Abstract: An elastic and an elastoplastic methyl methacrylate polymer, both in the glassy state, were subjected to mode I fracture characterization using two different tests: the single edge notch bending (SENB) test and the double cleavage drilled compression (DCDC) test. The toughness of the elastic material was assessed using linear elastic fracture mechanics analysis. For the elastoplastic material, the 𝐽-integral was computed when strain fields were available.
Numerical analyses were performed using finite element simulations with two damage approaches: cohesive elements and phase-field modeling. This provided a comparison between the calculated 𝐽-integral and an estimate of the critical energy release rate when it could not be calculated otherwise. Both modeling approaches yielded similar results; however, the phase-field approach could not always predict the material toughness due to its dependence on the model regularization parameter.
For each material and each test, the estimated values of the critical energy release rate are in good agreement with the literature. More interestingly, for the same material, both tests provided significantly different estimates of this material parameter, leaving engineers uncertain about which test to choose for assessing material toughness in crack opening mode.
Bio: Julie Diani is the The French National Centre for Scientific Research (CNRS) senior researcher in mechanics of polymers at Ecole Polytechnique in Palaiseau, France. After graduating from Université Pierre et Marie Curie (Paris) and École Normale Supérieure de Cachan, she completed a PhD in Mechanical Engineering in 1999, focusing on the mechanical behavior and cavitation of rubbers. She was hired as a researcher at CNRS in 2000 to work on the mechanical modeling of polymers, which remains her main topic of research. She spent two years (2004-2006) at the University of Colorado Boulder working on shape memory polymers and molecular dynamics simulations with Ken Gall. In 2015, she received the Sparks-Thomas Award from the Rubber Division of the American Chemical Society for my work on rubbers. I am currently working at the Laboratory of Solid Mechanics at École Polytechnique, where I led the Arkema Industrial Chair ‘Design and Modeling of Innovative Materials’ for five years.
Over the years, she has developed expertise in the experimental characterization and modeling of the mechanical behavior of polymers and reinforced polymers up to fracture. Her studies include topics such as Mullins softening in rubbers, shape memory behavior of amorphous polymers, the impact of filler/binder adhesion properties on the macroscopic behavior of propellants, viscoelasticity of interpenetrating networks, and the fracture of rubbers and glassy amorphous polymers, as well as shape optimization of viscoelastic thin structures.
Website: http://www.diani-research.com/
Host: Vicky Nguyen