PET is everywhere: bottles, packaging, fibers, films.
When we pull it, it can neck. What appears to be damage or the end of useful deformation can instead become the beginning of a new material state.
In our latest work, just published in JMPS, we revisit necking in PET films and show that stable in-plane plane-strain necking produces a highly oriented, anisotropic material state, with increased stiffness and strength along the drawing direction and nearly rate-independent behavior.
Video: https://www.youtube.com/watch?v=hERti_S-L4Y
Paper: https://www.sciencedirect.com/science/article/pii/S002250962600150X
Of course, any thoughts from the iMechanica community are very welcome.