报告内容摘要

Continuous material grading is one of the untapped tools for the design of better performing parts. Evolution, in its time-worn wisdom, grades practically all functional biologic parts. This allows, for example, a soft bodied squid to manipulate a hard beak. In number biological parts with uniform properties are the exceptions rather than the norm, a norm in which material grading provides optimal functionality to parts from teeth and bone to bamboo stalks. Practically every part could be improved if one could leverage the advantages obtained from grading. If one could do this, it would develop a new paradigm in design and manufacturing, a change that would require better understanding of processing, but that would also provide substantially better (lighter, stronger, simpler, etc.) parts.

True functional grading is a domain of engineering that requires merging of our knowledge in materials, characterization, modeling, simulation, optimization and processing. Yet, solutions for functional grading are inherently material system specific. Using interpenetrating polymer networks (IPNs) is one way to vary, by orders of magnitude, properties in the same material system. This provides a method to make variations at the molecular level so as to potentially achieve the finest grading possible. We consider a prototype IPN system and consider the possible benefits from optimization of its variation and also study possible ways to achieve the desired grading by printing. As will be shown, the benefits of grading are substantial and the possibility of producing such parts is tangible.

报告人简介

Mehrdad Negahban is a Professor of Mechanical & Materials Engineering at the University of Nebraska-Lincoln specializing in the characterization and modeling of large deformation thermodynamic response of materials and their numerical simulation. He graduated with a B.S. in Mechanical Engineering from Iowa State University of Science and Technology, and an M.S. and Ph.D. in Applied Mechanics from the University of Michigan. His research has focused on continuum mechanics and thermodynamics of solids, constitutive theory, characterization and modeling of glassy polymers and crystallizing polymers, finite deformation plasticity, numerical simulation at large deformations, finite elements for generalized shells, dynamic loading of materials and stereo-optical measurements of strains. His work combines theoretical, experimental, and computational methods. A new applied area of work is in 3D printing and the possibility of printing material properties on a molecular scale.  (mnegahban@unl.edu)
New Book: The Mechanical and Thermodynamical Theory of Plasticity, Mehrdad Negahban, 2012, CRC Press, Taylor & Francis Group

Mechanical & Materials Engineering
University of Nebraska-Lincoln, Lincoln, NE 68588-0526, USA.
 
 
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