Energy-based yield criterion for PMMA from large-scale molecular dynamics simulations

Eugenio Jaramillo, Texas A & M University
Nathaniel Wilson, Birck Nanotechnology Center, Purdue University
Stephen Christensen, Boeing Co.
Jonathan Gosse, Boeing Co.
Alejandro Strachan, Birck Nanotechnology Center, Purdue University

Date of this Version



Phys. Rev. B 85, 024114 – Published 17 January 2012


This is the published version of Eugenio Jaramillo, Nathaniel Wilson, Stephen Christensen, Jonathan Gosse, and Alejandro Strachan. 17 January 2012. Energy-based yield criterion for PMMA from large-scale molecular dynamics simulations. First published in the Physical Review B and is available online at:


We use molecular dynamics (MD) with the DREIDING force field to characterize the ultimate mechanical response of amorphous poly(methyl methacrylate). We characterize how volumetric and deviatoric strains contribute to yield for a wide range of loading conditions from pure deviatoric, volume-conserving cases to isotropic volume expansion. We propose and apply an energy-based yield criterion to define yield consistently for all cases. Our results show that permanent deformation occurs when either the deviatoric or volumetric strains reach critical values, except in a narrow region around the transformation between deviatoric- and volumetric-dominated yield where the two strain invariants interact. In contrast, the pressure-modified von Mises criterion is only applicable to shear-dominated loading conditions. These results provide insight into the physics of yield in amorphous polymers and provide quantitative information and guidance for physics-based yield criteria for polymer-matrix composite materials.


Nanoscience and Nanotechnology