The Daniel Guggenheim School of Aerospace Engineering
invites you to attend the talk
"Characterizing Strain Localization and
Dynamic Instabilities in Soft Materials"
Dr. Jin Yang
Postdoctoral Research Fellow | Department of Mechanical Engineering
University of Wisconsin-Madison
Thursday, January 23
3:30 - 4:30 PM
About the Talk:
Soft materials, e.g. foams, hydrogels, tissues, and various polymeric specimens, are capable of undergoing large deformations and exhibiting highly nonlinear stress-strain behavior. As a result, many soft materials are prone to strain localization and display various instability patterns. Characterizing their mechanical properties and understanding their microstructural changes under different loading conditions are important in a myriad of engineering and biological applications.
In this talk, I will present our recent research progress in experimentally characterizing the mechanical properties of soft materials from low to ultra-high strain-rates and building theoretical models of the dynamic behavior for these highly nonlinear soft viscoelastic materials based on continuum mechanics, including associated dynamic instability criteria. (i)For soft materials at low strain-rates (O(10-4)s-1~ O(10-1)s-1), I developed a fast, accurate and adaptive mesh digital image/volume correlation (DIC/DVC) algorithm to measure 2D & 3D full-field deformations in solids. This new method -- augmented Lagrangian (AL-)DIC/DVC -- takes advantage of the superior computational speed of previous local subset method yet produces globally kinematically compatible displacement and strain fields. It provides superior accuracy in quantitatively measuring full-field strain localizations compared to state-of-the-art methods. (ii)Next, via the application of controlled laser-induced inertial micro-cavitation, I will show that under dynamic, high-rate loading conditions, soft hydrogels exhibit significant strain stiffening effects, and that these effects can lead to a transitioning evolution between various types of surface instabilities. These types of dynamic rugae instability patterns, associated strain concentrations and potential fracture patterns have a significant impact on the material’s dynamic behavior, and thus are of significant interest in many of engineering and medical applications.
About the Speaker:
Dr. Jin Yang is currently a Postdoctoral Research Fellow at the University of Wisconsin-Madison, Department of Mechanical Engineering hosted by Prof. Christian Franck. He received his PhD in Mechanical Engineering from the California Institute of Technology in 2019 supervised by Prof. Kaushik Bhattacharya. His main research is focused on improving algorithms of digital image/volume correlation (a popular method in experimental mechanics to quantitatively measure deformations) and mechanics of soft, nonlinear viscoelastic materials at various strain-rates and dynamic instabilities therein.