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

Prediction of swell phenomena using adaptive local mesh refinement and weight optimization procedure in extrusion blow molding process

Peer reviewed: YesNRC 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

Polymer and salt selection for lithium polymer batteries

International audienceSeveral network-based polymer electrolytes provide both thermal, mechanical and redox stabilities, while insuring a high conductivity level. Linear unsaturated polyether precursors may be obtained either by step-growth polymerization from oligomeric polyethers or by ring-opening polymerization from oxirane mixtures. In addition, theoretical investigations on several lithium salts are presented, which allowed optimized geometries as well as charge densities to be established in the gas phase