Mechanics of Carbon Nanomaterials, Laminated Shells and Curing of Laminates

Wednesday, February 1, 2017

2:30pm - 3:45pm


115 Goodwin Hall

Mr. Priyal Shah, PhD Candidate
Biomedical Engineering and Mechanics
Virginia Tech

Abstract

The analysis of three problems of mechanics described below will be discussed.

The effective utilization of carbon nanotubes and graphene sheets as reinforcements in nanocomposites requires their strong interfacial binding with the surrounding matrix. One way to enhance this binding is their functionalization with covalent functional groups. However, this damages their pristine structures that may degrade their mechanical properties. By using molecular mechanics simulations we analyze the effect of covalent functionalization on elastic moduli of nanotubes and graphene sheets. This study will help material scientists interested in designing graphene based nanocomposites.

A shell theory that gives results close to the solution of the corresponding 3-D problem depends upon the problem being studied, i.e., the shell geometry, applied loads, and initial and boundary conditions. Here, by using a third order shear and normal deformable theory and the finite element method (FEM), we delineate for a doubly curved shell subjected to generalized tractions and different boundary conditions, stress singularities at points where interfaces meet the edges, and effects of geometric parameters on in-plane and transverse stretching and bending deformations. These results will help one decide which shell theory to employ for the problem being studied.   

A common technique to fabricate composite laminates is curing of prepregs, i.e., resin pre-impregnated fiber layers, in an autoclave under prescribed temperature and pressure cycles. A challenge is to reduce residual stresses developed during this process. Results for the optimization of the cure process parameters using the FEM and a genetic algorithm in conjunction with the Latin hypercube sampling method will be presented. The optimal cycles provide uniform and complete curing of laminates in the minimum time and simultaneously minimize the residual stresses. This will help manufacturing engineers find optimal cure cycle parameters for fabricating laminates of desired quality.

BIO

Priyal Shah is a Ph.D. candidate working with Professor Romesh Batra in the department of Biomedical Engineering and Mechanics at Virginia Tech. His research involves computational analysis of problems related to nanomechanics and structural mechanics. Prior to joining Virginia Tech, he earned his Master’s degree in Mechanical Systems Design from Indian Institute of Technology, Kharagpur, India and worked  with General Electric Aviation for two years.  Priyal’s research has thus far contributed to the scientific community in terms of 10 papers published in peer reviewed international journals, book and conference proceedings. He has received several awards for his academic and scholarly accomplishments at Virginia Tech including Terry and Bonnie Alfriend Graduate Fellowship and Manuel Stein Scholarship from the BEAM department, Torgersen award, Peebles award from the Adhesion Society, and two research travel awards