Finite element simulations of stretch-blow moulding with experimental validation over a broad process window

Abstract

Injection stretch blow moulding is a wellestablished method of forming thin-walled containers and has been extensively researched for numerous years. This paper is concerned with validating the finite element analysis of the free-stretch-blow process in an effort to progress the development of injection stretch blow moulding of poly(ethylene terephthalate). Extensive data was obtained experimentally over a wide process window accounting for material temperature and air flow rate, while capturing cavity pressure, stretch-rod reaction force and preform surface strain. This data was then used to assess the accuracy of the correlating FE simulation constructed using ABAQUS/Explicit solver and an appropriate viscoelastic material subroutine. Results reveal that the simulation is able to give good quantitative correlation for conditions where the deformation was predominantly equal biaxial whilst qualitative correlation was achievable when the mode of deformation was predominantly sequential biaxial. Overall the simulation was able to pick up the general trends of how the pressure, reaction force, strain rate and strain vary with the variation in preform temperature and air flow rate. The knowledge gained from these analyses provides insight into the mechanisms of bottle formation, subsequently improving the blow moulding simulation and allowing for reduction in future development costs.

Simulation of the Injection Stretch Blow Molding Process: An Anisotropic Visco‐Hyperelastic Model for Polyethylene Terephthalate Behavior

“…An accurate model of PET for stretch blow molding must be characterized at temperatures and strain rates typically seen in the process. Nixon et al [1] demonstrated through free-blowing preforms while monitored via high-speed video that the strain rate has an average of 40 s −1 [1], whereas it is well recognized in the industry the temperature range of interest is between 90 C and 120 C, that is, just above the T g but just below the cold crystallization temperature.…”

A numerical investigation of the effect of preform length for the fabrication of 1.5Lt PET bottle through the injection stretch blow molding process

“…More specifically three different preform length cases were taken under consideration preform length is a parameter that is has not been investigated before. The study also comprises the effort to ma the preform temperature as much as possible above the glass-rubber limit which is about 80°C [14]. Stretchi preform above this limit induces crystallization [14].…”

“…The study also comprises the effort to ma the preform temperature as much as possible above the glass-rubber limit which is about 80°C [14]. Stretchi preform above this limit induces crystallization [14]. Stretching may also occur during the material deform while the blown preform fills the mold cavities.…”

“…Stretching may also occur during the material deform while the blown preform fills the mold cavities. The amount of induced crystallization is influenced b deformation and strain-rate modes [14] [15] [16] [17]. The highest the percentage of crystals in the materi highest is the strength [18].…”

“…The concept beyond this selection is to investigate th kinetics during the deformation mode while the material is constraint by the mold walls. In the actual SBM pr such mold temperature selection is expected to induces more crystals within the material [14], thus influenci strength performance of the bottle [18]. The stretch rod velocity is represented by Vs, which was -0.8m/s cases.…”