SAMPE Journal - July/August 2012 - (Page 6)

Feature Article Development of New Lightweight Hybrid Sandwich Cores using FDM Technology S. Storck, J. Esteeves, and M. Zupan University of Maryland/Baltimore County, Baltimore, MD Abstract The high strength and low weight requirements of advanced land, air and sea vehicles are obtained by taking advantage of sandwich panel structures. The low density cores used are limited to feasible topologies by current manufacturing techniques. Fused deposition modeling combined with electroforming removes the manufacturing limitations and creates topologies with comparable mechanical properties to conventional cores. Tetrahedral, pyramidal and strut-reinforced tetrahedral (SRT) unit cell topologies will be optimized for specific strength. The response of fused deposition acrylonitrile butadiene styrene (ABS) plastic cores will be presented. In addition, scaling experiments such as 3D scaling and slenderness ratio scaling will be conducted on a unit cell analysis. Introduction With the demand for faster and more economical vehicles comes the need for more weight efficient materials. Sandwich panels are commonly used in advanced vehicle systems such as aerospace vehicles for weight critical applications. Sandwich panels provide superior strength and stiffness per unit weight, making them ideal structures for engineering applications. However, current core topologies are limited in geometry due to manufacturing techniques. Deformation processes generate two-dimensional periodic arrays such as pyramidal cores, while pinning can be used to produce cores with symmetrical or asymmetrical geometries. Many people have suggested more weight efficient core topologies that would be difficult if not impossible to manufacture using traditional manufacturing techniques1,2,3. With the development of new rapid prototyping techniques, core topologies can be manufactured beyond current limitations. For example, fused deposition modeling can be used to generate cores independent of geometric restrictions and allows optimal topologies to be created quickly and cost effectively4. Although the work by Markkula et al.4 has shown optimum unit cell core topologies can be produced with FDM technologies, arrays have yet to be explored. In order to expand this developing technology further the single unit cell must be expanded into periodic array form. Previous works have proposed the ideal core geometries for optimization4. Yet they have not explored the issue of scaling, vertical dimensions and relative density. For example, if the design of interest has space constraints then the core height must be limited. This can be easily accommodated by changing the scale of the FDM model within the software. If it is scaled 50% prior to production the slen- Figure 1. Plot showing idealized column response as a function of slenderness ratio. The point of highest efficiency is reached at the critical slenderness ratio value, on the onset of buckling. 6 SAMPE Journal, Volume 48, No. 4, July/August 2012

Table of Contents for the Digital Edition of SAMPE Journal - July/August 2012

SAMPE Journal - July/August 2012
Table of Contents
President’s Message
Technical Director’s Corner
Development of New Lightweight Hybrid Sandwich Cores using FDM Technology
Corporate Partners
Europe News & Views
SAMPE Europe’s SETEC 2012, Lucerne
SAMPE Journal Editorial Calender
Welcome SAMPE’s Newest Members
Materials & Products
Perspectives–The Art of a Well-Crafted BHAG
Out-of-Autoclave Sandwich Structure: Processing Study
SAMPE LinkedIn Communities
SAMPE Proceedings
SAMPE 2013|Long Beach Call for Papers
SAMPE Tech 2012|Charleston, SC
Industry News
Composite Payload Fairing Structural Architecture Assessment and Selection
SAMPE 2012|Baltimore-A Review
SAMPE 2012|Baltimore Photo Gallery
The SAMPE Foundation
Advertiser’s Index
Resource Center
SAMPE Membership Application
SAMPE Books & CD’s Order Form
Industry Events Calendar
Chapter Meetings Dates and Contacts

SAMPE Journal - July/August 2012