adequately evaluate the hydrocarbon permeation through this specific area.

A numerical simulation model for the prediction of fuel hydrocarbon permeation is presented in this work. The barrier layer thickness optimization for thermoplastic multilayer fuel tanks is also considered. The diffusion model is based on the continuum approach with steady-state permeation regime across the multilayer polymeric wall. The hydrocarbon flux through the multilayer wall is determined by assuming continuity in vapor pressure at the polymer-polymer interface. Since the pinch-off zone is known to be the major source of emission per unit area, a method has been developed to automatically detect this zone at the end of extrusion blow molding process. After then, an improvement to the diffusion model has been proposed in order to evaluate adequately the hydrocarbon permeation through this specific area. Finally, a gradient-based algorithm is applied to optimize the barrier layer thickness to satisfy the total hydrocarbon fuel emission constraint for a plastic fuel tank (PFT).

The accurate prediction of part deformation due to solidification in automotive formed parts is important to help achieve an efficient production. Forming processes are those where a molten preform is deformed to take the shape of a mould cavity and subsequently solidified. Tolerance issues are critical in automotive applications and therefore part deformation due to solidification needs to be controlled and optimized accordingly. Formed parts can have a wide range of deformations according to the conditions of solidification. Both a small displacement and a large displacement formulation are developed for prediction of part deformation due to solidification. Experimental results obtained on a simple as well as complex automotive part are compared to determine whether the small displacement theory or the more complex approach is more appropriate.