Title:

Cracking Up: Micromechanical and Probabilistic Modeling of Dynamic Failure of Brittle Materials from Concrete to Ceramics

Speaker:

Dr. Lori Graham-Brady

Affiliation:

Johns Hopkins University

When:

Friday, April 19, 2013 at 10:00:00 AM   Add to Calendar

Where:

SEB Building, Room 316

Host:

Kimberly Kurtis
kimberly.kurtis@ce.gatech.edu
(404) 385-0825

Abstract

Failure of many brittle materials is driven largely by the initiation and growth of cracks from pre-existing flaws in the materials. These flaws are associated with microstructural defects such as pre-existing cracks, grain boundaries, pores, or soft inclusions. In this talk I will describe a recently developed analytically and numerically based model that predicts the stress-strain response of a brittle material under a fixed strain rate. The model addresses the effect of the flaw population (in terms of size distribution and number density), the material elastic properties and fracture toughness, the stress state and the strain rate. This model provides an important link between the microstructure of the material and the constitutive properties that are key to larger scale models such as finite elements. Examples of the results obtained from the model are developed for an air-entrained mortar and for silicon carbide. Finally, the effects of uncertainty and/or random spatial fluctuations in the flaw population are addressed, and the results show that these can be significant.

Biography

Lori Graham-Brady is a Professor in the Civil Engineering Department at Johns Hopkins University, with a secondary appointment in Mechanical Engineering. Her research interests are in computational stochastic mechanics, multiscale modeling of materials with random microstructure and the mechanics of failure under high-rate loading. Prof. Graham-Brady received her doctorate from Princeton University in 1996. After spending four years as an Assistant Professor in the Department of Civil Engineering at the University of Virginia, she joined Johns Hopkins University in 2000. She is the Associate Director of the Hopkins Extreme Materials Institute and Director of an NSF-funded IGERT training program with the theme of Modeling Complex Systems. She has received a number of awards, including the Presidential Early Career Awards for Scientists and Engineers (PECASE), the Walter L. Huber Civil Engineering Research Prize, and the William H. Huggins Award for Excellence in Teaching.