Modeling the Elastic Recovery of
PET
Bottles via a Free‐Blowing of Preforms Campaign
Yun‐Mei Luo, Luc Chevalier ABSTRACT
This study aims to quantify the elastic properties induced by biaxial stretching at different temperatures in order to simulate the complete process including the final elastic recovery. The elastic modulus is identified from geometric measurements obtained during free‐blowing experiments. PET preforms are free‐blown under controlled pressure and temperature conditions. The evolution of the bubble diameter and height is monitored up to maximum inflation. The internal pressure is then maintained during cooling and subsequently released at a prescribed temperature, either above or below the glass transition temperature, allowing the measurement of geometric changes associated with elastic recovery and thermal contraction. To validate the modulus values identified from the free‐blowing process, mechanical pressure tests are performed at room temperature on the blown specimens. These complementary measurements also enable the analysis of the influence of recovery temperature on the final induced modulus. Based on these results, the existing incompressible visco‐hyperelastic VUMAT implemented in Abaqus is extended to incorporate an adapted orthotropic elastic constitutive model, allowing the simulation of elastic recovery during the final stage of the free‐blowing process.