Experimental study and numerical simulation of preform or sheet exposed to infrared radiative heating

International conference on Advances in Materials and Processing Technology, DUBLIN, IRELAND, AUG 03-06, 1999International audienceThermoplastic processing like the injection stretch blow moulding and thermoforming processes provide the heating stage with infrared oven. This is a critical stage of the process, as the final part thickness is strongly dependent on the preform or sheet temperature distribution prior to forming. Optimisation of the infrared oven is therefore necessary. Experiments have been conducted in order to characterise the heat source of the infrared emitter and the interaction between the heaters and a semi-transparent PET sheet. An 880 LW AGEMA infrared camera has been used to determine the surface distribution of the transmitted heat flux by measuring the temperature distribution on the surface of the thermoplastic sheet. In addition, numerical simulations of the temperature distribution using control-volume method have been carried out and compared with experimental data

Finite element modeling of fuel emission for thermoplastic multilayer fuel tanks with optimization of barrier properties

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).Peer reviewed: YesNRC publication: Ye

Neuroevolutionary multiobjective methodology for the optimization of the injection blow molding process

Injection blow molding process is widely used in the industry to produce plastic parts. One of the main challenges in optimizing this process is to find the best manufacturing thickness profiles which provides the desirable mechanical properties to the final part with minimal material usage. This paper proposes a methodology based on a neuroevolutionary approach to optimize this process. This approach focuses on finding the optimal thickness distribution for a given blow molded product as a function of its geometry. Neural networks are used to represent thickness distributions and an evolutionary multiobjective optimization algorithm is applied to evolve neural networks in order to find the best solutions, i.e., to obtain the best trade-off between material usage and mechanical properties. Each solution is evaluated through finite element analysis simulation considering the design of an industrial bottle. The results showed that the proposed technique was able to find good solutions where the material was distributed along the most critical regions to maintain adequate mechanical properties. This approach is general and can also be applied to different geometries.FCT - Fundação para a Ciência e Tecnologia in the scope of the project: PEst-OE/EEI/UI0319/2014 and the European project MSCA-RISE-2015, NEWEX, with reference 73420

Modelling of Parison Formation and Process Optimization for Blow Moulded Parts

Peer reviewed: NoNRC publication: Ye

Simulation of polymer forming processes: addressing industrial needs

The objective of this paper is to present the development of simulation and design optimization capabilities, for polymer forming processes, in the context of addressing industrial needs. Accomplishments generated from close to twenty years of research in this field, at the National Research Council (NRC), are presented. Polymer forming processes such as extrusion blow moulding, stretch blow moulding and thermoforming have been the focus of the work, yet the research is extendable to similar polymer forming operations such as micro-blow moulding, sheet blow moulding and composites stamping. The research considers material models, process sequence integration and design optimization, derivative processes and 3D finite elements with multi-body contact.Peer reviewed: YesNRC publication: Ye

Intelligent Advisor for the Design of Preforms in Stretch Blow Molding

Peer reviewed: NoNRC publication: Ye

Finite element modelling of the coupled pressure volume phenomena during inflation

In industrial blow molding machines, the inflation pressure is only controlled in the upstream blowing device and not inside the cavity. However, observations show that the inside measured pressure is considerably lower than the nominal one captured in the upstream air feeding system. Several recent investigations show that if the volume of the enclosed gas changes significantly during the inflation stage, then the assumption that the internal pressure is know and constant can be incorrect. In this case, the internal pressure becomes a function of the unknown cavity volume. This paper presents a thermodynamical model used for predicting the pressure evolution in molded cavities during the inflation process. A brief recall of the FEM formulation and implementation is also presented. Experimental validation of the numerical approach is performed on a one-stage stretch blow-molding machine.Peer reviewed: NoNRC publication: Ye