Title:

Nucleation and Growth of Cracks in Elastomers

Speaker:

Prof. K. Ravi-Chandar

Affiliation:

UT Austin

When:

Friday, October 31, 2025 at 11:00:00 AM   Add to Calendar

Where:

Weber Building, Room SST3 Classroom 2

Host:

Christos Athanasiou
athanasiou@gatech.edu

Abstract

We explore the nucleation and propagation of cracks within a transparent polydimenthylsiloxane elastomer using the ' poker-chip ' specimen. This is accomplished not just through the usual macroscopic load and displacement data, but also with synchronized optical images at high spatial and adequate temporal resolution to resolve the evolution of the failure processes. This is augmented with interrupted tests and x-ray computed tomography-based reconstruction of the three-dimensional geometry of cavities and/or cracks. These experiments and observations reveal that nucleation of multiple cracks dominates when the thickness to diameter ratio is small, because the incompressibility of the material induces substantial hydrostatic tension nearly uniformly in the specimen. In contrast, the specimens with larger thickness to diameter ratio tend to nucleate fewer cracks, and are dominated by the growth of cracks. At even greater thickness to diameter ratios, uniaxial tensile stress conditions are approached, and failure is then dominated by surface flaws. Analysis and numerical simulations are performed to understand the observed transitions in the cavitation/fracture process evolution and to extract the criterion for nucleation of cavities/cracks.

Biography

Dr. Krishnaswamy Ravi-Chandar received his Ph.D. degree (1982) in Aeronautics from the California Institute of Technology. He taught at the University of Houston from 1983 to 2000 and, since 2000, he has been a Professor at The University of Texas at Austin, currently holding the M.C. (Bud) and Mary Beth Baird Endowed Chair in the Department of Aerospace Engineering and Engineering Mechanics. Dr. Ravi-Chandar's research interests are in the general area of mechanics of materials; he has made seminal contributions to dynamic fracture and failure. He has published over 170 articles on fracture, high strain-rate mechanical behavior, dynamic instabilities, fragmentation, ductile failure, multiscale experimental methods, inverse problems in material characterization, and other topics. Dr. Ravi-Chandar is the Editor-in-Chief of the International Journal of Fracture (2000-present). He received the Murray Medal from the Society for Experimental Mechanics in 2004, the Drucker Medal from the American Society of Mechanical Engineers in 2015, the Prager Medal from the Society for Engineering Science, 2020 and the Yokobori Medal from the International Congress on Fracture, 2023.