Date: Thursday, February 23
Time: 3:30 pm - 5:00 pm
Location: 405 John D. Tickle Building
Numerical approaches to modeling fracture can be classified into: sharp interface approaches (e.g., linear elastic fracture or cohesive zone models) or diffuse interface approaches (e.g., nonlocal continuum damage or phase field models). However, it has been well documented in the literature that the cohesive zone and phase field models can be recast into the framework of damage mechanics. In this talk, I will present two instances of the “damage mechanics approach” based on nonlocal gradient damage and cohesive zone models. First, I will describe an updated Lagrangian mixed finite element formulation for the creep (incompressible Stokes) flow driven fracture of glacier ice. I will discuss the model equations, numerical verification, and consistency of the formulation compared with the total Lagrangian viscoelastic finite element formulation through benchmark studies. I will then present idealized numerical studies that examine the conditions enabling crevasse (fracture) formation in Antarctic ice sheets and ice shelves. Second, I will describe discrete and continuum cohesive zone models for high-cycle fatigue delamination of composites based on the concept of additive decomposition of damage. I will discuss the model formulation within the finite element framework for different static fatigue damage functions and its calibration and validation through benchmark studies. I will then present parametric studies to examine the sensitivity of fatigue crack growth results to important model parameters. I will conclude with some remarks on nonlocal damage and phase field models and discuss future research directions.
Originally from India, Ravindra Duddu got his B. Tech in Civil Engineering from the Indian Institute of Technology Madras. He obtained his M.S. and Ph.D. in Civil and Environmental Engineering from Northwestern University in 2006 and 2009, respectively. After that he worked as a postdoctoral research at the University of Texas at Austin Institute for Geophysics (2009 – 2010) and Columbia University in the City of New York (2010 – 2012) before joining Vanderbilt University as an Assistant Professor of Civil and Environmental Engineering. His research interests are in the general area of computational solid mechanics with an emphasis on computational fracture mechanics and multi-physics modeling of material state identification and evolution. Specific application interests include: deformation and fracture of glacier ice and granular earth materials; environmentally assisted degradation of materials including corrosion, moisture and temperature enhanced damage in composites; finite strain deformation and wave propagation in soft solids and biological tissues.