The Ohio State University

High strain rate deformation behavior of soft cellular materials
Spandan Maiti, Assistant Professor
Department of Mechanical Engineering-Engineering Mechanics, Michigan Technological University, Houghton, Michigan, USA 49931
Contact Email: spandan@mtu.edu

Abstract:

Owing to their light weight and high specific energy absorption properties, soft cellular materials are finding increasing use in automobile and aerospace industry, as well as in electronic packaging applications. These materials are characterized by their cellular microstructure, low stiffness and high flexibility. However, when subjected to high strain rate loading, heterogeneous localized deformation zones appear throughout the specimens that influence their energy absorption capability significantly. The localized deformation zones can result in progressive or uniform collapse during impact loading depending on microstructural and material properties of soft cellular specimens. A complex interplay among microinertia, microbuckling and microbending of the cell walls of these materials plays an important role in determining the ultimate deformation localization and collapse behavior, and ensuing energy absorption capability. An experimental evaluation of the dependency of the deformation behavior on these parameters may not be feasible due to extremely fast and complex wave propagation events occurring within the cellular specimen thus necessitating predictive computational models.
We have developed a computational framework that can examine the contribution of each of these effects on the deformation history of this class of materials. Our modeling effort relies on Voronoi tessellation based microstructure generation, and a corotational description of the large configurational change of cell walls typical to deforming elastomeric foams. Statistical features of the cellular microstructure have been incorporated into the model. An explicit finite element framework has been developed to simulate dynamic response of the specimen. An in-depth parametric study with various loading, microstructural and material parameters has been performed through this computational model. Microstructural deformation mechanisms operative under the influence of these parameters will be discussed in the presentation in detail. A simple micromechanical analytical model to delineate the effect of microinertia on the crushing strength of foams will also be presented. Finally, we will discuss the findings of some recent studies on functionally graded foams possessing controllable energy absorption capabilities. These research efforts will be useful in characterizing and designing high performance soft cellular materials in a dynamic loading regime.

Biography

Spandan Maiti obtained his Ph.D. in Aerospace Engineering at the University of Illinois at Urbana Champaign in 2002. He was a post doctoral fellow at the Beckman Institute in the University of Illinois before joining as an Assistant Professor in the Department of Mechanical Engineering-Engineering Mechanics at the Michigan Technological University in 2005.
His research interests lie at the interface of computational mechanics and computational materials science, and broadly encompass deformation and failure behavior of complex materials. He is specifically interested in dynamic failure and fragmentation of quasi-brittle materials, fatigue failure of metals and composites, computational design of biomimetic materials, deformation and failure response of soft materials, and multiscale modeling of heterogeneous materials. He has (co-) authored fifteen journal papers, six conference papers and one book chapter.