Extending the Finite Area Method for enhanced simulation of deformable membranes and its application to extrusion blow moulding

Abstract

This paper investigates the mechanics of the Extrusion Blow Moulding (EBM) process, focusing on the clamp and inflation phases. The simulation framework employed in this study has been developed using OpenFOAM ® and extends the available Finite Area Method with a vertex-centred approach. This cutting-edge developments integrated a corotational formulation with a quasi-static approximation. The computational code and algorithm are verified and validated through comparisons between analytical solutions, experimental measurements and simulation results, ensuring the accuracy and reliability of the proposed approach. The implemented code is verified by checking fundamental principles of hyperelastic materials behaviour, demonstrated through equibiaxial deformation of spherical balloons. The use of neo-Hookean and Mooney–Rivlin material models provides crucial insights into material responses under different inflation conditions. The studies begin employing a conceptual mould within the EBM process that allows examining the effects of mould clamping on parison deformation. Then the study extends to analysing a real bottle manufactured via EBM, employing Stereolithography (STL) digitization and thickness mapping to quantify the thickness distribution. The simulation results closely replicates experimental observations, capturing the inherent non-linearity of these process stages, including large deformations and displacements, hyperelasticity and parison-mould contacts. This interdisciplinary research enhances understanding of the EBM process phases and analogous processes, providing valuable insights for plastic manufacturing. It improves the design process for meeting specific requirements and offers guidelines to avoid potential failures. The findings underscore the importance of such studies in advancing sustainable and efficient plastic manufacturing practices, with applications ranging from inflatable structures to EBM processes.