Stress-Strain Relationships and Behavior

Thursday, March 16, 2017

11a.m. - 12p.m.

325 Norris Hall

Dr. Bilel Aidi
Department of Biomedical Engineering and Mechanics
Virginia Polytechnic Institute and State University


In this lecture, we will explore the three dimensional stress-strain relationship for linear elastic deformation in isotropic materials, analyzing the interdependence of stresses or strains imposed in one or more directions. We will first consider one dimensional stress-strain behavior and some corresponding simple physical models for elastic deformation. The discussion will be extended to three dimensions in materials with isotropic behavior where all elastic properties are the same in all directions. Then, we will extend the analysis of elastic behavior to anisotropic materials including fiber reinforced polymer composite sheets. We fill first consider the general anisotropic case and then we will present the Hooke’s law for two special anisotropic cases (orthotropic and transversely isotropic cases). In addition, a simple estimation of elastic modulus in unidirectional long fiber composites will be presented. Finally, a presentation of actual laboratory data and curves of different kinds of materials (composites, metals, and polymers) under loading, emphasizing the stress-strain relationships, will be quickly shown and analyzed.


Dr. Aidi is a Postdoctoral Researcher in the department of Biomedical Engineering and Mechanics at Virginia Tech. He is currently working on a multi-organization, multidisciplinary project entitled Tailorable Feedstock and Forming (TFF) funded by the Defense Advanced Research Projects Agency (DARPA). Prior to this appointment, he was an instructor of mechanical behavior of materials laboratory from Fall 2014 to Spring 2016. He earned his PhD in Engineering Mechanics from Virginia Tech in August 2016 and a master of science in Mechanical Engineering from National School of Engineering of Sfax (Tunisia). He recently received an award from the same department for his exemplary portfolio of publications and presentations at various national and international conferences as well as his mentoring of undergraduate students through lecture and laboratory courses. He was also selected as the best teaching assistant late 2014 based on the students feedback.