Mechanical and Aeronautical Engineering
Seminar
Dr. Florin Bobaru
University of Nebraska-Lincoln
Will present a talk titled:
Some Tough Problems To Crack In … Fracture Mechanics, And Their Peridynamic Solutions
Abstract: Material failure/degradation takes many forms: fracture/rupture/fragmentation, corrosion/dissolution, plastic yield, distributed damage, etc. Dynamic brittle fracture in glass, failure in fiber-reinforced composites, and fracture in concrete or similar heterogeneous materials have been, for a long time, considered difficult to simulate because of complex interactions between many cracks. Crack growth is influenced by the microstructure and stress waves in ways that seem, as first, arbitrary. Existing theories of fracture mechanics, for example, only consider simple, idealized cases (a single or a few cracks, and mostly under static conditions), leaving the actual evolution of complex material failure unsolved. To circumvent these complications, simplified theories for fragmentation have been developed separate from fracture mechanics in order to make some sense of cases when many cracks form, but these theories can only answer part of the questions related to predicting the evolution of material failure.
In this talk I will present solutions to several problems of this type using peridynamic (PD) models. Peridynamics is a very general, nonlocal formulation of classical mechanics that allows for autonomous initiation and propagation of cracks and damage. In a way, PD unifies fracture mechanics and fragmentation theories, and eliminates the distinction between “damage” and “fracture”. I will discuss a number of fracture problems that have been difficult to simulate with a computer before: thermally-driven fracture in glass, dynamic crack branching in glass and glassy polymers, fracture in FRCs, and quasi-static fracture in porous rock and concrete. If time allows, I will delve into other types of material degradation, e.g. corrosion damage, and show how PD models can be used to predict these dangerous processes which, when combined with fracture, can lead to catastrophic consequences.
Date: November 12, 2021
Time: 11:00 am
Location: Science Center 160
Bio: Florin Bobaru is a Professor and Hergenrader Distinguished Scholar of Mechanical Engineering in the Department of Mechanical and Materials Engineering at University of Nebraska-Lincoln. He received his B.S and M.S. degrees in Mathematics and Mechanics from University of Bucharest, Romania, in 1995 and 1997, respectively, and his Ph.D. degree from Cornell University in Theoretical and Applied Mechanics in 2001. He is one of the first contributors to peridynamic modeling for dynamic fracture and damage, and has introduced nonlocal modeling for diffusion problems with evolving discontinuities and corrosion damage. He was a Visiting Professor/Visiting Scholar at University of Padova, Italy (2015), Caltech (2011), Cambridge University (2008), and Sandia National Laboratory (2002-2004, 2005, 2009). He was the organizer of the first Workshop on “Nonlocal Damage and Failure: Peridynamics and Other Nonlocal Models”, sponsored by the USACM and held in San Antonio, Texas, in 2013. He was the main editor of the “Handbook of Peridynamic Modeling” (2016), an Associate Editor for “Journal of Peridynamics and Nonlocal Modeling”, and ta regional editor for “International Journal of Fracture”. His paper on “Peridynamic modeling of repassivation in pitting corrosion of stainless steel”, co-authored with S. Jafarzadeh and Z. Chen and published in Corrosion journal, was awarded the 2020 CORROSION Best Paper Award by NACE. A new book on “Corrosion Damage and Corrosion-Assisted Fracture: Peridynamic Modeling and Computations” is to appear in 2022 at Elsevier.