Session: Rising Stars of Mechanical Engineering Celebration & Showcase

Paper Number: 148118

148118 - Illuminating Interfacial Mechanics: Utilizing Mechanophores to Quantify Stress in Polymer Composites 

Many properties of polymeric systems are determined almost exclusively by the interfaces between various material components. The research in the Illuminating Interfacial Mechanics Lab focuses on the development of novel measurement tools to assess the micromechanical behavior of polymer surfaces and interfaces while observing the resulting deformation with various microscopy techniques. This talk will focus on the role of interfacial strength on the stress field developed upon loading in the matrix of a glass/polymer composite. Here, we utilize a mechanically-activated fluorescent dye molecule (referred to as a mechanophore, MP) to visualize stress gradients that develop around a rigid inclusion upon mechanical deformation. By coupling our experimental observations of mechanophore activation intensity with finite element analysis of the local stress states in the loaded composites, a novel approach to quantitatively calibrate the MP fluorescent activation intensity is established. We then apply our calibration to several test cases of silica/silicone composites with dramatically different levels of interfacial strength and varied geometries. This mechanophore/mechanical deformation approach enables stress fields to be directly observed in a powerful new way via confocal fluorescence imaging in a mechanically loaded polymer composite. Further experiments explore fiber reinforced polymer matrix composites, stress localization effects of fiber end geometry, and fiber fragmentation mechanics. This new approach enables direct quantification of stress distribution within polmer matrix composites towards better characterizing complex stress states in situ.

Presenting Author: Chelsea Davis University of Delaware

Presenting Author Biography: Dr. Chelsea Davis joined the faculty of the University of Delaware as an associate professor in the Departments of Mechanical Engineering and Materials Science and Engineering in 2023. Previously, she worked in the School of Materials Engineering at Purdue University as an assistant professor where she established the Illuminating Interfacial Mechanics Lab which focuses on the development of micromechanical characterization tools to investigate the interfacial and surface properties of soft materials. Dr. Davis obtained a B.S. in Textile Engineering from North Carolina State University in 2005 and an M.S. and Ph.D. in Polymer Science and Engineering from the University of Massachusetts Amherst in 2007 and 2012, respectively. Dr. Davis was a Michelin Postdoctoral Research Fellow at the ESPCI in Paris (2012-2013) and then an NRC Postdoctoral Fellow in the Polymers and Complex Fluids Group at the National Institute of Standards and Technology (2013-2016). Dr. Davis’s work has been recognized through the NSF CAREER Award and the Adhesion Society Early Career Scientist Award.

Authors:

Chelsea Davis University of Delaware