| dc.description.abstract | Glassy polymers are extensively used to make all kinds of structural components.
Polymers, such as epoxies, are often chosen as matrices in polymer matrix composites
(PMC). Ever since the 1960s, these types of composites have been gaining importance
in aerospace and automotive advanced applications due to their high sti ness and
weight saving potential.
In order to provide clues on the dependence of the fracture behavior upon the
stress triaxiality, a series of tensile tests on epoxy (Epon862) round notched bars were
carried out at NASA Glenn Research Center. Using state-of-the-art non-contact dig-
ital image correlation measurement technique, the mechanical quantities of interest
were extracted in order to understand how the fracture behavior responds when sub-
jected to various levels of stress triaxiality induced by varying the notch radius of
the specimens. E ects of aging on the fracture behavior were also investigated. A
physics-based macromolecular constitutive model that accounts for temperature and
pressure sensitivity as well as small-strain softening and large-strain hardening was
used to model the deformation behavior. Good correlation between experiments and
numerical simulations was achieved. To predict fracture, a pressure-sensitive model
motivated by previous work is introduced. Based on the experimental and numerical
results, the relation between the mean strain to failure versus the stress triaxiality
was de ned and it was shown that the fracture response of the material is strongly
a ected by the level of stress triaxiality. | en |
